Study on Utilization of Carboxyl Group Decorated Carbon Nanotubes and Carbonation Reaction for Improving Strengths and Microstructures of Cement Paste

Abstract

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.

Modification Effects of Carbon Nanotube Dispersion on the Mechanical Properties, Pore Structure, and Microstructure of Cement Mortar

“…Through scanning electron microscopy (SEM) observation of a CNT-cement-based material matrix, it was observed that CNTs bridged in the cracks, preventing crack growth and increasing material toughness [17]. CNTs are covered and cemented by cement hydration products in cement-based materials, thus demonstrating the effective mechanical properties of CNTs [18]. CNTs are nanometer in size, enabling them to effectively fill microscopic pores in cement-based materials [15].…”

Cockle shell-derived aragonite calcium carbonate nanoparticle for targeting cancer and breast cancer stem cells

“…Recently, the fabrication and therapeutic application of CaCO 3 nanoparticles in drug delivery has generated a lot of attention amongst scientists due to its availability, ease of synthesis, low toxicity and slow biodegradability (Mydin et al 2018;Dizaj 2015;Li et al 2019). CaCO 3 nanoparticles have been synthesized using various methods including wet chemical preparation, microemulsion technique and mechanical milling of sea and egg Yan et al 2016) shells (Mydin et al 2018;Dizaj 2015;Ranjan et al 2018). Ghiasi and Malekzadeh (2012) used the sol-gel citrate method to synthesize calcite nanoparticles by adding organic additives as emulsifiers.…”

Mechanical Properties of Cement Reinforced with Pristine and Functionalized Carbon Nanotubes: Simulation Studies

“…Some of these methods are based on ultrasonication combined with a functionalizing agent, which modifies the CNT surface to ensure a better dispersion [ 23 ]. Amid these methods, the addition of carboxyl groups to the CNT structure must be mentioned, since it boosts hydrophilic features and chemical bonding between CNTs and cement, causing improved adhesion between components [ 24 , 25 ].…”