低温复合胶凝材料体系水化动力学研究

发布时间：2018-04-10 04:20

本文选题：低温　切入点：复合胶凝材料　出处：《沈阳建筑大学》2014年硕士论文

【摘要】：我国严寒地区的冬季时间较长,可以对混凝土工程进行施工的工期较短,大大延长了混凝土工程的施工周期,延误了施工进度。另外,长期的低温环境也会给工程质量带来隐患。在此背景下,研究低温条件下,粉煤灰、硅灰等工业废弃物对胶凝材料的水化特性的影响,具有特别重要的现实意义。虽然我国在低温施工技术取得长足的进步和丰富的经验,但是在这方面的研究还相对较少,远不能为冬期施工提供系统的理论指导。在低温条件下,混凝土中分子活性较低,水泥水化反应速度减慢,力学性能发展受到限制,为了改善这种状况,施工中通常掺入适量的矿物掺合料及外加剂,虽然促进了水泥的水化反应,但是也使水化环境更为复杂,那么此时复合胶凝体系在低温条件下的水化进程如何,外掺料的加入,对水泥水化产生了什么影响。这是低温混凝土中有待解决的问题,也是解决冬季施工的重要问题。为了更有效的指导低温条件下混凝土的施工和矿物掺合料的综合利用,本文在固定水胶比的条件下,通过同步热分析仪和水化微量热仪,分别测试了低温条件下复合胶凝体系的结合水含量、水化时产生的温度变化等指标,并通过对试验数据的处理和转化,研究了低温养护制度(0℃、-5℃、-10℃)和矿物掺合料掺量(粉煤灰：0、10%、20%、30%；硅灰：0、2%、5%、8%)对复合胶凝体系早期水化程度的影响规律、对复合胶凝材料体系早期水化放热速率诱导期和二次放热峰的变化规律以及对复合胶凝体系早期水化动力学参数的影响规律。本文通过同步热分析仪,测试了复合胶凝体系的结合水含量,研究了不同低温养护制度和不同矿物掺合料掺量对复合胶凝体系早期水化程度的影响规律。结果表明：降低温度会对复合胶凝材料体系早期的水化产生抑制作用,而且这种抑制作用的效果随着温度的降低而减小。硅灰对低温复合胶凝材料体系早期的水化产生促进作用,随着硅灰掺量的增加这种促进作用会越来越不明显。粉煤灰对低温复合胶凝材料体系早期的水化产生起到抑制作用,随着粉煤灰掺量的增加这种抑制作用会越来越明显。在复掺硅灰和粉煤灰的复合胶凝体系中,硅灰对复合胶凝材料体系水化的促进作用要明显于粉煤灰对水化的抑制作用。本文通过水化微量热仪,测试了复合胶凝体系水化时产生的温度变化,研究了不同温度、不同矿物掺合料掺量对复合胶凝体系的水化放热速率诱导期和二次放热峰的影响关系,结果表明：随着温度的降低,水化诱导期会延长,水化二次放热峰出现时间推迟,次放热峰的最高放热速率降低。随着矿物掺合料的增加,水化诱导期时间延长,二次放热峰出现时间推迟。硅灰掺量的增加会使水化二次放热峰的最大放热速率提高,粉煤灰掺量的增加会使水化二次放热峰的最大放热速率降低。在复掺硅灰和粉煤灰的复合胶凝体系中,硅灰对复合胶凝材料体系水化的促进作用要明显于粉煤灰对水化的抑制作用。本文通过对复合胶凝体系水化放热速率曲线的分析,选择了Krstulovic-Dabic水化放热模型,研究了不同温度、不同粉煤灰和硅灰掺量对复合胶凝体系水化过程中的动力学参数中反应级数,反应速率常数和过程转变点的影响关系,结果表明：随着温度降低,反应级数增加,反应速率常数减小,过程转变点滞后,随着矿物掺合料的增加,反应级数增加,I过程反应速率常数增大,硅灰的掺入使NG和D过程的反应速率常数增加,过程转变点提前。粉煤灰的掺入使NG过程的反应速率常数降低,D过程无规律变化过程转变点滞后。总之,温度的降低对复合胶凝材料体系的水化过程起到了抑制作用。硅灰掺量的增加会促进水化过程,粉煤灰掺量的增加会抑制水化过程。在二者复掺的复合胶凝材料体系中硅灰对水化的促进作用大于粉煤灰对水化的抑制作用。
[Abstract]:Longer in winter cold area of our country, the construction can be carried out on the concrete project of short duration, greatly extend the construction period of concrete project, the delay of the construction schedule. In addition, low temperature environment for a long time will also bring risks to the quality of the project. Under this background, the research under the condition of low temperature, fly ash, water chemical characteristics the cementitious material of silica fume and other industrial waste, has important realistic significance. Although China's low temperature construction technology has achieved great progress and rich experience, but the research in this area is relatively small, can not provide theoretical guidance for the system construction in winter. Under the condition of low temperature, concrete Molecular low activity of cement hydration reaction rate, mechanical property development limited, in order to improve this situation, the construction is usually mixed with an appropriate amount of mineral admixtures and additives, while promoting the water The hydration reaction of mud, but also make the water environment is more complex, so how to composite cementitious system under the condition of low temperature hydration process at the same time, adding admixture, what is the impact on cement hydration. It is a problem to be solved in the low temperature of concrete, but also solve the important problem of winter Ji Shigong comprehensive utilization of concrete. In order to more effectively guide the construction under the condition of low temperature and mineral admixture, in the condition of fixed water binder ratio, by simultaneous thermal analyzer and hydration calorimetry, combined with the water content of the composite cementitious system under low temperature conditions were tested, produced during hydration temperature change other indicators, and through the processing and conversion of test data, studied the low temperature curing system (0 degrees, -5 degrees, -10 degrees C) and mineral admixtures (fly ash: 0,10%, 20%, 30%; 0,2%, 5%, 8%: