Abstract
Self-compacting concrete (SCC) is a new revolution in concrete technology that made with no vibration equipment in placing and compaction. Totally, filling formwork and accomplishing full compacting under its own weight only, even when is attendance of crowded reinforcement. One of the issues that impact SCC durability is sulphate attack. The influence of magnesium sulfate attack was investigated for SCC having treated alum sludge (TAS) with ordinary Portland cement (OPC) at replacement ratios of 5%, 10%, 15% and 20% as well as, six SCC containing TAS, fly ash (FA), silica fume (SF) and natural zeolite (NZ) replaced cement by15%, 15%, 6% and 10%, respectively. By visual inspection of all samples of SCC, there was no indication of deterioration on the surface of samples after 90 days and 180 days. In terms of compressive strength, there was developed with samples substituted OPC by 15% TAS compared with control SCC and the others SCC replacement levels. A similar conclusion was observed of the characteristics of SCC on weight compared with control SCC. Results proved that the SCC contain TAS have higher resistance against sulfate attack as well as the maximum value of mass loss and variation in weight are noted for the control SCC compared with SCC content TAS. Finally, in spite of the system of blended in SCC was investigated in several studies and so far, more investigations are required to fully explore its behavior, especially with new materials which is alum sludge that refer to the pioneering aspect of the present.
Highlights
The Sulfate in solid form condition does not attack the concrete, but in solution form, sulfates react with the cement paste compounds leading to increase in size and the deterioration of concrete
The purpose of this paper is to evaluate and obtain an index for Self-compacting concrete (SCC) deterioration due to sulfate attack and to explore the influence of treated alum sludge (TAS) on SCC against sulfate attack
In this case the optimum value of replacement cement by alum sludge was 20% and beyond that the results indicated for weakness in the matrix because of the reduction in strength reduction in resistance to aggressive environment represented by MgSO4 solution
Summary
The Sulfate in solid form condition does not attack the concrete, but in solution form, sulfates react with the cement paste compounds leading to increase in size and the deterioration of concrete. The source of ions in solution is provided from the soil, ground water and some cases from seawater which is considered as an external influence and as one of the main problems affecting concrete durability, whereas, internal resource for sulfate ions come from the materials that used for making concrete such as sand and water as main resource and little quantities from gravel. The mechanism of this interaction is leach Ca+ ion from the concrete matrix and replace by Mg- or Na+ ion, outcomes cause increase in volume of concrete leading to appear cracking. The effect of salts can be calculated through, loss in compression strength and elasticity, expansion of concrete, loss of weight and can be estimated by visual inspection
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