Mechanical properties and microstructure of self-compacting concrete with high volume of recycled coarse aggregate and supplementary cementitious material
Mechanical properties and microstructure of self-compacting concrete with high volume of recycled coarse aggregate and supplementary cementitious material
A total of 9 recycled aggregate self-compacting concrete(RA-SCC)mixes were produced by substituting natural aggregates and cement with supplementary cementitious material(SCM)and recycled coarse aggregate(RCA),respectively.The influences of RCA and SCM on the mechanical properties of RA-SCC were assessed,including cube compressive strength,axial compressive strength and elastic modulus.Based on the regression analysis of a large number of test results,the age compressive strength formulas and elastic modulus formulas were proposed.Furthermore,scanning electron microscope and X-ray diffraction were implemented to study the microstructure of RA-SCC.The results show that incorporating SCMs with a combination of 20%FA,20%ground granulated blast furnace slag(GGBFS)and 10%silica fume(SF)compensated for the detrimental effect of RCA on mechanical properties.The calculated values of the two formulas were in good agreement with the measured values.Microstructure analysis confirmed the reasons of improvement,which is mainly attribut-ed to the pozzolanic reaction of SCMs by replacing cement with a combination of fly ash(FA),GGBFS and SF,resulting in a stronger in-terfacial transition zone and more compact cement matrix.
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