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.

The design, analysis, and performance of structural concrete slabs under punching shear loading conditions are topics that have been studied extensively over many decades and are well documented in the literature. However, the majority of the work reported in these areas is generally related to conventional concrete slabs subjected to highly idealized loading conditions. Structural engineers need to find new, innovative ways and methods to design new structures but also to strengthen existing infrastructure to ensure safety, resilience, and sustainability. These challenges can be addressed through the use of integrated systems and high-performance technologically advanced materials. We live in a new era of improved computational capabilities, advances in high-performance computing, numerical and experimental methods, and data-driven techniques, which give us broader access to larger and better data sets and analysis tools. These new advancements are essential to develop deeper insights into the structural behavior of concrete slabs under punching shear and to implement and analyze new materials and loading conditions. This Special Publication presents recent punching shear research and insights relating to topics that have historically received less attention in the literature and/or are absent from existing codified design procedures. Topics addressed include: the usage and impacts of alternative/modern construction materials (new concrete and concrete-like materials, nonmetallic reinforcement systems, and combinations thereof) on slab punching shear resistance, novel shear reinforcement or strengthening systems, the influence of highly irregular/nonuniform loading and support conditions on slab punching shear, impact loading, new design and analysis techniques, and the study of the punching shear behavior of footings. This Special Publication will be of interest to designers who are often faced with punching-related design requirements that fall outside of traditional research areas and existing code provisions, as well as for researchers who are performing research in related areas. Perspectives from a broad and international group of authors are included in this Special Publication, relating to a variety of punching-related problems that occur in research and practice. In particular, researchers from the United States, Canada, Ecuador, the Netherlands, Italy, Brazil, Israel, Portugal, Spain, the United Arab Emirates, and Germany contributed to the articles in this Special Publications. To exchange views on the new materials, tests, and analysis methods related to punching, Joint ASCE-ACI Committee 421, “Design of Reinforced Concrete Slabs;” Joint ASCE-ACI Committee 445, “Shear and Torsion;” and subcommittee ACI 445-C, “Punching Shear,” organized two sessions titled “Punching shear of concrete slabs: insights from new materials, tests, and analysis methods” at the ACI Spring Convention 2023 in San Francisco, CA. This Special Publication contains several technical papers from experts who presented their work at these sessions, in addition to papers submitted for publication only. Co-editors Dr. Katerina Genikomsou, Dr. Trevor Hrynyk, and Dr. Eva Lantsoght are grateful for the contributions of the authors and sincerely value the time and effort of the authors in preparing the papers in this volume, as well as of the reviewers of the manuscripts. Aikaterini Genikomsou, Trevor Hrynyk, and Eva Lantsoght Co-editors

In reinforced concrete (RC) structures, a proper bond between the reinforcement and the concrete is key for appropriate composite action. To date, limited studies exist that evaluate the bond of fiber-reinforced polymer (FRP) bars in concrete members under flexure and its effect on the development length required to ensure a full stress transfer. In this paper, the bond strength developed by glass FRP (GFRP) and steel rebars is evaluated and compared by testing 16 RC beams under three-point bending. The beams were 1.83 m long and had a section of 150 x 360 mm. Different embedment lengths were evaluated as a function of the bar diameter (db): 30 db, 40 db, and 50 db for GFRP reinforced specimens, and 20 db, and 30 db for steel reinforced beams. Two different GFRP rebar types (six beams for each) and conventional steel (four beams) were used as reinforcement; all the rebars had a nominal diameter of 12.7 mm. Based on the results presented herein, GFRP rebars have a lower bond capacity than steel rebars. Also, the development lengths as suggested by actual code provisions for GFRP rebars (ACI 440.1R-15) appear to be over-conservative: the theoretical development length values were around 110% - 188% higher than the experimental results for the tested GFRP rebars, while the predicted development length for steel rebars according to ACI 318 was about 83% higher than the experimental results.

The recycling of waste materials from the construction sector represents an opportunity for environmental protection, to save expensive landfill costs, and promote sustainability. The increased interest in the use of recycled materials is seen in several European countries with the production of concrete using granulates from demolition material. In Switzerland, the SIA 2030 standard defines recycled concrete based on a minimum percentage of 25% recycled aggregates to be added. This research focuses on the possibilities of producing high-quality recycled concrete, starting from high-quality cementitious material, i. e. concrete. The original material with known properties was demolished and used as aggregates to replace the natural aggregates. Fresh, hardened, and durable properties of concrete were evaluated on blends containing 25, 50, and 100% recycled aggregates. At early stage (2 days), the lowest value of compressive strength was already above 15 MPa for the blend with 100% recycled aggregates. Most of the recycled concrete satisfies the main mechanical and durability features, in particular with the addition of 25 respectively 50% of the recycled aggregate component.

High purity lithium hydroxide and lithium carbonate for use in lithium-ion batteries are produced by the processing of spodumene ore from the Whabouchi mine (Northern Quebec, Canada). The main byproduct of this treatment is an aluminum silicate waste stream, which is produced in very large quantities and should be recycled to avoid its storage in landfills, which is not environmentally friendly. Previous research work by the authors on the characterization of this aluminum silicate waste stream showed its potential as a pozzolanic material and hence that it could be used by the cement and concrete industry, which would contribute to the sustainability of these industries. The purpose of this study was to assess the pozzolanic activity of this new material and its effects on the properties of concrete in its fresh and hardened states in order to evaluate the effects of replacing part of the cement with this aluminum silicate waste stream in various classes of concrete. Series of air-entrained and non-air entrained concrete mixtures were produced and tested in this study. Results from fresh state testing, mechanical and durability properties of the concrete made with this material were similar to those obtained with conventional supplementary cementitious materials and equal or superior to those obtained with reference concrete mixtures made with plain and ordinary portland cement.