低真空环境对硬化水泥浆体力学性能的影响

Effect of Low Vacuum Environment on the Mechanical Properties of Hardened Cement Paste

为研究低真空环境对硬化水泥浆体力学性能的影响,对低真空和室内大气环境下暴露的成熟水泥净浆试件(82 d和128 d龄期)进行了力学性能测试,并借助X射线衍射仪(XRD)和压汞仪(MIP)对水泥浆体的物相组成和孔结构进行了表征。结果表明:短期低真空暴露会促进成熟试件抗压强度的提升,但长期低真空暴露对试件强度的维持和发展是不利的。低真空环境基本不会改变硬化水泥浆体的物相种类,且低真空暴露后成熟试件的C-S-H凝胶含量与强度之间不存在明显的相关性。此外,与室内大气环境相比,成熟试件在低真空暴露28 d后最可几孔径和总孔隙率明显较小,而在低真空暴露168 d后最可几孔径和总孔隙率较大,这与成熟试件的强度发展规律具有良好的对应关系。

To explore the mechanical properties of hardened cement paste under low vacuum,the mechanical properties of mature specimens(82 d and 128 d)exposed to low vacuum and indoor atmosphere were tested,the phase composition and pore structure were also investigated through X-ray diffraction(XRD)and Mercury intrusion porosimetry(MIP).The results show that short-term low vacuum exposure can improve the compressive strength of the mature specimens,but long-term low vacuum exposure is detrimental to the maintenance and development of specimen strength.Moreover,the low-vacuum environment basically does not change the phase type of hardened cement paste,and there is no obvious correlation between the C-S-H gel content and the strength.Besides,compared with the indoor atmospheric condition,the most probable pore size and total porosity of the mature specimens are obviously smaller after 28 days of low vacuum exposure,but larger after 168 days of low vacuum exposure,which has a good corresponding relationship with the strength development law.