纳米SiO_(2)和碳酸钙晶须制备水泥基材料性能试验

Properties of Cement-based Material Mixed with Nano-SiO_(2) and Calcium Carbonate Whisker

采用纳米SiO_(2)和碳酸钙晶须制备水泥基材料,利用SEM、XRD和TG-DSC等技术手段对水泥基材料的水化产物、微观结构和热稳定性等进行有效表征,并试验研究了双掺0%、1%、2%、3%、5%、10%的碳酸钙晶须和1%纳米SiO_(2)保温水泥砂浆的力学性能和导热性能。研究结果表明:纳米-毫米两种尺度材料掺入水泥浆内部后,纳米SiO_(2)与水泥水化产物Ca(OH)_(2)晶体发生二次水化反应,生成C-S-H凝胶体,有效地填充水泥基体孔隙、细化水泥基内部孔径尺寸,碳酸钙晶须具备纤维和微粒双重作用,可以在水泥基中产生纤维的桥联效应,两者材料结合起来,可在水泥基内部形成密实网状絮凝结构;纳米SiO_(2)和碳酸钙晶须掺入后可以提高砂浆的强度,3%碳酸钙晶须和1%纳米SiO_(2)配制的保温水泥砂浆抗压和抗折强度分别为25.6 MPa和6.19 MPa,导热系数为0.4567 W/(m·K),强度和导热性能兼顾。

The hydration products,microstructure and thermal stability of cement-based materials prepared by mixing with nano-SiO_(2)and calcium carbonate whisker were effectively characterized by using SEM,XRD and TG-DSC.The mechanical properties and thermal conductivity of thermal-insulated cement mortar were also studied by adding 0%,1%,2%,3%,5%and 10% calcium carbonate whisker and 1%nano-SiO_(2).Test results revealed that by adding materials of nano-and-millimeter level scales,C-S-H gels were generated from the secondary hydration reaction between nano-SiO_(2)and Ca(OH)_(2) crystal,filling the voids in cement base and refining the pores in cement base.Moreover,calcium carbonate whisker has dual-function of fibers and particles,hence producing bridging effect in the cement based,forming a dense network flocculation structure inside the cement base.The strength of cement mortar can be improved by adding nano-SiO_(2)and calcium carbonate whisker.The compressive strength and flexural strength of thermal insulation cement mortar mixed with 3%calcium carbonate whisker and 1%nano-SiO_(2)is 25.6 MPa and 6.19 MPa,respectively,and the thermal conductivity is 0.4567 W/(m·K).Both the strength and thermal conductivity are taken into consideration.