矿渣—水泥复合胶凝体系低温水化特性研究

发布时间：2018-07-28 08:17

【摘要】：我国寒冷地区地域辽阔,包括了“三北”地区13个省、市、自治区,占全国面积的50%以上,冬季时间长达3-6个月,因此,在寒冷地区冬季混凝土施工技术的研究显得尤为重要。硅酸盐水泥的水化放热行为包括水化放热速率和放热量,其对混凝土的耐久性有很大影响；在碱性条件下,矿渣会发生水化反应,生成硅酸钙凝胶和沸石类的水化产物,其形成的固体结构十分致密。低温下水泥水化模型的提出,为寒冷地区冬季混凝土的施工提供了理论支持。因此,研究矿渣-水泥复合胶凝材料体系在低温下的水化规律,具有重大意义。本文重点研究矿渣-水泥复合胶凝材料体系在低温下的水化规律,研究矿渣掺量、水化温度等因素对复合胶凝材料体系水化放热速率、水化放热量、非蒸发水含量、力学性能及微观结构的影响。对矿渣-水泥复合胶凝材料体系低温水化动力学参数进行计算,验证并建立低温复合胶凝材料体系水化反应的数学模型。研究结果表明,当水化温度不变,随着矿渣掺量的增加以及矿渣掺量不变,随着水化温度的降低,矿渣-水泥复合胶凝材料体系水化放热速率与水化放热量、抗压与抗折强度、非蒸发水含量均呈现出下降的趋势。水化温度为-10℃时,矿渣掺量分别为0、10%、30%、50%,复合胶凝材料体系进入加速期的水化时间对比纯硅酸盐水泥体系,分别滞后了0.17h、0.43h、0.62h；另选取加速期,水化时间20h,水化温度为5℃、0℃、-10℃,此时,矿渣掺量为50%的复合胶凝材料体系的水化放热速率比纯硅酸盐水泥体系降低了25.77%、40.75%、43.25%；复合胶凝材料体系的非蒸发水含量随着矿渣掺量的增加而降低,随着龄期的延长而增加,掺加矿渣的复合胶凝材料体系非蒸发水量均低于纯水泥净浆体系。水化温度为-10℃,水化龄期为28d的复合胶凝材料体系非蒸发水含量随着矿渣掺量的增加,分别降低了11.79%、16.64%、45.38%。水化温度为-10℃,矿渣掺量为30%的复合胶凝材料体系非蒸发水含量随着龄期的增加,分别增加了83.87%、145.16%、]77.42%。随着矿渣掺量的增加、水化温度的降低,复合胶凝材料体系胶砂试件的抗压、抗折强度呈现下降的趋势。选取水化温度为-10℃,水化龄期为28d,不同矿渣掺量复合胶凝材料体系胶砂试件的抗压、抗折强度分别降低了12.96%、26.80%、34.58%及8.52%、24.03%、36.43%。根据Krstulovic-Dabic的水泥水化动力学模型,对水化反应的3个过程进行相应的表征,得到了低温条件下复合胶凝材料体系的动力学参数K、n以及各个阶段反应速率和反应度间的关系。通过计算获取各个阶段的反应速率曲线,可较好地对由量热实验数据绘制的复合胶凝材料体系实际水化速率da/dt曲线进行分段的模拟。通过计算获得的动力学参数,可以对低温条件下复合胶凝材料体系不同反应阶段水化反应程度进行预测。并建立了抗压强度的数学模型,通过建立的一元线性回归方程可以看出,不仅回归方程非常显著,R2值均大于99%,而且矿渣掺量对复合胶凝材料体系胶砂试件抗压强度的影响极其显著。利用SEM图谱分析可看出,纯水泥浆体中有大量生长良好的钙矾石晶体产生,并且外形完整；同龄期掺加矿渣的水泥浆体中,钙矾石晶体短小而纤细,外形不完整,试样微观结构较为松散,导致抗压强度降低；通过XRD研究可看出,水化龄期为3d,复合胶凝材料体系中CH所占晶体物质的比例随着矿渣掺量的增加而降低,这与非蒸发水含量值及抗压强度值的变化规律是一致的。
[Abstract]:China's cold region has a vast territory, including 13 provinces in the "Three North" areas, cities and autonomous regions, which account for more than 50% of the country's area and winter time for up to 3-6 months. Therefore, the study of concrete construction technology in cold regions is particularly important in winter. The durability of soil has a great influence. Under the alkaline condition, the slag will be hydrated and produce the hydrated product of calcium silicate gel and zeolite. The formation of the solid structure is very dense. At low temperature, the cement hydration model is put forward to provide theoretical support for the construction of concrete in cold area in winter. Therefore, the slag cement compound adhesive is studied. The hydration law of the condensate system at low temperature is of great significance. This paper focuses on the hydration law of the slag cement composite cementitious material system at low temperature, and studies the effects of the amount of slag and the hydration temperature on the hydration heat rate, the hydration heat, the non evaporative water content, the mechanical properties and the microstructure of the composite cementitious material system. The dynamic parameters of the low temperature hydration of the slag cement composite cementitious material system are calculated, and the mathematical model of the hydration reaction of the composite cementitious material system at low temperature is verified and established. The results show that the slag cement composite is combined with the increase of the amount of slag and the amount of slag admixture, and the decrease of the hydration temperature. The hydration heat rate and the hydration heat, the compressive strength and the flexural strength, the non evaporative water content of the cementitious material system decreased. When the hydration temperature was -10 C, the slag content was 0,10%, 30%, 