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Rajendra Soti, ,
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003902

Abstract:
Mass plywood panel (MPP) is a veneer-based engineered wood product that recently was introduced in the mass-timber construction industry. Preliminary studies show that MPPs can be a preferred construction material for shear walls, floor diaphragms, and roof assemblies. However, no design guide exists regarding the use of MPPs as structural elements. This is compounded by a lack of engineering properties and parameters needed beyond the generic values provided in the product report. To assess the engineering properties and provide a benchmark dataset, a comprehensive experimental testing program characterized the performance of MPPs in flexure, in-plane shear (parallel to major strength direction), compression, and tension. Additionally, the characteristic values of MPPs were derived based on the test results to provide an initial indication of design values of MPPs. The test results presented in this study provide a fundamental basis for the development of a design guide for MPPs.
, , , Jie Chen, Jing Xie, Songtao Lv, Guoping Qian, Hongfu Liu
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003900

Abstract:
An asphalt mixture is always in a complex stress state during the service life of pavement. Its resistance can be objectively characterized only by applying the strength theory to establish the failure criterion model in a three-dimensional stress state. Therefore, based on the double confining pressure triaxial test method, the failure characteristic test in complex stress state was carried out on AC-13 and AC-20 asphalt mixtures widely used in asphalt pavement in China. Meanwhile, according to the generalized octahedral theory, the experimental data of the failure characteristic point, and the strength characteristics of the asphalt mixture itself, the applicability of classical failure criteria, including Bresler-Pister, Ottosen, Willam-Warnke, Kotsovos, Podgorski, amended Zhao-Song, and twin-shear failure criteria was analyzed. In the aforementioned failure criteria models, the amended Zhao-Song failure criterion considered the difference in tension and compression of materials, the effect of hydrostatic stress, and the correlation of stress states of strength, which was consistent with the test results. Therefore, this model can be used as the resistance calculation model of asphalt mixtures in a complex stress state.
Mehdi Moazami Goodarzi, ,
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003875

Abstract:
There is a general trend toward improving the terminal blend process of producing rubberized asphalt mixtures. Recently, the addition of nanosized materials to strengthen the performance-related properties of terminal blend rubberized asphalt (TBRA) has gained popularity. In this study, the TBRAs were prepared using 8% and 15% crumb rubber and then modified using 2% and 4% of an organophilic nanoclay. The structures of the TBRA nanocomposite were evaluated by X-ray diffraction and scanning electron microscopy. Conventional physical properties, storage stability, rheological properties, and aging resistance were also assessed. Furthermore, the Glover-Rowe (G-R) cracking parameter for each asphalt binder was determined from the rheological properties. Finally, the semicircular bending test was implemented to determine J-integral (JC) and flexibility index (FI) parameters and characterize the cracking resistance of TBRA and TBRA nanocomposite mixtures. The results indicate that the use of the TBRA and its modification by nanoclay leads to an increase in asphalt mixture cracking resistance during the initiation cracking phase but increases the asphalt mixture’s brittleness during the crack propagation phase. There was a significant correlation between the G-R parameter for the asphalt binders and the FI parameters of the respective TBRA mixtures. Moreover, it was observed that TBRA modification by an organophilic nanoclay decreased the temperature susceptibility and phase separation, increased the viscosity, penetration, softening point, aging resistance, and elasticity, and improved high-temperature performance.
Juan Manuel Girao Sotomayor, , Michéle Dal Toé Casagrande
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003878

Abstract:
To investigate techniques that focus on mining waste applied to geotechnical works, the mechanical behavior of mining waste reinforced with polymeric fibers has been studied. The present research seeks to evaluate the effects of fiber insertion in gold ore tailings using a direct shear test evaluating the peak and residual behavior. For this purpose, several conventional direct shear tests and shear planes with a polished surface in flooded conditions were conducted. To collaborate with the analysis, chemical, mineralogical, and geotechnical characterization tests were carried out, in addition to fiber tensile testing and scanning electron microscopy (SEM) in the composite. The results showed a bilinear behavior on shear strength envelopes in pure tailing, which is changed to linear behavior with the addition of fibers. For high and low stresses, an increase in the friction angle at a reinforced composite was observed. The residual behavior is suggested by the results of the shear plane test with a polished surface, in which there was also an increase in the friction angle. The volumetric behavior showed that there was a change in the pure material from being contractive to dilating when reinforced. With these results, it is possible to recommend the use of this type of reinforcement in interface areas with materials that have different stiffness—due to its adaptability to strains—or as a maintenance measure in areas affected by landslides, providing better strength characteristics to the affected area.
, , , , Beatriz Marques, Arlindo Marques, , Faustino Patiño-Barbeito
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003891

Abstract:
This paper presents the characterization of new lightweight cement composites incorporating limestone dust and charcoal. The charcoal is used not only to make the composite lighter in weight but also to improve its hygrothermal performance. Additionally, limestone dust, a waste material, is used instead of sand in the mixtures to improve their sustainability. Results show that the limestone-charcoal-cement composites have low thermal conductivity, while retaining good mechanical strength, high water vapor permeability, and low flammability. It was also found that these composites do not release dangerous substances in concentrations that jeopardize the safety of the environment or human health. Overall, the results suggest that the new limestone-charcoal-cement composites can be applied as lightweight screeds and other construction solutions, such as mortars or plasters that do not require high mechanical strength.
Xinsheng Li, Jing Li, Lili Wang, Junan Shen, Zhen Dai, Zhaoxing Xie
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003829

Abstract:
The purpose of this paper is to study the microleveled rejuvenating effects of different rejuvenating agents on aged asphalt binders. In this study, an original asphalt binder (Shuanglong) with a grade of Pen70 was aged through an accelerated aging process specified by a strategic highway research program (SHRP). Two types of rejuvenating agents (one virgin asphalt binder and another petroleum product named HNCCY-1) were used to rejuvenate the aged asphalt binder at different concentrations. An atomic force microscopy (AFM) was used to study the microleveled properties of the rejuvenated aged asphalt binders, whereas the dynamic shear rheometer (DSR) was for rheological properties. The results showed that: (1) the number of bee structures increased, but their size decreased in the topographies of height or adhesion of the rejuvenated asphalt binders as the concentration of both the rejuvenating agents increased; (2) the roughness indexes gradually decreased and approached those of the original asphalt binder; (3) the diameter and threshold height decreased; and (4) the Young’s modulus and reduced modulus became smaller.
, Oluwatosin Abiodun Balogun, Abayomi Adewale Akinwande, Olanrewaju Seun Adesina, Oladele Samson Bello
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003903

Abstract:
The mechanical and thermal properties of clay bricks are important parameters that influence the durability and energy consumption of building bricks in service. This study investigates the influence of waste glass when combined with coconut shells on the properties of burnt bricks. Particulate coconut shell (PCS) of −75 μm was added to Orita-Obele clay at a varied proportion of clay (0%–2%), while waste glass (−75 μm) was utilized at a constant proportion (25% by weight of clay). The physical, mechanical, and thermal properties of the samples were evaluated as well as efflorescence. The surface morphology of each weight fraction was examined under a scanning electron microscope. From the results obtained, the samples evaluated exhibited reduced porosity, water absorption, initial rate of suction, efflorescence, and wear characteristics. Moreover, the linear shrinkage, bulk density, compressive strength, modulus of rupture, hardness, and thermal conductivity were observed to increase with the addition of waste glass and particulate coconut shell. All samples produced satisfied the minimum strength requirement for masonry application. Hence, PCS and waste glass can be combined in the production of fired masonry bricks.
Andres Lotero, , Cindy Johanna Moncaleano, Aziz Tebechrani Neto,
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003918

