The purpose of this study was to Analyze the characteristics of theaggregates used in concrete mixtures and analyze how muchincrease in compressive strength of concrete with a variation ofnickel slag substitution 0%, 5%, 15%, 25% compared with normalconcrete. The characteristics of the material examined are watercontent, sludge content, specific gravity and absorption, volumeweight, abrasion with los angeles machines, and filter analysis.While the large increase in compressive strength of concrete can betested at the age of 7 days, 14 days, 28 days and 35 days. From the results of the analysis of the characteristics of nickel slagwaste in concrete mixes meet the test standards in concretemixtures, with a moisture content of 0.86%, sludge content of 0.44%,specific gravity of 2.94 gr / cm3, volume weight of 1.76 gr / cm3,abrasion 36.07%. And a large increase in compressive strength ofconcrete with a variation of nickel slag substitution of 0%, 5%, 15%,25% compared to normal concrete is increasing. The highestpercentage increase in concrete compressive strength is found inconcrete compressive strength between a variation of 15% with avariation of 25% at 14 days concrete age, with a percentage increasein value of 13.13%.