silica fume) of composite cementitious system early hydration process Influence of the variation of the composite cementitious material system early hydration exothermic rate and the induction period of two exothermic peaks and the composite cementitious system early hydration kinetics parameters. The influence of the simultaneous thermal analyzer, combined with the water content of the composite cementitious system was tested on different low temperature curing system and different mineral admixtures on the influence of the hydration degree of composite cementitious system. The result shows that the decrease of temperature will cause the inhibition of composite cementitious material system of early hydration, but this inhibition effect decreases with decreasing temperature. Wollastonite promotes the low-temperature composite gel the material system of early hydration, with silica fume increases this effect will be more and more obvious. The low temperature of fly ash cementitious composite early hydration to produce inhibition With the increase of the inhibition effect will be more and more obvious. The amount of fly ash in composite cementitious system of fly ash and silica fume compound powder, inhibition of promoting effect of silica fume on the composite cementitious material hydration system is obviously in fly ash on hydration. Through hydration calorimetry, temperature change of composite cementitious system during hydration test, to study the effect of temperature, the different influence of mineral admixture content exothermic rate of hydration of composite cementitious system of the induction period and the two exothermic peak, the results show that with the decrease of temperature, hydration induction period will be prolonged, hydration the two exothermic peak time delay time, the highest peak heat release rate decreased with the increase of mineral admixture, the hydration induction period of time, the two exothermic peak appearing time delayed. Silica fume will increase the hydration exothermic peak maximum two times The rate increased with the increase of fly ash content will make water of two times the maximum peak heat release rate decreased. The composite cementitious system of fly ash and silica fume compound powder, inhibition effect of silica fume on the composite cementitious material hydration system is obviously in fly ash on hydration. Through the analysis of the composite cementitious system hydration exothermic rate curve, select the Krstulovic-Dabic hydration model to study the effect of temperature, fly ash and silica fume on the kinetic parameters of the composite cementitious system during hydration in series, affect the rate constant and reaction process of the transition point, the results show that: with the temperature the reaction order increased, decreased, decreasing reaction rate, the transition point lag, with mineral admixtures increases, the reaction order increased, I reaction rate constant increases, silica fume can NG and anti D process Should the rate constant increase, transition point in advance. The fly ash makes the reaction rate constant NG process decreased, D process has no regular change process change lag. In short, the decrease of temperature on hydration process of composite cementitious material system to suppress. Silica fume increases will promote water of course, the increase of fly ash can inhibit the hydration process. The inhibitory effect of silica fume on two composite cementitious material system of water is stronger than fly ash on hydration.

【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】：TU52;TQ177

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