Abstract:
The present research aims to evaluate the potential of combining two wastes, finely ground waste glass (GWG) and carbide lime (CL), together with a sodium hydroxide solution (SHS) to form a new material which, when compacted, can develop cementitious properties over time. Such blends have potential application in the construction of stabilized rammed walls, as well as in earthworks such as beds of pipelines, spread footings, fill materials, and generally, as a new material for replacement of geomaterials of inadequate specifications in localized geotechnical works. Blends compacted exclusively with water were also produced in order to understand and differentiate, in a comparative manner, the effects of the addition of SHS on the mechanical, mineralogical, and microstructural properties resulting from alkaline reactions. The effects of the CL content, degree of compaction, and inclusion of a SHS on the evolution of strength and stiffness at 7 and 28 days under controlled curing conditions (23°C±2°C and 95% relative humidity) were determined. An original parameter, called the porosity/lime index (η/Liv), was used to normalize the behavior of unconfined compressive strength (qu) and shear modulus in small strains (G0) of the blends. The results have shown that the GWG-CL blends (compacted with water and SHS) developed an evolution of the mechanical properties over time with increasing CL content and degree of compaction. This results from the reaction between the dissolved aluminosilicates present in the GWG and the calcium (Ca2+) in CL, as a product of the pozzolanic and geopolymerization reactions in a high-alkalinity medium by the addition of CL and SHS, respectively. The formation of stable compounds, hydrated calcium silicate (C─ S─ H) type, analogous to those produced in the hydration processes of portland cement after 28 days of curing in alkali-activated blends with SHS, has been verified. Additionally, correlation equations were established between the mechanical response of the blends and the η/Liv index, as a function of the curing time and the type of activating solution, which can be considered as dosage curves for the prediction of a required mechanical response.
Amal Abdelaziz, Eyad Masad, Amy Epps Martin, Edith Arámbula Mercado, Akash Bajaj
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003910

Abstract:
The use of high amounts of reclaimed asphalt pavement (RAP) in asphalt pavements has many economic and environmental benefits; however, there are concerns about brittleness and potential cracking of asphalt mixtures. One of the solutions to address this concern is through the inclusion of recycling agents (rejuvenators). The purpose of this study was to explore the effect of different types of recycling agents (biooils, vegetable oils, tall oil, aromatic extract, and paraffinic oil) on the rheological, microstructural, nanomechanical, and chemical properties of asphalt binder blends with high RAP content. Rheological properties were assessed using a dynamic shear rheometer. Atomic force microscopy was used to determine the microstructural characteristics and nanomechanical properties of the asphalt binder blends. A wavelet packet transform approach was proposed to quantify surface roughness characteristics. Fourier transform infrared spectroscopy was used to evaluate the chemical properties based on carbonyl and sulfoxide indices. Results indicated a correlation between the phases observed in the microstructure and rheological performance. Biooil recycling agents were the most effective in improving the microscopic distribution and rheological properties of binder blends, followed by vegetable oils. However, chemical analysis suggested that the addition of recycling agents did not reverse oxidative aging. Finally, the study recommended a rejuvenation index (RI) that quantified the effectiveness of recycling agents in improving blending and reducing stiffness and aging susceptibility. The RI signified that tall oil was the most susceptible to aging, followed by aromatic extract and paraffinic oil, whereas biooils and vegetable oils were the least susceptible to aging.
Yinfei Du, Pusheng Liu, Xiankai Quan, Cong Ma, Jun Tian, Xiaowei Wu
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003879

Abstract:
This study prepared a cement-based composite phase change material (CCPCM) that can be used as a filler for asphalt mixtures. A series of experiments were carried out to investigate the characteristics of CCPCM and its influence on the performance of asphalt mastic. In the matter of morphology, composition, particle size, and specific surface area, it is found that CCPCM particles were significantly different with limestone mineral filler that is usually used in asphalt mixtures. The thermal gravimetric result indicates that CCPCM could retain its original property in the process of hot mixing of asphalt mastic. In the light of the differential scanning calorimeter test, CCPCM and CCPCM-asphalt mastic had melting enthalpy as high as 37.47 and 18.75 J/g, respectively. Indoor irradiation test results reveal that CCPCM is a promising material for cooling asphalt pavement. The multiple stress creep recovery test results verify that CCPCM could improve the rutting resistance of asphalt mastic. Furthermore, CCPCM could extend the fatigue life of asphalt mastic, according to the linear amplitude sweep test results. The preceding findings show that CCPCM cannot only play the role of heat storage but also improve the rutting and fatigue properties of asphalt mastic.
, Robert Rea, Gerald Reinke, Afshar Yousefi, Davoud F. Haghshenas,
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003921

Abstract:
This study examined the effect of five chemically different recycling agents on the long-term performance and moisture sensitivity of modified aged asphalt binder. A control base binder was made from 35% virgin binder and 65% binder exposed to extended laboratory aging. Samples of this control base binder were modified by a recycling agent in one of five categories: paraffinic oil, aromatic extracts, naphthenic oil, triglycerides/fatty acids, and tall oil. Then these modified binders and the control base binder were evaluated under each of four different conditions: no aging, standard aging, extended aging, and severe aging. The resistance to cracking at low and mid-range temperatures was determined using a bending beam rheometer and a dynamic shear rheometer. In addition, the Wilhelmy plate test was performed on the unaged binders to estimate the binders’ resistance to moisture damage. The results indicated that the samples modified with recycling agents that contain carbonyl, hydroxyl, and sulfonyl groups did not comply with the low-temperature cracking criterion (m-value) after the extended aging process. Samples modified with recycling agents containing paraffinic and naphthenic oils, which have a high saturate content, showed the weakest long-term performance, while the performance of the aromatic extract recycling agent was superior, even after the extended aging process. The Wilhelmy plate test showed that recycling agents based on triglycerides/fatty acids or tall oil decreased both the cohesive and adhesive strengths of the samples more than other recycling agents, which might be related to the presence of a hydroxyl group in their structures.
, A. K. H. Kwan
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003906

Abstract:
Hybrid use of macro and micro steel fibers offers greater potential for enhanced performance of hybrid fiber-reinforced concrete (HFRC). However, predicting the properties of HFRC has been hindered by inadequate research on a suitable hybrid fiber factor, leading to lots of trial and error in the mix design. To fill such a research gap, an experimental program was launched by producing a total of 18 plain and HFRC mixes using macro and micro steel fibers at a constant total fiber volume of 2.0%. Then, the influences of various hybrid fiber combinations on the fresh and hardened properties of HFRC were investigated and correlated by regression analysis to some suggested hybrid fiber factors to identify the key factor governing each performance attribute. It was found that the hybrid use of macro and micro steel fibers at a constant total fiber volume yielded higher workability and strength, and the traditional fiber factor was not applicable to HFRC. Moreover, in the hybrid fiber factors, the fiber number was more fundamental than the fiber volume. Lastly, design equations for predicting the various performance attributes were derived for HFRC with discussions on the associated mechanism.
, Peng Liu
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003853

Abstract:
To develop high-performance microfine cementitious grout (HPMCG), the matrix [microfine Portland cement clinker (MPCC) + flue gas desulfurizing gypsum (MFGDG) + calcium carbonate (MCC)], microfine fly ash (MFA), silica fume (SF), and blast-furnace slag (MBFS) were selected. The viscoelasticity, fresh-state properties, mechanical performance, antipermeability, hydration mineral, and microstructure were investigated systematically. The 0%–3.0% naphthalene-based superplasticizer (N) and 1.0%–2.6% composite activator (CA) were applied, and the ratio of the water to binder (w/b) was selected as 0.8–3.0 by weight. The optimum component of HPMCG was acquired as the amount of MFA was 40% relative to that of the matrix, and the additional contents of SF and MBFS were 10% and 30%. The amounts of N and CA were suggested as 1.5%–2.0% and 2.4%, respectively. After optimization, the maximal flexural strength (FS) and unconfined compressive strength (UCS) of the HPMCG (91-day) can achieve 7.29 and 31.65 MPa; nearly all of the calcium hydroxide reacted, and more gels were generated. More generated gels interconnected with each other to form dense network structures, there were few microvoids and pores, and the entirety of the microstructure was enhanced obviously. The optimized HPMCG surpassed the expectation. The optimized HPMCG has superiorities, such as excellent viscoelasticity, good fluidity, high stability or stone rate, high mechanical strength, good antipermeability, an advantageous mineral component, and a microstructure. In civil engineering, they can satisfy high standard demands of construction and repair grouting practices.
, S. D. Suryawanshi, V. A. Khapne, M. S. Ranadive
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003872

