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Seyed Bahram Beheshti Aval, Mohammad Maldar, Ehsan Darvishan, Bahareh Gholipour, Nakisa Mansouri Nejad, Behrouz Asgarian
Proceedings of the Institution of Civil Engineers - Structures and Buildings pp 1-32; https://doi.org/10.1680/jstbu.21.00075

Abstract:
This article presents a novel approach to damage detection based on dispersion analysis and signal processing methods. The proposed method is conducted on a scaled experimental model of a jacket type offshore platform. A forced vibration test is conducted on the platform to acquire the acceleration signals. The frequency spectrum of the first Intrinsic Mode Function (IMF) of the recorded signals is obtained by Hilbert transform; as it turns out, damage engenders dispersion in extracted frequencies. Hence, a novel damage index, capable of accurate damage detection, based on Mahalanobis Distance Dispersion (MDD) of the Hilbert transform frequency spectrum is provided. Results show that the proposed index can determine the location and severity of the damage with acceptable accuracy.
R.L.E. Desbrousses, M.A. Meguid, S. Bhat
Published: 27 October 2021
Geosynthetics International pp 1-31; https://doi.org/10.1680/jgein.21.00032a

Abstract:
Understanding the tensile behavior of geosynthetic reinforcement materials at different temperatures is essential for the design of reinforced soil structures in seasonally cold regions. This study describes a series of tensile tests performed on two polypropylene geogrid materials, namely a biaxial geogrid and a geogrid composite. A total of 84 tests were performed in an environmental chamber with temperatures as low as −30°C and as high as +40°C. The response of each material is examined over the range of investigated temperatures to evaluate the effect of temperature changes on the tensile strength of the two geogrid materials. The response of the biaxial geogrid is found to be sensitive to temperature variations, with samples tested at low temperatures exhibiting brittle behavior characterized by high rupture strength and small ultimate strain while samples tested at elevated temperatures displayed ductile behavior with large elongation at failure and comparatively small rupture strength. Similar response was found for the geogrid composite, however, the rupture strength seemed to be less sensitive to temperature changes. The modes of failure observed at each temperature are examined based on photographic evidence taken during the experiments.
A. Pant, G.V. Ramana
Published: 27 October 2021
Geosynthetics International pp 1-42; https://doi.org/10.1680/jgein.21.00021a

Abstract:
Pullout behaviour of geogrids is critical to understand in the design of mechanically stabilized earth walls. The pullout coefficients are determined through laboratory testing on geogrids embedded in structural fill. Random forest (RF) is a data-driven ensemble learning method that uses decision trees for classification and regression tasks. In the present study, the use of random forest regression technique for estimation of pullout coefficient of geogrid embedded in different structural fills and at variable normal stress based on 198 test results has been investigated using five-fold cross-validation. 80 % of the data has been trained on the model algorithm and the accuracy of the model is then tested on 20 % of the remaining dataset. The performance of the model has been checked using statistical indices, namely R2, mean square error, as well as external validation methods. The validity of the model has also been checked against laboratory tests conducted on geogrid embedded in four different fills. The results of the RF model have been compared to results obtained with three other regression models namely, Multivariate Adaptive Regression Splines, Multilayer Perceptron, and Decision Tree Regressor. The results demonstrate superiority of the RF-based regression model in predicting pullout coefficient values of geogrid.
U C Sahoo, S R Dash, C S Sahu
Infrastructure Asset Management pp 1-11; https://doi.org/10.1680/jinam.21.00010

Abstract:
Cyclones and the associated floods have recently become a regular problem for many states of India on its west and east coast. Odisha (renamed from Orissa in 2011) is a state located along the eastern coast of India and experiencing tropical cyclones mainly from the Bay of Bengal. Some of the recent severe cyclonic storms that had caused large-scale devastation in Odisha in the last decade include cyclone Amphan in May 2020, cycloneFani in May 2019, cyclone Titli in October 2018, cyclone Hudhud in October 2014, and cyclone Phailin in October 2013. Roads, being one of the essential lifeline infrastructure facilities, commonly get damaged during these cyclonic floods in terms of floodwater overtopping, erosion of road surfaces, shoulders and embankment slopes, and even washing out of the whole roadway section. These recent events have indicated that special attention is needed for this vital lifeline infrastructure to minimize its damage by developing and adopting climate-resilient road infrastructure. This paper focuses on the damage assessment of transportation infrastructure during the recent cyclones and associated floods in Odisha, and some recommendations for possible measures to be taken for the design of cyclone and flood resilient road infrastructure are presented.
J.P. Giroud, J. Han, E. Tutumluer, M.J.D. Dobie
Published: 27 October 2021
Geosynthetics International pp 1-63; https://doi.org/10.1680/jgein.21.00046

Abstract:
This paper addresses unpaved and paved roads improved with geosynthetics, such as geotextiles, geogrids and geocells. The paper examines the mechanisms associated with the use of geosynthetics to improve roads, describes the principles of the design methods used to quantify the benefits of geosynthetics used in unpaved and paved roads, presents case histories to demonstrate the use of geosynthetics to solve challenging road problems, and discusses the relevance of tests and trials to real roads. This paper is supplemented by four presentations in pdf format that contain more than 800 slides. These four presentations are updated versions of the four presentations made during a one-day short course at the 11th International Conference on Geosynthetics held in Seoul, Korea, in September of 2018. The paper that follows contains a summary of each of the four presentations, with special emphasis on key issues.
E Abdeltwab, A Atta
Published: 27 October 2021
Surface Innovations pp 1-9; https://doi.org/10.1680/jsuin.21.00045

Abstract:
In this work, the structure and dielectric properties of flexible films composed of Zinc oxide nanoparticles (ZnONPs) mixed with polyvinyl alcohol (PVA) polymer, are irradiated with different fluence of argon ion beam (8x1017, 16x1017, and 24x1017 ions/cm2). The ZnO/PVA composites films have been synthesized using solvent casting preparation method and then characterized using X-ray diffraction (XRD) and Fourier transform infrared (FTIR). The XRD shows that ZnO/PVA composite films are successful fabricated, and the FTIR peaks indicating ZnONPs is chemically interaction with PVA polymer chains. Furthermore, the Ac conductivity, dielectric permittivity, electric modulus, and the energy density efficiency of the un-irradiated and irradiated films are determined using LCR meter in frequency range 102 to 106 Hz. The dielectric constant ε′ of the composite film has increased from 1.38 for un-irradiated ZnO/PVA to 1.88 after irradiated by 24x1017 ions.cm−2, and the conductivity is improved from 7.8x10 5 S/cm to 10.6x10−5 S/cm. The obtained results demonstrated that the dielectric characteristics of the irradiated ZnO/PVA composite films have been enhanced, which will support these materials in current electronic applications.
M. Samanta, R. Bhowmik, H. Khanderi
Published: 27 October 2021
Geosynthetics International pp 1-33; https://doi.org/10.1680/jgein.21.00016a

