Effect of nano‐SiO₂ on properties and microstructure of polymer modified cementitious materials at different temperatures

Abstract

In this study, the effect of nano-SiO 2 on mechanical properties and microstructure of polymer modified cementitious (PMC) materials under 20 and 6 C was studied through strength test, X-ray Diffraction Analysis, Mercury Intrusion Porosimetry, and Scanning Electron Microscopy. Results showed that the flexural and compressive strength of cement mortar was influenced seriously by polymer especially under low temperature condition. And nano-SiO 2 was contributed to enhance the flexural and compressive strength of PMC materials at early age under 20 C while the enhancement still existed at later age under 6 C. The disadvantage of polymer on the properties and microstructure of PMC materials at low temperature was modified by nano-SiO 2 due to the increase of hydration rate of cement, the decrease of the Ca(OH) 2 (CH) orientation aggregation, the modification of pore structure, and the promotion of polymer film formation. This study provides a prospective method on the performance optimization of PMC materials. K E Y W O R D S different temperatures, microstructure, nano-SiO 2 , PMC materials

Experimental studies on rheological, mechanical, and microstructure properties of self‐compacting concrete containing perovskite nanomaterial

“…In the last decades, significant research has been conducted on the application of nanomaterials and innovative materials for improving the structural, mechanical and durability characteristics of cement [1][2][3][4][5][6][7][8][9] and concrete [10][11][12][13][14][15][16][17] materials. Since self-compacting concrete (SCC) is increasingly used in construction of both conventional and advanced structures, 18,19 the enhancement of its properties can be highly beneficial, in particular, in terms of sustainable development in the construction industry.…”

Experimental evaluation on mechanical and thermal insulation properties of shotcrete under constant‐variable temperature

“…[5][6][7] On the one hand, it is due to the violent movement of magma, and on the other hand, surface water and original groundwater are heated by deep high-temperature rock masses to form high hot spring water and steam, which continuously release heat, resulting in a sharp increase of heat in construction roadway space. [8][9][10][11] Whereas, as a kind of heterogeneous brittle mixed material, when the ambient temperature exceeds the temperature that the shotcrete can resist, the concrete structure will crack, [12][13][14] resulting in great changes in the durability, heat insulation and adhesion of the shotcrete. [15][16][17][18] Moreover, Under high temperature environment, there is a temperature difference between the inside and outside of the shotcrete, which leads to the rapid temperature rise inside the shotcrete, the accelerated water evaporation rate, and the drying shrinkagecracking phenomenon inside the shotcrete, resulting in a serious loss of strength.…”

Hydrophobic nano SiO2 as flow-enhancing additives and flame retardant synergizes with CaCO3 to suppress gas explosion

“…At this time the micron-sized SiO 2 in the study is only used as a ame retardant, while the modied nano SiO 2 with its hydrophobicity has a greater surface area and hydrophobicity, so the nanometer powder at a certain concentration can reduce the tensile strength to the maximum, but there has been no study on the synergistic explosion suppression effect of this composite property. 23,24 In the present work, we designed an explosion test system based on LabVIEW, and explored the application of hydrophobic nano SiO 2 powder's owability enhancing effect and ame retardant effect in suppressing explosions. The experiment also analyzed the coupling relationship between velocity and pressure in the explosion and the mechanism of the powder suppressing the explosion.…”