Abstract:
Moisture damage occurs due to loss of cohesion and/or adhesion, which results in loss of stiffness and strength. Currently, the surface free energy (SFE) approach is used to calculate mixture performance in terms of various SFE parameters to assess moisture susceptibility of various newly developed binders. In the present study, the concept of SFE is used to evaluate the moisture-induced damage potential of newly modified bitumen using high-density polyethylene (HDPE) pyro-oil. For this purpose, parameters of SFE considered are work of adhesion, work of cohesion, wettability, and energy ratio (ER). HDPE pyro-oil was obtained from pyrolysis process at 750°C. For determination of surface tension properties of base and modified bitumen, this study used glycerol, formamide, and distilled water as probe liquid, and a sessile drop method was adopted to measure the static contact angle. The aggregates considered in this study were basalt, gravel, and limestone. Dispersive and polar components of aggregates were directly taken from the literature. In contrast, for base bitumen (VG30) and pyro-oil–modified bitumen (POMB), these components were determined using van Oss–Chaudhury–Good theory. Along with this, the variation in contact angle, SFE components and surface tension parameter of base and modified bitumen were studied for different time of ageing (0, 45, 85, and 150 min) using rolling thin film oven (RTFO) as per guidelines of Superpave. The investigation concludes that, for the parameters under study, the analysis of data does not show any regular pattern. Work of adhesion decreases whereas work of cohesion increases with ageing resulting in increased moisture susceptibility for pyro-oil–modified bitumen. Further, the results showed that pyro-oil was effective in enhancing the surface tension parameter as compared to the base binder for different ageing conditions. Based on the results of energy ratio, it is concluded that a combination of the binder with basalt gives higher resistance to moisture damage than limestone and gravel.
Yifan Min, Jun Wu, Bo Li, Jinjin Zhang
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003887

Abstract:
The objective of this study was to evaluate the effects of fly ash content on the strength development of soft clay stabilized by one-part geopolymer (OPG) under K0 stress conditions. In this study, a novel curing stress system under K0 conditions was developed to investigate the strength development of OPG-stabilized soil when subjected to different stresses at various depths. Several combinations of fly ash (FA) and ground granulated blast furnace slag (GGBFS) as aluminosilicate precursors triggered by solid NaOH (NH) with certain amounts of water were prepared as OPG binders. The OPG-stabilized soil samples were cured under vertical stresses of 0, 50, 100, and 200 kPa for 1, 3, 7, and 14 days. During curing, the skeleton improvement of OPG-stabilized soil was recorded by a tactile pressure sensor, and the strength development of samples under different curing stresses and curing times was evaluated by the unconfined compressive strength (UCS) and shear wave velocity (VS). Additionally, scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS) and X-ray computed tomography (CT) were also used to illustrate the role and contribution of factors on the hydrate composition and microstructure, especially the role of the porosity. The results indicated that the strength of the sample increased substantially with a reduction in porosity due to the curing stress. Furthermore, the optimum content of FA (FA/GGBFS=0.1) could improve the workability and microstructure of OPG-stabilized soil samples, as reflected by the increase in the UCS and VS. Finally, the UCS prediction of OPG-stabilized soft clay under curing stress is proposed based on the shear wave velocity.
Miras Mamirov, , Yong-Rak Kim
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003890

Abstract:
The effective reduction of cement content in pavement concrete without compromising its fresh, mechanical, and durability properties can lead to more economical and sustainable pavement engineering. Because a reduction in cement content in concrete can be achieved by improving the particle packing of aggregates, this study attempted to improve a practical mix design procedure based on both theoretical and experimental particle packing methods. In this study, optimum aggregate blends were first identified using the Modified Toufar Model, which indicated good correlation with the experimental packing results based on a combined void content test. The Modified Box Test was then used to evaluate the fresh concrete performance and to justify the effectiveness of cement reduction. The results indicated that cement content could be reduced by up to 56 kg/m3 from the reference mix with the optimum aggregate gradation. The results from hardened concrete tests, such as compressive strength, flexural strength, and resistivity, confirmed that concrete properties were not compromised by the reduced cement content. Freeze-thaw resistance was improved with up to an 11% increase in the relative dynamic modulus at 300 freeze-thaw cycles. The optimum mixes also demonstrated reduced shrinkages, with a 12%–20% reduced strain at 180 days of free shrinkage and a delayed cracking age based on the restrained shrinkage test. Based on the laboratory test results, an improved mixture design procedure aided by the particle packing degree and the minimum excess paste-to-aggregates volume ratio is presented.
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003897

Abstract:
This study examines the systematic decrease of concrete compressive strength with rubber scrap from the hydration reaction point of view. The work was focused on the determination of the hydration rate equation of normal, catalyzed, and rubberized Portland cement pastes. The basic idea was to prove the inhibiting effect of zinc compounds from rubber on the hydration kinetics of Portland cement. From the Jander rate equation, the data strongly suggested that the hydration kinetics of the rubberized cement composites could be improved if an accelerator were incorporated. Once the hydration reactions were improved by means of the catalyst, the mechanical properties of Portland cement/rubber scrap composites were improved. From the composite models for Young’s modulus, the Maxwell dispersed phase model was used to relate the compressive strength of rubberized cement in terms of rubber content. After 28 days, the control cement reaches a compressive strength of 52 MPa; meanwhile, the catalyzed composite incorporating 10% by weight rubber scrap and 2.5% by weight of silica fume withstands a compressive strength of 61 MPa. Without a catalyst, the same material tolerates just 40 MPa.
Shubham A. Kalore, G. L. Sivakumar Babu, Ratnakar R. Mahajan
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003917

Abstract:
Pavement materials are prone to damage due to mechanical loadings and rainfall infiltration. The rainfall initiates moisture movement within the layers and accelerates the damaging rate. A better understanding of the moisture flow and damage can be achieved by rigorous and efficient modeling. The hydraulic conductivity function (HCF) is one of the essential soil properties for numerical seepage modeling. Due to the difficulty in direct HCF measurements, it is generally predicted empirically or statistically by integration along the soil-water retention curve (SWRC) based on the fundamentals of fluid flow in porous media. This paper presents an analytical approach to predict the HCF from experimentally obtained data of an SWRC for noncohesive soils. The model is derived based on the Hagen-Poiseuille law and Darcy law and considered the pore size distribution, porosity, and geometry of the soil grains as inputs. The pore size distribution is considered analogous to a normalized SWRC based on the fundamentals of the capillary theory. The proposed model is validated based on a large number of published experimental data of SWRC and HCF, illustrating the robustness of the model. Additionally, the application of the model is presented for the pavement drainage design.
Federico C. Ayala, Peter E. Sebaaly, Adam J. Hand, Elie Y. Hajj, Gaylon Baumgardner
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003821

Abstract:
Cold in-place recycling (CIR) of asphalt pavements is a process that has successfully been used for many years. The use of CIR for rehabilitation offers many advantages over reconstruction. When looked at closely its sustainability aspects are particularly positive. Regardless of good performance and positive sustainability, however, the performance characteristics of CIR have not been developed. Here, CIR mixtures were designed with different emulsion types and lime slurry levels. The mixtures were then subjected to dynamic modulus, repeated load triaxial, and flexural beam fatigue testing over a range of temperature and loading conditions. The performance test data generated were then used to generate CIR rutting and fatigue performance models developed for use in the Nevada Department of Transportation’s Pavement ME software. In addition, the reflective cracking characteristics of the CIR mixtures were evaluated in terms cycles to failure, crack initiation, and crack propagation.
Hussein Al-Dakheeli, Rifat Bulut, G. Scott Garland, Christopher R. Clarke
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003880