Abstract:
The seismic stability of geosynthetic structures incorporating soil-geomembrane interfaces depends largely on their response to dynamic loads caused by earthquakes or traffic. The present study investigates the dynamic shearing response of sand-smooth geomembrane interface through fixed–block type shake table tests. The influence of dynamic loading parameters, like, sliding velocity, loading frequency, normal stress, displacement amplitude and the number of cycles, and relative density of sand on the shearing behavior of the sand-geomembrane interface are examined. Results show that the peak cyclic shear stress is significantly influenced by normal stress, shear displacement amplitude, loading cycles, and relative density of sand. The dynamic coefficient of friction of the sand-geomembrane interface displays an increasing trend with an increase in loading frequency, shear displacement amplitude, and relative density of sand but decreased for the rest of the considered parameters. The shape of the hysteresis loops is dependent on the normal stress and displacement amplitude. The dynamic coefficients of friction are also compared with the corresponding values under static conditions. The results from the present study emphasize the importance of considering the design basis value of the dynamic coefficient of friction for each parameter during the design stage of geosynthetic structures involving sand and geomembrane.
Chunhua Gao, Jieqiong Wang, Xiaobo Yuan, Yonghe Zhang, Yanping Yang, Mengyuan Qin
Proceedings of the Institution of Civil Engineers - Smart Infrastructure and Construction pp 1-9; https://doi.org/10.1680/jsmic.21.00007

Abstract:
The shaking table is well reproduction of the structure response test method in the laboratory. This paper explores the vibration table from the aspects of construction, control technology, test method and application. The construction time of typical shaker table at home and abroad is given, and the indicators such as table size and performance parameters are summarized, This paper expounds the significance of the construction of the shaking table, analyzes the development and advantages and disadvantages of the control technology, and discusses the existing mainstream test methods and application process. The application of shaking table technology in related research fields is introduced in detail, which provides a reference for the further selection, upgrade, development and utilization of seismic simulation shaking table.
Xuefan Gu, Long Gao, Yan Sun, Weichao Du, Jie Zhang, Gang Chen
Published: 27 October 2021
Green Materials pp 1-8; https://doi.org/10.1680/jgrma.21.00016

Abstract:
To develop an green drilling fluid additive, the modification and application of persimmon peel in water-based drilling fluid was studied in this work. A series of natural product derivative, aluminium chloride-persimmon peel (ACPP), was prepared from aluminium chloride and persimmon peel, and was assessed as shale inhibitor. Clay-swelling ratio in 0.3% ACPP-3 solution was reduced to 28.1% from 69.5%. Rolling recovery tests and rheological evaluation of drilling fluids concluded that ACPP-3 has high inhibition property to montmorillonite hydrated expansion. ACPP-3 can adjust the particle size of montmorillonite in a large scale. ACPP-3 reduces the apparent viscosity (AV) of carboxyl methyl cellulose (CMC) drilling fluids effectively and reduces the volume of filtration, furthermore, ACPP-3 can reduce the viscosity and the volume of filtration under high temperature, which can be used as a additive for deep drilling. The inhibition mechanism of ACPP-3 was investigated by thermogravimetric analysis and scanning electron microscope. The results will benefit the related work in the eco-friendly drilling fluid materials.
F.M. Naftchali, R.J. Bathurst
Published: 27 October 2021
Geosynthetics International pp 1-31; https://doi.org/10.1680/jgein.21.00015a

Abstract:
Analytical solutions for geosynthetic reinforced fills over a void have appeared in the literature starting in the 1980s. Current solutions pay little or no attention to the influence of the creep-reduced stiffness of the geosynthetic reinforcement under tensile loading. This paper addresses this gap by introducing a reinforcement stiffness limit state in the design of these systems. The choice of reinforcement stiffness is based on a simple two-parameter hyperbolic isochronous load-strain model developed by the authors and applied to a large database of uniaxial and biaxial geogrids and woven geotextiles. The paper provides a design chart procedure that can be used with four well-known analytical solutions to compute the maximum reinforcement load. In addition to the stiffness limit state, the design chart approach includes vertical deformation and reinforcement strain serviceability limit states, and a tensile strength limit state. A novel feature of the design charts is a quantitative link to the ultimate strength of the reinforcement to estimate the isochronous stiffness of the reinforcement for different elapsed loading times and strains. There are many instances in the literature where the reinforcement stiffness was taken from a constant rate-of-strain tensile test. The paper shows that this is non-conservative for design.
Kaikai Tang, Jun Xiao, Mengqi Long, Jun Chen, Hong Gao, Hao Liu
Published: 27 October 2021
Surface Innovations pp 1-7; https://doi.org/10.1680/jsuin.21.00053

Abstract:
Lithium-sulfur batteries (LSBs) are suffered from the unavoidable “shuttle effects” of lithium polysulfides (LPS) and the infinite volume change of the sulfur. Herein, we prepared a yolk-shell structured N-doped carbon nanotubes/sulfur/poly(3,4-ethylenedioxythiophene) nanotubes (N-CNTs/[email protected]) composite as cathode for LSBs. The yolk-shell structure with void spaces can effectively buffer the volume expansion of sulfur, while the outer “shell” can act as a physical barrier to minimize the “shuttle effects” of LPS. Moreover, the N-CNTs with high conductivity and superior structural stability are able to improve the electron transfer efficiency and cycling performance. Therefore, the specially designed yolk-shell structured N-CNTs/[email protected] composite cathode exhibits an extraordinary rate performance and enhanced cycling stability (602 mAh g−1 after 200 cycles at 0.1 C).
Xuandong Chen, Qing Zhang, Yang Ming, Feng Fu, Hua Rong
Proceedings of the Institution of Civil Engineers - Structures and Buildings pp 1-27; https://doi.org/10.1680/jstbu.21.00049

Abstract:
Electrochemical repair is one of the most effective methods of removing chloride from offshore engineering structures to improve their durability. The diffusion of chloride and electrochemical repair are key stages in this process. In this paper, a new numerical chloride migration-diffusion model is established by using Nernst-Planck equation. The distributions of free chloride ions in concrete in the stage of free chloride diffusion and the stage of electrochemical repair are simulated, and the effects of external potential and cathode position on electrochemical repair efficiency are analyzed. The numerical results show that electrochemical repair can effectively remove chloride ions from concrete. After 12 weeks of the electrochemical repair, the electrochemical repair efficiency is more than 66%. With the increase of repair time, the increase amplitude of electrochemical repair efficiency decreases gradually. In the initial stage of electrochemical repair, the chloride concentration on reinforcing bar surface decreases rapidly. After 4 weeks of electrochemical repair, the chloride concentration tends to be stable. As external potential increases, the electrochemical repair efficiency is also improved, and the chloride concentration on reinforcing bar surface decreases rapidly. When the cathodes are set on both sides of the concrete, the electrochemical repair time should be extended, and external potential should be increased to achieve better repair effect.
Jin-Sun Lim, Young-Do Jeong, Yon-Dong Park, Sokhwan Choi, Seong-Tae Yi
Proceedings of the Institution of Civil Engineers - Structures and Buildings pp 1-27; https://doi.org/10.1680/jstbu.21.00105

