Study on the Influence of Nanosilica Sol on the Hydration Process of Different Kinds of Cement and Mortar Properties

Abstract

Compared with nanosilica collected in a gaseous state, nanosilica sol has great economic value and application significance for improving the performance of concrete and mortar. In this study, the influence of nanosilica sol on the hydration process of different kinds of cement is studied by means of hydration heat analysis,X-ray diffraction analysis(XRD)and other methods, and the properties of mortar such as setting time, mechanical properties and porosity are also studied to characterize the influence of nanosilica sol on the macroscopic properties of mortar. The experimental results show that nanosilica sol can accelerate the hydration rate of two kinds of cement and promote the hydration reaction degree of cement, and this promotion effect increases with the increase in nanosilica sol content. At the same time, nanosilica sol can significantly shorten the setting time of the two kinds of cement, and it is more obvious with the increase in content. Excessive content of nanosilica sol will adversely affect the permeability resistance of mortar. It may be caused by the weak interval formed by nanosilica particle clusters in the mortar matrix, which can be supported by the mortar pore structure distribution test. At the same time, the influence of nanosilica sol on the hydration of the two kinds of cement is different, and the compressive strength of HBSAC cement mortar increases first and then decreases after adding nanosilica sol; However, the compressive strength of P·O 42.5 cement mortar increases gradually after adding nanometer silica sol. This shows that nanosilica sol does not effectively promote the hydration of β-C2S in high belite sulfoaluminate cement (HBSAC) mortar. Based on the above experimental results, it can be concluded that when the content of nanosilica sol is about 1%, it has the best promotion effect on the hydration of the two kinds of cement and the performance of mortar.

Influence of pozzolanic addition on strength and microstructure of metakaolin-based concrete

“…These materials can be acquired from industrial wastes, including fly ash (FA) [ 45 ], silica fume (SF) or microsilica (MS) [ 46 ], metakaolin (MK) [ 47 ], slag [ 48 ], nanosilica (NS), and even an agricultural waste, such as sugarcane bagasse ash [ 49 ]. Researchers have utilized various types of SCMs to improve the characteristics of cement-based structures [ 50 ]. Pozzolans can greatly improve the performance of cementitious materials in terms of their resistance to the chemical attack, durability, and strength [ 51 ].…”

Effect of Nano-Al2O3 on Properties of Alkali Activated GBFS Cementitious Materials

“…Nanomaterials (nano SiO2, nano Al2O3, nano Fe2O3, etc.) have special nano size effect and pozzolanic activity, and are often used to improve the mechanical properties and microstructure of cement-based materials [4][5][6][7][8]. Xie studied the influence of nano Al2O3 on the early rheology, middle hydration and late mechanical properties of portland cement paste; the results showed that the addition of nano Al2O3 increased the plastic viscosity and the maximum increase of strength was more than 110% [9].…”

A Study on the Cement Gel Formation Process during the Creation of Nanomodified High-Performance Concrete Based on Nanosilica

“…The most effective dosages of microsilica vary from 5 to 20%, depending on the raw materials used and the types of concrete. At the same time, the increase in strength characteristics varies from insignificant, when only microsilica is added, to quite impressive (30–80%), when other additives are used along with microsilica, in particular, flask and diatomite [ 27 ], fly ash [ 19 ], carbon nanotubes [ 26 ], nanosilica, and nanosilica sol [ 19 , 41 , 43 , 44 ]. Microsilica densifies and strengthens the structure, increasing its uniformity and stabilizing the cement hydration process [ 19 , 27 , 40 , 41 , 42 , 43 , 44 ].…”

“…The nano-modification of concrete with nanosilica [ 12 , 13 , 18 , 19 , 23 , 24 , 25 , 35 , 41 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ] has already shown efficiency in improving the properties of concrete, but still requires a solution for many issues. The main problem associated with the introduction of nanoparticles into cement-based materials is how to evenly distribute them in the matrix [ 23 ].…”