The effect of nanosilica addition on flowability, strength and transport properties of ultra high performance concrete

Abstract

The experimental study herein presented was conducted aiming to evaluate the influence of nanosilica (nS) addition on properties of ultra-high performance concrete (UHPC). Thermo gravimetric analysis results indicated that nS consumes much more Ca(OH) 2 as compared to silica fume, specifically at the early ages. Mercury intrusion porosimetry measurements proved that the addition of nS particles leads to reduction of capillary pores. Scanning electron microscope observation revealed that the inclusion of nS can also efficiently improve the interfacial transition zone between the aggregates and the binding paste. The addition of nS also resulted in an enhancement in compressive strength as well as in transport properties of UHPC. The optimum amount of cement replacement by nS in cement paste to achieve the best performance was 3 wt.%. However, the improper dispersion of nS was found as a deterrent factor to introduce higher percentage of nS into the cement paste.

Chloride Resistance Behavior on Nano-Metaclayed Ultra-High Performance Concrete

“…The pore system will also become finer and more segmented with increase in exposure time due to continuing pozzolanic reaction. As well documented in previous studies, the used of nano-silica in concrete will delay and reduce the chloride resistance [13][14][15][16].…”

“…Numerous studies outlined that the use of nano-silica in UHPC can promote the hydration of cement to generate more C-S-H gel thus, leads to reduction of capillary pores in concrete [13][14][15][16]. Another researcher also found that UHPC contains ultra-fine POFA exhibited the greatest improvement in permeability properties such as porosity, rapid chloride permeability, water permeability and gas permeability [17].…”

Development of an eco-friendly Ultra-High Performance Concrete (UHPC) with efficient cement and mineral admixtures uses

“…11. Comparison of embedded CO 2 emission of the developed eco-friendly UHPC (EUHPC) and other UHPCs or UHPFRCs [14,[75][76][77][78][79][80][81][82][83][84].…”

Pore- and micro-structural characterization of a novel structural binder based on iron carbonation

“…However, since the emphasis is on comparative evaluation of pore sizes, this inaccuracy is not deemed to be critical. The pore diameters can be evaluated using Washburn equation, based on the assumption that the pores in the porous media are cylindrical in shape [24][25][26]. A minimum pore diameter of 0.003 µm can be evaluated using MIP.…”