This study employs a co-calcination method, using Mg(OH) 2 and H 3 BO 3 to simulate the behavior of boron impurity (B) during the calcination of MgO expansive agent (MEA). The investigation included systematic monitoring of the characteristics and micro-morphologies of B-containing MEA (BMEA), the hydration process of cement pastes containing BMEA, and the compressive strength and expansion behavior of mortar specimens. The results indicate that, under the light-burned regime (LBR), B accelerates the hydration of MgO while delaying the hydration of cement, leading to reduced compressive strength, and enhanced expansion. Conversely, under the high-burned regime (HBR), B reduces the reactivity of MgO, thereby decreasing the expansion of the specimens during the first 35 days while increasing the expansion in the later stages. Through analyses of pore structure and micro-morphologies in BMEA-containing cement pastes, this study elucidates the differential impacts of BMEA on microstructural evolution under varying calcination temperatures, as well as the underlying mechanisms responsible for distinct expansion rates in specimens. These findings establish a theoretical foundation for the application of boron-containing magnesium slag in MEA production.
Yan Xinlong,Yang Yingli,Wang Chao,Hu Xiaoyan,Zhou Min,Komarneni Sridhar
Abstract The synthesis of mesoporous zeolitic imidazolate framework-8/silica composites with foam-like structure templated by Pluronic P123 ( EO
20
PO
70
EO
20
) block copolymer surfactant in the presence of swelling agent was demonstrated in this study. It was found that 1,3,5-trimethylbenzene was a suitable swelling agent, which worked effectively in the pluronic-P123-templated synthesis of zeolitic imidazolate framework-8/silica composites when a moderate amount was added. The pore diameter of the foams in resulting composites increased to 50–60 nm when the 1,3,5-trimethylbenzene /P123 weight ratio of 3/4 was used during the synthesis. In addition, the composite with enlarged diameter of foams showed superior adsorption capacity to phthalic acid (H 2 -PA) at 20 °C in comparison with aggregated bulk zeolitic imidazolate framework-8. Graphical Abstract
Municipal solid waste incineration (MSWI) fly ash is classified as hazardous waste and requires proper treatments. Sintering of MSWI fly ash for the production of lightweight aggregate (LWA) is a promising treatment technology , while the dependence on natural bloating clay to produce high quality LWA has limited its wide application. In this study, by using SiC as a bloating agent, normal clay could be used to produce super-lightweight aggregate (bulk density <500 kg/m 3 ) with MSWI fly ash. Effects of SiC addition amount, sintering temperature and duration on LWA performance were studied. The results showed that LWA with SiC addition of 0.1–0.5 wt% had significant expansion at sintering temperature of 1120 °C–1160 °C. The optimal conditions were 0.3 wt% SiC addition and sintering at 1120 °C for 30 min, and the bulk density could reach 212 kg/m 3 with other properties meeting the LWA standard (GB/T 17431.1-2010). Further, the heavy metal leaching toxicity was significantly decreased after sintering and met the MSWI fly ash utilization standard (HJ 1134–2020). The X-ray diffraction results revealed the formation of a complex diopside-based phase after sintering. This study provides a new approach for recycling MSWI fly ash in LWA without dependence on specific clay resources, and makes this technology wider applicability.
危险品化学品经营许可证（带存储）