Abstract:
An analytical exploration of the effects of shear span-to-depth ratio on the shear strength of reinforced concrete beams was carried out using a meso-scale finite-element method. Prior to the numerical analysis, a method of defining concrete as meso-scale composites of multi-phases was described. The concrete was assumed to be a composite with three phases (aggregates, cement matrix, and interfacial transition zone), and the material properties of each phase were applied for the numerical analysis. The shear failure behaviour of reinforced concrete beams was examined by the constructed numerical model, and the effect of span-to-depth ratio on shear strength was confirmed through these analyses. An investigation of cases where span-to-depth was less than 1.0 was also carried out. Moreover, the performance of the numerical model was evaluated by comparing the numerical results with the experimental results obtained from the model code and other researchers. It was confirmed that the application of a meso-scale finite-element method was appropriate for the study on the effect of span-to-depth ratio on shear strength and the occurrence and progress of bending and shear cracks.
Hassan Abbasi, Ata Hojatkashani, Khaled Sennah, Hossein Nematianjelodar
Proceedings of the Institution of Civil Engineers - Structures and Buildings pp 1-34; https://doi.org/10.1680/jstbu.21.00125

Abstract:
Structural insulated panels are structural elements comprising a core of expanded polystyrene insulation sandwiched between two oriented-strand boards. They can replace conventional joist floors and stud walls in low-rise residential construction. Three identical samples of a full-scale structural insulated panel and a stud wall were tested according to the ASTM standards, and the experimental results for the specimens are presented in terms of ultimate load capacity and failure mechanism. Comparing the load–deformation diagrams for the structural insulated panels and stud walls showed that tangential stiffness variation of the former occurred in the hardening mode, whereas such variation for the latter was in two stages: hardening and softening. The results show that regarding compressive loading, structural insulated panels are as good as conventional wood framing of the same size. Therefore, structural insulated panel walls are very efficient in the case of axial compressive loading.
K. Hatami, J. Boutin
Published: 27 October 2021
Geosynthetics International pp 1-43; https://doi.org/10.1680/jgein.21.00052

Abstract:
The influence of backfill type and material properties on the performance of field-scale GRS abutment models is investigated. Two alternative types of backfill as recommended in the FHWA guidelines (called open graded and well graded) were used to build two field-scale model abutments and compare their load-bearing performance under a loading beam. Results are presented and discussed relative to the loading beam settlement, facing deformation and reinforcement strains. The well-graded backfill was found to result in smaller beam settlements and facing lateral deformations, especially at smaller loads that were comparable to service load levels. However, it was significantly faster and easier to compact the open-graded aggregate to the unit weight recommended in the guidelines. Nevertheless, performances of both abutment models were found to be satisfactory relative to the limiting requirements on the beam settlement and facing deformations at service load levels.
Yifa Wang, Mark J. Cassidy, Britta Bienen
Published: 26 October 2021
Abstract:
A macro-element model for predicting the load-displacement behaviour of a spudcan foundation in clay overlying sand when subjected to combined vertical, horizontal, and moment loading is introduced. Observations from detailed drum centrifuge tests that measured the effect of the underlying sand layer on the foundation behaviour are combined with finite-element results and theoretical developments to derive the components of the model. The yield surface defined by the centrifuge test results suggests that as the spudcan nears the underlying sand layer, the absolute horizontal capacity remains relatively constant, while the vertical and moment capacities increase at approximately the same normalised rate. The model is demonstrated to accurately predict foundation behaviour by retrospectively simulating the experimental results. This macro-element model has the advantage that it can be integrated into the structural analyses of jack-up platforms required for site-specific assessments.
Ahlam Abdulnabi, Nicholas A Beier, Lianna Smith, Hilary L Smith, Gord Macdonald
Published: 26 October 2021
Environmental Geotechnics pp 1-10; https://doi.org/10.1680/jenge.21.00012

Abstract:
Physical and chemical stability of tailings deposits sometimes have conflicting priorities, yet they are rarely examined congruently in a comprehensive research program. This paper presents an investigation of the combined geotechnical and geochemical behaviour of two samples of diamond ore tailings. Detailed basic and advanced geotechnical laboratory characterization tests were conducted to evaluate the particle size distribution, hindered sedimentation, compressibility, hydraulic conductivity and undrained shear strength of both tailings. Furthermore, duplicate specimens to evaluate the drainage effluent's geochemical compositions were conducted to evaluate compliance with regulatory concentration criteria. The cation and anion concentrations of the expelled water were analyzed at different consolidation stages along with other basic geochemical index properties such as pH, redox potential and electrical conductivity. Both the geotechnical large strain consolidation testing and the geochemical pore fluid collection were performed in a controlled-temperature environment to represent the cold climatic regime at the mine site. Tests were performed in a walk-in freezer with a nominal ambient temperature of 4-5°C. Moreover, the drainage effluent from the large strain consolidation geochemical duplicates was collected using an innovative sampling system that ensured the sample was not exposed to the atmosphere. The geotechnical and geochemical implications of both tailings treatments are discussed.
Lei Zhang, Quansheng Guo, Dong Li, Jiaxing Pan, Chuyuan Wei, Jianxin Lin
Proceedings of the Institution of Civil Engineers - Transport pp 1-25; https://doi.org/10.1680/jtran.21.00024

Abstract:
Due to the complex routes and the dynamic changing factors in transportation, the precise traffic speed prediction is very difficult. Traditional prediction methods only focus on a single monitoring site, without establishing the relationship between different sites, so the precision is inferior. The deep learning method can model the traffic network well, but it exists information loss and the disadvantages of single input data. This paper proposes a Multi-source Spatio-temporal Hybrid Dilated Graph Convolutional Network (MS-ST HDGCN) for forecasting the traffic speed. Graph Convolutional Network (GCN) based on hybrid dilated convolution can extract the influence of adjacent information and capture the dynamic spatial and nonlinear temporal correlation. Considering multisource data will increase the forecasting precision and improve the generalization ability obviously. On real-world dataset, this paper validated the proposed model's performance with other baselines, such as Fully Connected Neural Network (FNN), Convolutional Neural Network (CNN) and Spatio-temporal Graph Convolutional Network (STGCN). The proposed model is superior to those of other models because of considering proximity information which is easily overlooked and multifactorial influence.
Alexander W. Swallow, Brian B. Sheil
Published: 25 October 2021
Abstract:
In this paper, the lateral limiting pressure on rectangular pile groups in undrained soil is explored using two−dimensional finite element modelling. The primary aim of the study is to assess the influence of pile group shape effects on the soil limiting pressured offered by the deep ‘flow-around’ failure mechanism, and associated soil failure mechanisms, considering both a small (four piles) and large (36 piles) group. Additional parameters considered in the modelling include pile spacing and pile-soil interface roughness. The finite element results show that group shape has a significant influence on the behaviour of closely spaced pile groups. In particular, the number of piles parallel to the direction of loading is shown to dominate the lateral bearing capacity factor such that significant increases in capacity efficiency can be achieved by slight modifications to the group shape for a given number of piles. The load-sharing across the group, traditionally defined using p-multipliers, was also shown to be highly non-uniform and dependent on group size, pile-soil roughness and group geometry in addition to the pile spacing. The finite element output is presented in the form of design charts for the determination of group p-multipliers whereas a library of existing design solutions is presented for the calculation of the overall group response.
Published: 25 October 2021
Abstract:
The performance of plate anchors in sand, relative to clay, is not well understood, particularly for the more realistic case of an inclined load. This paper investigates the effect of load inclination on horizontal plate anchors in sand through centrifuge tests and numerical finite element (FE) simulations. The centrifuge tests were performed using rectangular plate anchors in loose and dense sand, at shallow embedment depths with four different load inclinations. The experiments showed that anchor capacity of horizontal plates increased progressively as the load inclination became progressively more horizontal, with anchor capacity under pure horizontal loading being approximately 1.8 times higher than that under pure vertical loading. These experimental observations were also replicated in finite element simulations using a bounding surface plasticity model. Investigation of the underlying failure mechanisms and stress paths showed that the slip planes become longer and the mobilised lateral stresses increase as the load inclination becomes increasingly horizontal, which leads to higher anchor capacities. Finally, the anchor resistance factors from the numerical probe analyses were decoupled into vertical and horizontal components and represented as interaction diagrams, providing a basis for performing hand calculations of anchor capacity for a given embedment depth, load inclination and relative density.
Ahmed S Abdulrasool, Saad F A Al-Wakel
Published: 22 October 2021
Geotechnical Research pp 1-9; https://doi.org/10.1680/jgere.21.00005a

