新型晶核型早强剂的性能与早强机理研究
发布时间：2018-08-16 07:39
【摘要】：早强剂是一种常用于水泥混凝土制品生产,快速施工的混凝土工程,低温及负温施工的混凝土工程的混凝土外加剂。传统的早强剂在使用中存在混凝土工作性降低、强度倒缩、弹性模量后滞、碱-骨料反应、泛霜等问题。如何开发和应用早强效果显著、对混凝土性能无不良影响的新型早强剂,是目前混凝土早强剂研究与应用的重要课题。本文围绕新型晶核型早强剂Vivid300(CN)的性能与早强机理,通过砂浆的流动性试验、凝结时间试验、干燥收缩试验,研究了Vivid300(CN)对砂浆流动性、凝结时间及体积稳定性的影响。通过砂浆及混凝土的力学试验研究了Vivid300(CN)对砂浆及混凝土强度发展的影响。分析密闭条件下水泥的水化温度变化,研究了Vivid300(CN)对水泥水化温度发展的影响;采用化学结合水法研究了Vivid300(CN)对水泥水化程度的影响;基于Krstulovic-Dabic模型,探讨了Vivid300(CN)对水泥水化动力学过程的影响;利用X射线衍射仪及扫描电子显微镜,分析了Vivid300(CN)对水泥水化产物成分及形貌的影响。基于以上研究对新型晶核型早强剂的早强机理进行了分析。试验结果表明:新型晶核型早强剂Vivid300(CN)不会造成砂浆流动度的明显降低;Vivid300(CN)与高减水型聚羧酸减水剂复合使用,砂浆的凝结时间随掺量的增加而缩短;Vivid300(CN)与早强型聚羧酸减水剂复合使用,掺量小于2.0%时不会明显缩短砂浆的凝结时间,掺量为5.0%时使砂浆的初凝及终凝结时间均有明显缩短。新型晶核型早强剂能够使水泥水化温峰提前,峰值增加,加快水泥水化进程;新型晶核型早强剂能够加快水泥早期水化产物的生成,提高水泥的水化程度;新型晶核型早强剂不会使水泥水化产生新相,且能够促进早期水化产物中C-S-H凝胶的生成。新型晶核型早强剂能够明显提高砂浆及混凝土1d以内的超早期强度;新型晶核型早强剂不会引起砂浆后期强度的倒缩;在蒸养养护条件下,新型晶核型早强剂能够有效提高混凝土的蒸养脱模强度,掺5.0%新型晶核型早强剂的混凝土,50℃蒸养3h后的脱模强度相比空白组强度提升160%。新型晶核型早强剂Vivid300(CN)的早强机理分析表明:新型晶核型早强剂的主要组分A为水泥水化早期C-S-H凝胶的生成提供细小晶核,降低其结晶成核与晶体生长的阻力,加快C-S-H凝胶的早期生成,大量生成的C-S-H凝胶将钙矾石、氢氧化钙等及其他水化产物胶结在一起,加快水泥浆体结构的形成,提高水泥石的密实度,进而起到早强作用。本文对新型晶核型早强剂Vivid300(CN)的研究将会为晶核型混凝土早强剂的应用和发展提供支持。
[Abstract]:Early strength agent is a kind of concrete admixture which is often used in the production of cement concrete products and the rapid construction of concrete engineering and the construction of low temperature and negative temperature concrete engineering. There are some problems in the use of traditional early strength agents, such as low workability of concrete, shrinkage of strength, lag of elastic modulus, alkali-aggregate reaction, frost flooding and so on. How to develop and apply a new type of early strength agent, which has remarkable effect on early strength and has no adverse effect on the performance of concrete, is an important subject in the research and application of early strength agent of concrete at present. In this paper, the effects of Vivid300 (CN) on the fluidity, setting time and volume stability of mortar were studied by means of flow test, setting time test and drying shrinkage test. The influence of Vivid300 (CN) on strength development of mortar and concrete was studied through mechanical tests of mortar and concrete. The influence of Vivid300 (CN) on the hydration temperature of cement is studied by analyzing the change of hydration temperature of cement under the closed condition, and the influence of Vivid300 (CN) on the hydration degree of cement is studied by chemical combined water method. Based on the Krstulovic-Dabic model, the effect of Vivid300 (CN) on the hydration degree of cement is studied. The effect of Vivid300 (CN) on the hydration kinetics of cement was discussed, and the effect of Vivid300 (CN) on the composition and morphology of cement hydration product was analyzed by X-ray diffraction and scanning electron microscope. Based on the above studies, the mechanism of early strength of the new type of nucleated early strength agent is analyzed. The experimental results show that the new type of early strength crystal core agent Vivid300 (CN) will not significantly reduce the flow degree of mortar. Vivid 300 (CN) and high water reducing polycarboxylic acid water reducer are used in combination. The setting time of mortar shortens the combination of Vivid300 (CN) and early-strength polycarboxylic acid superplasticizer with the increase of content. When the content is less than 2.0, the setting time of mortar will not be significantly shortened, and the initial setting time and final setting time of mortar can be obviously shortened when the content is 5.0. The new crystal core early strength agent can advance the hydration temperature peak and increase the peak value of cement and accelerate the hydration process of cement, and the new crystal core early strength agent can accelerate the formation of cement hydration products and improve the hydration degree of cement. The new nucleated early strength agent does not make the hydration of cement produce new phase, and it can promote the formation of C-S-H gel in the early hydration product. The new type of crystal core early strength agent can obviously improve the super early strength of mortar and concrete within 1 day, the new type of early strength agent of crystal core type can not cause the shrinkage of the later strength of mortar, and under the condition of steaming and curing, The new type of nucleated early strength agent can effectively improve the strength of steaming and demoulding of concrete. The strength of concrete mixed with 5.0% of the new type of early strength agent at 50 鈩，
