*Article* **Hydration Kinetics of Composite Cementitious Materials Containing Copper Tailing Powder and Graphene Oxide**

#### **Shuhua Liu \*, Qiaoling Li and Xinyi Zhao**

State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China; qllee@whu.edu.cn (Q.L.); xinyizhao@whu.edu.cn (X.Z.)

**\*** Correspondence: shliu@whu.edu.cn; Tel.: +86-27-6877-2233

Received: 19 October 2018; Accepted: 6 December 2018; Published: 8 December 2018

**Abstract:** The hydration heat evolution curves of composite cementitious materials containing copper tailing powder (CT) and graphene oxide (GO) with different contents are measured and analyzed in this paper. The hydration rate and total hydration heat of the composite cementitious materials decrease with the increase of CT dosage, but improve with the increase of CT fineness and GO dosage. The hydration process of the cementitious systems undergoes three periods, namely nucleation and crystal growth (NG), phase boundary reaction (I), and diffusion (D), which can be simulated well using the Krstulovic–Dabic model. The hydration rates of the three controlling processes of the composite cementitious system decrease with the increase of CT content, but improve slightly with the increase of CT fineness. GO enhances the controlling effect of the NG process of the cementitious systems with or without CT, thus promotes the early hydration as a whole.

**Keywords:** composite cementitious materials; copper tailing powder; graphene oxide; hydration kinetics
