Abstract

The coral-sand (CS) foundations built in the marine environment inevitably suffer from chemical invasion of seawater. Graphene oxide (GO) has been considered as a feasible additive to improve chloride penetration ability of cement mortar, but limited studies have been carried out on GO-modified CS cement stones. In this study, a series of rapid chloride migration (RCM) tests were respectively conducted on CS or river-sand (RS) cement stones with various GO contents. Meanwhile, scanning electron microscope (SEM) tests were also performed to study microscopic features of the cement stones. Experimental results revealed that the chloride migration coefficient D_RCM for both CS and RS samples firstly decreased and then increased with increasing GO content. The lowest D_RCM values were achieved while adding 0.02 wt% GO for CS samples and 0.03 wt% GO for RS samples. Meanwhile, the D_RCM values of CS samples were higher than those of RS samples at a given GO content. Microstructural results demonstrated that as the GO content increased, the shape of hydration crystals gradually transformed from a needle-like shape to a flower-like shape. The addition of GO could promote hydration products to fill the holes inside the cement stones, effectively inhibiting the chloride ion penetration.

摘要

在海洋环境中建造的珊瑚砂（CS）基础不可避免地会遭受海水的化学入侵。氧化石墨烯（GO）被认为是一种提高水泥砂浆氯离子渗透能力的可行添加剂，但对GO改性CS水泥石的研究还很有限。本研究分别对不同GO含量的CS或河沙（RS）水泥石进行了一系列快速氯离子迁移（RCM）测试。同时，还进行了扫描电子显微镜（SEM）测试，以研究水泥石的微观特征。实验结果表明，随着GO含量的增加，CS和RS样品的氯离子迁移系数D _RCM先减小后增大。最低D _RCM对于 CS 样品添加 0.02 wt% GO，对于 RS 样品添加 0.03 wt% GO，获得了这些值。同时，在给定GO含量下，CS样品的D _RCM值高于RS样品。微观结构结果表明，随着GO含量的增加，水化晶体的形状逐渐从针状转变为花状。GO的添加可以促进水化产物填充水泥石内部的孔洞，有效抑制氯离子的渗透。