SAP和PVA纤维复掺对混凝土性能的影响及机理

Effects and Mechanisms of Combined Incorporation of SAP and PVA Fiber on Properties of Concretes

摘要:

针对正交异性钢桥服役过程中对铺装层材料的性能需求，制备了高吸水性树脂（SAP）与聚乙烯醇（PVA）纤维复合混凝土材料，通过力学性能和耐久性试验，探究了SAP和PVA纤维复掺对混凝土强度、自收缩性能和抗氯离子渗透性的影响及机理。结果表明：SAP和PVA纤维的复掺虽使混凝土强度整体呈下降趋势，但可有效调控混凝土自收缩发展进程，试件S_0.5P_0.4的7 d自收缩率较基准组降低56.2%；当低掺量SAP（质量分数0.05%~0.20%）与中掺量PVA纤维（体积分数0.25%）复掺时，二者可发挥正向协同作用，提高混凝土抗氯离子渗透性；SAP的释水作用能够延缓水泥水化进程，并优化混凝土内部孔径分布，PVA纤维则通过表面水化产物的锚固效应强化界面咬合作用，二者协同可显著优化混凝土的微观结构。

Abstract:

To address the performance requirements of pavement materials for orthotropic steel bridge decks during service， superabsorbent polymers（SAP） and polyvinyl alcohol （PVA） fibers composite concretes were prepared. Through mechanical properties and durability tests， the effects and mechanism of the combined incorporation of SAP and PVA fibers on the strength， autogenous shrinkage， and chloride ion penetration resistance of concretes were investigated. The results show that the combined incorporation of SAP and PVA fibers leads to an overall decreasing trend in the strength of concretes， but it can effectively regulate the development process of concrete autogenous shrinkage. The 7-day autogenous shrinkage rate of specimen S_0.5P_0.4 is 56.2% lower than that of the reference group. The combined incorporation of low dosage SAP（mass fraction of 0.05%-0.20%） and moderate dosage PVA fibers（volume fraction of 0.25%） can lead to synergistic effect and enhance the chloride ion penetration resistance of concretes. The water release effect of SAP can delay the hydration process of cements and optimize the internal pore size distribution of concretes， while PVA fibers strengthen the interfacial bonding effect through the anchoring effect of hydration products on the surface. The synertistic action of the two components significantly optimizes the microstructure of concretes.