早期高温水养护对矿物料混凝土力学性能影响的研究

发布时间：2018-04-10 20:38

本文选题：矿物料混凝土 + 高温水养护　；参考：《中国矿业大学》2014年硕士论文

【摘要】：本文主要探讨早期高温水养护对矿物掺合料混凝土力学性能和微观结构的影响。由于早期高温养护会对混凝土后期性能造成一定隐患，本文采用延长预养时间和加入矿物掺合料的方式来进行改善，同时探究水养温度、预养强度、配合比类型和放置龄期对混凝土性能的影响，为现有养护制度尤其是预制构件的蒸汽养护提供参考和借鉴，同时得到矿物料混凝土性能随养护条件的变化规律。论文首先通过探索试验得到预养时间和不同水养温度下的养护持续时间，以确定基准养护制度。然后对不同配合比混凝土按照基本养护制度进行养护后测试不同龄期的抗压强度和劈裂抗拉强度，根据力学实验结果选择试验进行微观结构试验和水化程度试验，探究宏观力学性能与微观结构和粉煤灰水化程度的关系。研究主要结果如下 1.无论是普通混凝土还是掺矿物掺合料混凝土，其早期抗压强度和抗拉强度随养护温度升高而增大，长期强度同养护温度的变化规律同早期强度正好相反。 2.普通混凝土和掺矿物掺合料混凝土在高温水养之前都适合进行较长时间的预养，提高预养强度可以减少浆体内部微裂缝、改善水化产物的微观形貌并细化孔结构。 3.无论采用哪种养护方式，普通混凝土的长期抗压强度大于矿物混凝土，三掺矿物混凝土在20℃水养28d后长期抗拉强度最大。单掺和双掺矿物料混凝土可采用高温养护，三掺矿物料混凝土和普通硅酸盐水泥混凝土宜采用标准养护。 4．高温养护时，混凝土长期抗压强度没有随着龄期延长而回缩，抗拉强度没有呈现始终增长的趋势，20℃~80℃范围，混凝土的抗拉强度随放置龄期的增长大约在100d龄期达到峰值，其后开始出现倒缩，而且早期养护温度越高，后期的倒缩程度越大。 5.矿物料水泥体系的微观结构（孔结构、水化产物形貌）和抗压强度有着良好的相关关系。提高预养强度后可以有效细化浆体的孔隙分布和改善水化产物的形貌；养护温度提高，矿物料水泥体系长期微观形貌较差；高预养后40℃水养护的粉煤灰水泥体系长期微观形貌好于标准养护。 6．粉煤灰水化程度实验可以得到：预养强度的提高和早期养护温度升高显著提高粉煤灰水化程度；随着龄期的延长，每一种配合比的胶凝材料的粉煤灰水化程度呈现增长趋势，但增长幅度变小；同时，，养护温度越低，粉煤灰水化程度随龄期的增长幅度越大，与单掺粉煤灰相比，加入其他矿物料会降低粉煤灰粉煤灰水化程度。
[Abstract]:This paper mainly discusses the early high temperature water curing on the influence of mineral admixture on mechanical properties and microstructure of concrete. Because of high temperature curing will cause some hidden dangers to the later concrete performance, the extension of pre curing time and adding mineral admixture to improve, and explore the water temperature, pre curing strength, mix type and place the age effect on the properties of concrete, especially for the existing maintenance system and provide reference for steam curing prefabricated, and get the variation properties of mineral aggregate concrete with the curing conditions.
Firstly, through the experiment to obtain the pre curing time and different water temperature curing duration, to determine the base maintenance system. Then the different mixing ratio of concrete in accordance with the basic maintenance system maintenance after testing compressive strength at different ages and splitting tensile strength, according to the experimental results of mechanical test microstructure and hydration test the degree of test, the relationship between macroscopic mechanical properties and microscopic structure and hydration degree of fly ash.
The main results of the study are as follows
1., no matter ordinary concrete or mineral admixture concrete, its early compressive strength and tensile strength increase with the increase of curing temperature. The rule of long-term strength and curing temperature is contrary to that of early strength.
2. ordinary concrete and mineral admixture concrete in hot water for a long time before the pre curing, improve pre curing strength of slurry can reduce internal micro cracks, improve the hydration products and microstructure refinement of the pore structure.
3. no matter what kind of curing method, long-term compressive strength of ordinary concrete is greater than 20 degrees in the concrete mineral, water 28d after long-term tensile strength of three mineral concrete. Single or double doped mineral material concrete can be made of high temperature curing, three mineral aggregate concrete and Portland cement concrete should be used in standard curing.
4. high temperature curing, long-term compressive strength of concrete with no age extension and retraction, the tensile strength has always increased, 20 DEG ~80 DEG range, the tensile strength of concrete with the age of about 100D age peak, then began to fall down, and early maintenance of higher temperature the retraction is greater.
The microstructure of 5. mineral material cement system (pore structure, hydration products morphology and compressive strength) have good correlation. To improve the pre curing strength can effectively refine paste pore distribution and improve the morphology of hydration products; improve the curing temperature, mineral material cement system long term microstructure is poor; high pre after a 40 DEG C water curing fly ash cement system long-term morphology was better than the standard maintenance.
6. fly ash hydration experiments can be obtained: pre curing strength increase and early curing temperature significantly improve the hydration degree of fly ash; with increasing age, each with the cementitious material than the hydration degree of fly ash increased, but the growth rate decreases; at the same time, curing temperature is low degree of hydration of fly ash with age range is larger, compared with single fly ash, adding other mineral materials will reduce the hydration degree of fly ash.

【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

【参考文献】