Boosting Portland cement-free composite performance via alkali-activation and reinforcement with pre-treated functionalised wheat straw

Utilising wheat straw reinforced OPC-free composites in the construction industry requires efficient, eco-friendly pre-treatment coupled with surface functionalisation methods to turn it into a high-performance material. Herein, alkali-activated material (AAM) was used as an OPC-free matrix, while eco-friendly hybrid pre-treatment and surface functionalisations were applied to mitigate the surface quality deficiencies of wheat straw and improve its compatibility with low-carbon binders. Wheat straw particles were subjected to a mild physical pretreatment (hot-water followed by steam) and surface functionalisation using attapulgite nanoclay and graphene nanoplatelets to improve their capacity as an effective reinforcing material in AAM. Comprehensive characterisation verified successful pre-treatment and surface functionalisation, which led to the improved interfacial bond between wheat straw and AAM. The best results were obtained for the AAM samples reinforced with pretreated straw that was functionalised with attapulgite nanoclay (i.e., H+S-AT), in which the volume of permeable voids decreased by 18%, while compressive and flexural strength at 90 d increased by 41% and 27%, respectively, compared to the control sample. However, the effect on the thermal properties of the resulted composites was not significant.

Automated summary

This study investigates the use of wheat straw as reinforcement for OPC-free composites in the construction industry. It proposes efficient and eco-friendly pre-treatment and surface functionalisation methods to improve the performance of wheat straw and its compatibility with low-carbon binders. The results show that the pre-treated and functionalised wheat straw enhances the interfacial bond between the straw and the OPC-free matrix, leading to improved mechanical properties of the composite materials.