Influence of Using Fly ash and Silica Fume on the Concrete Performance against Chloride Attack

Abstract

This paper is part of a research project deals with the study of the possible use of by-product materials such as fly ash (FA) and silica fume (SF) with Ordinary Portland Cement (OPC) in ternary system in different applicable measured properties of concrete. In this research, six concrete mixtures with water/cement ratios 0.4 and 0.5 have been investigated. Trial mixes were carried out to produce concrete with same slump and air content percentage. Also the influence of using fly ash and silica fume with Portland cement on the concrete performance against chloride attack has been studied. The potentiometric apparatus was used to measure the chloride concentrations through the concrete samples by titration chemical analysis. In addition, the diffusion coefficients were determined for the tested specimens. It is concluded that the addition of fly ash and silica fume to Portland cement in ternary system improved concrete resistance to chloride attack and reduced its diffusion coefficient as well as can be reasonably used in concrete industry with considerable proportions. Moreover, the change in the cementitious materials content, type and their replacement percent has significant effect in the studied properties of concrete. Furthermore, results show that the total and soluble chloride content for zone 10~20 mm and zone 20~30 mm are very low .This results leads that such type of concrete needs less concrete cover depth which leads to protect the reinforcement.

Keywords

• fly ash
• silica fume
• concrete
• total
• chloride attack