Effect of Sisal Fibers on the Rheology of Cement Paste Plasticized by Polycarboxylate Superplasticizer

Abstract

Sisal fibers (SF) and polycarboxylate superplasticizers (PCE) contribute to the sustainable development of cementitious materials by improving and optimizing their hardening properties. In this study, the impact of SF and PCE on the workability of cement pastes was investigated. The workability was evaluated through spreading diameter, yield stress, and plastic viscosity measurements, and the adsorption behavior of PCE was analyzed. The results showed that the introduction of SF had a negative effect on the workability of PCE plasticized cement pastes, reducing flowability and increasing yield stress and plastic viscosity, regardless of aspect ratio or dosage. A contact angle tester and a scanning electron microscope (SEM) were employed to examine the surface properties of SF. The mechanism behind this interaction of cement-PCE-SF was explored and found to be due to the rough surface of SF, which increased the consumption of PCE, and the formation of hydrogen bonds between PCE and SF. Additionally, PCE modified the interfacial structure between SF and the cement matrix, strengthening the relationship between the different phases. These findings provide new insights into the modification of fiber-reinforced cementitious materials. This paper presents a comprehensive study on the workability and rheology behavior of cementitious material that coupled PCE superplasticizer and SF. The interaction between PCE and SF was experimentally studied by suitable tests, and the results and mechanism behind were well explained. The fresh properties were evaluated through a mini slump test, rheological properties, and the adsorption behavior of PCE on the surface of cement and SF was analyzed. The results showed that the introduction of SF decreases the spread diameter and increases the yield stress and plastic viscosity, regardless of aspect ratio and dosage, which indicate that a negative effect on the workability of PCE plasticized cement pastes. The mechanism behind the cement-PCE-SF interaction was explored in depth by the surface properties of SF, which revealed that the rough surface of SF increased the consumption of PCE. In addition, the formation of hydrogen bonds between PCE and SF provides an additional explanation. The significance of this study provides valuable guidance in using fibers and PCE together in cementitious materials.