Topic
Silica fume
About: Silica fume is a research topic. Over the lifetime, 10177 publications have been published within this topic receiving 173857 citations.
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TL;DR: In this article, the effects of supplementary cementitious materials (SCMs) on the chloride binding of portland cement pastes were investigated. And the binding relationships were best described by the Freundlich isotherm and binding coefficients were given for all the binders tested.
403 citations
TL;DR: In this paper, the performance of slag, fly ash, and silica fume concretes under four different curing regimes was investigated and the compressive strength was determined at various ages, and the resistance to chloride-ion penetration was measured according to ASTM C 1202 at different ages up to 180 days.
Abstract: This paper reports an investigation in which the performance of slag, fly ash, and silica fume concretes were studied under four different curing regimes. The water-cementitious materials ratio of all the concrete mixtures was kept constant at 0.50, except for the high-volume fly ash concrete mixture, for which the ratio was 0.35. The concrete specimens were subjected to moist curing, curing at room temperature after demoulding, curing at room temperature after two days of moist curing, and curing at 38 °C and 65% relative humidity. The compressive strength was determined at various ages, and the resistance to chloride-ion penetration was measured according to ASTM C 1202 at different ages up to 180 days. Mercury intrusion porosimetry tests were performed on the 28-day old mortar specimens for comparison purposes. The results indicate that the reduction in the moist-curing period results in lower strengths, higher porosity and more permeable concretes. The strength of the concretes containing fly ash or slag appears to be more sensitive to poor curing that the control concrete, with the sensitivity increasing with the increasing amounts of fly ash or slag in the mixtures. The incorporation of slag or silica fume, or high volumes of fly ash in the concrete mixtures, increased the resistance to chloride ions and produced concretes with very low permeability.
403 citations
TL;DR: In this paper, the authors present several approaches used to improve the durability performance of VFRMCs incorporating sisal and coconut fibres, such as carbonation of the matrix in a CO2-rich environment, immersion of fibres in slurried silica fume prior to incorporation in the ordinary Portland cement (OPC) matrix, partial replacement of OPC matrix by undensified silica Fume or blast-furnace slag, and a combination of fibre immersion and cement replacement.
Abstract: The primary concern for vegetable fibre reinforced mortar composites (VFRMC) is the durability of the fibres in the alkaline environment of cement. The composites may undergo a reduction in strength and toughness as a result of weakening of the fibres by a combination of alkali attack and mineralisation through the migration of hydration products to lumens and spaces. This paper presents several approaches used to improve the durability performance of VFRMCs incorporating sisal and coconut fibres. These include carbonation of the matrix in a CO2-rich environment; the immersion of fibres in slurried silica fume prior to incorporation in the ordinary Portland cement (OPC) matrix; partial replacement of OPC matrix by undensified silica fume or blast-furnace slag and a combination of fibre immersion in slurried silica fume and cement replacement. The durability of the modified VFRMC was studied by determining the effects of ageing in water, exposure to cycles of wetting and drying and open air weathering on the microstructures and flexural behaviour of the composites. Immersion of natural fibres in a silica fume slurry before their addition to cement-based composites was found to be an effective means of reducing embrittlement of the composite in the environments studied. Early cure of composites in a CO2-rich environment and the partial replacement of OPC by undensified silica fume were also efficient approaches in obtaining a composite of improved durability. The use of slag as a partial cement replacement had no effect on reducing the embrittlement of the composite. © 2002 Published by Elsevier Science Ltd.
393 citations
TL;DR: In this paper, the strength and durability performance of normal and high-strength pozzolanic concretes incorporating silica fume, fly ash, and blast furnace slag was compared at elevated temperatures up to 800°C.
384 citations