Use of nano-silica to increase early strength and reduce setting time of concretes with high volumes of slag

Properties of Fiber-Reinforced Mortars Incorporating Nano-Silica

“…For instance, compared to the control specimens without Ns (C-S and CG-BP) and irrespective of the type of fibers included, the compressive strength of the NFRM increased by up to 168% and 108% at three days for mixtures without and with slag, respectively. These results are consistent with the effect of nano-silica on cementitious systems, which effectively contributes to the strength development of cement-based materials through multiple mechanisms, including accelerated pozzolanic activity [15][16][17][18][19][20][21][22], filler effect [20,21], and water absorption into the high surface area of silica particles/agglomerates (i.e., reduction of w/b in the paste) [21]. In addition, the results of the NFRM at 28 and 56 days indicated that there was continuous and significant improvement in strength beyond seven days in comparison to the fiber reinforced mortars without nano-silica, especially for mixtures containing slag.…”

“…Previous studies indicated that the amount of drying shrinkage in cementitious systems containing slag is associated with the amount of calcium silicate hydrate produced, and, thus, it may vary with the degree of cement hydration and densification of the matrix [45][46][47]. Thereby, this trend may be linked to the reactivity of slag and the significant reduction of the cement (clinker) factor in these mixtures, which led to discontinuity of the pore structure without excessive refinement, as reported by Zhang et al [18]. This might have reduced the driving force in the capillaries, and consequently lower tensile stress was exerted on the walls of pores [45].…”

“…For instance, at 40 days, the NFRM with steel fibers (C-Ns-S) yielded a higher cumulative shrinkage (an increase of 34%) than that of the control specimens without Ns (C-S). The increase in the drying shrinkage of NFRM might be primarily due to the densification of the matrix as a result of incorporating nano-silica, resulting in increasing the volume of fine pores in the matrix (e.g., [16][17][18]). For instance, Said et al [16] reported that the total porosity and the proportion of micro-pores (less than 0.1 µ m) were reduced when up to 6% nano-silica was added to concrete mixtures, due to the pozzolanic and filling effects of nano-silica.…”

Optical transparency and mechanical properties of semi-refined iota carrageenan film reinforced with SiO2 as food packaging material

“…Tween 80 was added as surfactant for SiO2 and mixed for 1 minute at low speed and 2 minutes at high speed [19]. The solution of SR Iota Carrageenan was prepared separately by adding 2 g of SR Iota Carrageenan powder in 50 mL distilled water.…”

The Effect of Nano-SiO2 Dispersed Methods on Mechanical Properties of Cement Mortar

“…(1) Direct mixing is to refer to the nanomaterials and cement at a given speed to stir 5 min by using cement mortar mixer, (2) mechanical pre mixing is a mixture of 5 min to be mixed with a mixer (a certain amount of small steel ball is added in the mixing machine, increasing the impact force to produce more mechanical energy, so that the nanoparticles are dispersed more evenly), (3) ultrasonic dispersion (Zhang, Islam, & Peethamparan, 2012) refers to ultrasonic dispersion 5 min using ultrasonic cleaner (the ultrasonic frequency is 40 kHz).…”