Abstract
In order to develop textile reinforced concrete (TRC) with good flowability and strength, colloidal nano-SiO2 (CNS) is adopted to improve the performance of TRC. The flowability, compressive strength, flexural strength, and four-point bending tests of TRC matrix with CNS are carried out, and the changes of internal micromorphological characteristics of TRC matrix are analyzed by combining with scanning electron microscopy. The results show that the CNS has an inhibitory effect on the flowability of TRC matrix, and the greater the amount of admixture is, the smaller the slump expansion of TRC matrix is. The compressive strength and flexural strength of TRC matrix show a trend of increasing and then decreasing as the amount of CNS increases, and the compressive strength reaches the maximum at each age (7 d, 14 d, 28 d) when CNS and silica fume replace 5% cement by 1 : 4 equal mass. The flexural strength reaches the maximum at each age (7 d, 14 d, 28 d) when 5% cement is replaced by CNS and silica fume with 3 : 7 equal mass. The flexural strength increases with the increase of CNS admixture. It is found by electron microscope scanning that the incorporation of CNS consumes more Ca(OH)2, refines the Ca(OH)2 crystal size, and generates more C-S-H gels. These C-S-H gels are distributed in a net-like pattern inside the concrete, filling the internal pores, effectively densifying the interfacial transition zone between the cementitious material and the aggregates, and optimizing the internal structure.
Highlights
Textile reinforced concrete (TRC) has the superior characteristics of crack resistance, impact resistance, and durability properties, which has been widely applied in lightweight thin-walled structures, such as large span arches, shells, and domes [1,2,3]
Silica fume is mixed with colloidal nano-SiO2 (CNS) for the TRC matrix with a water-cement ratio of 0.38, a cement-sand ratio of 0.7.20% cement is replaced by equal mass of fly ash in the cementitious material, and 5% cement is replaced by equal mass of silica fume and CNS in different proportions
The slump expansion of TRC matrix decreases in different magnitudes with the increase of CNS admixture
Summary
Textile reinforced concrete (TRC) has the superior characteristics of crack resistance, impact resistance, and durability properties, which has been widely applied in lightweight thin-walled structures, such as large span arches, shells, and domes [1,2,3]. Wang [15] studied the mechanical properties and microstructure at 25°C, 200°C, 400°C, and 600°C by static load test, scanning electron microscopy, and X-ray diffraction and found that the addition of nano-SiO2 improved the high temperature performance of concrete at different temperatures. The changes in the microstructure of the TRC matrix are analyzed to compare the differences between them in improving the interfacial properties and to reveal the mechanism of the effect of CNS on the performance of fine-grained concrete. These experiments in this paper are designed to further investigate the effect of nanoSiO2 on the flowability and strength of TRC matrix
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