International Concrete Abstracts Portal

The construction industry is one of the world’s largest drivers of environmental impact, consuming large quantities of energy, water, and raw materials while generating significant carbon emissions. Concrete is a central contributor, with portland cement production alone responsible for roughly 7–8% of global CO₂ emissions. As decarbonization becomes a priority, demand for sustainable, resilient, low-carbon concrete materials is accelerating innovation in binder systems, mixture strategies, and design practices. For civil engineering students and future professionals, understanding the environmental impacts of concrete and methods to reduce them without compromising performance is essential. This paper presents an advanced concrete materials course reframed through the lens of sustainability and resiliency. Teaching strategies and resources are described, including in-class activities, laboratory demonstrations, case studies, mixture design competitions, and applied project work. Collectively, these methods emphasize decision-making in material selection, mixture proportioning, and design for long-term durability and performance of concrete structures.

With the concrete industry undergoing a period of innovation and a broadening spectrum of cements available in the market, a key question to consider is: What’s next after Type IL cement, and how can we use blended cements successfully in concrete construction? A panel of experts explored this question at the Hot Topic Session at the ACI Concrete Convention Fall 2025 in Baltimore, MD, USA.

Using particle packing models (PPMs) in combination with limestone fillers has been shown to be effective in proportioning eco-efficient concrete mixtures with reduced Portland cement content, resulting in suitable performance in fresh and short-term hardened states. However, the decrease in Portland cement and increase in limestone fillers may lower the pH of concrete, raising concerns about durability and long-term performance, potentially leading to increased corrosion of steel reinforcement in the presence of carbonation or chlorides. In this study, the performance of three eco-efficient concrete mixtures with varying cement (250, 200, and 150 kg/m³) and inert filler contents is evaluated against accelerated chloride exposure. The findings highlight the influence of the mixture proportioning and water-to-cement ratio on the resistance to chloride ingress. Ultimately, it is verified that the distance between cement particles is a major contribution towards chloride ingress.

Performance-based specifications (PBS) may increase concrete quality and sustainability by facilitating innovations in material selection and proportioning. This is particularly relevant now with increased interest in a broader set of minimally processed minerals for use as supplementary cementitious materials (SCMs) or fillers; these are often industrial and agricultural byproducts and with limited performance history in concrete. This study compares traditional largely prescriptive concrete design, following practices currently allowed by the Georgia Department of Transportation, with three new concrete designs which do not comply with current specifications but offer increased sustainability. Three metrics are assessed for each mixture: the associated cradle-to-gate CO₂ emissions, a metric that incorporates the environmental burden of concrete, compressive strength at 28 days, and surface resistivity measurements taken weekly from 28 to 56 days. A framework is proposed to statistically analyze compressive strength data to pre-qualify mix designs, which can be broadly applied to reduce time-consuming iterative testing and to help meet sustainable development goals. The aim is to foster innovation in material use and mixture design towards an increased durability and performance, while reducing environmental impact and minimizing risk.

Reducing Normal Portland Cement (NPC) has been a major concern of concrete industry and research community over the last 2-3 decades. As much as 8% of the global CO₂ emissions stem from clinker production. Hence, a wide number of research projects have been focusing on reducing NPC in cementitious materials using numerous strategies such as the use of supplementary cementing materials (SMC’s), limestone fillers (LF) and/or advanced mixproportioning techniques. Yet, the impact of these procedures on the overall behaviour of materials with low NPC content, especially in the fresh state and long-term durability, is still not fully understood. This work aims to understand the influence of the distance between the fine particles, the so-called Inter-Particle Separation (IPS), on the fresh state behaviour of cement-base pastes designed through the use of Particle Packing Models and incorporating LF. Evaluations on the fresh (i.e. rheological behaviour and setting time) and hardened states (compressive strength) were conducted in all mixtures. Results show that IPS directly correlates with the viscosity of cementbase pastes for all shear rates appraised. Moreover, the use of LF increases the hydration rate of NPC pastes. Finally, it is clear that the water-to-cement ratio keeps being the main factor controlling the compressive strength of cement pastes with reduced NPC content and high levels of LF replacement.