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The production of ordinary portland cement (OPC) is very carbon expensive, and with an increased focus on application of eco-friendly cementitious materials, interest in alternative cements has grown. One of these alternatives is calcium sulfoaluminate (CSA) cement. The manufacturing of CSA cement emits about 50% less carbon per lb. of cement produced and has other advantages such as rapid hardening due to a greater formation of ettringite when compared to OPC. However, there are a limited number of studies concerning the freeze-thaw resistance of CSA cement systems in cold environments. This study directly compares Type I OPC and CSA cement paste and mortar mixtures at water-to-binder ratios (w/b) of 0.40, 0.45, and 0.50 to determine the differences in freeze-thaw durability. This study implements thermomechanical analysis (TMA) to quantify the frost-induced damage in CSA and OPC systems with micron-scale resolution. Additionally, water absorption, bulk electrical resistivity, and porosity measurements along with microstructure characterization were performed to relate the freeze-thaw performance to the microstructural and mass transport properties of CSA systems.

It is well known that the concrete industry is at a watershed towards sustainability, focused on reducing its environmental impact and improving the performances and the service life of concrete structures. One of the main causes of the huge environmental impact of mortars and concretes is portland cement, an energy-intensive binder characterized by strong greenhouse gases emissions and high natural raw materials consumptions. For this reason, several low-environmental impact alternative binders to portland cement have been proposed in recent years. However, it is clear that the massive volumes required by construction industry, together with technological limitations, inconsistency of properties and price issues, make the replacement of significant portions of portland cement in concrete production practically impossible. Nevertheless, alternative “green” binders may play a fundamental role in the formulation of special mortars and concretes due to their peculiar properties at fresh and hardened state. This paper presents different “special” applications of alternative binders (alkali activated materials, calcium sulphoaluminate clinker-based blends) such as expansive concretes for jointless slabs on ground, heat-insulating reinforced plasters for seismic and energy retrofitting of poor-quality masonry structures, cement-free renders for structural applications on existing buildings and pervious concretes made only with recycled raw materials.

The most recent advancements in the field of the concrete industry don’t only represent the possibility to satisfy the demand of an ever-changing market demand but could also be the opportunity to reach important improvements in terms of holistic sustainability which is an essential topic nowadays. In view of this, the current work investigates the case of nanofunctionalized Ultra High-Performance Concrete (UHPC) to address also the potential advantages coming from the better structural and durability performances when exposed in specific aggressive environmental scenario. The benefits of adding alumina nanofibers or cellulose nanofibrils/crystals in terms of enhanced crack control, reduced autogenous shrinkage and improved durability self-healing capacity will be quantified in a life cycle perspective, also considering the impact and cost of the nano-particle production. In this framework a holistic assessment perspective will be provided through the Life Cycle Assessment methodology, employed to quantify such advantages on a local, regional, and global scale using the worldwide recognized 10 CMLA impact categories to also show how such procedures, being employed within an “a priori” de-sign phase, can help to drive the sector to more conscious choices.

Earlier, a simplified, excel based tool was developed based on extensive experimental data by innovative/new test methods to do durability-based performance evaluation of conventional coal ashes in HPC. The aim was to offer the contractor an easy-to-use tool to predict the durability performance of the concrete mixes in terms of ASR, chloride-induced corrosion, freeze-thaw damage, and shrinkage-based cracking potential during the mix design development stage. Some uncommon coal ashes (e.g., blended ash, bottom ash, harvested ash, etc.) were subsequently evaluated through (i) detailed characterization including reactivity measurements, and (ii) durability-based performance evaluation using the developed tool with selective validation testing. The merits of an easy-to-use tool for rapid durability-based performance evaluation of some of these uncommon coal ashes will be highlighted.

NEU: An ACI Center of Excellence for Carbon Neutral Concrete recently launched its Validation/Verification Program to assess and validate/verify the environmental claims of innovative and new products/technologies associated with low-carbon cement and concrete production. The end result of this program is to issue an independent third-party verification or validation statement, which is aimed at securing the trust of customers, investors, and consumers in the long term, and by using reliable methods, to separate plausible statements from insubstantial marketing promises. This presentation by Mahmut Ekenel, PhD, PE, FACI, Validation Director for NEU, aims to introduce the program, identify the difference between verification and validation statements, and introduce the ISO/IEC 17029 standard under which the program is set to operate.

Speaker biography
Mahmut Ekenel, PhD, PE, FACI, is Validation Director for NEU: An ACI Center of Excellence for Carbon Neutral Concrete. Ekenel has extensive experience in developing acceptance criteria for the evaluation of building materials in accordance with the model building codes, building code development, and a working knowledge of International Standards Organization (ISO) standards and quality control inspections. Ekenel received his PhD from the Missouri University of Science and Technology and became a Fellow of ACI in 2020. Prior to joining the ACI Staff, Ekenel served as Senior Staff Engineer for the International Code Council Evaluation Service (ICC-ES) and was employed by ICC-ES for 17-plus years. He is a licensed civil engineer in the State of California and a licensed professional engineer (PE) in the states of Ohio, Michigan, and Pennsylvania.

As the pressure shifts to the concrete industry to deliver cost-effective, efficient low-carbon solutions, it can feel that the options are limited, the risks are high and the margins tight. However, there are options that can reduce carbon in concrete and cement industry at scale and without excessive cost and demand on limited power sources stretched thin by increased demand from economic growth and the implementation of AI and a multitude of decarbonizing technology solutions. Steve Bryan, Managing Director of Ecocem Americas, and John Reddy, Director of Concrete Technology Deployment at Ecocem, will discuss how Ecocem’s ACT—a next-generation low-carbon cement technology—offers the greatest potential to decarbonize the global cement and concrete industry cost-efficiently and at speed.

Presenters:
Steve Bryan, Managing Director, Ecocem Americas
Bryan joined Ecocem in 2013, bringing with him over 35 years of experience in cement operations, technology, global trading, strategic planning, and business development. He is responsible for Ecocem business development outside of Western Europe.

John Reddy, Director of Concrete Technology Deployment, Ecocem and Vice President, Institute of Concrete Technology
Reddy joined Ecocem in 2004 when the environment was only beginning to become a focus for the construction industry and over the past 20 years has seen the business evolve from a startup to become Europe’s low-carbon cement technology business.