Mechanical properties of geopolymer concrete solidified with waste materials

Geopolymer concrete Mechanical properties Solidified soil Waste slurry Waste recycling
["Zhang, Peng","Ding, Junyao","Dai, Xiaobing","Zheng, Yuanxun","Zheng, Mengyuan"] 2025-01-24 期刊论文
A large quantity of waste slurry (WS) is produced during the process of drilled grouting piles, which is mainly composed of bentonite, clay, and metal ions. Improper disposal of WS will bring about serious environmental problems. In this study, flocculation technology and solidification technology were combined to treat WS using three types of flocculant solution, and waste slurry geopolymer concrete (WS-GPC) was prepared using treated WS, slag powder (SP), fly ash (FA) and alkali activator. The results showed 100 mL WS treated with 25 mL APAM flocculant solution with a concentration of 0.1 % had the lowest filtrate turbidity and the lowest mud moisture content (50.30 %). The bone-glue ratio, sand rate and water-to-cement ratio of the concrete samples was 3.0, 0.4 and 0.42, respectively. Taking into account the 7-day compressive strength of WS-GPC and the maximum application rate of WS, the optimal slurry cake content was 35 %. At this time, the total amount of slag powder and fly ash used was 65 %. The effects of slag powder dosage (SPD), alkali activator dosage (AAD), and alkali activator modulus (AAM) on the compressive, flexural, and splitting properties of WS-GPC were discussed. And X-ray diffraction (XRD), scanning electron microscope (SEM), and mercury intrusion porosimetry (MIP) tests were also taken to analyze the phase composition, microstructure, and pore structure of WS-GPC. There was a positive correlation between the mechanical strength of WS-GPC and SPD. While when the AAD or AAM increased, the mechanical strength of WS-GPC first increased followed by a decrease. The mechanical properties of WS-GPC with 60 % SSD, 29 % AAD and AAM being 1.3 were optimal due to more hydration products, smoother and denser microstructure, lower porosity and smaller average pore diameter of the WS-GPC. This study is expected to create a new way of green treatment of WS and provide a theoretical basis for the application of WS-GPC.
来源平台:CONSTRUCTION AND BUILDING MATERIALS