Hydration Characteristics Of Self-repairing Coarse Particle Clinker And Effects On Cement Strength

Cement fineness has been a focus recently. Problems of superfine cement havebeen widely known: for example, exothermic centralization in early stage, lack ofincrease of strength in late stage and decrease of durability, etc. Thus, research onstrength of coarse-particle cement in the long run can help to build theoretical basisto improve cement durability and to fulfill cement self-repairing.Existence of coarse particles can decrease the amount of water necessary tokeep cement in standard consistency. Increases of both percentage and size ofcoarse particles contribute to the decrease. However, the effect is not as obvious asestimated. When the size of coarse particles is less than30μm, no change of wateruse has been observed. As to time of condensation, no obvious effect exists becauseof coarse particles.As to hydration, with enough water, coarse particles can be sufficientlyhydrated up to50percent degree of cement. As size of particles increases, degree ofhydration will go down. For low heat cement, the overall degree of hydration islower than that of the ordinary Portland cement clinker, but with better growth trendin later stage.Moreover, this article studies surface hydration process of coarse particles.From the precipitation of Ca（OH）₂, the formation of gel network, to the gap filling,the higher hydration activity of coarse particles is a premise to fulfill cementself-repairing.This article also studies3kinds of coarse clinker with different particle sizesand discusses their mineral components and particle degree distribution. Further,this article also studies the effects of particle size, with different contents, oncompressive strength, hydration characteristics and early condensation performance.Experiment results show that as percentage of coarse clinker increases, strengthfirst decreases and then increases. Where particle size falls within80μm¹50μm,strength loss is significant and no obvious activity can be observed in late stage;where particle size falls within60μm⁸0μm, activity exists but not in an obviousway.