Abstract:
This paper presents experimental results and analysis of sulfate-bearing soils treated with ground granulated blast-furnace slag (GGBS). The experiments involve the unconfined compression strength test, shrinkage, free swelling, suction measurements, and microstructural examination. Short- and long-term swelling tests were conducted to inspect the durability of GGBS stabilization against the sulfate-induced heave. The concept of the shrinkage curve was employed to elucidate how GGBS stabilization alleviates soil shrinkage behavior and alters the pore size distribution. The results manifested that 7% GGBS was sufficiently adequate to improve the 28-day strength of the tested sulfate-bearing soils about five times. The GGBS treatment mainly results in the decline of calcium sulfate content and the formation of calcium silicate hydrate, ettringite, and calcite. The results of long-term swelling tests indicated a delayed sulfate-induced heave that started beyond a month from the time of exposing the treated soils to water. The delayed heave was still not significant as compared with that of the untreated control soil specimens. Accordingly, it is recommended that the treated sulfate-bearing soils are tested with the selected GGBS content for any delayed swelling before application in the field. The GGBS treatment has significantly escalated suction magnitude during curing mainly due to the consumption of water in the hydration process and the formation of ettringite.
Ahmed G. Bediwy, M. T. Bassuoni, Ehab F. El-Salakawy
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003922

Abstract:
In this study, the performance of basalt pellet–reinforced cementitious composites (BPRCC) was evaluated after exposure to harsh conditions. The exposure consisted of consecutive 300 freeze–thaw cycles followed by 75 wet–dry cycles simulating successive winter and summer seasons. The mixtures, incorporated general-use cement, slag, and nanosilica, and reinforced with either the recently developed basalt fiber pellets (BP)—basalt fiber strands coated by a polymeric resin—or steel fibers. The resilience of composites was assessed by internal damage, residual compressive and flexural strengths, as well as their compatibility with base/parent concrete, when used in a layered system with normal concrete. The presence of BP at a dosage of 4.5% or 6.9% in the nanomodified cementitious composites effectively discounted the rate of deterioration, resulting in lower reductions in stiffness, compressive and flexural capacities, as well as toughness after the exposure to aggravated environmental conditions. Hence, such composite may present a promising option for construction of exposed infrastructural elements.
, Lotfi Guizani, Chandrasekhar Bhojaraju, Claudiane M. Ouellet-Plamondon
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003881

Abstract:
Improved autogenous healing capacity of concrete using superabsorbent polymers (SAPs) was used as an efficient approach for mitigating damage between steel rebar and self-consolidating concrete (SCC). The results for normal concrete (NC) and those for SCC mixtures were compared. Two SAPs with different particle sizes and chemical compositions were used in the experimental program. Results showed that despite the greater reduction effect of SAP with a smaller particle size on compressive strength, SCC containing this type of SAP had the highest bond strength in uncracked specimens, compared with SAP with larger particle sizes, for SAP-modified NC and SCC mixtures. Moreover, results showed that SCC and NC containing SAP had considerably greater healing improvement factors for large crack widths (w≥0.30 mm) compared with mixtures without polymers; almost 46%, 30%, and 24% healing improvement factors were obtained for average bond stress, bond strength, and residual bond stress of SAP-containing concrete mixtures, respectively. Furthermore, complete strength recovery (100% healing improvement factor) was obtained for SCC mixture with w=0.10 mm after a 28-day healing period.
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003901

Abstract:
Structures constructed on expansive soils experience higher upward pressure due to their swelling characteristics. Various conventional treatment methods developed to counteract swell–shrink characteristics of expansive soil are deemed time consuming and not feasible for use in pavement. Geotextiles (GTs) have been used as a filtration and separation medium; however, their effect on swell pressure and shear strength of expansive soil has not been well explored. This study aimed to address these issues by using GT to control swelling behavior, drain moisture content, and provide support at the soil interface. Swell pressure and shear strength were quantified by constant volume swell pressure and direct shear and unconfined compressive strength tests, respectively. The influence of single-layer, double-layer, and triple-layer GTs at varying depths was studied. The higher tensile strength of the GT layer restrained the swell pressure mobilized by resisting internal soil movements and facilitating in-plane drainage conditions. Additionally, soil–geotextile interfacial interactions were observed to contribute to improvement in shear strength. Comprehensive statistical analysis using one-way analysis of variance (ANOVA) was carried out on swell and strength properties. The present study ascertained the use of GT for the dual function (i.e., strength and swell control) of stabilizing expansive subgrades.
Ran Bir Singh, Bhupinder Singh
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003907

Abstract:
Effect of selected volumetric replacement (0%, 20%, 40%, and 60%) of cement with class-F fly ash in a binary binder and of three water-cementitious material ratios (0.40, 0.34, and 0.28) on rheology of self-compacting concrete (SCC) has been investigated using a coaxial concrete rheometer. The effects of the same parameters have also been studied on self-compacting recycled aggregate Concretes (SCRACs) made with 100% volumetric replacement of natural coarse aggregates with coarse recycled concrete aggregates. Data obtained from the flow-curve tests were used to calibrate selected rheological models, and it was noted that degree of shear-thinning in the SCCs and SCRACs was inversely proportional to fly ash dosage. Shear-thinning rheology transitioned to shear-thickening as the water-cementitious material ratio decreased from 0.40 to 0.28, and other mix characteristics remaining unchanged. Degree of shear thinning further decreased (in terms of increase in flow index of HB model and c/μ parameter of MB model) upon substitution of the natural coarse aggregates of SCCs with the coarse recycled aggregates in the SCRACs. Predictive efficacies of the selected rheological models are shown to be similar, and useful correlations between them have been proposed.
Lei Lyu, Yongkang Dong, Dongliang Zhao, Yong Wen, Rui Li, Xin Ren, Jianzhong Pei
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003904

Abstract:
Existing low-noise pavement has gradually lost its function with the development of urban road traffic. A poroelastic road surface (PERS), mainly composed of tire rubber granules, polyurethane, and aggregate, is considered to be the material with the most potential to construct future low-noise pavements. This study aims to optimize the material composition of PERS to improve the mechanical and acoustic properties further. The orthogonal experiments of three factors with three levels were designed to evaluate the effects of the composition design of PERS on rutting resistance, skid resistance, moisture resistance, and aging resistance. To ensure the acoustic properties, the selected initial composition was optimized through the tire free-drop test and transfer-function method. In this study, the Pearson correlation coefficient (r) was used to describe the correlations between the properties of PERS and material composition. It was concluded that skid and moisture resistance are largely influenced by polyurethane content. Meanwhile, the rubber content is significant for rutting resistance, aging resistance, and damping property. Acoustic experiments indicate that rubber particles show a significant effect on the sound absorption property. Results demonstrate that the optimal material composition of PERS is 5.5% polyurethane content, 10% rubber content, and 1.18 mm rubber particles, with a 60 mm thickness.
Prasanna Kumar Behera, , K. Mondal
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003912

