Piezoresistivity of Carbon Fiber Graphite Cement-based Composites with CCCW

The electrical conductivity and piezoresistivity of carbon fiber graphite cement-matrix composites（CFGCC） with carbon fiber content（1% by the weight of cement）,graphite powder contents （0%-50% by the weight of cement） and CCCW（cementitious capillary crystalline waterproofing materials,4% by the weight of cement） were studied.The experimental results showed that the relationship between the resistivity of CFGCC and the concentration of graphite powders had typical features of percolation phenomena.The percolation threshold was about 20%.A clear piezoresistive effect was observed in CFGCC with 1wt% of carbon fibers,20wt% or 30wt% of graphite powders under uniaxial compressive tests,indicating that this type of smart composites was a promising candidate for strain sensing.The measured gage factor （defined as the fractional change in resistance per unit strain） of CFGCC with graphite content of 20wt% and 30wt% were 37 and 22,respectively.With the addition of CCCW,the mechanical properties of CFGCC were improved,which benefited CFGCC piezoresistivity of stability.

水工混凝土防水涂料抗渗漏性能研究

模拟大坝上游面变态混凝土产生0.5 mm和1 mm裂缝工况,研究涂刷聚合物水泥防水涂料和水泥基渗透结晶型防水涂料后混凝土的抗渗性能以及涂料剥落后混凝土的抗渗性能。结果表明:混凝土产生贯穿裂缝后,抗渗能力明显降低,涂刷防水涂料可以提高混凝土抗渗性能,聚合物和渗透结晶型防水涂料复合使用对裂缝混凝土抗渗性能的改善效果比单一防水涂料要好;带裂缝的涂料混凝土90 d龄期铲除涂料后(模拟涂料剥落)抗渗性能有所下降,涂刷水泥基渗透结晶型涂料混凝土在铲除涂料后仍有一定的二次渗透结晶效果。

几种水工混凝土涂料抗渗性能试验研究

采用1种聚合物水泥型防渗涂料和3种水泥基渗透结晶型防渗涂料,试验研究了涂刷单一类型涂料和复合涂刷2种类型涂料时混凝土的抗渗性能,以及铲除涂料后混凝土的抗渗性能;并模拟大坝上游面混凝土产生贯穿裂缝,在涂刷不同防渗涂料组合下,对不同涂料涂刷厚度、涂料铲除前后的裂缝混凝土自修复性能进行研究。结果表明:渗透结晶型防渗涂料具有较好的渗透结晶及自修复能力,而聚合物水泥型防渗涂料无渗透结晶和自修复效果;混凝土产生贯穿裂缝后,抗渗能力明显降低,涂刷防渗涂料可以提高混凝土抗渗性能,其中两种类型防渗涂料复合使用较单一使用能更好地改善裂缝混凝土的抗渗性能;带裂缝的涂料混凝土90 d铲除涂料后抗渗性能有所下降,涂刷水泥基渗透结晶型防渗涂料的混凝土在铲除涂料后仍有一定的二次渗透结晶效果。