Study On The Influence Of Strength And Durability Of Concrete Owing To Different Qualities Of Silica-fume

In the past few centuries, More and more reinforced concrete structure destories due to insufficient durability caused by progressive worsening environment,which causes great loss of national economy. The durability and reliability of reinforced concrete structure has become a worldwide problems and causes great attentions. There are also many experts and researchers at home and abroad have furetherly study the durability of reinforced concrete, gained mass of results and proposed many measures to improve the durability of reinforced concrete. such as adopting mineral admixtures into concrete.Silica-fume is a by-product collecting from waste gas of ferrosilicon smelting and industry, is one of the "three wastes" of industry. Adopting silica-fume into concrete,could improve strength and durability of concrete. But the silica-fume resources is not sufficient, and include large proportion of low quality silica-fume. Now, the study on development and use of low quality silica-fume is very lack. In this paper, through concrete strength and durability experiment, testing concrete strength and durability index, analysis its rule. Through mercury intrusion testing pore structure parameter and pore size distribution of concrete cement paste, analysis the effect of different quality silica-fume on double mixed concrete, and explains corresponding concrete macroscopic behavior. At the basis of pore structure analysis, using grey relational grade analysis, study the relations between concrete pore structure parameter, pore size distribution and concrete strength and durability, find the biggest influencing factors. The conclusions as follows:(1)When silica-fume mixing amount is constant, the higher of the quality of silica-fume, the performance of concrete is better; when silica-fume quality is constant, for high and mid-quality silica-fume, the bigger of the mixing amount, the strength is higher and the durability is better; for low quality silica-fume, there has no obviously law. Through comprehensive analysis, low and mid-quality silica-fume should be applied in practical project selectively.(2)The effects on strength and durability of double mixed concrete of different quality silica-fume due to improving on pore structure of concrete caused by silica-fume and fly-ash.(3)Through grey relational grade analysis,the result shows that:Effect weight on strength and durability of pore structure parameter is different. For concrete strength, the sequence is Total porosity, Critical pores diameters and Most probable pore size. For concrete resistance to chloride ion permeability, the sequence is Average pore size, Most probable pore size and Critical pores diameters. For concrete frost resistance, the order is Total porosity, Critical pores diameters, Most probalble pore size. The effect weight numerical of different levels hole on concrete performance is different, but the order is the same. Aperture>200nm, aperture is 50-200nm, aperture is 20-50nm and aperture<20nm.