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Shotcrete materials
Published in Dudley Robert (‘Rusty’) Morgan, Marc Jolin, Shotcrete, 2022
Dudley Robert (‘Rusty’) Morgan, Marc Jolin
Next to fly ash, the most widely used supplementary cementing material in shotcrete in North America is silica fume. Silica fume is a by-product of the production of silica metal in a submerged electric arc furnace. Very pure quartz rock, with wood chip as a fluffing agent, is melted in the furnace and the molten silica metal is tapped out of the bottom of the furnace. The silica fume is the smoke that goes up the stack. It is collected in electrostatic bag houses and then conveyed to process tanks where it is converted to condensed silica fume by tumbling air currents. In this densified form, it is suitable for transport and handling and mixing in ready mix concrete or dry-bagged concrete products production plants (Silica Fume Association, 2005; ACI 234R).
Study on the Properties of Coir Fiber Reinforced Self Compacting Concrete Containing Silica Fume
Published in P. C. Thomas, Vishal John Mathai, Geevarghese Titus, Emerging Technologies for Sustainability, 2020
Mineral Admixture: Silica Fume is used as the mineral admixture in this project. Silica fume is a by-product of the silicon and ferrosilicon alloy production and consists of spherical particles with an average particle diameter of 150 nm.
The Influence of Silica Fume on Durability of Concrete and Reinforced Concrete
Published in Christer Sjöström, Durability of Building Materials and Components 7, 2018
Silica fume in Poland is a by-product of smelting process used to produce of ferrosilicon alloys in metallurgical plant “Łaziska”. Its annual output is about 20 Mt and utilisation of silica fume became an important problem [1]. In Building Research Institute the research works on the possibilities of silica fume application as an additive for concrete have been developed. The results indicated the beneficial influence of silica fume on concrete properties, first of all on its microstructure. Porosity tests have shown the decreasing of pores volume in the range 7500 nm − 5 nm and significant increasing of gelous pores volume, with the increase of silica fume in concrete [2], The chemical composition of Polish silica fume indicates rather high stability of its main parameters.
Flexural behavior of sustainable reinforced concrete beams containing HDPE plastic waste as coarse aggregate
Published in Cogent Engineering, 2022
Milad M. Radhi, Wasan I. Khalil, Sarmad Shafeeq
This study used ordinary Portland cement type I from local manufacturers for all mixtures. The cement was manufactured following the recommendations of Iraqi Standard No. 5/1984 (Iraqi Standard Specification No. 5, 1984) and has the chemical composition and physical properties listed in Table 1. Silica fume was also used in the mixtures of this study as a secondary binder, which was adopted as a partial replacement of cement. Silica fume is known for its significantly finer particles compared to cement and thus is used to improve the strength and durability characteristics of the mixtures. The silica fume used was Mega Add MS (D), which has the chemical composition and physical properties listed in Table 2. Local natural sand from Al-Kut city was used as the fine aggregate, while local natural gravel was adopted as the mixtures’ coarse aggregate. The maximum particle sizes of the fine and coarse aggregates were 4.75 and 10 mm respectively. The sieve analysis and properties of the sand and gravel were tested per the Iraqi Standards No. 45/1980 (Iraqi Standard Specification No. 45, 1984). The physical properties of the used sand and gravel are listed in Table 3, while their grading analyses are shown in Figure 1. Both aggregates were well washed and surface dried before being used to remove the dust and other pollutants from the particle surfaces.
Expanded clay basalt fiber concrete: Solving structural defects caused by water penetration
Published in Cogent Engineering, 2021
Paschal Chimeremeze Chiadighikaobi, Bewuket Bekele Tefera, Tarka Rilwan Olakunbi, Jean Paul Vladimir
When using silica fume for the manufacture of especially strong concrete, thousands of spherical microparticles surround each cement grain, compacting the cement mortar, filling the voids with strong hydration products, and improving adhesion to aggregates, much more effectively than other mineral additives, such as zeolite tuff, blast furnace, and boiler slag. It is used as a highly active additive to concrete. It is intended for the preparation of special high-grade concrete for strength and waterproofness, foam concrete, dry building mixes, rubber, ceramics, tiles, tiles, and refractory masses (Sami Elshafie, 2015). The addition of silica fume helps reduce cement consumption (up to 200–450 kg/m3). As a result of physical and chemical effects, a favorable change in the microstructure of the test occurs, associated with a significant decrease in porosity in the zone of capillary pores. A change in the structure of pores in concrete is considered by many researchers as the main factor in the influence of silica fume on the mechanical properties and strength of concrete. These changes are reflected in the decrease in concrete permeability. Reduced water permeability enhances the resistance of concrete to aggressive environments. High properties of silica fume improve concrete characteristics such as compressive strength, adhesion and wear resistance, frost resistance, chemical resistance, and significantly reduce permeability.
Silica fume stabilization of an expansive clay subgrade and the effect of silica fume-stabilised soil cushion on its CBR
Published in Geomechanics and Geoengineering, 2020
B. R. Phanikumar, Jagapathi Raju m, Ramanjaneya Raju e
Silica fume is a fine non-crystalline silica produced in electric arc furnaces as a by-product of alloys containing silica. It is in powder form looking like an ash (Negi et al. 2013). It is a pozzolanic material containing a high amount of amorphous silicon dioxide (Fattah et al. 2015a). As silica fume is hazardous in nature, it is being used in various civil engineering applications such as modification of concretes, alteration of clay behaviour and strengthening of pavement subgrades. Soft clays blended with silica fume and lime showed reduced plasticity and increased workability and strength. Moreover, the clay-silica fume blends were found to be more granular with increased particle size (Fattah et al. 2015b). Kaoline clay mixed with lime and 4% silica fume exhibited improved strength (Alrubaye et al. 2016, 2018). The bearing capacity of a square footing founded in a soft clay improved when the soft clay was grouted with lime-silica fume mix (Fattah et al. 2015a, 2015b). Expansive clay treated with silica fume showed reduced plasticity, free swell index (FSI) and swelling pressure of expansive soils (Negi et al. 2013, Al-Soudany 2017). The degree of stabilization of expansive clays was enhanced when they were treated with cement and silica fume (Goodarzi et al. 2016). Silica fume also effectively reduced desiccation cracks of expansive clays (Kalkan 2009). Further, silica fume was also proved to be effective in controlling progressive swelling and shrinkage of expansive clays subjected to wetting-drying cycles (Kalkan 2011).