Effect of nanosilica on durability and mechanical properties of high-strength concrete

Abstract

The effect of amorphous nanosilica particles on the mechanical properties and durability of two high-strength concrete (HSC) mixes was investigated. Nanosilica in powder form was used as a partial replacement of cement at dosages of 1 wt% and 2 wt%, and significant improvements in performance were observed for 2 wt% replacement of cement by nanosilica. Micromechanical studies were performed on the nano-modified HSCs to determine the impact of nanosilica on pozzolanic reactivity. Durability assessments such as the rapid chloride penetration test, water sorptivity test and water absorption test revealed significant resistance to chloride penetration, sorptivity and water absorption. These improvements can be mainly attributed to the larger specific surface area of nanosilica, which effectively stimulates both pozzolanic reactivity and the filler effect over the cementitious matrix. Notation a exposed area of specimen (mm 2 ) d density of water (g/mm 3 ) I absorption I 0 , I 30 , I 60 … I 330 , I 360 current (A) at 0, 30, 60 … 330, 360 min m t change in specimen mass (g) at time t Q charge passed (C)

Avaliação dos efeitos da nanosílica em concretos submetidos à ação de íons cloreto

“…Regarding the nanosilica addition, although the present work has not obtained satisfactory results, Revista ALCONPAT, 8 (2), 2018: 138 -149 Evaluation of nanosilica effects on concrete submitted to chloride ions attack T. Zanon, R. Schmalz, F. G. S. Ferreira 148 some studies indicate that 3% and 6% colloidal nanosilica addition in mortars could reduce 70% and 77% 28-day chlorides migration, respectively, in comparison to reference mortars (Joshaghani;Moeini, 2017). Likewise, Ganesh et al (2016) studied the nanosilica solution on concrete's durability, by means of chloride migration test. The authors observed that, at 28 days, 2% nanosilica addition increased the concrete resistance to aggressive ions penetration.…”

“…Regarding tensile strength by diametrical compression (Figure 4), results indicated that additions use did not induce significant improvements, especially when considering the standard deviations. However, Ganesh et al (2016) observed gains of 17% and 24% in 28-day tensile strength of concrete, incorporating 1% and 2% nanosilica solution, respectively. It should be emphasized that the nanosilica used in this work is dispersed in superplasticizer and it makes the study of its incorporating at higher levels difficult, including the recommended levels.…”

“…Revista ALCONPAT, 8 (2), 2018: 138 -149 Evaluation of nanosilica effects on concrete submitted to chloride ions attack T. Zanon, R. Schmalz, F. G. S. Ferreira 140 Ghafoori;Batilov;Najimi, 2016;Joshaghani;Moeini, 2017;Li et al, 2017a;Li et al, 2017b). Among these different aggressive agents present in environment are chloride ions and their ability to initiate reinforcement corrosion, even when the solution contained in concrete pores has high pH.…”

High calcium cementless fly ash binder with low environmental footprint: Optimum Taguchi design

“…Reactive nanosilica has already been verified to exert beneficial effects on fly ash‐based geopolymer or typical portland cement products . The 3 levels for the amount of nanosilica, 0 wt%, 3 wt%, and 5 wt% within each mixture proportion were selected based on previous publications where nanosilica was mostly applied in the amount less than 10 wt% of the entire solid mass .…”

Transport of Chloride Ions Evaluation through Modulated Concrete Microstructures

“…They are different from classified rock additives that are called aggregates. Regarding the nano and micro silica role in modulating the concrete properties can be found in the review articles by Aggarwal et al (2015), Sing et al 2013, and an article by Ganesh et al (2016).…”