Abstract:
Collapsible soils such as gypseous soil are problematic in geotechnical engineering because their volume changes significantly upon saturation. Foundations constructed on gypseous soil undergo sudden and large settlement if the underlying soil experiences an unanticipated moisture. The present study aims to improve the gypseous soil behaviour so that it can be used to support shallow foundations. To better understand the mechanisms of stabilisation, a laboratory study is performed to evaluate how polyurethane foam in different amounts influences the volumetric strain, collapse potential, and mechanical behaviour of gypseous soil. Physical models of footing on treated gypseous soil with polyurethane foam is examined to determine the effective treatment zone. Based on the obtained results, 3% polyurethane foam can be recommended to improve the gypseous soil behaviour, the particular reason is its effectiveness in decreasing the change in volumetric strain and collapse potential. The present study develops a theoretical approach that depends on a non-dimensional parameter to predict the ultimate bearing capacity for a footing on the surface of treated gypseous soil using the existing conventional theories.
Daniel Fujiwara, Daniel Dass, Emily King, Myriam Vriend, Richard Houston, Kieran Keohane
Proceedings of the Institution of Civil Engineers - Engineering Sustainability pp 1-11; https://doi.org/10.1680/jensu.21.00029

Abstract:
As the infrastructure and built environment sectors shift from traditional economic valuation towards more holistic approaches, projects are being designed, built and evaluated in new ways. An important emerging technique for the economic evaluation of projects is social value measurement. This paper sets out the foundations for the social value measurement techniques that underpin the methods and frameworks developed in central governments and by multilateral and international organisations and describes how these can be adapted to value the broader societal and environmental effects of infrastructure and built environment projects. The paper provides practical evidence of social value measurement in valuing heritage impacts for Stonehenge World Heritage Site as well as presenting a detailed account of the foundations of cost-benefit analysis as a tool for social value measurement and non-market valuation.
Abu Mahmud, Chaity Dev, Moumita Tasnim Meem, Abdul Gafur, Asadul Hoque
Published: 22 October 2021
Green Materials pp 1-9; https://doi.org/10.1680/jgrma.21.00020

Abstract:
So far, epoxy is being extensively used in various engineering and structural applications. Epoxy is non-biodegradable and thus creating ecological problems. Apart from ecological problems, epoxy resin shows poor biofouling prevention in marine, fresh water and offshore environment. To search an eco-friendly solution of this problem, epoxy/chitosan/silver nanocomposites were devised. Chitosan was extracted from the shrimp shells following deacetylation of chitin and silver (Ag) nanoparticles were synthesized using chemical reduction process of silver salts. All the composite samples were prepared utilizing solution casting method. The XRD pattern and FTIR analysis predict the successful creation of silver (Ag) nanoparticles and chitosan respectively. Different mechanical testing elaborate the fact that addition of chitosan into epoxy resin increases hardness, lowering tensile and flexural strength whereas incorporation of silver (Ag) nanoparticles reverses those properties creating analogous mechanical properties with neat epoxy resin. Besides, soil burial biodegradation test has ensured relatively greener characteristics of the final nanocomposites. Herein, the combined effect of chitosan and Ag-nanoparticles on epoxy matrix is reported for the first time.
Kexin Zhang, Dachao Li, Xinyuan Shen, Wenyu Hou, Li Yanfeng,
Proceedings of the Institution of Civil Engineers - Civil Engineering pp 1-9; https://doi.org/10.1680/jcien.21.00116

Abstract:
A comprehensive programme of construction monitoring and load testing was carried out on the recently completed Dongxing Temple pedestrian suspension bridge in China. Construction monitoring showed that the maximum stresses and displacements of the structure were minimal, confirming the accuracy of the design, specification and construction. A load test using water tanks showed that maximum stresses, strains and displacements were lower than design values, confirming the bridge’s elastic behaviour and better-than-expected stiffness. A dynamic test found that the completed bridge’s natural frequency of 0.81 Hz was higher than the design value of 0.53 Hz, both confirming its structural integrity as well as its better-than-expected stiffness. The monitoring test programme could serve as a useful reference for design and construction of future pedestrian suspension bridges.
Dirk Proske, T. Walti, D. Kurmann, Philippe Renault
Proceedings of the Institution of Civil Engineers - Bridge Engineering pp 1-21; https://doi.org/10.1680/jbren.21.00043

Abstract:
Older bridges are often not adequately designed for earthquakes. To enable a structural proof, new methods such as conditional spectra and conditional mean spectra have been developed to estimate seismic hazards more accurately. To quantify the advantage of the latter method for regions with low and moderate seismic hazards, seismic internal forces of four Swiss existing bridges were calculated and compared based on conditional mean spectra and uniform hazard spectra. The bridges were two reinforced concrete and two steel bridges, one of which was used for road traffic and one for railway traffic. The bridge selection was intended to show the validity of the results for different bridges. On average, the computations using conditional mean spectra showed lower internal forces than using uniform hazard spectra. However, the difference was smaller than expected. In addition, the practical application in the engineering office would be very time-consuming with today's software solutions. The calculations also showed that the differences at component level can be significant.
Renata A. González, Miguel A. Mánica, Efraín Ovando-Shelley
Proceedings of the Institution of Civil Engineers - Geotechnical Engineering pp 1-16; https://doi.org/10.1680/jgeen.21.00081

Abstract:
The now-abandoned project for the New International Airport for Mexico City was located at a site on the former Texcoco Lake, where extremely difficult subsoil conditions prevail. In this paper, we look at the behaviour of one of the trial embankments built to test foundation solutions for the runways. We use observational data gathered during 50 months at the so-called reference embankment, where no special foundation or soil improvement techniques were adopted. This paper addresses the performance of this reference embankment, which is interpreted through finite element simulations in which an elasto-viscoplastic constitutive model was implemented in a commercial software to carry out the analyses. The model incorporates key features such a time dependence, long-term deformations, and an anisotropic flow surface. Results provide an assessment of the constitutive description adopted as well as the role of anisotropy in the simulation of the case study.
Miguel A. Mánica, Marcos Arroyo, Antonio Gens, Lluis Monforte
Proceedings of the Institution of Civil Engineers - Geotechnical Engineering pp 1-15; https://doi.org/10.1680/jgeen.21.00001

