Chuanqing Fu,Hailong Ye,Aoke Lei,Guojun Yang,Pan Wan
In this work, the poly(sodium-acrylate acrylamide) superabsorbent polymer (SAP) composites reinforced with micro silica and kaolin clay particles are evaluated as novel additives to control and improve the fresh and hardened properties of alkali-activated slag (AAS). The water swelling and retention capacity of plain and modified SAPs in various solutions pertinent to AAS binder systems (including deionized water, saturated Ca(OH) 2 , 1.0 M NaOH, 0.5 M Na 2 CO 3 , and 0.5 M Na 2 SO 4 ) are studied using the gravimetric ‘tea bag’ and thermogravimetric methods, together with molecular analysis. The results show that the use of micro silica and kaolin clay-reinforced SAP composites slightly alleviates the negative influence of conventional SAP counterparts on the flowability, setting, and early-age compressive strength of AAS pastes. Nevertheless, the addition of SAP composites merely postpones the early-stage drying shrinkage development but tends to increase the long-term deformation of hardened AAS in unsealed conditions, likely due to the reduced bulk stiffness with enlarged porosity.
Alkali-activated slag mortars with recycled fine aggregate (AASRMs) have attracted high concern due to their promising properties, low carbon emissions, and solid waste utilization. However, high shrinkage made the AASRMs susceptible to cracking, limiting their application in construction industry. This study intends to use green bamboo cellulose nanofibers (CNFs) as reinforcement to overcome the problem. Two CNFs surface modifications including nano-SiO 2 coating and KH590 silane were adopted to improve the dispersibility of CNFs and their compatibility with AASRM matrix. Fourier transform infrared spectroscopy, thermal gravimetric analysis, Zeta potential, and scanning electron microscopy were adopted to characterize the CNF modification. The results showed that adding CNFs evidently improved the mechanical strengths, and reduced the chemical and dry shrinkages of AASRMs. CNF to modifications improved their dispersibility within the matrix, strengthened the fiber/matrix interface bonding, and refined the pore structure of the mortars, enhancing the overall performance of AASRMs. Particularly, the incorporation of 0.3 wt% nano-SiO 2 - and KH590-modified CNFs into AASRMs enhanced the 28-day flexural strength by 15.5 % and 18.3 %, respectively, compared to the control without CNFs. Moreover, these modifications significantly reduced the 14-day dry shrinkage by 49.9 % and 37.1 %, with nano-SiO 2 proving more effective than KH590 in mitigating dry shrinkage. This study offers an effective and green strategy for enhancing the performance of AASRMs by using renewable materials, being beneficial for their large-scale application as sustainable building materials.
危险品化学品经营许可证（带存储）