Compressive and shrinkage behaviors of recycled aggregate concrete containing recycled sand from weathered residual soil of granite and MgO expansion agent

作者：Wu, Bo^*; Cao, Huixuan; Wu, Qianlan

来源：Journal of Building Engineering, 2023, 68: 106154.

DOI：10.1016/j.jobe.2023.106154

• Recycled coarse aggregate
• Weathered residual soil of granite
• MgO expansion agent
• Compressive behavior
• Shrinkage behavior

The simultaneous use of recycled coarse aggregate and recycled sand from weathered residual soil of granite to prepare recycled aggregate concrete can further promote the recycling of construction and demolition waste. However, the shrinkage performance of concrete containing both recycled coarse aggregate and recycled sand remains unknown. In this study, compressive and shrinkage tests were conducted on recycled aggregate concrete with recycled coarse aggregate, recycled sand and MgO expansion agent (MEA). The compressive and shrinkage behaviors suggest an optimum MEA dosage of 6%. The results showed that: (a) increasing recycled sand replacement ratio (30-70%) has little effect on compressive behaviors of concrete, but including 50% recycled coarse aggregate decreases the compressive strength, as does increasing MEA dosage (4-8%); (b) the autogenous shrinkage of concrete decreases with the addition of 50% recycled coarse aggregate, but it increases with increased recycled sand replacement ratio, this can be significantly compensated by incorporating MEA; (c) the drying shrinkage of concrete increases with the adoption of 50% recycled coarse aggregate and increased recycled sand replacement ratio. Adding MEA compensates, with the compensation increasing with its dosage. Finally, models for predicting autogenous and drying shrinkage of recycled aggregate concrete with recycled coarse aggregate, recycled sand and MEA are proposed.