Mechanical Properties and Microstructure of Cement Mortar Incorporating with Nano-Silica

• Main Authors: Ten-Mien, 呂添民
• Other Authors: Ta-Peng
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/76819764726333936336

碩士 === 國立臺灣科技大學 === 營建工程系 === 93 === This research studies the mechanical properties and microstructure of portland cement mortar incorporate with nano-silica. The variables were three water-binder ratios（W/B）of 0.45, 0.50 and 0.55, three sand/cement ratios of 2.25, 2.5 and 2.75 and four different nano-silica additions of 0.2, 0.4, 0.6 and 0.8% by the weight of cement. The influence of each variable on the property of cement mortar was studied. The mechanical properties include flow, viscosity, compressive strength, splitting tensile strength, cohesive strength, ultrasonic pulse velocity, dynamic modulus of elasticity, dynamic modulus of rigidity and drying shrinkage. Analysis of microstucture by field emission scanning electron microscope (FE-SEM), energy dispersion spectrum (EDS) and element distribution (MAP) were also performed. Statistical analysis of compressive strength, split tensile strength, cohesive strength and ultrasonic pulse velocity were also carried out which includes coefficient of variation analysis, multiple regression analysis and scaling data processing. Experimental results show that adding nano-silica to cement mortar will increase the compressive strength about 10~26.9% and raise the split tensile strength about 4~17.4%. The best addition dosage of nano-silica is found to be of 0.4~0.6% by the weight of cement. Nano-silica beneficially increases the mechanical property of cement mortar. Adding nano-silica to cement mortar will increase the cohesive flexural strength between cement mortar and stone about 7~23%. It has a positive improvement for cohesiveness between cement mortar and stone. The field emission scanning electron microscope observation show that nano-silica material improves hydration products with the higher density and enhance Si/Ca ratio on the interface of aggregate and cement. The nano-silica has the advantage to intensify the interface transition zone of microstructure.