This research studies the use of a fractional coarse aggregate replacement product (PA). PA is a unique blend comprised of recycled plastics, glass, and minerals; all collected from the waste stream. The use of PA and other similar products may contribute to reducing plastic waste in the waste stream. To test the feasibility of PA as a partial, natural aggregate replacement, four different mixtures of concrete were batched and tested. The concrete mixtures were based on the standard commercial interior normal-weight concrete mixture. This is a non-air-entrained mixture, provided by a local concrete batching plant (MCM), with a design strength of 4000 psi (27.6 MPa). The four concrete mixtures tested were a control mixture with no variations to the original mixture design as well as three mixtures with 15%, 30%, and 45% coarse aggregate replacement by volume. The compression strength, tensile splitting strength, modulus of rupture, and density of the concrete are examined. The focus of the paper is the concrete compressive strength because it is the primary determining factor in concrete design. Fresh concrete properties and hardened concrete properties were examined and recorded. Slight changes to the overall fresh concrete properties of workability, density, and slump were recorded. The hardened concrete properties include compression, tensile splitting, and modulus of rupture. The results of the compression tests show a strength proportionally decreased with the percent increase in PA replacement – 15% replacement with an 18.1% decrease, 30% replacement with a 35.6% decrease, and a 45% replacement indicated a 45.3% decrease at the 28-day test. The results of the tensile splitting tests and modulus of rupture tests both indicate similar results of a decrease in strength as the replacement rate of PA increased.

Worldwide, the need for additional and improved infrastructure is critical. The deterioration of infrastructure has become an increasing challenge and burden on the world's economy, environment, and society. Historically, most structures worldwide have been built without durability and service-life consideration, and their premature failure reflects an acute crisis within the construction industry and the environment. Including synthetic polypropylene macrofiber in concrete structures ensures the maximizing of durability and service life extension and offers potential reductions in the binder content and reinforcing steel materials that contribute to resource depletion, environmental impacts, and increased economic burden. These material reductions and service life improvements present housing and infrastructure construction opportunities that protect the environment and ensure public safety, health, security, serviceability, and life cycle cost-effectiveness.

To support a rapid integration of sustainability principles into paving concrete practice, this study provides a closer look into readily implementable cement and concrete decarbonization strategies. To do so, this study relies on combined stakeholder involvement, quantitative analysis using Life Cycle Assessment (LCA), and the state-of-the-practice in the US paving concrete industry to understand merits of each solution. The results indicate that concrete mix design optimization is a promising, yet not widely applied solution that can reduce costs, enhance durability, and provide average carbon emissions savings of 14 percent. Use of supplementary cementitious materials (SCM) is another solution with multiple benefits, however, the use of SCM is already widely implemented across the USA. Industry-wide improvement in cement carbon footprint due to energy efficiency can provide additional savings of up to 10 percent. Quantifying the environmental footprint of concrete is critical to inform decision-making and enable more sustainable outcomes.

Concrete has played a pivotal role in shaping the modern world’s infrastructure and the built environment. Its unparalleled versatility, durability, and structural integrity have made it indispensable in the construction industry. From skyscrapers to long-span bridges, water reservoirs, dams, and highways, the ubiquitous presence of concrete in modern society underscores its significance in global development. As we stand at the crossroads of environmental awareness and the imperative to advance our societies, the sustainability of concrete production and utilization is becoming a new engineering paradigm. The immense demand for concrete, driven by urbanization and infrastructure development, has prompted a critical examination of its environmental impact. One of the most pressing concerns is the substantial carbon footprint associated with traditional concrete production. The production of cement, a key ingredient in concrete, is a notably energy-intensive process that releases a significant amount of carbon dioxide (CO2) into the atmosphere. As concrete remains unparalleled in its ability to provide structural functionality, disaster resilience, and containment of hazardous materials, the demand for concrete production is increasing, while at the same time, the industry is facing the urgency to mitigate its ecological consequences. This special publication investigates the multi-faceted realm of concrete sustainability, exploring the interplay between its engineering properties, environmental implications, and novel solutions, striving to provide an innovative and holistic perspective. In recent years, the concrete industry has witnessed a surge of innovation and research aimed at revolutionizing its sustainability. An array of cutting-edge technologies and methodologies has emerged, each offering promise in mitigating the environmental footprint of concrete. Notably, the integration of supplementary cementitious materials, such as calcined clays and other industrial byproducts, has gained traction to reduce cement content while enhancing concrete performance. Mix design optimization, coupled with advanced admixtures, further elevates the potential for creating durable, strong, and eco-friendly concrete mixtures. Concrete practitioners will gain an advanced understanding of a wide variety of strategies that are readily implementable and oftentimes associated with economic savings and durability enhancement from reading these manuscripts. The incorporation of recycled materials, such as crushed concrete and reclaimed aggregates, not only reduces waste but also lessens the demand for virgin resources. Furthermore, the adoption of efficient production techniques, along with the exploration of carbon capture and utilization technologies, presents an optimistic path forward for the industry. This special publication aspires to contribute to the ongoing discourse on concrete sustainability, offering insights, perspectives, and actionable pathways toward a more environmentally conscious future.

Concrete continues to be the most widely used material in the world, second only to water. Concrete is used in most civil infrastructure systems, but it often remains inadequately understood by the profession. For civil engineers to adapt to a world requiring ever-increasing efficiency, durability, and sustainability, and in which novel material formulations and products are introduced monthly, engineers must be able to make decisions as to the acceptability of these materials, and their effect on the performance of civil infrastructure. Essential to that ability is students’ understanding of the basics of cement hydration and its relationship to property development in the fresh and hardened concrete state. Towards that goal, this paper presents the basics of cement hydration, resources for learning more about the subject, and approaches to transferring knowledge to undergraduate-level students, through both lecture- and lab-based activities. Topics addressed include prioritization of topics for undergraduate civil engineering students to learn with regards to cement hydration processes, approaches to effective teaching of these topics including active learning in the classroom and laboratory, as well as knowledge exchange strategies, assessment techniques, and lessons learned from past experiences teaching these topics.