International Concrete Abstracts Portal

With the reduced availability of traditional supplementary cementing materials (SCMs), a need arises for alternatives. This study presents an investigation into the reactivity of powders derived from reactive siliceous aggregates, some of which demonstrated pozzolanic potential by reducing concrete expansion associated with alkali-silica reaction (ASR). A dissolution test was conducted to quantify the amounts of soluble silica and alumina available for pozzolanic reaction. The aggregate powders were immersed in an alkaline solution designed to simulate the alkalinity of concrete pore fluid and tested at four different temperatures to evaluate the effect of temperature on the dissolution behavior. These tests were performed in parallel with ASR expansion testing to determine whether dissolution data could serve as a rapid indicator of pozzolanic potential, reducing the need for long-term monitoring. The results indicated that dissolution kinetics varied significantly with temperature, raising concerns about the use of high-temperature methods to evaluate pozzolanic activity. Aggregate powders containing calcium exhibited notable physical changes, suggesting reactions involving both silica and calcium in the solution. A strong inverse relationship was observed between dissolved silica and aluminum concentrations; all solutions exhibited either high aluminum and low silica, or high silica and low aluminum, but never elevated levels of both simultaneously. Finally, the powders were analyzed using X-ray diffraction (XRD) to assess mineralogical changes following alkaline exposure. Cryptocrystalline quartz, muscovite, and kaolinite phases were altered during the dissolution test, whereas other phases, including crystalline quartz, did not.

Hybrid cements contain a small amount of Portland cement; the rest of the binder is made up of pozzolanic or latent hydraulic admixtures. Another component is an alkaline activator. These binders, therefore, combine the advantages of alkaline activation and Portland cement. In this work, a combination of Portland cement, ground granulated blast furnace slag (GBFS), siliceous fly ash (FA), and ground recycled masonry (GRM) is chosen. The GRM mainly contains ground bricks - i.e., heat-treated clay with potential pozzolanic properties and usually about 7-8% CaCO3 from the original mortar. Sodium water glass modified with potassium hydroxide is used as an activator. Potassium ions improve the workability of the mixture and limit the efflorescence of the hardened mixture. The dose of cement was optimized, as well as the dose of the activator. Furthermore, mixtures with different GBFS or FA and GMR ratios were tested. With an optimal composition and a water-to-binder ratio of 0.50, it is possible to achieve compressive strengths between 15 and 20 MPa at the age of 28 days, with the expectation of further improvement.

Concrete specimens containing iron sulfide-bearing aggregates were investigated under electrochemical acceleration to evaluate potential damage mitigation strategies. Cylinders were prepared with different aggregate sizes, sulfide contents, water-to-cement ratios, cement types, and pozzolanic replacements, and subjected to controlled electrochemical exposure to reproduce field-like deterioration within weeks. Damage progression was monitored using resonance frequency measurements, visual crack quantification, and microstructural analysis. Results showed that higher sulfide contents accelerated modulus loss and crack initiation, with coarser aggregates producing visible cracking and greater stiffness reductions, while finer aggregates largely avoided macrocracking. Higher water-to-cement ratios further accelerated deterioration, whereas lower ratios delayed both onset and propagation. Cement type and pozzolanic additions also influenced deterioration, with all mixtures exhibiting damage under electrochemical acceleration. Specimens containing Type I white Portland cement demonstrated greater resilience against rapid failure, while partial cement replacement with glass powder delayed early crack propagation. These findings demonstrate that electrochemical acceleration provides a reliable platform for evaluating potential mitigation strategies and show how mixture design parameters influence deterioration progression in iron sulfide-bearing concrete, offering insights that support the development of practical approaches to manage this durability problem.

