功能组分对石灰石资源全利用混凝土干燥收缩的影响

Affects of Function Constituents on Dry Shrinkage of Concrete with Total Utilization of Limestone Resources

为降低石灰石资源全利用混凝土的开裂敏感性,采用自制的试验装置,研究了聚乙烯醇(PVA)纤维、减缩剂和膨胀剂对该混凝土干燥收缩的影响规律,以得到有效降低干燥收缩的技术措施,并结合内部相对湿度和孔隙率分析了相应的影响机理。结果表明,减缩剂和膨胀剂可以有效降低石灰石资源全利用混凝土的干燥收缩,其中以减缩剂降低效果更好,而PVA纤维反而增加了其干燥收缩;相比于基准混凝土相应砂浆的孔隙率,掺加减缩剂砂浆的不同孔径的孔隙率均最低,掺加膨胀剂砂浆的次之,而PVA纤维明显增加了对干燥收缩影响较大的小于100nm的孔隙率;同步测试得到的干燥收缩与内部相对湿度有较好的线性回归关系,通过测试内部相对湿度可以计算出同龄期的干燥收缩。

In order to decrease the cracking sensitivity of concrete with total utilization of limestone resources, the in-fluence law of polyvinyl alcohol （PVA） fiber, shrinkage reducing admixture and expansive agent on drying shrinkage of the concrete was studied by the self-made test device to obtain the effective technology measure of decreasing drying shrink-age, and the corresponding influence mechanism was analyzed by testing internal relative humidity and porosity. The re-sults indicate that the shrinkage reducing admixture and expansive agent can effectively decrease drying shrinkage of con-crete with total utilization of limestone resources, the better decreasing with shrinkage reducing admixture, however, PVA fiber increases drying shrinkage. Compared with the porosity of the controlled concrete corresponding mortar, the different aperture porosities of mortar with shrinkage reducing admixture are minimum, and those of mortar with expansive agent are second, and nevertheless, PVA fiber increases the porosity which has an important effect on drying shrinkage and whose aperture is less than 100nm. The better linear relationships between the synchronized drying shrinkage and internal rela-tive humidity are obtained, and the same period drying shrinkage can be calculated by testing internal relative humidity.