应变硬化水泥基复合材料高温后弯曲韧性研究

Research on the Flexural Toughness of Strain Hardening Cementitious Composites(SHCC) after High Temperature

传统水泥基材料强度低、韧性差,表现出明显的脆性破坏。掺加聚乙烯醇(PVA)纤维的应变硬化水泥基复合材料(SHCC)可以改善传统水泥基材料的脆性,常温下表现出明显的应变硬化特征,提高了基材的强度和韧性。通过四点弯曲试验研究在不同温度作用下SHCC的弯曲韧性,结果表明,随着温度的升高,SHCC的强度和韧性呈现下降趋势,100℃之前降幅较小;约在10%以内;200℃时开始大幅下降(降低约50%),300℃时丧失韧性,发生脆性破坏。试验还表明,内掺Protectosil MH50硅烷乳液防水剂时,高温作用下,其韧性降低规律与未掺加防水剂时大致相同,但同条件下会使SHCC的强度略微降低。

Due to low strength, poor toughness, plain cement mortar shows obvious brittle failure mode. Polyvinyl Alcohol （PVA） fiber can reduce the brittleness of eementitious composites. Therefore, SHCC exhibits typical behavior such as strain hardening, high strength and toughness at normal temperature. Four-point bending test was carried out to investigate the flexural toughness of SHCC under different temperature action. The results show that, with the temperature increasing, the strength and toughness of SHCC present a downward trend, and the drop is less than 10% at 100 ℃ ,is sharp degressive at 200 ℃ （ about 50% ）. At 300℃, the toughness of SHCC is lost and cause brittle failure to the samples. The results also indicate that internal adopting silane emulsion waterproof agent has the same law with those not adopt at high temperature, while at the same condition, the strength of SHCC with silane is decreased slightly.