Silk fibroin as a multifunctional admixture: Exploring the synergistic effects with nanomaterials in cementitious composites

Abstract

The synthesis of silk fibroin (SF) composite for eco-friendly concrete additives addresses the growing need for sustainable building materials. This study investigated the role of SF in modifying the hydration and mechanical properties of silicate cement, and the potential of SF as a multifunctional admixture in cementitious composites. The incorporation of SF into silicate cement modifies key properties, acting effectively as a water reducer, retarder, and air-entraining agent, thus facilitating the optimisation of pore structure and matrix uniformity. Building upon these advantages, the study further investigates the synergistic effects of SF combined with nanosilica (NS) or Ti₃C₂T_x (MXene) concerning rheological properties, pore distribution, cement hydration kinetics, and microstructure. Rheological evaluations indicate that the SF-SiO₂ group substantially decreased the yield stress and viscosity of the cement paste to approximately 24.8 Pa and 0.13 Pa s, while conserving about 20 % of water resources. In the SF-MXene group, the proportion of gel pores significantly increased to 84.7 % at 28 days, refining pore distribution by minimising deleterious pores and improving gel pore uniformity. Concurrently, the additional nucleation sites were supplied by NS and MXene with a high specific surface area, accelerating the hydration process and affecting subsequent exothermic reactions. This study highlights the viability of SF composites in promoting cleaner production within the construction industry, presenting a sustainable alternative.