Study on the Effect of Super-absorbent Polymer on the Self-shrinkage Performance and Shrinkage Prediction of Cementitious Materials Containing Recycled Aggregates
To study the shrinkage properties of cementitious materials containing recycled aggregates and to reduce the shrinkage,the effects of high absorbent resin SAP admixture(0.1%-0.3%)and SAP particle size(30,60 mesh)on the self-shrinkage performance of cementitious materials with different recycled aggregate admixtures(0,50%,100%)at ultra-early age,early age and long age were investigated using a non-contact self-shrinkage instrument.The results showed that:1)the self-shrinkage of recycled cementitious materials in the ultra-early(within 3 d)stage could reach 53.1%～91.6%of the total shrinkage,and the control effect of self-shrinkage was closely related to the amount of recycled aggregate admixture,SAP admixture and SAP particle size;2)100%recycled aggregate could increase the self-shrinkage rate in the ultra-early(3 d)stage and long-term(90 d)stage by 53%～118%and 36.2%-78.5%,respectively;3)Under 50%recycled aggregate admixture,0.1%～0.3%SAP admixture can reduce 90d self-shrinkage rate by 32.6%～53.9%,while under 100%recycled aggregate admixture,only 0.3%SAP can reduce the shrinkage effect;4)The reduction effect of SAP mesh on self-shrinkage is highly sensitive by the amount of recycled aggregate admixture;5)BP neural network can accurately predict the relationship between self-shrinkage and recycled aggregate dosage,SAP dosage,and SAP particle size at different ages,based on which an optimized design strategy for low-shrinkage recycled cementitious materials is proposed.
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