Abstract:
Some of the steel bars used in reinforced concrete construction experience plastic strain due to various operations at construction sites. The present work concentrates on the corrosion behavior of such prestrained reinforced bars (rebars) embedded in chloride-contaminated cement mortar and exposed to laboratory conditions (temperature of 27°C±2°C and relative humidity of 60%) for 18 months. The corrosion behavior of these rebars was examined in terms of the electrochemical parameters [open circuit potential (OCP) and polarization resistance (RP)], effective volumetric expansion ratio, and the thickness of the rust at the metal–mortar interface. Cyclic change in the OCP and RP of the bars with time has been observed due to the formation of corrosion products at the interface. The preinduced plastic strains affected both the polarization resistance and the corrosion-induced mass loss of the rebar. The strained rebars showed higher corrosion susceptibility and corrosion amount than the unstrained rebars due to the changes in the surface condition and microstructure on account of high plastic deformation. The mass of the iron lost to form rust at the interface has been estimated using a novel volumetric expansion ratio model by taking the individual contribution of corrosion products at the interface. Correlation between the degree of straining and the corrosion-induced cracks at the end of 18 months of exposure has also been established.
, Dong-Min Wang, Hui Li
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003920

Abstract:
The effect of curing conditions (sealed and standard) on the mechanical properties of fly ash (FA) and ground-granulated blast-furnace slag (GGBFS)–based alkali-activated materials with NaOH and waterglass alkali activators are investigated in this study. The results show the highest 28-day compressive strength of samples was obtained in the A-3 samples and researched to 59.8 MPa under sealed curing conditions. Using scanning electron microscopy (SEM), it was found that samples with sealed curing condition have higher mechanical properties associating to the denser microstructure and low crack width. Under the sealed curing condition, lower carbonation degree of samples has higher content of Na+ to form the Si-O-Na bond resulting in the higher content of amorphous gel and geopolymerization degree based on the experiments results of electron paramagnetic resonance (EPR), Fourier transform infrared (FTIR) spectrometer, X-ray photoelectron spectroscopy (XPS), chemical bond water, and selective dissolution.
, Velaga Sarath Babu, Arunachalam Srinivasan
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003908

Abstract:
The use of recycled aggregate (RA) generated from construction and demolition (C&D) waste to produce new concrete would minimize the need for the use of natural aggregate (NA). The authors propose a new hybrid method in the present work by combining presoaking in mild acetic acid followed by mechanical grinding to produce high-quality RA. A total of six different types of treated recycled aggregates (TRAs) [i.e., TRA (0 min), TRA (3 min), TRA (5 min), TRA (7 min), TRA (10 min), and TRA (12 min)] were used to replace NA in an M40 grade control mix to study the influence of TRAs. In this study, various percentages (i.e., 0%, 25%, 50%, 75%, and 100%) of TRAs were used to replace NA in each concrete mix. Experiments were performed to investigate the workability, strength, and durability properties of concrete made with TRAs. Typically, at a 50% replacement level of NA with TRA (7 min), the compressive strength reduced by 7.58%, and the rapid chloride permeability test (RCPT) value increased by 23.74% compared with the control mix. A 50% replacement level of NA with TRA (7 min) is suggested for structural concrete. Based on the present study, 72 h of soaking in mild acetic acid, followed by 7 min of the rotation time, are recommended as an optimum treatment for producing high-quality TRA.
Dehui Wang, Qingnan Gong, Qiang Yuan, Surong Luo
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003894

Abstract:
Fiber-reinforced polymer (FRP)–reinforced seawater–sea sand concrete (SWSSC) is a new structure form for coastal infrastructure, especially for island construction. The degradation mechanism of FRP bars in SWSSC involves water molecules, hydroxide ions, chloride ions, high temperature, and stress. In general, water molecules and hydroxide and chloride ions react with some ingredients in FRP bars, destroy the interface between fiber and resin, and reduce the properties of FRP bars. In the environment of water molecules, hydroxide ions, and chloride ions, the strength retentions of FRP bars were 71%–77%, 26%–98%, and 49%–77%, respectively, depending on composition and manufacturing techniques of fiber. High temperature and stress accelerate the degradation of FRP bars. Under different temperatures and stress levels, the strength retentions of FRP bars were 0.6%–98% and 43%–93%, respectively, depending on the fiber type, temperature, and stress levels. The presence of chloride ions accelerates the hydration of cement and improves the properties of SWSSC at early age. However, the conclusions on the properties of SWSSC at later age are still controversial. Based on previous studies, some future needs on FRP-reinforced SWSSC are also recommended.
, Ziqi Wang, Zhanshuo Liang, Lei Xu
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003889

Abstract:
The objective of this paper is to to ascertain the reliable mechanical properties of cold-formed Q345 steel at elevated temperatures while considerting the effects of tensile strain rate and specimen width. This paper presents an experimental study on the mechanical properties of cold-formed Q345 steel at temperatures ranging from 20°C to 800°C tested with two specimen widths and three tensile–strain rates, namely 0.06/min, 0.6/min, and 1.2/min. Tensile specimens were fabricated from a steel plate with a nominal thickness of 2.5 mm and tensile tests were carried out to determine the stress–strain relationship, yield strength, tensile strength, and elastic modulus. The test results showed that the tensile–strain rate has a maximum influence of 9% on yield and tensile strength at 600°C and the specimen width has a maximum influence of 14% on yield and tensile strength at 400°C. The maximum influence of the tensile–strain rate and specimen width on the elastic modulus is 18% and 12% respectively at 500°C. The necking phenomenon is less noticeable at temperatures below 300°C but is clearly observed at temperatures above 300°C. The comparison of the test results with predictions obtained from design standards (EC3, AISC, and AS4100) indicates a good agreement on the yield and tensile strength, but the magnitudes of elastic modulus obtained from the test are considerably higher than those obtained from the design standards. Based on averaged values of the test results associated with different tensile–strain rates and specimen widths, predictive equations were proposed to determine the mechanical properties of cold-formed Q345 steel at elevated temperatures.
Hansong Wu, Aiqin Shen, Xiaolong Yang, Ziming He, Youhua Zhang
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003899

Abstract:
Photocatalytic pavements materials are being developed to purify toxic automobile exhaust gas, especially in tunnels where the pollution concentrations are high. This study investigated the photocatalytic efficiency and pavement performance of asphalt mixtures containing steel slag and different contents of CeO2 and TiO2 as photocatalyst materials. Photocatalytic testing equipment was developed to calculate the photodegradation efficiency for CO, CO2, NO, and HC. The pavement performance of the asphalt mixtures was evaluated using rutting tests and low-temperature bend tests. The texture depth was measured to evaluate the antislide performance. The excessive addition of the CeO2 and TiO2 nano photocatalysts had an adverse effect on the pavement performance of the steel slag asphalt mixture. The optimal contents of CeO2 and TiO2 were 7% and 0.6% by weight of the asphalt binder weight, respectively, as obtained by a gray target decision process based on principle component analysis. These findings are expected to contribute to the development of functional pavement materials that improve the surrounding air quality and have a lower environmental impact due to the use of waste slag.
, Zachary Grasley
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003827

Abstract:
The influence of sand particles, aging, and water–cement (w/c) ratio on the viscoelastic relaxation modulus of cement paste and mortars was measured at early ages (1–28 days). Furthermore, the relaxation modulus obtained approximating the strain state as constant or obtained considering the real strain history observed during testing were compared; significant error was encountered when a constant strain was assumed. In contrast, little error was introduced when aging during the relaxation experiments was neglected, which is likely due to the relatively short duration of the experiments and the nonconstant strain history that led to rapid stress decay. In contrast to conventional wisdom, lower w/c samples loaded at very early ages exhibited similar relaxation to higher w/c samples; however, at later ages, lower w/c materials exhibit lower relaxation rate. For samples loaded at later ages, the similarity between the shape of the relaxation curves for samples containing differing sand content and w/c suggests a method to simply quantify the effects by shifting the spring constants in a Kelvin–Voigt or Maxwell-type model.
, Wittakran Sudsaynate, , Avirut Chinkulkijniwat, , Jitwadee Horpibulsuk
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003751

