Influences of molding processes and different dispersants on the dispersion of chopped carbon fibers in cement matrix

Abstract

Chopped carbon fiber-reinforced cement composite (CFRC) has become one of the potential smart materials in recent years. The key process of preparing this kind of composite at the early stage is how to disperse carbon fibers evenly into the cement matrix to achieve CFRC composite with good properties. In this study, a three-step mixing process and a six-step mixing process for the preparation of CFRC were suggested, respectively. The fracture morphology was observed by scanning electron microscopy. The influence of mass fractions of three common dispersants methyl cellulose (MC), carboxymethyl cellulose sodium (CMC) and hydroxyethyl cellulose (HEC) on the dispersion of short carbon fibers in water under certain temperature was investigated prior to the manufacture of CFRC. The correlation between mass fraction and viscosity was discussed, and the dispersion effect was assessed from the structure of dispersants and molding process. A hypothetical capsule theory was proposed to reasonably explain the dispersion effect of MC, CMC, and HEC. The experiments showed that pre-dispersion by ultrasonic vibration improved the dispersion of carbon fibers greatly. The dispersivity of carbon fibers was closely related to the category and mass fractions of dispersants. With the same mass fraction of dispersants at a certain temperature, the dispersion effect was in order of HEC > CMC > MC. Meanwhile, when the mass fraction of HEC was between 0.6 and 0.8 wt% by weight of cement and the mass fraction in the aqueous solution was between 1.65 and 1.80 wt%, carbon fibers dispersed most ideally and distributed further uniformly in the cement matrix.

Smart cement‐sensor composite: The evolution of nanomaterial in developing sensor for structural integrity

“…179 Another research proposed three step and six step mixing processes for filler mass fraction <1.2% and >1.2%, respectively, and observed that the six step process (includes dispersant agent and ultrasonication method) is suitable for all filler mass fractions. 180 The dispersion process suspends the functional filler homogeneously using of various flourishing dispersion methods. The dispersion methods proposed by several scientific researchers are basically categorized into physical and chemical methods.…”

The Synergetic Impact of Anionic, Cationic, and Neutral Polymers on VES Rheology at High-Temperature Environment

“… Structures of ( a ) Carboxymethyl cellulose (CMC), ( b ) Hydroxyethyl cellulose (HEC), and ( c ) Diallyl dimethylammonium chloride (DADMAC) [ 34 , 35 ]. …”

Effect of fibre loading on the microstructural, electrical, and mechanical properties of carbon fibre incorporated smart cement-based composites

“…For this purpose, the polycarboxylate superplasticizer was used. In comparison to other dispersants such as cellulose which can only make the surface of carbon fibres hydrophilic, and sodiumbased superplasticizer which can only make the surface of cement grain hydrophilic, polycarboxylate superplasticizer has superior dispersion ability thanks to its "double dispersion" feature for improving the wettability of both the surfaces of carbon fibres and cement grain (Han et al, 2012;Metaxa, 2015;Chuang et al, 2018;Papanikolaou et al, 2021). The anchorage group on the superplasticizer can adsorb on the surfaces via intermolecular forces.…”