The first international symposium on “Advances in Concrete Technology” was sponsored jointly by Canada Centre for Mineral and Energy Technology (CANMET), the American Concrete Institute (ACI), and several other international organizations in Athens, Greece, in May 1992. Dr. Mohan Malholtra served as the chairman of the symposium. In June 1995, CANMET, in association with ACI and various professional organizations from the United States and Canada, sponsored the Second CANMET/ACI Symposium on Advances in Concrete Technology in Las Vegas, NV, USA. This event focused on high-performance normalweight and lightweight concretes, with the proceedings formally published as ACI SP-154. The Third CANMET/ACI Symposium on Advances in Concrete Technology was held in Auckland, New Zealand, in August 1997, sponsored by CANMET, ACI, and partner organizations from Canada and New Zealand. The symposium brought together industry, university, and government representatives to explore new areas of research, resulting in the publication of 33 refereed papers from 15 countries as ACI SP-171. In June 1998, the Fourth CANMET/ACI Conference on Advances in Concrete Technology took place in Tokushima, Japan, sponsored by CANMET, ACI, the Japan Concrete Institute (JCI), and several organizations from Japan and Canada. From more than 80 submissions across 20 countries, 61 refereed papers were published as ACI SP-179, while more than 30 additional technical contributions were presented. The Fifth CANMET/ACI Conference on Advances in Concrete Technology was held in Singapore in July and August 2001, under the sponsorship of CANMET, ACI, and multiple Singaporean organizations. This milestone event saw over 100 papers from 25 countries, leading to the publication of 46 refereed papers as ACI SP-200, and more than 25 additional papers were presented. In June 2003, the Sixth CANMET/ACI Conference on Advances in Concrete Technology was held in Bucharest, Romania, with sponsorship by CANMET, ACI, and several Romanian organizations. During this event, more than 40 technical papers were distributed to participants as received, though no formal ACI Special Publication was issued for this symposium. The Seventh CANMET/ACI Conference on Advances in Concrete Technology was held in May 2004 in Las Vegas, USA, sponsored by CANMET, ACI, and several U.S. organizations. The technical program resulted in 17 refereed papers from more than 10 countries published as ACI SP-222. In May 2006, CANMET, ACI, and organizations from Canada and the United States sponsored the Eighth CANMET/ACI Conference on Advances in Concrete Technology in Montreal, QC, Canada. The proceedings, consisting of 17 refereed papers, were published as ACI SP-235, supplemented by more than 30 additional technical papers distributed at the venue. The Ninth CANMET/ACI Conference on Advances in Concrete Technology was conducted in Warsaw, Poland, in May 2007, under the sponsorship of CANMET, ACI, and partners from Canada, Europe, and the United States. The final proceedings included 10 refereed papers published as ACI SP-243 along with more than 20 supplementary papers. Sponsored by ACI in association with several organizations from Canada, Europe, and the United States, the Tenth ACI Conference on Advances in Concrete Technology took place in Seville, Spain, in October 2009. This event produced 20 refereed papers published as ACI SP-261, while more than 20 additional papers were released in a supplementary volume. In May 2010, the Committee for the Organization of International Conferences (COIC) (formerly CANMET/ACI Conferences) and the Chinese Ceramics Society (CCS) sponsored the Eleventh International Conference on Advances in Concrete Technology and Sustainability Issues in Jinan, China. This gathering featured the presentation of more than 40 papers, with the formal proceedings published by the CCS, Beijing, China. The Twelfth International Conference on Advances in Concrete Technology and Sustainability Issues was held in Prague, Czech Republic, in October 2012, sponsored by COIC and ACI with a new focus on sustainability issues. The resulting volume, ACI SP-288, featured more than 30 refereed papers, while an additional 40 papers were included in a supplementary volume. In July 2015, COIC and ACI sponsored the Thirteenth International Conference on Advances in Concrete Technology and Sustainability Issues in Ottawa, ON, Canada. This technical exchange yielded 28 refereed papers published as ACI SP-303, alongside with more than 40 other papers presented in a supplementary papers volume. The Fourteenth International Conference on Recent Advances in Concrete Technology and Sustainability Issues was sponsored by the CCS, the China Academy of Building Research (CABR), and COIC in Beijing, China, in October 2018. The technical output included 19 refereed papers published as ACI SP-330, with more than 52 additional papers featured in the supplementary volume. After a postponement due to the COVID-19 pandemic, the Fifteenth International Conference on Recent Advances in Concrete Technology and Sustainability Issues was sponsored by the ACI Italy Chapter and the University of Bergamo in Milan, Italy, in July 2022. This event focused on decarbonization and alternative binders, resulting in 44 refereed papers published as ACI SP-355, and approximately 20 papers were published in the supplementary volume. The Sixteenth International Conference on Recent Advances in Concrete Technology and Sustainability Issues is being held in Munich, Germany, from 8 – 10 July, 2026. This prestigious gathering is hosted by the Technical University of Munich (TUM) with the support of ACI. The conference continues its long-standing mission of advancing concrete science, with a sharp focus on the industry’s most pressing challenge: the transition of the cement industry towards decarbonization and the implementation of new technologies for long-term sustainability. 19 refereed papers for this conference are published herein as an ACI Special Publication, focusing on topics including: use of supplementary cementitious materials such as alkali-activated slag, calcined clay, red mud and other industrial wastes; pozzolanic reactivity of SCMs; long-term investigation on cement and cement additives; reduction on CO2 emission, etc. Additionally, more than 50 other papers will be presented at this event, most of them available in a Supplemental Papers Volume. The organizing committee expresses its profound gratitude to the authors, reviewers, and partner organizations whose dedication continues to drive the evolution of concrete technology toward a more sustainable future. Special thanks are also given to the American Concrete Institute for the publication of the proceedings. The Editor Prof. Dr. Johann Plank

The mitigation of CO₂ emissions in cement production increasingly relies on alternative cementitious materials (SCMs), given the declining availability of traditional sources such as blast furnace slag and fly ash. This study examines the mechanochemical activation of clays as a low-carbon alternative to thermal calcination. Mechanochemical activation - implemented through high-energy dry grinding in an industrial agitated bead mill - induces pronounced structural modifications in clay minerals and enhances their pozzolanic reactivity. Experimental results indicate a lower demand for superplasticizers and accelerated early strength development in cementitious systems incorporating mechanochemically activated clays. The first industrial-scale application at the SCHWENK plant in Allmendingen (Allmeca) demonstrates the scalability of this process, which utilizes locally sourced clays and ensures consistent activation performance. Furthermore, the integration of activated clays with limestone powder, aligned with the LC3 concept, significantly improves both workability and concrete strength. This approach provides a sustainable pathway for cement production that leverages regional resources while reducing environmental impact.