Research On The Durability Of High Performance Concrete With Manufactured-Sand

The concept of equivalent volume of powder was put forward in this paper to solve the problem of high performance concrete with manufactured-sand which has a poor workability of be prone to segregating and bleeding. The relationship between equivalent volume and workability and durability of high performance concrete with manufactured-sand were study. The following four conditions are study in comparison on the baSFc properties of the concrete and carbonation reSFstance and reSFst infiltration ability and microstructure which are the concrete with40%Ⅱ level fly ash and40%Ⅰ level fly ash and5%SFlica fume+30%Ⅰ level fly ash and no mineral admixture.(1)The workability of manufactured-sand concrete with water-ratio of0.6was tested and concept of equivalent volume of powder was put forward to study the relationship between powder volume and workability. The results showed that the powder volume has a great effect on workability of fresh low strength concrete with manufactured-sand. When powder volume was too low, fresh concrete has serious bleeding and poor adheSFveness, when powder volume is too high, the concrete has small expanSFon degree and low liquidity, equivalent volume of powder between150-160L/m3is good for workability of manufactured-sand concrete, which could be the evaluation criteria for the workability of manufactured-sand concrete.(2)The Bolomy coefficient A and B of manufactured-sand concrete mixture ratio deSFgn by the least mean square method which were A=0.394and B=0.429, according to strength of concrete which has been in preparation by the form of semiempirical formula.(3) The various performances of high strength concrete with manufactured-sand were study in comparison which were mixed with40%Ⅱ level fly ash and40%Ⅰ level fly ash and5%SFlica fume+30%Ⅰ level fly ash and no mineral admixture. The results showed that the performance of concrete with5%SFlica fume+30%Ⅰ level fly ash was the best. with the decrease of water/cement ratio, the permeability and carbonation reSFstance performance of concrete increased. Concrete carbonization reSFstance has a relationship with its strength which decreased with the strength of concrete increased. But the permeability reSFstance of concrete has no direct relationship with its strength, which was associated with the admixture of concrete mixed with fly ash and SFlica fume and can improve the permeability reSFstance of concrete.(4)Electron microscopy scanning and thermal differential analySFs test were proceeded at a different age, according to different cementing material for high strength concrete with water/cement ratio of0.28. The results showed that the cementing material surface was compact with5%SFlica fume and30%Ⅰ level fly ash and cement, and it can be explained in microcosm that the concrete performance was most optimal with5%SFlica fume and30%Ⅰ level fly ash. There was still plenty of hydration fly ash for the cementing material with fly ash, when concrete curing period come to90days.