Title: Kappaphycus alvarezii Seaweed as Novel Viscosity- Modifying Admixture for Cement-Based Materials

Author(s): Asma Boukhatem, Kamal Bouarab, and Ammar Yahia

Publication: Materials Journal

Volume: 120

Issue: 4

Appears on pages(s): 15-28

Keywords: cement suspensions; compressive strength; hydration kinetics; kappa (κ)-carrageenan; Kappaphycus alvarezii (K. alvarezii); rheology; viscosity-modifying admixtures (VMAs)

DOI: 10.14359/51738805

Date: 7/1/2023

Abstract:
The effect of different conditioning and processing parameters of Kappaphycus alvarezii (K. alvarezii) seaweed solutions—such as their dosage, heating temperature, and pre-hydration method on the rheological behavior, hydration kinetics, and compressive strength of cement suspensions—was evaluated. The use of marine K. alvarezii seaweed in fluid cement matrixes could be an excellent alternative for a wide range of existing viscosity-modifying admixtures (VMAs) given its environmental and economic advantages. The use of K. alvarezii increased the yield stress, plastic viscosity, and rigidity of cement suspensions. This was not always the case when conventional VMAs were used, which shows the effectiveness of K. alvarezii as a VMA. On the other hand, incorporating a 0.5% dosage of K. alvarezii resulted in comparable yield stress and plastic viscosity values compared to (κ)-carrageenan, which confirms the feasibility of using K. alvarezii instead of (κ)-carrageenan as a VMA. Unlike (κ)-carrageenan, the use of K. alvarezii did not increase the dormant period of cement suspensions, which is very interesting in terms of compatibility between this new VMA and cement. The use of K. alvarezii generally showed no significant effect on the strength development of the cement suspensions compared to the reference mixture. This validates the feasibility of using K. alvarezii seaweed as a VMA.