Abstract
The significant difference between recycled aggregate and natural aggregate is the content of the attached mortar layer. With the increase of the replacement rate of recycled aggregate, the shrinkage and creep of recycled aggregate concrete is significantly increased. In this paper, 180-day shrinkage and creep tests of recycled aggregate concrete with different water–cement ratios were designed in order to analyze the effect of the substitution rate and water–cement ratio on shrinkage and creep properties. The results show that the shrinkage strain of recycled aggregate concrete with a substitution rate of 50% and 100% at 180 days is 26% and 48% higher than that of ordinary concrete, respectively, and the growth of group II is 22% and 47%, respectively. When the load was 180 days old, the creep coefficient of recycled aggregate concrete with a substitution rate of 50% and 100% in group I increased by 19.6% and 39.6%, respectively compared with ordinary concrete, and group II increased by 23.6% and 44.3%, respectively. Based on the difference of adhering mortar content, the creeping increase coefficient and shrinkage increase coefficient of the attached mortar were proposed, and a shrinkage and creep model of recycled aggregate concrete was established. When compared with the experimental results, the model calculation results met the accuracy requirements.
Highlights
The recycling of construction waste (RCW) refers to the crushing of construction waste to obtain different types of products and reuse them as resources
The results show that the creep properties of recycled base concrete with a low water–cement ratio are significantly affected by recycled coarse aggregate (RCA), and the establishment of a prediction model for the creep of recycled base concrete needs to consider the influence of the water–cement ratio
At 180 days, compared with ordinary concrete, the shrinkage of group I Recycled aggregate concrete (RAC) with a substitution rate of 50% and 100% was increased by 26% and 48%, respectively, and the group II RAC was increased by 22% and 47%, respectively
Summary
The recycling of construction waste (RCW) refers to the crushing of construction waste to obtain different types of products and reuse them as resources. Brito et al [19] studied the Gómez-Soberón test data, and the concrete creep coefficient was corrected considering the difference in apparent density or water absorption between recycled aggregate and natural aggregate. Luo et al [23] proposed a model for the shrinkage and creep of RAC that considered the two factors of the regenerated aggregate grade and substitution rate, and the regression coefficient was used to obtain the influence coefficient expression. The existing method of proposing the correction coefficient by a certain influencing factor fails to establish the prediction model of the shrinkage and creep of RAC. For the effect of recycled aggregate-attached mortar on concrete shrinkage and creep, there is a lack of predictive models with universal significance. Based on the two increasing factors, the shrinkage and creep model of RAC is established, and the applicability of the model is checked
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