Performance Concrete: Enhancing Durability, Cost Effectiveness And Reducing Carbon Footprint

This research aimed to develop performance-based, generic concrete mix designs with locally sourced aggregates that can be readily adopted by regional concrete producers. The goal is to mitigate delays in mix design approvals, thus reducing project delay costs. Also, the use of local aggregates will help minimize the cost associated with hauling aggregates from other states. The concrete mixes were optimized for cost-effectiveness, durability, and sustainability using the packing density approach with locally sourced aggregates. This method reduces the binder content required to fill inter-particle voids, potentially lowering material costs and enhancing mechanical properties. Additionally, the research explored incorporating low-carbon supplementary cementitious materials (SCMs), such as Portland Limestone Cement (PLC) and recycled Ground Glass Pozzolan (GGP), as partial replacements for conventional cement. These substitutions aim to reduce the environmental impact of cement production without compromising performance. The experimental program included two stages: The screening and final. In the screening stage, 12 mixes with an additional control mix were developed and tested for compressive strength, freeze-thaw resistance, and surface permeability. Based on the results, four PLC based mixes were selected for further modifications and investigation including shrinkage measurements, alongside the screening tests. Their performance was evaluated against HPC-A control mix. Mixes containing 25% GGP and 25% Slag demonstrated higher compressive strength and freeze-thaw durability compared to the HPC-A control mix. The durability factors of the concrete mixes ranged from 87% to 95%, all exceeding the minimum threshold of 60%. All the mixes showed very low surface permeability within the range of 80-150 kΩ.cm and passed the minimum threshold of 22 kΩ.cm. All four mixes met or exceeded the minimum performance requirements set by the 2018 standard specifications of construction by the Vermont Agency of Transportation, with the exception of shrinkage. At the conventional duration of 28 days, 3 out of 4 met the shrinkage specification of 0.032% for PCD, the other was 0.034%. All 4 mixes met the shrinkage specification of 0.042% for PCS. All four mixes continued to shrink after 28 days and did not meet the specification at 56 days. These findings provide a framework for regional concrete producers to use locally sourced aggregates and adopt a sustainable mix design approach thereby reducing the carbon footprint of concrete production while ensuring good performance.