Strength, shrinkage and creep of concrete including CO2 treated recycled coarse aggregate

Abstract

Strength development and long-term behaviour of recycled aggregate concrete (RAC) were investigated. Recycled coarse aggregate (RA) replaced natural coarse aggregate (NA) by 30%, 50%, and 100% by vol. in this study while natural fine aggregate was always used. For the investigation of strength development, 3, 7, 28, 56, 90, and 180 day compressive strengths and 28 day split tensile strength and flexural strength have been determined. Shrinkage and creep behaviours of RAC with 0%, 50%, and 100% RA replacing NA have been studied up to 6 months. The compressive strength of RAC was not affected by 30% replacement, but it was reduced by 50% and 100% replacement. Split tensile strength was not affected significantly while flexural strength was reduced with increasing amount of replacement. Shrinkage strain of RAC with 50% RA was similar to that of natural aggregate concrete, but shrinkage increased with 100% replacement. Specific creep of RAC with 100% RA increased by 38% over that of natural aggregate concrete. The strength of concrete with CO2 treated RA was lower than that of concrete with RA without CO2 treatment. Shrinkage of RAC with and without CO2 treatment was similar, while the creep of RAC with CO2 treated RA was smaller than that of RAC including RA without CO2 treatment.

The Workability and Crack Resistance of Natural and Recycled Aggregate Mortar Based on Expansion Agent through an Environmental Study

“…There are many reasons that may explain the shrinkage compensating mechanism of EXP used in RAM and NAM. Firstly, the EXP cement which forms ettringite occurs in the early stage of cement hydration, as shown in Formula (1). It is suitable for function in lower temperature under 60 • C. The solid volume of the system increases by almost 120% before and after the reaction [32][33][34].…”

“…Such a huge output of construction waste not only brings trouble to people's daily life, but also destroys the ecological environment. It will not only occupy a lot of land, but also destroy aquatic ecology [1][2][3].…”