Effect Of Phosphorus Slag Additive On Performance Of Concrete

The mineral additives have been the important sixth portion excepte for sand, stone, cement, water and super water-reducer with the development of high-strength and high-performance concrete. The main mineral admixtures are fly ash, granular blast-furnace slag and silicon fume because of the serious resource discrepancy in different areas in our country. Phosphorus slag as a kind of industry waste slag which is discharged largly has higher latent hydraulic reactivity; The study that making phosphorus slag as mineral additives of concrete.Phosphorus slag that is industry waste slag in local area of Guizhou is the object in this study. This paper studied the law of workability, mechanical properties, durability(drying shrinkage, carbonization resistance, chloride ion penetration resistance, freezing-thawing resistance) of the concrete adding phosphorus slag. This paper compared and analysed the economical and technical character of the use of phosphorus slag and fly ash as mineral admixture of concrete. This paper also discusses the effect of chemical method on reactivity of phosphorus slag. The research results can be concluded as following:①It can improve workability and reduce slump-loss of concrete by adding phosphorus slag, and it also can improve the pumpablility of concrete.②Although the early compressive strength of concrete can be clearly decressed by adding phosphorus slag, the later compressive strength of concrete can be enhanced greatly. The strength becomes lower and lower with increasing of phosphorus slag content when the phosphorus slag content is below 50%. The later compressive strength becomes larger and larger with the increasing of phosphorus slag fine ness, but there is almost no effect in early compressive strength.③Introducing phosphorus slag to concrete is bad to drying shrinkage of concrete before 90 day, and the shrinkage factor becomes larger and larger with the increasing of phosphorus slag content. But the range of shrinkage factor enhance is lower than datum contete after 90 day. Increasing phosphorus slag fine ness can augment shrinkage factor of concrete, but the range of shrinkage factor enhance is not serious. Adding phosphorus slag in concrete can apparently improve carbonization resistance,Cl-penetration resistance and freezing-thawing resistance,, and the suitable contents of phosphorus slag respectively is 30% ~ 40%. ④Comparing with fly ash which is usual mineral additive, phosphorus slag as mineral additive of concrete is better than it in improving the workability, compressive strength of concrete.⑤The reactivity of phosphorus slag can be apparently improved by adding Calcium hydroxide or Sodium sulphate alone, it can enhance strength of mator. The result of Sodium sulphate is obviously better than Calcium hydroxide and the suitable content of Sodium sulphate is 1.5% of all binding materials. By combinations of Calcium hydroxide and Sodium sulphate using the proportion of 0.5, the reactivity of phosphorus slag is much better than adding Calcium hydroxide or Sodium sulphate alone, and the suitable content is 4% of all binding materials.