Abstract:
The use of stress-deformation analyses to evaluate the characteristics of possible static liquefaction events is rapidly becoming the norm for tailings dams exposed to such risk. Ideally, those analyses should be based on constitutive models that incorporate the fundamental mechanics of the problem, that are able to perform robustly in commercial numerical platforms, and are simple to calibrate. This work proposes a model that aims to fulfil that specification. The model presented is a new implementation of CASM (Clay And Sand Model), a model based on critical state concepts able to represent static liquefaction. The model formulation is elaborated to show that all required inputs can be related to familiar concepts such as the critical state line, the state parameter, the normalised undrained peak strength, or the coefficient of earth pressure at rest. The methodology is then illustrated by analysing the failure of the Merriespruit tailings dam, which took place in South Africa in 1994 and was instrumental in the recognition of how widespread liquefaction risk might be in saturated tailings. Numerical analysis of the case evidences how a large static liquefaction failure might have been triggered by a relatively small slope erosion caused by overtopping.
, Suelly Helena De Araújo Barroso, Samuel De Almeida Torquato E Silva
Proceedings of the Institution of Civil Engineers - Geotechnical Engineering pp 1-8; https://doi.org/10.1680/jgeen.20.00055

Abstract:
The decreasing supply of soils with geotechnical parameters suitable for pavement designs are visible problems in our environment. In order to establish more efficient designs and adequate construction criteria, it is essential to understand the performance of materials. This is a study of the permanent deformation (PD) of soil used in pavement layers, obtaining prediction models of PD and modulus of resilience (MR), in addition to the design of pavement structures using mechanistic-empirical (CAP3D) and empirical (DNIT) methods. The multistage repeated load triaxial (RLT) test was used as well as numerical analyses of stresses and displacements using the CAP3D program. The results showed that both the test procedure and the prediction models performed satisfactorily in obtaining PD behavior. Moreover, designs using the methods adopted resulted in distinct structures, that is, thickness different from the granular pavement layers. It was concluded that the model and test procedure exhibit significant potential for characterizing and modeling the permanent deformation of granular materials.
Jessica Sandberg, David Bishop, Louisa Man, David A. Smith
Proceedings of the Institution of Civil Engineers - Bridge Engineering pp 1-11; https://doi.org/10.1680/jbren.21.00022

Abstract:
This paper sets out the challenges from the perspective of the designer associated with the construction of the River Dee bridge built by the balanced cantilever method. The importance of managing the construction sequence and its impact on both the design and programme are discussed. Monitoring and managing the loads in the temporary works were crucial to ensuring the stability of the structure. The issues associated with the temporary jacking system and the monitoring adopted are also considered.
Hugh D. Miller, , Sara Mesgari,
Magazine of Concrete Research pp 1-13; https://doi.org/10.1680/jmacr.20.00366

Abstract:
The ability of fibres to resist crack growth in fibre-reinforced concrete (FRC) can be significantly influenced by the fibre/matrix bond. This investigation reveals surface treatment of fibres as a viable technique to develop a uniform bond along the fibre/cement interface to resist growth of microcracks and thereby complement the physical restraint against pull-out provided by fibres’ shape and friction. Previous reports have shown effective chemical treatment of glass, carbon, and polypropylene fibres. However, research into chemical surface treatment processes for steel fibres, the most common in concrete, is scarce and focused on corrosion and dispersion, rather than the fibre/matrix bond. Here, a silane treatment technique is proposed to strengthen the steel fibre/cementitious matrix bond. Surface energy measurements and XPS demonstrate the effectiveness of this treatment. Fibre pull-out tests conducted on silane-treated fibres show an apparent increase in pull-out energy, accompanied by a delay in reaching the peak load, compared to untreated fibres, suggesting increased resistance to crack initiation and growth. Furthermore, the results indicate improved flexural strength and direct tensile strength of mortar reinforced with silane-treated fibres compared to untreated fibres. The improvements are further corroborated by results from restrained drying shrinkage and volume of permeable voids.
C R Neeraj,
Published: 19 October 2021
Geotechnical Research pp 1-13; https://doi.org/10.1680/jgere.21.00013

Abstract:
The current practices of factor of safety computation of pile-stabilised slopes majorly depends on either the extension of methods for normal slopes with the pile-contribution introduced as an additional term or the finite element modelling. Extending conventional methods to analyse pile-stabilised slopes fail to capture the key mechanisms like soil arching, gradual transfer of resistance offered by the pile through the slope, change in slip surface due to introduction of piles, etc. In this paper, a new algorithm is proposed to compute the factor of safety of pile-stabilised slopes, in which, the Morgenstern-Price method is modified to incorporate the effect of pile. The resistance offered by pile is obtained using a pressure-based method which considers the soil arching effect in horizontal and vertical directions. The gradual propagation of this resistance offered by pile is incorporated through an iterative procedure unlike the conventional methods. The algorithm considers the change in slip surface due to introduction of the pile. The factor of safety values computed using the proposed algorithm were found to be in close agreement with that obtained from finite element modelling. In addition, a simple technique to determine the optimal location of stabilising piles and pile-spacing is also presented.
Prapti Giri, Kam Ng, William Phillips
Published: 19 October 2021
Geotechnical Research pp 1-10; https://doi.org/10.1680/jgere.21.00014

Abstract:
Topple is a common rock slope failure and usually the predecessor of a rockfall that depends on the slope and rock geometries. This paper presents a laboratory simulation and field generation of a single-column rock topple failure. Innovative Inertial Measurement Unit (IMU) sensors were used to collect three-dimensional acceleration and angular velocity data during four laboratory experiments to understand and characterize general toppling behaviors. Topple is identified by the gradual change in at least two gravity accelerations, the continuously increase in at least one of the angular velocities and a significant change in the linear acceleration in the direction of toppling. The field experiment showed similar sensor data patterns to those observed from the laboratory experiments. An isolated-block stability analysis of a single-column topple provides the basis for incorporating the IMU sensors into the development of future monitoring and early warning system.
Xuan Hien Ta, Babak Abbasi, Balasingam Muhunthan, Dong-Hwa Noh, Tae-Hyuk Kwon
Published: 18 October 2021
Environmental Geotechnics pp 1-10; https://doi.org/10.1680/jenge.21.00107

