Matching Hydration Of Mineral Of Portland Cement Clinker And Its Adjustment

Cement-based materials are the largest amount of man-made building materials,and they play an irreplaceable role in the iterative development of human society.The performance of cement-based materials is closely related to the hydration of cement minerals.The coordination of hydration among various minerals and the uniform and compact accumulation of products are conducive to the sound development of cement-based materials’strength and durability.However,the size of their product is different;and the dissolution rate of mineral particles is not consistent with the rate of product generation.These defects will seriously affect the uniformity and compactness of the hardened paste structure and limit the development of the mechanical strength and durability of cement-based materials.In addition,the regulation mechanism of the matching hydration of cement-based materials and the evolution of the structure and properties of the hardened body are still unclear.In this paper,four kinds of mineral in Portland cement are synthesized in advance.Then,based on the different hydration activity of each mineral in Portland cement,the relationship between mineral composition and properties in C₃S+C₃A,C₃S+C₄AF and C₃S+C₃A+C₄AF systems are selected and studied.On the basis of the optimal ratio,through mechanical properties,hydration properties and microstructure characterization,the regulation effects of nanomaterials,water reducing agents and other common additives on the hydration matching of each mineral system and the formation of hardened paste structure are studied.The main results and conclusions obtained are as follows:（1）According to the development of different ages and strengths,experiments have determined the optimal mineral composition of each system:C₃S+C₃A system C₃S:C₃A=4:1;C₃S+C₄AF system C₃S:C₄AF=4:1;C₃S+C₃A+C₄AF system C₃S:C₃A:C₄AF=80.35:9.3:10.35,which is close to C₃S:C₃A:C₄AF=4:1:1.（2）The ettringite formed by the reaction of C₃A and gypsum can promote the hydration of C₃S and the formation of Ca（OH）₂.The preferentially formed ettringite provides nucleation sites for the formation of Ca（OH）₂ crystals in the subsequent products, reducing the nucleation energy,and promotes the hydration of C₃S minerals.（3）The presence of nano-SiO₂ inhibits the consumption of gypsum and hinders the formation of ettringite.The reason drawn from the references is that the negatively charged nano-SiO₂ is adsorbed on the surface of positively charged C₃A minerals through electrostatic effect,occupying the reaction sites of C₃A minerals,thereby inhibiting the reducing the nucleation energy,and promotes the hydration of C3 S minerals.（4）The addition of nano-SiO₂,nano-Ti O₂ and nano-CaCO₃ can induce C₃S to hydrate in advance,and nano-SiO₂ can greatly increase the hydration rate of C₃S,generating more hydration products.（5）The addition of nano-SiO₂,nano-Ti O₂,and nano-CaCO₃ all inhibit the dissolution of C₄AF minerals,which is related to the adhesion of nano-materials on the surface of C₄AF particles.Nanomaterials are adsorbed on the surface of C₄AF particles due to their large surface energy,so that a dense product layer is formed on the surface of C₄AF particles,which prevents the direct contact between C₄AF and water.（6）The polycarboxylate superplasticizer can inhibit the dissolution of C₃A,C₄AF and C₃S.The improvement of the macromechanical properties of each system by the water reducer is mainly achieved by optimizing the pore structure.