Study On The Optimized Matching Of Limestone Powder And Cementitious Materials

Limestone powder and manufactured sand as the original sample,which was grinding by the ball mill.After the treatment,the limestone powder is used as the admixture for cementitious material.Study on the effect of working property,rheological property,mechanical property and durability on cement paste,mortar and manufactured sand of concrete,which were blending the limestone powder.The main conclusions were as follows:1.According to the linear fitting of least square method,the particle size distribution of limestone powder which was fitting of the RRB model is good(R2>0.990).The characteristic parameters of De and the uniformity coefficient n could quantitatively describe the particle size distribution of different limestone powder.2.Limestone powder could improve the standard consistency and setting time of the cement paste.With the increase of the substitution quantity(0 ~ 20%),the water consumption is reduced,and the proportion of the compound is optimal.The fluidity of the cement paste increased with the increase of the amount of limestone powder.3.As for the limestone powder replaced the cement,the yield stress and plastic viscosity of cement paste have different degrees of improvement.The area of hysteresis loop of limestone powder and cement system was decreased with the increase of super plasticizer.With the increase of super plasticizer,the area of hysteresis loop of pure cement paste was decreased and then increased.4.w/c of mortar is fixed,the replacement of limestone powder is increased from 5%to 30%,and the fluidity of mortar has not been improved,and even has been reduced.With the increase of the amount of limestone powder,3d and 28 d of flexural strength and compressive strength showed downward trend.Besides,the strength contribution rate of 3d and 28 d of flexural strength and compressive strength about the coarse grain size graded limestone powder is less than that of fine grain size distribution.5.Under different rotating speed,the mortar of limestone powder-cement has occurred shear thinning.The yield stress and plastic viscosity of cement mortar were improved.6.Limestone powder has been a positive and negative effect on the resistance to chloride ion permeability of mortar.With the increase of substitution(0~30%),resistance tochloride ion permeability was gradually decreased.For the drying shrinkage property,in the whole drying age,limestone powder filling effect and particle gradation optimization improved the pore structure of cement mortar system and reduced the drying shrinkage.7.With the increase of the amount of limestone powder,the 7d and 28 d compressive strength of the manufactured sand concrete were decreased.The 28 d splitting tensile strength of concrete was maximum value,when the amount of limestone powder was 10%.8.Designing the damage environment model of freezing thawing cycle of NaCl solution and Dry wet cycle of MgSO4 solution,The change of the mass loss and the relative dynamic elastic modulus of the manufactured sand concrete was similar.