Abstract:
This study investigates changes in low-frequency attenuation responses of sands during microbial formation of soft viscous biofilms, or extracellular polymeric substances (EPS). The resonant column experiments were conducted with two model bacteria Shewanella oneidensis MR1 and Leuconostoc mesenteroides, while monitoring changes in the wave velocities and damping ratios associated with EPS formation in sands. The results show that the accumulation of soft, viscous EPS hardly changes the wave velocities, both the shear and flexural modes. By contrast, the low-frequency attenuations, both torsional and flextural damping ratios, show significant increases with the accumulation of highly viscous EPS. It is found that contribution of EPS to seismic responses of water-saturated sands is mainly limited to the pore fluid component, causing additional energy dissipation during wave propagation, but with no or minimal impact on skeletal stiffness or no involvement in seismic stress transfer. With these unique and unprecedented low-frequency seismic data of biofilm-associated sands, the results suggest that formation and accumulation of soft, viscous EPS or biofilm by bacterial activities can be detected by monitoring seismic attenuation and can also alter the seismic attenuation responses of sands, such as the cases under earthquake loading or blast-induced compaction.
V. Sivakumar, S. Walker, A. Ewart, C. Doherty, S. Donohue
Proceedings of the Institution of Civil Engineers - Ground Improvement pp 1-33; https://doi.org/10.1680/jgrim.20.00013

Abstract:
Soil mixing are considered to be effective for a range of applications and the required design specifications can be achieved by varying the percentage of additives, commonly cement and lime. This paper describes the results of a comprehensive laboratory investigation, involving the assessment of cement/lime treatments for improving the geotechnical characteristics of three different soft clays, kaolin, sleech and Belfast clay. The investigation is coupled with an assessment of the durability of the treated soil and the effects of water-ingress after treatment. Observations have shown that that the large strain Young's modulus increased significantly with curing period after 28 days. The evolution of small strain shear stiffness GMAX was progressive, and all soils exhibited a steady increase in stiffness, the rate of which reduced as the curing period approached 7 days. The relative increase in strength of the different soils was highly variable. It is postulated that suction was one of the contributors to undrained shear strength gain. When allowed access to water, strength and stiffness increased, although at a much reduced rate. The stress-strain behaviour of kaolin also changed from ductile untreated to highly brittle as the curing period approached 90 days.
Kulvendra Patel, S.K. Singh
Proceedings of the Institution of Civil Engineers - Waste and Resource Management pp 1-23; https://doi.org/10.1680/jwarm.21.00018

Abstract:
Various municipal solid waste management technologies were evaluated using life-cycle analysis. The study aimed to compare different municipal solid waste management approaches: landfill with composting, anaerobic digestion combined with landfill, incineration, and anaerobic digestion combined with incineration. The Impact 2002+ approach and Simapro 9.1.1.1 software using the Ecoinvent v3.6 database were used to compare environmental impacts. The study showed that landfill with composting had the highest environmental impact due to its high potential of global warming and depletion in ecosystem quality, while other scenarios showed reduced impacts. Anaerobic digestion combined with incineration was found to have least environmental impact, mainly because of energy recovery from anaerobic digestion. The goal of the study was to determine more environmentally sustainable alternatives for municipal solid waste management using life-cycle assessment within the system boundary.
D Vijayakumar, Athira Gopinath, Bahurudeen A, Prakash Nanthagopalan
Proceedings of the Institution of Civil Engineers - Engineering Sustainability pp 1-12; https://doi.org/10.1680/jensu.21.00076

Abstract:
The production of cement is a carbon-intensive process. Replacing ordinary Portland cement with industrial by-products can bring down the carbon footprint associated with cement production. Various industrial residues are currently used as alternative cementitious materials in this regard. However, developing a low carbon composite cement with different pozzolans alter the packing density, which influences its properties. Although studies have been conducted on the use of fly ash and slag at lower cement replacement levels, studies on the packing density and strength of ternary and quaternary composite cements with higher replacement levels are limited. In this study, fly ash, blast furnace slag, ultra-fine fly ash and ultra-fine slag are used as a partial replacement for cement in various proportions. Out of the 51 mixtures tested in the study, 11 combinations were selected based on the maximum packing density for further investigations on fresh and hardened properties to arrive at the best trade-off between cement reduction and desired properties. The early age strength is influenced by the packing density of composite cements whereas, the later age strength is found to be highly governed by the amount of OPC and the pozzolanic potential of the industrial by-products.
Hirochika Hayashi, Hijiri Hashimoto, Osamu Hatakeyama, Yuichiro Kido
Proceedings of the Institution of Civil Engineers - Ground Improvement pp 1-11; https://doi.org/10.1680/jgrim.20.00017

Abstract:
This paper discusses the strength characteristics of cement-treated soil cured at extremely low temperatures ranging from 5°C to −20°C. When cement stabilisation is used to improve soft ground in cold regions with severe winter conditions, there is the possibility that the low curing temperature will hinder the solidification of cement-treated soil. To examine how extremely low curing temperatures affect the strength of cement-treated soil, a field study of cement stabilisation executed in the severe winter of Hokkaido, Japan, is presented in the first part of this paper. This study reveals that extremely low air temperatures prevented the shallow part of the cement-treated ground at the site from solidifying sufficiently. Then the influence of extremely low curing temperatures on the strength characteristics of cement-treated soil is discussed, based on the results of laboratory cement mixing and other tests. It is found that cement-treated soils cured at lower temperatures (−20°C, −5°C, 0°C, and 5°C) have lower unconfined compressive strengths (UCSs) than that cured at 20°C (a standard curing temperature according to the Japanese Geotechnical Society Standard). Cement-treated soils cured at −5°C and −20°C showed almost no gain in UCS. For cement-treated soils cured at 0°C or above, the UCS increased with an increase in maturity. Finally, based on the above experimental results, we proposed points to be noted in the construction of cement stabilisation in winter in cold regions.
Pugalanthipandian Sankaralingam, Poornimadevi Sakthivel, Priscilla A.S., Abirami Periyasamy, Jenifa Begam Rahumathullah, Vijayakumar Chinnaswamy Thangavel
Bioinspired, Biomimetic and Nanobiomaterials pp 1-8; https://doi.org/10.1680/jbibn.21.00025

Abstract:
The objective of the work is to investigate the influence of fluoride in the bioactivity of phosphate bio-glass to utilise in bone tissue engineering. The fluorophosphate bio-glass system was formulated by varying fluoride content in phosphate-based glass 45 P2O5-(30-X) CaO-25Na2O-XCaF2 (X = 0, 1.25, 2.5, 3.75, and 5.0) using melt quenching technique. The elemental composition and fluoride retention in the prepared material was investigated by X-ray Photoelectron Spectroscopy. The bioactivity test in simulated body-fluid (SBF) exhibited apatite layer and its bone bonding ability which was characterized by XRD patterns and FTIR spectra. The viability of human gastric adenocarcinoma (AGS) and MG-63 cells of the bio-glass confirmed the nontoxic nature. In vivo studies demonstrated the conversion of the fluorophosphate glass to bone in the femoral condyle of the rabbit. After ten weeks, SEM_EDAX and CLSM examinations reveal the resorption rate, bone-glass interface qualitatively and quantitively. Consequently, the biocompatible and bioresorbable nature of the fluorophosphate bioglass can be exploited as a potential bone graft substitute in the near future.
Proceedings of the Institution of Civil Engineers - Municipal Engineer pp 1-15; https://doi.org/10.1680/jmuen.20.00033

