自密实自养护混凝土研制及性能试验研究

发布时间：2018-05-13 19:58

本文选题：自密实 + 自养护　；参考：《重庆大学》2016年硕士论文

【摘要】：近年来,钢管混凝土不断应用在高层建筑和超高层建筑中,但是钢管混凝土浇筑的质量以及后期的养护一直是实际应用中的盲点。自密实自养护混凝土的出现为解决混凝土的浇筑质量和后期养护提供了一种新的思路。本文通过大量的试验,研究了在自密实混凝土基础上加入高吸水树脂(SAP)来得到既能满足自密实性能也能达到一定自养护效果的混凝土(SAP-SCC)。本文的试验中以SAP掺量和额外引水量倍数为两个基本参量,研究了自密实混凝土在加入不同SAP掺量和不同额外引水量倍数后的力学性能变化规律、体积稳定性变化规律和自养护效果评价。通过湿度扩散理论建立了SAP释水前后SAP-SCC内部湿度场微分方程,为解释SAP自养护机理提供了一定的理论依据,也为定量分析SAP自养护提供一种思路。本文基于规范方法设计了SCC的配合比,在此基础上利用Powers理论得到了理论SAP掺量和额外引水量,并进行SAP-SCC试配。结果表明,完全满足工作性和力学性能的要求。SAP-SCC力学试验结果表明,适当的SAP掺量和额外引水量倍数不会使混凝土强度显著下降,并且28d强度还略有提高。但是SAP掺量和额外引水量倍数都不宜过大,否则各龄期混凝土强度会显著下降。本文中,SAP的最佳掺量为0.15%(占胶凝材料的百分比)左右,最佳的额外引水量为10~15倍(高吸水树脂的质量)左右。SAP-SCC体积稳定性试验结果表明,SAP掺入SAP-SCC后会显著减小混凝土的自由收缩和自收缩。SAP释水前,试验组与空白基准组之间的自由收缩和自收缩的变化趋势和大小均基本相同;SAP释水后,试验组与空白基准组之间的收缩变形差距开始显现。本文中,SAP掺量为0.15%左右,额外引水量为15倍左右时,SAP-SCC的自由收缩和自收缩的减缩效果最佳。本文基于Fick第二定理,通过湿度扩散定理和湿度守恒建立SAP-SCC在SAP释水前后的湿度场微分方程,发现SAP释水前后的微分方程具有相同形式,说明SAP释水前后SAP-SCC内部湿度场的扩散规律相似。然后,通过毛细孔压力理论,根据拉普拉斯方程和Kelvin方程建立了混凝土相对湿度与毛细孔表面张力之间的关系,并根据应力-应变关系建立了SAP-SCC内部相对湿度与相对收缩之间的关系。SAP-SCC养护效果试验研究结果表明,无论是SAP掺量还是额外引水量对电阻率的影响都与电极埋入深度有关,即SAP掺量和额外引水量对养护效果的影响是与混凝土内部深度有关。在电极埋入深度小于3cm时,合适的SAP掺量和额外引水量可以显著改善混凝土内部的湿度,从而减小混凝土的电阻率。可以认为深度小于3cm时SAP自养护效果明显,深度大于3cm后,虽然有一定的自养护效果,但没有深度小于3cm时效果明显。基于此,可以认为,加入SAP和引入额外水分后,对混凝土内部起到了一定的养护作用,使用加入SAP这种方式来达到自养护的效果是可行的。
[Abstract]:In recent years, concrete-filled steel tubular (CFST) has been used in high-rise buildings and super-high-rise buildings, but the quality of concrete-filled steel tubular (CFST) pouring and its later maintenance have been the blind spots in practical application. The appearance of self-compacting self-curing concrete provides a new way to solve the problem of concrete pouring quality and later curing. In this paper, a large number of experiments have been carried out to study the addition of superabsorbent resin SAP on the basis of self-compacting concrete to obtain the concrete which can not only satisfy the self-compacting performance but also achieve a certain self-curing effect. In this paper, the mechanical properties of self-compacting concrete with different SAP content and multiple of extra water diversion are studied by using two basic parameters: the addition of SAP and the multiple of extra water diversion. Changes of volume stability and evaluation of self-curing effect. Based on the theory of humidity diffusion, the differential equation of humidity field in SAP-SCC before and after the release of SAP water is established, which provides a theoretical basis for explaining the mechanism of SAP self-curing, and also provides a way of thinking for quantitative analysis of SAP self-curing. In this paper, the mix ratio of SCC is designed based on the standard method, and based on the Powers theory, the theoretical SAP content and the extra water diversion are obtained, and the SAP-SCC trial match is carried out. The results show that the strength of concrete can not be significantly decreased with proper SAP content and extra water diversion ratio, and the 28d strength is slightly increased. The results show that the concrete strength is satisfied with the requirements of workability and mechanical properties. The results of SAP-SCC mechanical test show that the concrete strength can not be significantly decreased with proper SAP content and extra water diversion ratio. However, neither the addition of SAP nor the multiple of extra water diversion should be too large, otherwise the strength of concrete at different ages will decrease significantly. The optimum dosage of SAP in this paper is about 0.15% of the cementing material. The results of the bulk stability test of SAP-SCC show that the free shrinkage and autogenous shrinkage of concrete can be significantly reduced after the addition of SAP-SCC to the concrete. Before the release of water, the optimum amount of additional water diversion is about 10 ~ 15 times (mass of superabsorbent resin). The variation trend and magnitude of free contraction and autogenous contraction between the test group and the blank reference group were basically the same. After SAP released water, the difference of shrinkage deformation between the test group and the blank reference group began to appear. In this paper, the free shrinkage and autogenous shrinkage of SAP-SCC are the best when the addition of SAP is about 0.15% and the extra water diversion is about 15 times. Based on the second theorem of Fick, the differential equation of humidity field of SAP-SCC before and after SAP water release is established by means of humidity diffusion theorem and humidity conservation. It is found that the differential equation before and after SAP release has the same form. The results show that the diffusion law of moisture field in SAP-SCC is similar before and after SAP release. Then, according to the theory of capillary pressure, the relationship between the relative humidity of concrete and the surface tension of capillary is established according to Laplace equation and Kelvin equation. According to the stress-strain relationship, the relationship between relative humidity and relative shrinkage in SAP-SCC is established. The experimental results show that the influence of SAP content and extra water diversion on the resistivity is related to the electrode embedding depth. That is, the effect of SAP content and extra water diversion on the curing effect is related to the depth of concrete. When the electrode embedding depth is less than 3cm, the proper SAP content and extra water diversion can significantly improve the humidity of concrete, thus reducing the resistivity of concrete. It can be considered that when the depth is less than 3cm, the self-curing effect of SAP is obvious. When the depth is greater than 3cm, although there is a certain self-curing effect, but no depth is less than 3cm, the effect is obvious. Based on this, it can be concluded that adding SAP and introducing extra moisture will have a certain curing effect on the concrete interior, and it is feasible to use the method of adding SAP to achieve the effect of self-curing.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU528

【相似文献】