Abstract
As the first batch of products after the resource utilization of construction and demolition waste, low-grade recycled aggregate (RA) has not been fully utilized, which hinders the development of the comprehensive recycling industry of construction waste. Therefore, this paper studies the mechanical properties of porous concrete (POC) with low-grade RA. An improved relationship between porosity and compressive strength of brittle, porous materials is used to express the compressive strength of POC with recycled aggregate (RPOC), and the prediction for compressive strength of porous concrete with low-grade RA is constructed by analyzing the mechanism of compressive damage. The results show: the compressive strength of porous concrete decreases with the addition of low-grade recycled aggregate, but the effect is not obvious when the replacement rate is less than 25%. The error range of the relationship between porosity and compressive strength of RPOC is basically within 15% after improvement. The prediction model for compressive strength based on the ideal sphere model of aggregate can accurately reflect the compressive strength of porous concrete with low-grade RA. The results of this study can provide a reference for the staff to learn about the functional characteristics of recycled products in advance and provide security for the actual project.
Highlights
It is observed that that the compressive strength of porous concrete (POC) decreases in varying degrees after mixing recycled aggregate (RA)
The specific changes are as follows: when the replacement rate of RA is less than 25%, the compressive strength of POC hardly changes, and the compressive strength gradually decreases with the increase in replacement rate
The experiment starts with the existing strength prediction model of POC, compares and analyzes its applicability to with sive strength of POC with low-grade RA
Summary
The average annual production of construction waste in the world has exceeded 8 billion tons [1], and China alone produces no less than 3.5 billion tons of construction waste every year, accounting for 30%~40% of the total urban waste [2]. This takes up a lot of land for landfill storage and causes serious pollution of land, air, and water resources. In order to solve the problems of construction waste treatment and depletion of natural resources, the technology of recycled aggregate (RA) and recycled concrete has been widely studied and applied and has become a hot spot in various fields
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