Abstract:
Public value capture is defined as the capture of the increase in value that occurs as a result of plan decisions, changes in land-use functions and/or infrastructure investments. Despite the high-value capture capacity of urban renewal projects, value capture cannot be achieved in all urban renewal areas depending on differences in the projects. The aim of this study is to examine public value capture capacity in a renewal project area centrally located, offering high housing demand and supply, and enabling high development rights. The study is based on a scenario work in the Fikirtepe Urban Renewal Project in Istanbul (Turkey). In this study, public value capture capacity is examined by taking into consideration each stage in the urban renewal process. In the process, ‘land contribution’ from the land of property owners, and ‘the infrastructure participation fee’ are taken according to plan notes and these can be evaluated within the scope of public value capture. However, these are limited to only 1.8% of the total real estate value. The capturing of the public value remained quite limited in an urban renewal area such as Fikirtepe that has a high-value capture capacity. This hinders the economic viability of urban renewal projects.
Wen-Yao Lu, Tung-Ming Lee, Hsueh-Cheng Ko, Jui-Ting Tsai
Magazine of Concrete Research pp 1-36; https://doi.org/10.1680/jmacr.21.00221

Abstract:
This study reports the test results for eight high-strength concrete square pile caps. The main variables are area of flexural steel bars and the configuration patterns of flexural steel bars. The test results show that the ultimate load on the pile cap increases as the total area of the flexural steel bars increases. The load-displacement curves are not significantly affected by an increase in the total area of the flexural steel bars. For a specific area of flexural steel bar, the ultimate load on pile caps in a bunched square reinforcement pattern is no greater than that for pile caps in a grid reinforcement pattern. Pile caps in a bunched square reinforcement pattern exhibit no significant mechanical advantage over pile caps in a grid reinforcement pattern. Square pile caps in a grid reinforcement pattern perform better because this pattern is more conducive to concrete casting than a bunched square reinforcement pattern. The softened strut-and-tie (SST) model more accurately predicts the ultimate load for pile caps than the ACI Sectional method for various shear span-to-depth ratios and compressive strengths of concrete. The ACI Sectional method overestimates the flexural strength of the square pile cap.
A.R. Pourkhorshidi, J. Sobhani, A.A. Ramezanianpour
Published: 18 October 2021
Advances in Cement Research pp 1-28; https://doi.org/10.1680/jadcr.21.00078

Abstract:
Pozzolans are available in natural resources as raw materials potentially applicable in the cement and concrete industries. Proper identification and exploration methods are very crucial regarding the technical and economical purposes. In this paper, a two-phase study employed based on the geochemical data processing and experimental investigations. Chemical and petrography of natural pozzolans (NPs) were utilized to develop the proposed method. This method proposes three geochemical indexes including the limiting values of SiO2/CaO, alumina saturation and alkali content to qualify the natural pozzolan regarding the supplementary cementetious requirements. Then based on ASTM C618 and EN 196-5 standards and complementary tests, the chemical and physical properties of two natural pozzolans were assessed to validate the proposed method. The results showed that the proposed method could be used as a robust method to identify the natural pozzolans as a direct method.
Greg Watts, Anthony Higham, Rukaya Abowen-Dake
Proceedings of the Institution of Civil Engineers - Engineering Sustainability pp 1-7; https://doi.org/10.1680/jensu.21.00052

Abstract:
The need to create social value during the delivery of infrastructure projects is growing in importance. However, it can be argued that the initial expectations of stakeholders at the outset of projects are not being achieved once the project is delivered. At present there is no consistent and widespread methodology for the successful delivery of social value outcomes. The problem therefore exists that despite infrastructure having the potential to play a transformative role in the creation of social value; current outcomes are arguably not as effective as they could be. The aim of this research is to understand how social value is currently created and delivered in gas infrastructure works. Through the use of five case studies of small community-based gas infrastructure projects that are part of a wider nationally significant network, the tensions at the heart of social value delivery are revealed. How the social value agenda moves through project stages is revealed as key to minimising social value barriers and ensuring successful social value delivery. The results serve as important lessons for ensuring infrastructure projects effectively create and deliver desired social value outcomes.
Guilherme Faria Souza Mussi de Andrade, Bruno Teixeira Lima, Ana Cristina Castro Fontenla Sieira
Proceedings of the Institution of Civil Engineers - Ground Improvement pp 1-34; https://doi.org/10.1680/jgrim.21.00009

Abstract:
Laboratory investigations using balloon tests were performed on normally consolidated kaolin samples to investigate their behavior during and after the balloon expansion. The tests were carried out to simulate a soft soil improvement technique called CPR Grouting (Radial Deep Consolidation). The results allowed estimations of the parameters used in the design method, such as the consolidation potential, and evaluating the generation of pore pressures, injection pressures, post improvement deformation and optimized expanded volume. It was observed that the consolidation potential was extremely dependent on the substitution ratio. The tests satisfactorily reproduced the behavior of the technique and represent a new device for geotechnical engineers, especially for those concerned with the improvement of soft soils.
Bartolomeo Pantò, Claudia Casapulla, Ivo Caliò
Proceedings of the Institution of Civil Engineers - Engineering and Computational Mechanics pp 1-55; https://doi.org/10.1680/jencm.21.00010

Abstract:
The numerical modelling of the torsion behaviour of masonry block interfaces is a key aspect for the assessment of the out-of-plane response of masonry walls. Nevertheless, it still represents a challenging computational issue due to the high non-linear coupling between the torsion and other internal forces (shear, bending moment and axial load), which rigorously requires the adoption of complex 3D non-linear constitutive laws. Some limit analysis-based approaches, proposed in the specific literature, represent efficient and reliable numerical tools for predicting the ultimate states of brick masonry structures subjected to combined in-plane and out-of-plane actions, while involving complex torsion loads and combined actions. This paper originally introduces a simplified discrete inelastic interface able to simulate the non-linear torsion-shear behaviour of masonry contact joints, within the context of static incremental analysis. The more general mechanical behaviour of the interface is ruled by six degrees of freedom and is governed by four rotating links (RL), whose actual orientation is updated during the step by step analysis, by taking into account the current position of the twisting centre of the interface. The incremental torsion-shear capacity curve and the corresponding ultimate domains obtained by the proposed model are compared with the ultimate load limit analysis predictions and with some experimental data available in the literature. The results highlight the ability of the new discrete interface to effectively reproduce the full non-linear behaviour of masonry contact interface subjected to different loading combinations.
Bojiong Zhang, Yonggang Lin, Wenting Chen, Hang Liu, Wei Li, Yong Sun, Di Zhang
Proceedings of the Institution of Civil Engineers - Energy pp 1-41; https://doi.org/10.1680/jener.21.00086

