Study on Strength Enhancement Factors of Cement-Stabilized Recycled Aggregate

Abstract

With the rapid development and urbanization, huge amounts of construction and demolition (C & D) waste are produced. In order to protect the environment and conserve natural resources, promoting renewable materials, with C & D waste as raw materials, is imperative. However, the poor mechanical properties of recycled aggregate hinder its applicability in projects. In this study, two kinds of recycled aggregates, that is, concrete and brick slag, were strengthened with polyvinyl alcohol (PVA) solution, and the optimal strengthening time and soaking concentration were determined. Recycled mixed aggregate and brick slag were designed with two kinds of graded recycled aggregate. Recycled cement-stabilized crushed stone specimens were prepared for a 7-day unconfined compression and freeze-thaw cycle test. The results showed that the recycled aggregate strength was improved to a certain extent, while the improvement of brick slag aggregate was more pronounced. The recycled mixture with less cement-stabilized brick slag can be used for the base course of heavy traffic secondary highways before strengthening. Cement-stabilized unreinforced brick slag has shown low strength, so it is not suitable to be used as a base on heavy traffic roads. The strengthened cement-stabilized recycled mixture and cement-stabilized brick slag could meet the requirements of heavy traffic class I and class II highways, respectively. When the cement grade, dosage, and grading type were kept the same, the strength of cement-stabilized crushed stone prepared with larger aggregates was slightly lower. After the freeze-thaw cyclic test, the strength loss of the recycled stable gravel was low, and its durability did not significantly improve after the reinforcement of recycled aggregate.