50% respectively. The hydration time of the compound cementitious material system entered the accelerating period compared to the pure Portland cement system, which lagged behind 0.17h, 0.43h, 0.62 respectively. H, in addition to the acceleration period, the hydration time is 20h, the hydration temperature is 5 C, 0 C and -10 C. At this time, the hydration heat rate of the composite cementitious material system with the slag content of 50% is 50% lower than that of the pure Portland cement system by 25.77%, 40.75%, 43.25%; the non evaporative water content of the composite cementitious material system decreases with the increase of the slag content, with the age of age. The non evaporation water content of the composite cementitious material mixed with slag is lower than that of pure cement paste system. The non evaporative water content of the composite cementitious material system with hydration age of 28d is -10 C and the amount of slag is increased by 11.79%, 16.64%, and 45.38%. hydration temperature is -10 C, and the slag content is 30%. The non evaporative water content in the cementitious material system increased by 83.87%, 145.16%, respectively, with the increase of the slag content and the decrease of the hydration temperature. The compressive strength of the mortar specimens of the composite cementitious material system was reduced. The hydration temperature was -10 C, the age of hydration was 28d, and the content of different slag was mixed. The compressive strength of the cementitious material system was reduced by 12.96%, 26.80%, 34.58% and 8.52%, 24.03%, and 36.43%., according to the Krstulovic-Dabic dynamic model of cement hydration, was used to characterize the 3 processes of hydration reaction, and the dynamic parameters of the composite cementitious material system under low temperature, K, N and each other, were obtained. The relationship between the rate of reaction and the degree of reactivity. By calculating the reaction rate curves of each stage, the actual hydration rate da/dt curve of the composite cementitious material system, drawn by the calorimetric data, can be simulated in a piecewise way. By calculating the obtained kinetic parameters, the composite cementitious material under low temperature conditions can be obtained. The degree of hydration reaction in different reaction stages is predicted and the mathematical model of compressive strength is established. Through the established linear regression equation, it is found that not only the regression equation is very significant, the R2 value is more than 99%, but the slag content has a very significant effect on the compressive strength of the composite cementitious material system. The use of SEM Atlas It can be seen that a large number of fine ettringite crystals are produced in the pure cement paste, and the shape is complete. In the cement slurry with the age of the slag, the crystal of ettringite is short and fine, the shape is incomplete and the microstructure is loose, which leads to the reduction of the compressive strength. The age of hydration is 3D and compound glue can be seen through the XRD study. The proportion of CH in the condensate system decreases with the increase of slag content, which is the same as that of the non evaporative water content and the compressive strength.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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