Effect of reed straw on the performance of recycled brick aggregate concrete and evaluation of economic benefits

Abstract

In this study, brick aggregate reed straw concrete (BARSC) was prepared by utilizing reed straw with brick aggregate. Reed straw was soaked in NaOH solution and H2SO4 solution to test the water absorption, moisture absorption and tensile strength of the treated straw. The thermal conductivity, compressive strength, and tensile strength before and after the high temperature of BARSC were investigated, and the compressive strength-tensile strength conversion formula was established. Damage patterns were observed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. The results showed that the tensile strength of the straw soaked in NaOH solution increased, the water absorption increased and a significant shrinkage occurred, and after the test, the NaOH-soaked reed straw was not suitable to be added to the concrete. The thermal conductivity of BARSC at room temperature decreased by 15.9% compared with that of brick aggregate concrete (BAC) without reed straw, and the thermal conductivity gradually decreased with the increase of temperature. The tensile strength of BARSC increased by a maximum of 21.2% over that of BAC, with the 2% content of reed straw contributing the most to the tensile strength. Reed straw negatively affected the compressive strength, which decreased by a maximum of 20.2%. The compressive and tensile strengths of BARSC decreased significantly after high temperature. According to scanning electron microscopy analysis, the interfacial transition zone of the reed straw with the matrix was the weak point in the BARSC. The BARSC produced in this study provides a new idea for protecting the watershed environment and promoting green and sustainable development.