冻融循环作用下GORC界面过渡区的微观力学性能

Micromechanical Properties of GO RC Interface Transition Zone underFreeze Thaw Cycles

摘要:

为了研究冻融循环作用下氧化石墨烯(GO)对再生混凝土（RC）界面过渡区的影响，采用纳米压痕技术对骨料新砂浆和新砂浆旧砂浆2个界面过渡区的微观力学性能进行了研究.结果表明：经历100次冻融循环作用后，氧化石墨烯再生混凝土(GORC)和普通再生混凝土(ORC)的力学性能均有不同程度下降；GO在水化过程中的凝结核效应，提高了再生混凝土在各界面过渡区内高密度水化产物的数量，高密度水化硅酸钙的体积分数较ORC提高了7.02%~14.10%；界面过渡区内弹性模量提高了14.79%~17.74%，硬度提高了42.11%~60.80%.GO可以改善再生混凝土的微观结构，提高其抗冻性能.

Abstract:

In order to study the effect of graphene oxide(GO) on the interface transition zone(ITZ) of recycled concrete under freeze thaw cycle, the mechanical properties of the interfacial transition zone of aggregate new mortar(AG NM) and new mortar old mortar(NM OM) were studied by nano indentation technique. The results show that the mechanical properties of graphene oxide recycled concrete(GO RC) and ordinary recycled concrete(ORC) decrease in varying degrees after 100 freeze thaw cycles. Due to the condensation nucleus effect of GO in the hydration process, the number of high strength hydration products is increased in ITZ. The volume fraction of high density calcium silicate hydrate(HD C S H) is 7.02%1410% higher than that in the ORC. Elastic modulus of GO RC increases by 14.79%17.74% and its hardness increases by 42.11%60.80% in ITZ. According to the relationship between the microscopic mechanical properties and the macroscopic mechanical properties of concrete, it can be concluded that graphene oxide can enhance the microstructure of the recycled concrete so as to improve the frost resistance.