硫酸盐侵蚀对不同养护制度UHPC水化产物微结构的影响

采用29Si和27Al MAS NMR、XRD、SEM等测试技术研究了硫酸盐侵蚀对不同养护制度的超高性能混凝土(UHPC)水化产物微结构的影响.结果表明:标准养护和80 ℃高温蒸汽养护条件下,UHPC水化产物主要为C-S-H、Ca(OH)2、AFt、AFm和TAH;210 ℃、2 MPa蒸压养护8 h后,水化产物主要为tobermorite、Ca(OH)2和TAH.硫酸盐侵蚀对不同养护制度的UHPC抗压强度和水化产物微结构的影响微弱,但可促进210 ℃蒸压养护的UHPC胶凝浆体中TAH向AFm和AFt的转化.同时硫酸盐侵蚀180 d时,C-S-H凝胶MCL和Al4]/Si略有降低,但降低幅度较小,UHPC具有良好的抗硫酸盐侵蚀能力.

Effects of Sulfate Attack on Microstructure of UHPC Hydration Products under Different Curing Regimes

By using the 29Si and 27Al Magic Angle Spinning Nuclear Magnetic Resonance(MAS NMR), XRD and SEM,effects of sulfate attack on microstructure of Ultra-High Performance Concrete(UHPC) hydration products under different curing regimes was studied.The results indicate that the hydration products of UHPC are mainly C-S-H,Ca(OH)2,AFt,AFm and TAH in standard curing and 80℃high temperature steam curing.After 210℃,2 MPa autoclave curing for 8 h,the main hydration products are tobermorite, Ca(OH)2and TAH.The effect of sulfate attack on the compressive strength and microstructure of UHPC with different curing regimes is weak, but the transformation from TAH to AFm and AFt in UHPC gel cured in autoclave regime is promoted at 210 ℃.At the same time, when the sulfate attacked to 180 d, the MCL and Al4]/Si of C-S-H gel decreases slightly, but the reduction range is small.UHPC has good resistance to sulfate attack.