|Series||BRE digest -- 363|
|Contributions||Building Research Establishment.|
|The Physical Object|
|Number of Pages||12|
The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance while maintaining acceptable compressive strength properties. The acid and sulfate hardenable mixtures of the invention containing fly ash comprise Cited by: sulfate. The method of predicting deterioration of coated concrete when subjected to sulfuric acid and sulfate attack has not yet been established. It is understood that the depth of deterioration of concrete due to sulfuric acid attack is proportional to the square root of the exposure time. This relationship is. This study is centered on the use of ground bagasse ash (GBA) and recycled concrete aggregate (R-CA) as raw materials to produce ecofriendly high-strength concrete (HS-C) with high durability. Specifically, GBA with high fineness was used as a replacement for cement up to 50%wt of the binder, and R-CA was used as a coarse aggregate to produce by: 4. reduces sulfate resistance regardless of the type of cement used. Conclusion In addition to producing air-entrained concrete with a moderate water content (not more than water/cement), it is also good practice to use Type II cement where mild sulfate attack may be encountered and Type V cement is a must where the attack may be more severe.
The role of Sulphate ions in causing deterioration of concrete has been investigated intensively. Based on the literature available, the present paper discusses this aspect with particular. Abstract. Sulfate attack comprises a series of chemical reactions between sulfate ions and the components of hardened concrete. As these reactions may lead to cracking, spalling or strength loss of concrete structures, appropriate test methods are needed to determine the resistance of concrete under sulfate exposure. Prusinski, J.J., Carrasquillo, R.L.: Using medium – to high volume fly ash blended cements to improve the sulfate resistance of high-lime fly ash concrete. In: Proceedings of the Fifth-International Conference on Natural Pozzolans in Concrete, Milwaukee, ACI SP, pp. 43–65 () Google Scholar. The sulfate ions must penetrate the concrete and be concentrated by evaporation to cause disturbance. Acid resistance is dependent on the cement matrix of the concrete and its ability to resist the formation of soluble calcium products that affect the surface.
When mortar or concrete reacts to sulfuric acid, dihydrated gypsum film is formed around the particulate of the fine aggregate. This dihydrated gypsum film could retard the penetration of sulfuric acid, thus improving the resistance to sulfuric acid. However, the resistance to sulfuric acid depends on the hardness of the dihydrated gypsum film. concrete in dry sulfate-bearing soils will not be attacked (7), while alternating wetting and drying increases the severity of sulfate attack. (7, 8) To repair or avoid sulfate attack on concrete slabs on grade, Robinson recommends Type V cement (highly sulfate-resistant cement), vapor barrier. The results demonstrate that sulfate resistance of concretes containing a high volume of mineral admixtures is equivalent to concrete made with SRPC cement when they were buried in sulfate soil. Concrete specimens presented a good visual appearance, without cracking at the edges, and they retained the strength and the elastic modulus. In this paper, the sulfate resistance of mortars made from ordinary Portland cement containing available pozzolans viz., fly ash and ground rice husk ash (RHA) was studied.