氧化石墨烯对水泥基复合材料自收缩的影响

氧化石墨烯(GO)表面富有大量的含氧基团,具有良好的亲水性,是新型纳米碳材料,会对水泥水化产物的形状及聚集态造成影响。本文将多层GO和水超声分散后形成GO分散液,对不同GO掺量的新拌水泥浆体的自收缩进行测试,并采用氮吸附法对其孔隙结构进行表征。结果表明,掺入GO会增加凝胶孔中的自由水,加快水泥水化速率,增大自收缩,且随着掺量的增加,自收缩会更加明显。由迟滞效应的特征推论出GO使得水泥浆体内部的孔隙呈现狭缝形。根据Kelvin方程的BJH法进行孔分布分析,探索GO对自收缩的调控机理。发现GO有助于细化内部孔径,使水泥浆体内部的大毛细孔向着小毛细孔转变,导致毛细孔压力增加,进而增加了水泥基复合材料的自收缩。

Influence of graphene oxide on autogenous shrinkage of cement-based composites

Graphene oxide(GO)surface contains a large amount of oxygen-containing groups,which is of good hydrophilicity.It is a new type of nano-carbon material that affects the shape and aggregation state of cement hydration products.In this paper,multilayer GO and water were mixed to form GO dispersions by ultrasonic dispersion.The autogenous shrinkage of fresh cement paste with different GO content was tested and its pore structure was characterized by nitrogen adsorption method.The results showed that the incorporation of GO increased the free water in the gel pores and accelerated the hydration rate of the cement.The autogenous shrinkage increased as the GO content increased.It was deduced from the hysteresis effect that GO made the pores inside the cement paste develop into a slit.The pore distribution was analyzed by the BJH method of Kelvin equation to explore the regulation mechanism of GO on autogenous shrinkage.It was found that GO could refine the internal pore diameter.The large capillary pores inside the cement slurry were transformed toward the small capillary pores,which led to an increase in capillary pore pressure,thereby increasing the autogenous shrinkage of the cement-based composite material.