Abstract:
Research on the usage of industrial by-products to improve mechanical properties of low-quality materials in infrastructure applications is of global interest. Two industrial by-products, namely, fly ash (FA) and asphalt emulsion (AE), were used in this research to develop an FA-AE stabilized marginal crushed rock (CR) as a sustainable pavement base material. A liquid alkaline activator was used, comprised of a mixture of sodium hydroxide (NaOH) and sodium silicate hydrate (Na2SiO3) at Na2SiO3:NaOH=50∶50 and NaOH concentration = 5 M. In this research study, the mechanical properties of FA-AE stabilized CR were investigated via unconfined compressive strength (UCS), indirect tensile strength (ITS), flexural strength (FS), indirect tensile resilient modulus (IT Mr), and indirect tensile fatigue life (ITFL) tests. The UCS of FA geopolymer stabilized CR (without AE) was found to be dependent on the FA content and curing time. For all the curing times studied, the higher FA replacement ratio resulted in higher UCS values. Although the asphalt film enhances particle confinement, it was found to retard the geopolymerization reaction. According to the local road authority, which requires a UCS>1.75 MPa for a stabilized base course, the addition of AE reduced the UCS of FA-AE geopolymer stabilized CR. To meet the minimum 7-day strength requirement for both low and high-traffic roads, a geopolymer mix was suggested with an FA replacement ratio≥20% and an AE content≥1%. Compared with the cement stabilized CR at a similar UCS value, the FA-AE geopolymer stabilized CR had higher FS, ITS, IT Mr, and ITFL but lower carbon footprints.
Seyed Hadi Sahlabadi, , Mohsen Mousivand, Mohsen Saadat
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003905

Abstract:
Many studies have been carried out on the influence of freeze–thaw cycles on the mechanical behavior of cement- or lime-stabilized soils. However, very limited studies have considered the effects of freeze–thaw cycles on cement-stabilized soil reinforced with fibers. The main objective of this study is to determine the effects of polypropylene fiber (PPF) and basalt fiber (BF) content (0%, 0.5%, 1%, 2%, and 5%), cement content (0%, 3%, and 9%), number of freeze–thaw cycles (0, 2, 4, 8, and 10), and initial moisture content on the unconfined compressive strength (UCS) of clay soil. The study reveals that adding cement, PPF, or BF to soil causes a remarkable increase in strength, where the strength of the PPF-reinforced specimens is significantly more than that of BF-reinforced ones. The UCS values of the specimens compacted at optimum moisture content (OMC) are almost more than those that were prepared at a molding moisture content of 0.8 OMC or 1.2 OMC. The strength of specimens increases with increases in cement content and curing time. However, the axial strain at failure for cement-stabilized specimens decreased with increasing cement content or curing time. Furthermore, it is concluded that the increase in the UCS of combined PPF or BF with cement inclusion is more than that caused by each fiber without cement. A regression model is developed to predict the UCS in terms of four effective agents for each case of stabilization by BF or PPF. Results indicate a satisfactory performance of the model where the Pearson correlation coefficient above 0.95 for UCS prediction is obtained.
Sujata Subedi, Gabriel A. Arce, Hassan Noorvand, , , Louay N. Mohammad
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003892

Abstract:
This study investigates the effects of raw sugarcane bagasse ash (SCBA) used as a partial or complete replacement for silica sand in engineered cementitious composites (ECCs). ECC mixtures with five different replacement levels of sand with SCBA were produced (i.e., 0%, 25%, 50%, 75%, and 100% by volume). The SCBA utilized in this study was comprehensively characterized. Furthermore, the fresh and hardened properties of the produced ECC materials were thoroughly evaluated. The characterization of SCBA revealed that raw SCBA consisted mainly of small (i.e., 256 μm average particle size), porous, and irregularly shaped particles with carbon and silica as the main constituents. Furthermore, the SCBA met the pozzolanic component requirement for Class C pozzolans; however, it did not meet the minimum strength activity index requirement to be classified as a pozzolan; however, it did not meet the minimum strength activity index requirement to be classified as a pozzolan. In terms of ECC fresh properties, the incorporation of SCBA produced an important loss in workability, which was mitigated with increasing dosages of high-range water reducer for increasing amounts of SCBA, which also resulted in a substantial increase in the air content. In the case of hardened material properties, the incorporation of SCBA as sand replacement produced a slight decrease (up to 11%) of the compressive strength of ECCs. However, the tensile strength and especially the tensile ductility of the composites were substantially enhanced (up to 22.3% and 311%, respectively). The tensile strength improvements were credited to the pozzolanic and/or filler effect of SCBA. On the other hand, enhancements in the tensile ductility were associated to the combined effect of the reduction of crack-tip matrix toughness (credited to the decrease in aggregate particle size), reduction in ECC cracking strength (due to increase in air content), and increase in the complementary energy (attributed to the potential decrease in the chemical bond of the fiber/matrix interface and an enhanced fiber dispersion). The surface resistivity of ECC materials was negatively affected by the addition of SCBA. Furthermore, the length change of all SCBA-ECC materials, at all ages of curing, was higher in comparison with that of the control mixture, except for the mixture with 25% replacement at 28 days of curing.
, , Markus S. Rebmann, Erol Tutumluer
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003824

Abstract:
The standard method of using a caliper to determine aggregate particle dimensions is not sufficient to describe the shape, texture, angularity, and volume of particles, and there is not a reference method to determine aggregate surface area. A three-dimensional (3D) structured-light scanner seems to be a viable and economical alternative with enough speed to obtain 3D data from hundreds of particles. This work used a 3D scanner to evaluate morphological properties of coarse aggregates and compared results with those from conventional techniques. Two types of aggregates (around 60 particles of each type) were scanned and manually measured by a single operator with a digital caliper using two different methodologies: (1) the minimum bounding box (MBB), and (2) a conventional standard test method (STD). The 3D structured-light scanner proved to be accurate for assessing the morphology, surface area, and volume of coarse aggregates, and with a processing rate of 10 min/particle, it was faster than other techniques such as X-ray computed microtomography (micro-CT) or laser scanning. Compared with the manual method (caliper) or the most commonly used two-dimensional (2D) image analysis techniques, it also was more accurate. The MBB using a caliper overestimated volume by about 17% and underestimated surface area by 11%, which was estimated by assuming an ellipsoid with the dimensions obtained. The 2D circularity had a poor correlation with the 3D sphericity, especially for flat or elongated particles.
, , Allex E. Alvarez, Francisco Thiago Sacramento Aragão, Marcos A. Fritzen
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003849

Abstract:
Sugarcane agriculture contributes to the greenhouse effect by the polluting action of residue disposal, given that most sugarcane bagasse (SB) is burned. Because it is a low-cost fiber and ecofriendly material, SB can be an alternative to the construction of permeable friction course (PFC) pavement layers. Due to SB-specific properties, its effects on PFC mixtures are unknown. This study aims to evaluate for the first time the feasibility of incorporating SB fibers in a PFC mixture. For this purpose, a PFC mixture that included SB fibers (PFC-SB) was compared to a control PFC mixture fabricated using synthetic cellulose fibers (PFC-CEL), which are currently the most used fibers for fabricating these mixtures. The results suggest that the SB fibers can be successfully added to PFC mixtures to control binder draindown without compromising their volumetric properties. Additionally, the PFC-SB mixture presented an increase in stiffness and resistance to both cracking and raveling compared to the PFC-CEL. However, the mix design should be optimized to ensure proper mixture permeability. These findings suggest that the incorporation of SB fibers in PFC mixtures can be further explored, which encourages additional research.
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003842

