高吸水树脂对高强混凝土早期减缩效果及机理研究

发布时间：2018-11-22 19:30

【摘要】：研究了预吸水高吸水树脂(super-absorbent polymer,SAP)作为内养护剂掺入高强混凝土后对其早期收缩及力学性能的影响.预吸水SAP额外引入的水量分别控制为水泥质量的5%和10%.研究结果表明:(1)预吸水SAP对高强混凝土自收缩及早期干燥条件下的总收缩有明显的减缩作用,14d自收缩减缩率可达90%以上,干燥条件下总收缩可减少75%,其机理主要在于掺入SAP后可大大提高相同龄期混凝土的内部相对湿度,减小自收缩和干燥收缩产生的驱动力;(2)预吸水SAP的加入会对高强混凝土的强度发展造成不利影响,但对其后期强度影响不大;当SAP额外引入的水量控制在水泥质量的5%时,高强混凝土28d抗压强度可达基准组的95%以上,因此不会影响SAP作为内养护剂在高强混凝土中的工程应用;(3)与简单增加拌和水量相比,加入预吸水SAP对于混凝土的减缩作用更为显著,掺量适中时对其强度的不利影响更小.
[Abstract]:The effect of preabsorbent superabsorbent resin (super-absorbent polymer,SAP) as internal curing agent on early shrinkage and mechanical properties of high strength concrete was studied. The additional amount of water introduced by SAP is controlled to 5% and 10% of the cement quality, respectively. The results show that: (1) SAP has obvious effect on the shrinkage of high strength concrete under the condition of autogenous shrinkage and early drying. The reduction rate of autogenous shrinkage in 14 days can reach more than 90%, and the total shrinkage of high strength concrete under dry condition can be reduced by 75%. The main mechanism is that the internal relative humidity of concrete at the same age can be greatly increased by adding SAP, and the driving force of autogenous shrinkage and dry shrinkage can be reduced. (2) the addition of pre-absorbent SAP has a negative effect on the strength development of high strength concrete, but has little effect on the later strength of high strength concrete; When the amount of water added by SAP is controlled at 5% of the cement quality, the compressive strength of high strength concrete can reach more than 95% of the benchmark group for 28 days, so the engineering application of SAP as internal curing agent in high strength concrete will not be affected. (3) compared with the simple increase of mixing water, the effect of adding preabsorbent SAP on the shrinkage of concrete is more significant, and the negative effect on the strength of concrete is less when the content is moderate.
【作者单位】：清华大学土木工程系;清华大学土木工程安全与耐久教育部重点实验室;
【基金】：国家自然科学基金联合基金资助项目(U1262107)
【分类号】：TU528.31

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