Effect of recycled concrete aggregate with different degrees of initial alkali–aggregate reaction damage on the mechanical behavior and porosity of self-compacting recycled aggregate concrete. (11th January 2023)

• Record Type: Journal Article
• Authors: Wang, Haoyu; Nie, Ding; Li, Pengfei; Wang, Duoyin; Wang, Chengzhi; Liu, Wei; Du, Sanlin
• Is Part Of: Construction & building materials. Volume 363(2023)
• Publication Date: 2023-01-11
• Subjects: Self-compacting recycled aggregate concrete -- Alkali-aggregate reaction -- Recycled concrete aggregate -- Mechanical property -- Porosity; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2022.129797
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Residual alkali activity of RCAs with initial AAR damage is evaluated. RCA with a certain level of AAR can improve the strength of SCRAC. AAR product filled and reinforced the adhering mortar in RCA. Compressive strength of SCRAC is predicted by a model considering filling effects. Abstract: The use of recycled concrete aggregate (RCA) is an effective approach to achieve environmental sustainability. However, the presence of defects due to previous alkali–aggregate reactions (AARs) has caused reluctance toward its use in constructions. This study investigated the application and influence of RCAs with different degrees of initial AAR damage on the mechanical behavior and porosity of self-compacting recycled aggregate concrete (SCRAC). Concrete cubic specimens with different degrees of AAR were produced by soaking the raw materials in a high-alkaline solution. In order to obtain RCAs with different initial AAR durations of 7, 28, 60, and 210 days. The specimens were then crushed using a jaw crusher. The residual reactivity of the RCA produced from concrete affected by the AAR was detected using the accelerated mortar bar test. The rheological properties of the SCRAC with different RCAs were tested. Compressive strength, flexural strength, mercury intrusion porosimetry, and scanning electron microscopy tests were conducted to analyze the effects of RCAs with different degrees of initial AAR damage on the mechanical properties and porosity of the SCRAC. The results show that the RCA can maximally strengthen the compressive strength of the SCRAC after 60 days of alkali immersion at a replacement rate of 30 %. Furthermore, a prediction model considering the filling effect for calculating the influence of RCAs with initial AAR damage on the compressive strength of the SCRAC was proposed. For practical engineering applications, the AAR can strengthen RCAs and improve the utilization rate of RCA, which is beneficial for the sustainable development of the environment.