Abstract:
In recent researches, the “Cyclops” effect of the light detection and ranging (LiDAR) system has been revealed, which presents the shortcoming of LiDAR measurement. The “Cyclops” effect means that the LiDAR system can only measure wind speed at one point in space at a certain moment. Thus, for the wind turbine control concern, considering the wind information at the rotor plane with time-stamps can be more precise. Taylor's frozen hypothesis is commonly used in the application of LiDAR for the rotor effective wind speed estimation. It assumes that the wind moves with the speed unchanged when getting close to the turbine. Thus, the time of the wind transmission can be easily calculated. In fact, the wind speed attenuates along the process from the LiDAR measured point to the rotor plane because of the induction zone. Without considering the attenuation effect, the wind turbine is controlled directly by LiDAR measured data with constant time delay, which weakens the effectiveness of LiDAR. In this paper, a novel LiDAR data pre-processing method is demonstrated for rotor effective wind speed estimation. In this method, the Medici induction zone model is further refined with initial wind speed and different measured distances for accurate estimation. Furthermore, it makes online variable time delay of LiDAR data computation possible with the solution of the separated differential equation. Finally, the novel method is fully verified through field test results. The results show that the initial wind speed affected the attenuation factor within 1.4 times rotor radius and the error between the experimental value and the theoretical value is within 0.1m/s.
Ronak Mehrabi, Mohammad Hassan Baziar, Ali Nabizadeh, Wen Yi Hung
Proceedings of the Institution of Civil Engineers - Geotechnical Engineering pp 1-37; https://doi.org/10.1680/jgeen.21.00134

Abstract:
Using discrete element numerical method (DEM), the present paper aims at simulating the interaction between underground tunnel in sand deposit while a reverse fault rupture propagates from the bedrock to the ground surface. Propagation pattern of fault ruptures and the deformation profiles of the soil at the ground surface are discussed in detail considering the effect of tunnel location and tunnel rigidity. Numerical simulations are verified against a set of centrifuge laboratory experiments. The DEM simulations are compared with a set of finite elements (FEM) numerical models and the efficiency of each method in simulation of fault rupture-tunnel interaction is discussed for the first time. Both DE and continuum numerical models are effective complementary tools capable of providing valuable insight into tunnel-fault rupture interaction mechanisms, however, the findings indicate a better correlation between DEM simulations and the experimental results.
Xianxi Liu, Chuan Tian, Hongying Hou, Jian Lan
Published: 18 October 2021
Surface Innovations pp 1-9; https://doi.org/10.1680/jsuin.21.00026

Abstract:
Ferrous gluconate has been widely used in the treatment of iron deficiency anemia due to good therapeutic effect, high utilization and low toxicity. However, the improper management of waste expired ferrous gluconate may also result in the flow of excessive Fe2+ into the environment, which may do harm to the organisms in the world. For this purpose, expired waste ferrous gluconate was firstly recycled in form of CoFe2O4/C by a fluid method and a post-calcination at the different temperatures of 400°C and 500°C, and the effect of the calcination temperature on the morphology, micro-structure and super-capacitive performances was also studied. The results showed that the obtained dark brown CoFe2O4/C powders exhibited the loose mesoporous tremella-like morphology and satisfactory electrochemical super-capacitive performances, in which CFO-400 delivered higher electrochemical performances than CFO-500 due to lower crystalline, higher electrical conductivity and higher surface area. For example, the specific capacitance of CFO-400 electrode was as high as about 503 F/g at 0.5 A/g in the three-electrode system, and it remained 106 F/g after 5000 cycles at 5.0 A/g with 86 % capacity retention in the symmetrical two-electrode capacitor, showing the satisfactory long cycle stability. No doubt, these results provided a new successful recovery strategy for the circular economy of expired ferrous gluconate.
Yuan Gao, Hongwen Jing, Zefu Zhou, Xinshuai Shi, Zhenlong Zhao
Published: 18 October 2021
Advances in Cement Research pp 1-24; https://doi.org/10.1680/jadcr.21.00112

Abstract:
A theoretical model is presented to predict the water permeability of nano-reinforced cement pastes from its pore structure, including the pore size distribution, pore interconnection, porosity and microcracks. The model is based on the General Effective Media (GEM) theory and multifractals, which considers both the bridging roles in microcracks and capillary pores and the filling roles in the nano gel pore of nano-admixtures reinforcing cement pastes. For comparison, a hybrid graphene oxide, multi-walled carbon nanotube was selected as a nano-reinforced material mixed into cementitious composites, for the water permeability experiments. The calculated results show good agreement with the experimental measurements, decreasing the maximum error from 67.8% to 9.7%, compared with the previously proposed GEM theory. Moreover, the theoretical calculation results suggest that the reinforcing roles of nano-admixtures in cement paste to strengthen the permeability-related properties may be mainly due to the bridging effects in microcracks and capillary pores, rather than filling the nano gel pores. The findings of this study enrich our understanding of the mechanism of nano-admixture reinforcing cement-based materials and can measure the permeability of cementitious composites directly, instead of using time-consuming methods.
Kathia Fabritius-Vilpoux, Joachim Enax, David Mayweg, Frederic Meyer, Michael Herbig, Dierk Raabe, Helge-Otto Fabritius
Bioinspired, Biomimetic and Nanobiomaterials pp 1-12; https://doi.org/10.1680/jbibn.21.00017

Abstract:
Enamel and dentin are susceptible to acids from food sources leading to dental erosion, a global problem affecting millions of individuals. Particulate hydroxyapatite (HAP) on the tooth surface can influence the effects of acid attacks. Standardized bovine enamel and dentin samples with artificial saliva are used in an in vitro cyclic demineralization-remineralization protocol to analyze the structural changes experienced by tooth surfaces using high-resolution scanning electron microscopy and to evaluate the potential of a HAP-based oral care gel in the protection of teeth from erosive attacks. The interfaces between HAP particle and enamel HAP crystallites are investigated using focused ion beam preparation and transmission electron microscopy. The results show that erosion with phosphoric acid severely affects enamel crystallites and dentin tubules, while artificial saliva leads to remineralization effects. The HAP-gel forms a microscopic layer on both enamel and dentin surfaces. Upon acid exposure, this layer is sacrificed before the native tooth tissues are affected leading to significantly lower degrees of demineralization compared to the controls. This demonstrates that the use of particulate HAP as a biomaterial in oral care formulations can help to protect enamel and dentin surfaces from erosive attacks during meals using a simple and effective protection principle.
Kuan-Hung Lin, Chung-Chin Yang
Magazine of Concrete Research pp 1-36; https://doi.org/10.1680/jmacr.21.00110

Abstract:
This study focused on the effects of changing the types and surface areas (Sa) of activated materials on the compressive strength of Ground Granulated Blast-furnace Slag (GGBS) cement (GGBS > 60%). This study is divided into two parts. The first part involves the selection of activated materials. The compressive strength results show that gypsum improves the early strength of GGBS cement more effectively that does sodium silicate or NaOH. The gypsum activators increase GGBS activity through sulfates, which generates ettringites and C-S-H to increase compressive strength. Chemical analysis shows that the SO3 in GGBS cement has more stable compressive strength at 6%–8%. The second part of this study is on the influence of Sa. Gypsum was used as a strength activator. The SO3 in GGBS cement was controlled at 6.5%±0.5%, and Sa was adjusted as the variable. Linear regression analysis shows that the change in GGBS cement Sa (MSa) is positively correlated with compressive strength. The MSa can be estimated according to the Sa and quantity of ingredients used for the study results (cement, GGBS, and gypsum). The compressive strengths of GGBS cement at various curing ages can be predicted with MSa.
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