Alkali-treated corn straw and polypropylene fibers in cementitious composites

The search for sustainable solutions in civil construction has driven the use of natural fibers to replace synthetic fibers, leading to a reduction in environmental impact and the reuse of agricultural waste. Therefore, this work investigates the performance of cementitious composites reinforced with the addition of 1% corn straw and polypropylene fibers, and the effect of hybridization of these fibers in cementitious composites. To this end, corn straw was cut and subjected to alkaline treatment with calcium hydroxide (Ca(OH)2) to remove impurities, reduce water absorption, and improve adhesion to the cementitious matrix. Consistency index, density in fresh and hardened states, capillary water absorption, flexural tensile strength, and axial compression strength tests were performed at 7, 28, and 42 days, in addition to scanning electron microscopy (SEM-FEG) and Energy Dispersive Spectroscopy (EDS) at 28 days for the mixes containing corn fiber and synthetic fiber. The results demonstrated that the addition of treated fibers showed good performance in terms of workability, reduced water absorption, and increased toughness of the cementitious composites at 7 days, highlighting the efficiency of the alkaline treatment with Ca(OH)2. At 28 and 42 days, a reduction in performance was observed compared to the mixes with lower corn straw fiber content, pointing to a possible degradation of the fiber due to the alkaline medium. It is concluded that the use of treated natural fibers presents technical viability and environmental benefits, representing a promising alternative for the production of sustainable cementitious composites.