本文编号：2185317
[Abstract]:Early strength agent is a kind of concrete admixture which is often used in the production of cement concrete products and the rapid construction of concrete engineering and the construction of low temperature and negative temperature concrete engineering. There are some problems in the use of traditional early strength agents, such as low workability of concrete, shrinkage of strength, lag of elastic modulus, alkali-aggregate reaction, frost flooding and so on. How to develop and apply a new type of early strength agent, which has remarkable effect on early strength and has no adverse effect on the performance of concrete, is an important subject in the research and application of early strength agent of concrete at present. In this paper, the effects of Vivid300 (CN) on the fluidity, setting time and volume stability of mortar were studied by means of flow test, setting time test and drying shrinkage test. The influence of Vivid300 (CN) on strength development of mortar and concrete was studied through mechanical tests of mortar and concrete. The influence of Vivid300 (CN) on the hydration temperature of cement is studied by analyzing the change of hydration temperature of cement under the closed condition, and the influence of Vivid300 (CN) on the hydration degree of cement is studied by chemical combined water method. Based on the Krstulovic-Dabic model, the effect of Vivid300 (CN) on the hydration degree of cement is studied. The effect of Vivid300 (CN) on the hydration kinetics of cement was discussed, and the effect of Vivid300 (CN) on the composition and morphology of cement hydration product was analyzed by X-ray diffraction and scanning electron microscope. Based on the above studies, the mechanism of early strength of the new type of nucleated early strength agent is analyzed. The experimental results show that the new type of early strength crystal core agent Vivid300 (CN) will not significantly reduce the flow degree of mortar. Vivid 300 (CN) and high water reducing polycarboxylic acid water reducer are used in combination. The setting time of mortar shortens the combination of Vivid300 (CN) and early-strength polycarboxylic acid superplasticizer with the increase of content. When the content is less than 2.0, the setting time of mortar will not be significantly shortened, and the initial setting time and final setting time of mortar can be obviously shortened when the content is 5.0. The new crystal core early strength agent can advance the hydration temperature peak and increase the peak value of cement and accelerate the hydration process of cement, and the new crystal core early strength agent can accelerate the formation of cement hydration products and improve the hydration degree of cement. The new nucleated early strength agent does not make the hydration of cement produce new phase, and it can promote the formation of C-S-H gel in the early hydration product. The new type of crystal core early strength agent can obviously improve the super early strength of mortar and concrete within 1 day, the new type of early strength agent of crystal core type can not cause the shrinkage of the later strength of mortar, and under the condition of steaming and curing, The new type of nucleated early strength agent can effectively improve the strength of steaming and demoulding of concrete. The strength of concrete mixed with 5.0% of the new type of early strength agent at 50 鈩，
本文编号：2185317
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