Study On Hydration Heat Release Of Cement Clinker In Early Induction Stage And Its Influencing Factors

The heat evolution process of cement hydration will greatly influence the structural performance of cement paste and concrete.The behaviors of cement and concrete including fluidity,slump,setting time,additive adaptability,etc.play an important role in the hydration heat release of induction period.And to study the heat evolution in the induction period of hydration process is of great significance to the improvement of the performance of cement and concrete.In this thesis,the hydration heat evolution of the four major minerals and the influence of different solutions,rates and additives on the hydration heat liberation of cement clinker are studied using methods of chemical analysis,XRD,thermal characterization,etc.The findings are summarized below.（1）Among the four major components of cement clinker,the C₃A contributes the most to the heat evolution in induction period,accounting for about 68%,followed by the alite,C₄AF and belite.（2）Gypsum will decrease the heat evolution and delay the hydration in the induction period.The addition of natural gypsum in industrial clinker reduces the heat released in the induction period by 54k J/kg,roughly 45%.And different gypsum leads to different effects on the heat evolution in the induction period of hydration of cement clinker.For instance,titanium gypsum with dihydrate gypsum as the major component decreases the heat evolution and the release rate in the induction period,while fluorogypsum with anhydrite as the major component increases the heat evolution and the release rate in the induction period.（3）The ratio value influences the heat release process of cement clinker in induction period by changing the relative proportion of the four components of the clinker.Generally,the higher the content of the C3A,the more the heat released and the higher the rate of heat evolution.The heat evolution and the rate first decrease and then increase as the saturation ratio increases,decrease as the silicon ratio increases,and are positively correlated with the change of the aluminum ratio.Among the three ratios,the aluminum ratio has the greatest influence on the heat evolution of clinker in induction period,followed by the silicon rate,and the saturation ratio has the lowest effect.（4）Salicylic acid in SAM solution plays an important role in the reaction between SAM solution and cement clinker by promoting the process.The heat released by the reaction between potassium hydroxide-sucrose（KOSH）solution and cement clinker will increase first and then decrease as the solute concentration increases.When the ratio of KOSH solution is KOH:sucrose:water=1:1:10,the heat evolution of reaction between KOSH and cement clinker reaches the maximum with the peak moved forward and a larger peak width ratio.If the IM is small,the maximum reaction rate of clinker in the KOSH solution with the ration KOH:sucrose:water=1:1:5 is less than the maximum reaction rate of the KOSH solution with the ration KOH:sucrose:water=1:1:10.If IM is large,the opposite is true.（5）Water reducer（ether water reducer）,early strength agent（Na₂CO₃）,retarder（Ba Cl₂）reduce the heat evolution in the early hydration of industrial clinker and delay peak time.The effect on the heat released during the early hydration of industrial clinker:Na₂CO₃>ether water reducer>Ba Cl₂.The effect on the peak time:Ba Cl₂>ether water reducer>Na₂CO₃.