Research On The Influences Of Particle Size Distribution Of Admixture On Cement Properties

Cement admixture are cementitious material with a certain degree of hydration activity.They affect on the hydration of cement paste and hardening process. Mainly for changing thehydration process of cement clinker and helping to increase the packing density of cementpowder. They also can be used to improve the performance of cement and the all ages strengthof hardened paste. The effect on the performance of cement by cement admixture has beencement industry energy conservation and the important way of green technology development.However, the hydration activity of cement admixture is relatively low, as the incorporation ina large amount, it will affect the early strength of cement. Besides, the fineness and particlesize distributions of cement admixture have an important impact on the cement grindingpower consumption and its age strength. Therefore, research the matching relationship ofparticle size distribution between cement admixture and clinker can give full play to thepotential activity of cement admixture and improve the mechanical properties of cement.This paper selects three commonly used in cement admixture, they are: slag, fly ash,limestone. Through different pre-grinding time, different particle size distributions for each offive kinds of mixed material can be obtained. With different quality scores to replace cementclinker by the cement admixture, the effect on cement performance has been researched.Combined with pore structure characteristic parameters of hardened cement paste and throughgray system theory to analysis the gray correlation between the particle size distribution andall ages strength of cement. In order to find the influence law of composite particle sizedistribution of cement performance, optimization of cement admixture and cement clinkermatch between the particle size distribution.The experimental results show that:When slag incorporated in an amount of30%,＜11μm slag powder content from59.33%increased to77.31%, the water requirement of standard consistency of slag cementdid not change significantly. The initial setting time and the final setting time of slag cementreduced more than30min. The flexural strength hydrating for3d、28d increased byapproximately10%, compressive strength increased by about7%. By calculating the degreeof correlation between the slag powder particle size range and the compressive strength ofhardened cement paste we got that:0~23μm slag powder content played an enhancing role on cement compressive strength hydrating3d and28d,>23μm slag powder content played anweakening effect on it.0~5μm,5~11μm slag powder content did the strongest factor oncement compressive strength. In addition, the incorporation of slag lead harmless hole andless harm hole increased significantly in slag cement paste, much harm hole significantlyreduce.When fly ash incorporated in an amount of10%,＜10μm fly ash powder contentincreased from33.1%to59.3%, the water requirement of standard consistency of fly ashcement increased more than3%. The initial setting time and final setting time decreasedapproximately14%with increasing levels of fine particles. The flexural strength of fly ashcement hydrating for3d,28d increased by approximately8%, the compressive strengthincreased by about11%. By calculating the degree of correlation between the fly ash powderparticle size range and the compressive strength of hardened cement paste we got that:0~33μm fly ash powder content played an enhancing role on cement compressive strengthhydrating3d and28d,>33μm fly ash powder content played an weakening effect on it. Theincorporation of fly ash lead harmless hole and less harm hole increased approximately12.24%,12.11%in slag cement paste, much harm hole significantly reduced13.51%.When limestone powder incorporated in an amount of5%,0~11μm limestone powdercontent increased from51.7%to83.3%, the water requirement of standard consistency oflimestone cement reduced4%. The initial setting time and final setting time decreasedapproximately15%with increasing levels of fine particles. The flexural strength of limestonecement hydrating for3d,28d increased by approximately10%, the compressive strengthincreased by about6%. By calculating the degree of correlation between the limestonepowder particle size range and the compressive strength of hardened cement paste we got that:0~23μm limestone powder content played an enhancing role on cement compressive strengthhydrating3d and28d,>23μm limestone powder content played an weakening effect onit.5~11μm,0~5μm limestone powder content did the strongest factor on cement compressivestrength.