| Cement-based material is the largest amount of and most widely used engineeringmaterials. It plays a major role in the national economic development. But it is a kind ofmaterial with inherent flaws such as the poor toughness and the low flexural strength. Itsstructure may be ruined because of the intrusion of various corrosive ions in the harshenvironments. Various measures were taken to solve the problems above by many scholars inrecent years such as developing the HPC by mixing the all kinds of admixtures; it has improvedthe strength and durability of concrete at some degree. However，it is the not very densestructure that lead to the destruction of cement-based materials.We should further improve the performance of cement-based material based on theresearch of its structure, study the mechanism of matching hydration of clinker mineral,control all kinds of factors forming the homogeneous dense hardened cement paste, thus wecan produce a homogeneous dense concrete with good durability and high quality and longservice life.In the present work, the effect of clinker mineral composition, induction of seed crystalsand the particle size distribution of clinker to the matching hydration of clinker mineral werestudied to produce a homogeneous dense hardened cement paste by controlling the formationrate, size and shape and packing of hydrate. The main obtained results and conclusions are asfollows:1. Effect of matching hydration of clinker mineral composition to the structure andproperties of hardened cement paste(1) There is a good correlation between compressive strength of hardened cement pastecuered for1day and C3A content, But it is related with KH, When the KH equals0.87, theratio of (C3S+C3A)/C4AF has a better correlation to the strength of hardened cement paste, thecorrelation coefficient is0.9996. C3S content has a good correlation to the strength ofhardened cement paste cured for28days, the correlation coefficient is0.9251. But it is relatedwith KH, When the KH equals0.87the ratio of (C3S+C3A)/C4AF has a better correlation tothe strength of hardened cement paste cured for28days, the correlation coefficient is0.9684.When the KH equals0.93the ratio of C3S/C2S has a better correlation to the strength of hardened cement paste cured for28days, the correlation coefficient is0.9989. The ratio of(C3S+C2S)/C4AF has a good correlation to the strength of hardened cement paste cured for90days when the KH equals0.87, the correlation coefficient is0.9998.(2) The content C3A in the clinker is the main factor influencing the rate of heatevolution during the hydration in one hour, the C3S content has important influence on therate of heat evolution during the hydration of samples when the C3A content in differentsamples are smaller. The C3S content also has important influence on the rate of heatevolution during the hydration of samples after30hours.(3) The sample with average pore diameter9.35μm, the most probable pore size3.15μmand the porosity of sample5.29%has the highest hydration degree. All minerals of it play animportant role in forming the homogeneous dense hardened cement paste. The mineralcompositions of Portland cement clinker are as follows: C3S58.6%，C2S17.9%，C3A9.6%，C4AF11.3%%.2. Effect of induction of seed crystals to the matching hydration of clinker mineral andstructure and properties of hardened cement paste(1) Seed crystal has a certain role of accelerating the hydration and setting of the cements,the optimization to the properties of cement paste is best when adding the seed crystal withwater cement ratio0.28curing for56days into cement.(2) The compressive and flexural strength of cement mortar are increased when the seedcrystals are mixed into the cement and the best dosage is4%. The effect of seed crystals madewith water cement ratio0.28and curing for56days on compressive and flexural strength ofcement is better than that of other seed crystals under the optical dosage. Through acomprehensive analysis, adding about4wt%seed crystals made with water cement ratio0.28and curing for56days into cement, the3days’ compressive and flexural strength of cementmortar were increased by13.63%and45.26%,7days’ strength by10.29%and17.23%, and28days’ strength by13.83%and23.03%.3. Effect of particle size distribution of clinker to the structure and properties of hardenedcement pasteWith the reasonable controlling over the particle size distribution of clinker, the rate ofheat evolution during the hydration of clinker can match in all particle size range. Furthermore dense and homogeneous cement paste with higher strength and optimal structureare obtained. In this paper, the hardened cement paste has the highest strength with averagepore diameter11.9μm, the most probable pore size3.5μm and the porosity4.3%when theclinker with the particle size0.4-6.0μm make up28.61%,6.0-20μm42.8%,20-40μm26.2%. |
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