Study on Utilization of Carboxyl Group Decorated Carbon Nanotubes and Carbonation Reaction for Improving Strengths and Microstructures of Cement Paste.
Carbon nanotubes (CNTs) have excellent mechanical properties and can be used to reinforce cement-based materials. On the other hand, the reaction product of carbonation with hydroxides in hydrated cement paste can reduce the porosity of cement-based materials. In this study, a novel method to improve the strength of cement paste was developed through a synergy of carbon nanotubes decorated with carboxyl group and carbonation reactions. The experimental results showed that the carboxyl group (-COOH) of decorated carbon nanotubes and the surfactant can control the morphology of the calcium carbonate crystal of carbonation products in hydrated cement paste. The spindle-like calcium carbonate crystals showed great morphological differences from those observed in the conventional carbonation of cement paste. The spindle-like calcium carbonate crystals can serve as fiber-like reinforcements to reinforce the cement paste. By the synergy of the carbon nanotubes and carbonation reactions, the compressive and flexural strengths of cement paste were significantly improved and increased by 14% and 55%, respectively, when compared to those of plain cement paste.
Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, College of Civil Engineering, Shenzhen University, Shenzhen 518060, China. yanxiantong@email.szu.edu.cn.
Xiantong
X
Yan
Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, College of Civil Engineering, Shenzhen University, Shenzhen 518060, China. h.z.cui@szu.edu.cn.
Hongzhi
H
Cui
Research School of Engineering, Australian National University, Canberra 2601, ACT, Australia. qinghua.qin@anu.edu.au.
Qinghua
Q
Qin
School of Architecture and Built Environment, the University of Newcastle, Callaghan 2308, NSW, Australia. patrick.tang@newcastle.edu.au.
Waiching
W
Tang
Department of Mechanical, Aerospace and Civil Engineering, Brunel University London, Uxbridge, Middlesex UB8 3PH, UK. xiangming.zhou@brunel.ac.uk.
Xiangming
X
Zhou
calcium carbonate; carbon nanotube; carbonation; cement hydration; crystal morphology; functional group; strength