Abstract:
Sulfate-rich dispersive soils are worldwide responsible for damaging earthworks, such as roadway roadbeds and embankments. One of the causes for such behavior is the high amount of exchangeable sodium ions adsorbed on their clay particles vastly increasing erosion susceptibility, being responsible for problems as piping, ravines, and water turbidity. In order to reduce the erodibility, it is usual to treat such soils with calcium-based stabilizers. However, in the presence of sulfates, when combined with calcium-based stabilizers in the soil, reactions take place between stabilizers and sulfates to form expansive minerals. Namely, these minerals are known as ettringite and thaumasite and are responsible for excessive volumetric swell. In this context, the present research aims to develop alternative soil stabilizers (industrial byproducts plus artificial pozzolans) and reinforcements (fiberglass) to solve problems associated with sulfate-rich dispersive soils. Thus, a binder composed of carbide lime and ground glass was used. In addition, fiberglass was applied to look for enhanced mechanical properties of the materials. To assess the efficiency of the proposed stabilization and reinforcement, unconfined compressive and splitting tensile strength, ultrasonic pulse velocity, wet and dry durability, and fatigue life tests were carried out. Soil–ground glass–carbide lime-fiberglass blends were molded at different porosities, carbide lime, ground glass, and fiberglass contents. Results show that unconfined compressive and split tensile strength and initial shear modulus are highly dependent on changes in porosity and lime content. Durability, expressed as the accumulated loss of mass, could be assessed through the adjusted porosity/lime index (η/Liv). Fiberglass inclusion resulted in higher tensile strength. The fatigue life was correlated to the η/Liv index through a negative exponent. The greater the carbide lime level, the smaller was the fatigue life for all treated specimens. An increase in porosity results in fewer contacts between particles, whereas an increase in carbide lime content enhanced the specimen’s rigidity.
, M. Emin Kutay
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003830

Abstract:
Modification of asphalt binders has been one of the common techniques to overcome the climatic and traffic-related distresses that develop in bituminous materials. Over the past decade, many new methods of incorporating recycled tire rubber as a modifier have been developed and evaluated by states and county road departments. This study focuses on the use of the so-called devulcanized recycled tire rubber modifier and its effects on the performance grade, fatigue cracking resistance, and rutting resistance of asphalt binder. Devulcanized rubber was incorporated into hot liquid asphalt at various percentages using high and low shear blending, consecutively. First, the effect of modifications on continuous performance grades (PG) at low, intermediate, and high temperatures was investigated. Second, equistiffness temperatures of the binder-rubber mixes were established, and the fatigue cracking resistances of the rubber-binder blends were measured by using the linear amplitude sweep (LAS) test at different strain levels. Last, the multiple stress creep and recovery test (MSCR) was conducted on the modified asphalt samples to characterize the high-temperature performance. Although there was a significant improvement on high PG as the modifier amount increased, the improvement for intermediate and low PGs was minimal. The same trend observed for high PG of the modified asphalt binders was also obtained for fatigue cracking resistance and rutting resistance. The results showed that the use of devulcanized rubber modification could successfully extend the life of bituminous materials.
Jean-Baptiste Mawulé Dassekpo, Weipeng Feng, Lixin Miao, Zhijun Dong
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003784

Abstract:
The possible utilities of geopolymers likely are due to their potentially high mechanical, physical, and durability properties that make geopolymers similar to ceramic materials. The similarity largely is because of a mineralogical and chemical composition silimar to that of ceramic materials. However, to produce effective similar properties, a measured dissolution of source materials in an adequate alkaline solution is required for geopolymerization. This paper examines the effects of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions on the properties of loess geopolymer and its effective use in ceramic tiles repairing. The experiments involved 8M concentration of sodium hydroxide and a combination of NaOH and sodium silicate with the same molarity at a ratio of SiO2:Na2O=2.5. Compressive and split tensile strengths of the loess geopolymer mortars (GPMs) were assessed at 7 and 28 days. X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron micrographs (SEM), and mercury intrusion porosimetry (MIP) analysis were carried out to determine the GPM behavior under alkali solutions as well as the correlation between its strength and structure. The resulting geopolymer loess was used to fill ceramic tile gaps. The experiment showed that the reaction and strength performance of loess geopolymer depended on the precursors and alkali liquids used. It was also established that the mixture of NaOH and Na2SiO3 not only reduced the pores in the loess based–geopolymer matrix but also had adequate mechanical behavior, effective adhesion, and durability for filling ceramic tile gaps.
Fan Gu, Raquel Moraes, Chen Chen, Fan Yin, Donald Watson, Adam Taylor
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003862

Abstract:
This study aimed to evaluate the effects of additional antistrip additives on the durability and moisture susceptibility of granite-based open-graded friction course, referred to as FC-5 asphalt mixture. The laboratory testing involved two granite-based FC-5 mixtures containing 1% hydrated lime (by weight of aggregate), 1% hydrated lime plus 0.5% liquid antistrip (LAS) additive (by weight of asphalt binder), 1.5% hydrated lime, and 1.5% hydrated lime plus 0.5% LAS additive. Two sources of granite aggregates were obtained, one from Junction City, Georgia, and the other from a regional supplier with an original source from Nova Scotia, Canada. Four types of LAS additives were collected for this study. A binder bond strength test was used to select the LAS agents that provided the best improvement in moisture resistance. The FC-5 mixtures were fabricated in the laboratory using two FC-5 mix designs provided by the Florida DOT. The specimens were conditioned by the asphalt pavement weathering system to simulate long-term aging and moisture conditioning in the field. Mixture performance tests, including the Cantabro test, tensile strength ratio test, and Hamburg wheel tracking test, were used to evaluate the durability and moisture susceptibility of FC-5 mixtures. Finally, a cost-benefit analysis was performed to determine the cost-effectiveness of the FC-5 mixtures with antistrip additives. This study found that the addition of LAS additive, an extra 0.5% hydrated lime, or both produced longer lasting FC-5 mixtures, and the additional antistrip additives would improve the cost-effectiveness of FC-5 mixtures.
Jianhua Yang, Ying Fang
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003828

Abstract:
At present, the rationality and applicability of various high-temperature performance evaluation indexes for polymer-modified asphalts have not been comprehensively explored. This study aimed to fully explore their rationality and applicability. For this purpose, five asphalt binders including four representative polymer-modified asphalts and one neat asphalt (NA) were chosen, and many of their high-temperature performance indexes were first obtained by using a series of tests. Then the five corresponding asphalt mixtures were fabricated and their high-temperature performance indexes were also obtained by performing a wheel tracking test. On this basis, the high-temperature potential of asphalt binders was evaluated using the obtained indexes, and the correlation between the indexes of asphalt binders and their mixtures was analyzed via data processing software. Results show that the rankings of high-temperature performance of these five asphalt binders are not exactly consistent when all the high-temperature performance indexes—including penetration (P) at 25°C, penetration index (PI), equivalent softening point (T800), softening point (SP), dynamic viscosity (DV) at 60°C, rutting factor (G*/sinδ), improved rutting factor [G*/(sinδ)9], Shenoy’s nonrecoverable compliance (JShenoy), critical temperature of rutting factor (TG*/sinδ), nonrecoverable creep compliance (Jnr), creep modulus (GV), zero shear viscosity (ZSV), and generalized dynamic shear modulus (GDSM)—are utilized for evaluation. However, all the indexes can distinguish the polymer-modified asphalts from NA well. Among these indexes, the evaluation results of Jnr at different temperatures are consistent at the same stress level (0.1 or 3.2 kPa), and all the correlation coefficients between the Jnr and dynamic stability (DS) of asphalt mixtures exceed 0.9; thus, the Jnr is recommended as the dominant evaluation index. The G*/sinδ, TG*/sinδ, and GV correlate weakly with the DS, and the ZSV performs poor repeatability in the test; thus, their rationality needs to be further verified using more asphalt samples.
Zhenpeng Yu, Rui Tang, Guoqing Liu, Zhaoyuan Guo, Qiao Huang
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003846

