A Colombian case study in Rice Husk Ash (RHA)-modified Portland cement concrete: integrating mechanical performance, pavement design, and life-cycle assessment

Rice Husk Ash (RHA), a byproduct of rice production, offers a promising opportunity to enhance the sustainability of Portland Cement Concrete (PCC) in Colombian road pavements. Despite its potential, limited research has addressed both the technical performance and environmental feasibility of RHA-modified pavements under local conditions. Thus, the novelty of this investigation lies in developing the first comprehensive Colombian case study that integrates the mechanical behaviour of RHA-modified PCC, its use in pavement structural design, and the evaluation of potential environmental savings via Life-Cycle Assessment (LCA). For this purpose, four concrete mixes were prepared at different RHA replacement levels (i.e., 0, 5.2, 12.4, and 19.6% of the total mass of cementitious material). Firstly, the experimental campaign comprises workability, flexural strength, and compressive strength. Subsequently, hydraulic pavements were designed employing the AASHTO-93 method. Finally, a cradle-to-laid LCA was executed by considering a one-kilometer two-lane roadway as the functional unit and 13 impact categories, namely acidification, ecotoxicity, eutrophication, global warming, habitat alteration, Human Health (HH) cancer, HH criteria air pollutants, HH noncancer, indoor air quality, natural resource depletion, ozone depletion, smog, and water intake. Consequently, the results from this research indicate that the PCC mix design containing 5.2% RHA meets the technical requirements for low- to medium-traffic pavements while achieving a 2.6% reduction in total environmental loads compared to the conventional scenario. These findings demonstrate that modest RHA substitution can enhance sustainability without compromising mechanical performance, providing valuable insights for policymakers and engineers seeking greener pavement solutions in tropical agricultural regions.