Modification of nanoparticles for the strength enhancing of cement-stabilized dredged sludge

• 作者: Lei Lang Bing Chen Haijuan Duan
• 来源期刊: 岩石力学与岩土工程学报（英文版）
• 年，卷（期）: 2021,（3）
• 页码范围: 694-704
• 页数: 11页
• 语种: 英文

摘要

This paper investigates the effectiveness of nano-modification on the strength enhancement of cement-stabilized dredged sludge (CDS). Three types of nanoparticles including nano-SiO2 (NS), nano-Al2O3 (NA) and nano-MgO (NM) were used as cement admixtures for dredged sludge stabilization. Effects of single nanoparticle content, mass ratio of composite nanoparticles and curing time on the strength develop-ment of CDS were evaluated via a series of unconfined compressive strength (UCS) tests. The pH evo-lutions of CDS caused by nanoparticles were also examined by a range of pH tests. Furthermore, micro-mechanisms reflecting the strength evolutions were analyzed by performing scanning electron micro-scopy (SEM) and X-ray diffraction (XRD) tests. The results indicated that adding nanoparticles can significantly improve the UCS of CDS. For single nano-modification, the optimum contents of NS, NA and NM were 4％-6％, 6％and 8％, which can increase the 7-and 28-d UCSs of CDS by 38％and 50％, 17％and 35％, 65％and 67％, respectively. Compared with single nano-modification, composite nano-modifications were more effective in improving the strength gain of CDS. The optimum mass ratios of composite nanoparticles, namely NS/NA, NS/NM and NA/NM, were 9/1, 3/7 and 3/7, respectively. Based on the strength growth rate, the composite nanoparticles with NS/NM of 3/7 were highly recommended. The addition of nanoparticles obviously affected the pH evolution of CDS, which was mainly determined by the difference of OH- production and consumption inside nano-modified CDS. The microstructural analysis revealed that C-S-H and C-A-H gels are the main cementitious products, and the addition of nanoparticles can obviously contribute to a denser and more homogenous microstructure of CDS.