Abstract:
To examine the uniaxial behaviors of plain concrete and lightweight aggregate concrete under dynamic loadings, the plain concrete specimens and lightweight aggregate concrete specimens prepared by shale ceramsite were designed and tested under the loading strain rate range of 10−5/s–10−2/s. The hydraulic servo machine and shear device were applied to conduct the uniaxial compression, splitting tensile, and shear tests of both types of concretes, and the failure modes and stress-strain curves of two concrete at varying loading conditions were obtained from the test results. By comparing and analyzing the test results, the following conclusions are obtained: the failure of cementing layer occurs in plain concrete at low strain rates, while some coarse aggregates are damaged at high strain rates, but the failure of lightweight aggregate concrete is caused by the fracture of shale ceramsite at all strain rates. As the loading strain rate increases, the uniaxial compressive strength, splitting tensile strength, and shear strength of plain concrete and lightweight aggregate concrete are significantly increased, with the improved percentages of 35.63%, 43.75%, and 41.29% for plain concrete and 44.87%, 55.97%, and 49.44% for light aggregate concrete, respectively. For both types of concrete, the increase of strain rate has a more significant effect on the increase of splitting strength than compressive strength. In addition, the strain rate effect on the strength of lightweight aggregate concrete is significantly higher than that of plain concrete. The dynamic increase factor of peak stress of both concretes under uniaxial loadings is linearly related to the dimensionless logarithmic values of the strain rate. Based on the test results and analysis, two different relationship expressions between compressive strength, splitting tensile strength, and shear strength of two types of concretes are proposed, and the dynamic effects of concrete are explored from the perspective of the damage mechanism. This study is meaningful to the engineering applications and development of plain concrete and lightweight aggregate concrete.
, Abhishek Singh, Shashank Bishnoi
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003861

Abstract:
Soluble alkalis play a vital role during early age hydration and strength development in cement. This study investigates the influence of alkali addition on the hydration, phase assemblage, and strength development in ordinary portland cement (OPC) and limestone–calcined clay cement (LC3) produced with 50% clinker replacement. The alkalinity (% Na2Oeq) of OPC and LC3 was increased using four different alkali salts: NaOH, Na2SO4, KOH, and K2SO4. An acceleration of the early age hydration and an increase in the early age compressive strength development was observed with increasing alkalinity in OPC and LC3 systems. The characteristic features of the calorimetry curves were seen to be significantly influenced by the presence of alkalis. The presence of additional sulfate ions was seen to modify the phase assemblage, with additional ettringite forming in these systems. However, increasing the alkalinity was also seen to reduce the later age clinker hydration and strength development.
Fizza Hussain, , Muhammad Irfan
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003855

Abstract:
Laboratory performance testing of the phase angle of asphalt concrete (AC) mixtures is often expensive and requires enormous human effort and time. To circumvent this problem, several regression-based methods have been proposed in the literature to model the phase angle behavior of AC mixtures using various approaches. However, these methods impose strict assumptions on the underlying relationship between phase angle and its corresponding covariates as well as how well and accurately these covariates are measured, restricting us from fully analyzing the predictive capability of any modeling method. To this end, this study proposed an alternative approach for modeling the phase angle characteristics of AC mixtures based on a recurrent neural network (RNN) that inherently and implicitly captures the effects of covariates. This approach is suitable to model the sequential nature of data recorded in laboratory testing where phase angle testing was repeated for a set of six loading frequencies forming a recurrent pattern. The proposed RNN model (P-RNN) was applied separately to wearing and base course mixtures by considering the historical values of phase angle as input and to predict its value for the next loading frequency, keeping temperature as a constant. To demonstrate the superiority of the proposed approach, the P-RNN model is compared with other competing models from the literature, and the results reveal superior performance of the P-RNN model.
Ying Xu, Yunze Li, Moxuan Duan, Jie Ji, Shifa Xu
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003808

Abstract:
To investigate the compaction characteristics of a single-component polyurethane (PU) mixture with dense gradation, the effects of temperature, humidity, catalyst content, and standing time on the compaction energy index (CEI) of the mixture were analyzed in this study. The air void ratio and splitting tensile strength of the polyurethane mixture at 15°C under different compaction times were also tested. Based on the test results, the effects of compaction time on the volume and strength characteristics of the polyurethane mixture were analyzed. The results showed that temperature, humidity, catalyst content, and standing time have significant positive correlations with the CEI, where standing time has the strongest correlation, followed by catalyst content, temperature, and humidity, respectively. A multiple linear regression model relating the CEI and the aforementioned factors was established. Compaction time, as characterized by the CEI, significantly influenced the air void ratio and splitting strength of the polyurethane mixture after curing. If the compaction of the polyurethane mixture is premature or delayed, the void ratio of the mixture increases after curing and the splitting strength decreases. Therefore, an optimal compaction time exists for the single-component polyurethane mixture. At this compaction time, the CEI of the mixture is approximately 600–800. During the process of single-component polyurethane curing, the increase in the adhesive force of polyurethane and the damage to the structure of the mixture, caused by the released CO2, served as a pair of mutually restricting effects, resulting in different volume characteristics and splitting strengths of the polyurethane mixture under different compaction times.
Nafise Hosseini Balam, Bahareh Tayebani, Davood Mostofinejad
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003857

Abstract:
The present study investigates the use of bacteria (namely, Sporosarcina pasteurii) to enhance the durability of structural concrete members with lightweight weight aggregates (LWAs) or normal weight aggregates (NWAs). As an innovative development, bacterially-induced calcium carbonate crystals have been widely used for improving the properties of concrete materials. In this research, seawater is used as a source of calcium and chloride for calcium carbonate formation by bacteria, whereby seawater serves as a curing environment with beneficial effects on both concrete matrix and durability. For this study, concrete specimens are cured in the two seawater and tap water environments up to the test time. Experimental results indicate that the inclusion of bacteria in the concrete mix water leads to acceptable results in seawater medium and both types of concrete tested. This is evidenced by a decrease of 4% in water absorption and an increase of almost 26% in compressive strength observed in normal-weight aggregate concrete after 91 days of curing. Moreover, both types of concrete made with bacterially-impregnated mix water exhibit reductions in their chloride penetration. In this regard, compared with the control specimens cured in plain water, the bacterially-treated LWA concrete specimens exhibited a reduction of almost 1% in their water absorption and a rise of about 16% in their compressive strength. It is, therefore, expected that exposure to seawater as a threat to concrete structures can be turned into an opportunity for improving their properties if the concrete is properly treated with bacteria.
Jianqiang He, , Boyu Yao, Johnny Ho
Journal of Materials in Civil Engineering, Volume 33; https://doi.org/10.1061/(asce)mt.1943-5533.0003812

Abstract:
Engineered cementitious composite (ECC) is a relatively recent construction material with characteristics of high ductility and energy dissipation capacity. Such ductility is fulfilled by adding polymeric fibers, such as polypropylene (PP), polyethylene (PE), and polyvinyl alcohol (PVA) fibers, which would inevitably experience fusion under fire. This paper focuses on the behavior deterioration of postexposure high-strength engineered cementitious composite (HSECC). Color change, surface cracking, and spalling phenomena of HSECC specimens were inspected after specimens exposed to 200°C, 400°C, 600°C, 800°C, and 1,200°C for 1 h. Weight loss, residual compressive/flexural strength, and failure modes of cubes were evaluated correspondingly. Experimental results indicated that the threshold temperature for HSECC to crack is lowered in comparison with ECC of normal strength, whereas explosive spalling behavior could still be prevented effectively with 2.0 vol% PVA fiber. The loss ratio of weight and strength in HSECC was lower than that in ECC, but the failure modes under compression were found to be more catastrophic. HSECC exhibits lower intensity in an X-ray diffraction (XRD) curve than that of ECC. Apparent needle-like channels were observed beyond 400°C, then were gradually filled with reaction products ascribed to the synergistic effect of thermal expansion, volume increase caused by chemical reactions and pore-structure coarsening, and manifested by the results of mercury intrusion porosimetry (MIP).
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