Swelling caused by alkali-silica reaction (ASR) in concrete is a deleterious behavior due to reactions between alkaline pore solution and amorphous or metastable forms of silica in aggregates. Generally, mitigation by using pozzolanic materials is commonly adopted. This study compared the effectiveness of a highly-reactive nano-SiO 2 (NS) and a slowly-reactive waste glass powder (WGP) on mitigating ASR of cement mortars prepared with crushed glass cullet as aggregates. The experimental results showed that incorporating 2% NS or 10% WGP or a hybrid of the two in the mortar can decrease the ASR expansion. Using WGP resulted in larger reduction in the ASR expansion than using NS. Meanwhile, there was an improvement of strength from 7 d to 28 d for the mortar prepared with WGP. The composition of reaction products containing the ASR gel formed in a simulated ASR condition and the macro-/micro-structure of the tested mortars were further analyzed. It was found that the reaction products formed with high ratios of Na/Si and Ca/Si were favorable in mitigating the ASR expansion. For the specimen prepared with WGP, the increase in the ratio of Ca/Si would increase the stiffness of the ASR gel, and a higher Na/Si ratio would help reduce the osmotic pressure. The findings from this study would be useful for the selection of pozzolans to mitigate the ASR effect when using crushed glass cullet as aggregates in cement mortars.
To address the low resource utilization efficiency of incineration bottom ash (IBA) caused by its insufficient reactivity, this study systematically investigates the influence mechanisms of alkali activation modification on ash (IBA)–cement composite systems. IBA was activated using NaOH and Na₂SiO₃ as alkali activators, with particular emphasis on the enhancement of mechanical properties and the evolution of microstructure under different activator ratios. Results indicate that when the Na₂O content concentration in the alkali activator is 0.8 %, the latent reactivity of IBA can be effectively activated, promoting the formation of high-strength gel in the hydration products, resulting in a 25 % increase in 28-day compressive strength compared to the control group. Notably, when the Na₂O content increases to 1.6 %, excessive alkali not only disrupts the normal hydration process but also significantly intensifies the alkali-silica reaction (ASR), leading to severe degradation of specimen performance. In addition, it was observed that Na₂SiO₃ accelerates specimen hardening, necessitating strict control of its dosage within the range of 0.7–1.3 %. Excessive dosage may lead to overly rapid hardening, severely hindering the complete progression of hydration, while dosages below 0.7 % result in suboptimal performance improvement.
危险品化学品经营许可证（带存储）