Study on the Strength Performance of Recycled Aggregate Concrete with Different Ages under Direct Shearing

Abstract

In order to study the mechanical properties of recycled aggregate concrete (RAC) at different ages, 264 standard cubes were designed to test its direct shear strength and cube compressive strength while considering the parameters of age and recycled aggregate replacement ratio. The failure pattern and load–displacement curve of specimens at direct shearing were obtained; the direct shear strength and residual shear strength were extracted from the load–displacement curves. Experimental results indicate that the influence of the replacement ratio for the front and side cracks of RAC is insignificant, with the former being straight and the latter relatively convoluted. At the age of three days, the damaged interface between aggregate and mortar is almost completely responsible for concrete failure; in addition to the damage of coarse aggregates, aggregate failure is also an important factor in concrete failure at other ages. The load–displacement curve of RAC at direct shearing can be divided into elasticity, elastoplasticity, plasticity, and stabilization stages. The brittleness of concrete decreases with its age, which is reflected in the gradual shortening of the elastoplastic stage. At 28 days of age, the peak direct shear force increases with the replacement ratio, while the trend is opposite at ages of 3 days, 7 days, and 14 days, respectively. The residual strength of RAC decreases inversely to the replacement ratio, with the rate of decline growing over time. A two-parameter RAC direct shear strength calculation formula was established based on the analysis of age and replacement rate to peak shear force of RAC. The relationship between cube compressive strength and direct shear strength of recycled concrete at various ages was investigated.

Construction and Demolition Waste Management Research: A Science Mapping Analysis

“…Studies on the CDW recycled products have been undertaken from different viewpoints, including CDW management performance [26], behavior and properties of CDW or recovered products [94], applications for recyclable waste materials [95], and performance improvements of CDW recycled products [96]. Meanwhile, other research focuses on particular performance-related tests of recycled aggregates (e.g., strength, deformation, tensile strength, stiffness, and durability) [97,98]. Evaluating the type and behavior of waste assists in determining the suitable strategy, while assessing the characteristics of recycled aggregates is a necessity to determine their optimum applications.…”

Experimental and damage modeling research on compression‐shear behavior of carbon fiber recycled aggregate concrete

“…According to previous studies, the surface of recycled coarse aggregate is relatively rough, the edges and corners are clear, and the surface remains cement slurry 18,19 ; compared with natural coarse aggregate (NCA), it has larger porosity, higher water absorption, and lower density. [20][21][22][23] As a result, the RCA is different from NCA in mechanical properties and durability. To solve this problem, many scholars try to improve the mechanical properties of RAC by adding various fibers.…”

“…Recycled coarse aggregate (RCA) in the preparation process will inevitably cause damage. According to previous studies, the surface of recycled coarse aggregate is relatively rough, the edges and corners are clear, and the surface remains cement slurry 18,19 ; compared with natural coarse aggregate (NCA), it has larger porosity, higher water absorption, and lower density 20–23 . As a result, the RCA is different from NCA in mechanical properties and durability.…”