Influences of rock types and rock powder contents of manufactured sand on the properties of concrete

The influences of rock types and rock powder contents of manufactured sand on the properties of concrete are examined in this study. With a fixed content of rock powder, the effect of rock types is little on the slumps of concrete, but significant on the air content and compressive strength. Granite manufactured sand concrete has the greatest air content, 1.4% greater than that of limestone on an average. The air content of sandstone concrete ranks the second, only 0.5% greater than that of limestone concrete on an average. The compressive strength of these manufactured sand concretes takes an order of limestone > sandstone > granite. The strengths of sandstone concrete at 7d and 28d ages are 0.96 and 0.84 times of those of limestone concrete, and the granite concrete 0.88 and 0.80 times, respectively. For all the three concretes, an increase in rock powder content causes linear decrease in air content and slump, and linear increase in compressive strength. In the condition of 10% increase in rock powder content, air content is decreased by 2.5%, slump decreased by 5.5cm, and strength increased by 15.8%. Copyright.