The present paper shows the study of a mixture design of the concrete used in the reinforced foundations of the bridge on the Straits of Messina in Italy. A cube compressive characteristic strength of 35 MPa (5,075 psi) is required for the foundation concrete. Due to the peculiar shape of the concrete foundations (completely embedded in the excavated ground), the damages caused by the thermal stress, the steel corrosion, and the alkali-silica reaction cannot be monitored and repaired. Therefore, a concrete structure must be designed without any damage for at least 200 years due to the very important role of this structure from a social point of view. In order to guarantee this long-term durability, there are two problems to be faced and solved: 1) the heat of cement hydration could cause cracks inside the foundation due to thermal gradients between the hotter nucleus of the massive structure and the colder peripheral areas; 2) the corrosion of the metallic reinforcements caused by the reaction between the metallic iron and the oxygen (O₂) present in the air to an extent of about 20%; 3) the alkali-silica reaction causing a local disruption in the concrete. All these problems can be solved using a blast-furnace slag cement such as CEM III B 32.5 R characterized by a very small heat of hydration and adopting a ground coarse aggregate with a maximum size as large as 32 mm (1.28 in): the choice of this aggregate produces a reduction in the amount of mixing water and then of the cement content and reduces the volume of the entrapped air at about 1.3% by concrete volume. This amount of O₂ would cause the corrosion of a negligible amount of iron corresponding to only 10 to 13 g (0.4 to 0.5 oz) of steel in 1 m³ (1.31 yd³) of concrete of each foundation. In order to prevent any ingress of air from the environment, the top of the foundation should be protected by self-compacting, self-compressing, and self-curing concrete.

Polycarboxylates (PCEs) currently dominate the global superplasticizer market. Among them, HPEG and IPEG PCEs have attained a prominent position as they present the most cost-effective PCEs known at present. Recently, novel vinyl ether PCEs designated as EPEG and GPEG PCEs were introduced, thus broadening the family of VPEG PCEs, and their overall performance is still evaluated. Well documented are now the advantages of novel phosphated comb polymers which can significantly reduce the stickiness of concrete e.g. in UHPC. In spite of many attempts, so far no overall cost-effective clay tolerant superplasticizer has been identified, the challenge being that such a structure must include side chains that however do not contain polyethylene glycol/polypropylene glycol (PEG/PPG) or polyamines. Fortunately, for calcined clay blended cements, HPEG PCEs of specific molecular design as well as zwitterionic (amphoteric) PCEs have proven to be highly effective. Moreover, AAS binder systems were successfully fluidized with APEG or HPEG PCEs exhibiting particularly short side chains (nEO < 10). This review underlines the critical role that innovation in chemical admixtures will play in the future to facilitate a successful migration to low-carbon binders.

The Canada Centre for Mineral and Energy Technology (CANMET) of Natural Resources of Canada, Ottawa, ON, Canada, has played a significant role for more than 40 years in the broad area of concrete technology in Canada. In recent years, CANMET has become increasingly involved in research and development dealing with supplementary cemen¬titious materials, high-performance normalweight and lightweight concretes, and alkali-aggregate reactions. As part of CANMET’s technology transfer program, an international symposium on Advances in Concrete Technology was sponsored jointly with the American Concrete Institute (ACI) and other organizations in Athens, Greece, in May 1992. In June 1995, CANMET, in association with ACI and other organizations in Canada and the United Staes, sponsored the Second CANMET/ACI Symposium on Advances in Concrete Technology in Las Vegas, NV, USA. For the Athens symposium, the CANMET publication “Advances in Concrete Technology,” constituted the proceedings of the symposium. The proceedings from the Las Vegas symposium were published by ACI as SP-154. In August 1997, CANMET, in association with ACI and other organizations in Canada and New Zealand, sponsored the Third CANMET/ACI Symposium on Advances in Concrete Technology in Auckland, New Zealand. The main purpose of the symposium was to bring together representatives from industry, universities, and government agencies to present the latest information on concrete technology, and to explore new areas of research and development. Thirty-three refereed papers from 15 countries were presented and distributed at the symposium. The proceedings were published as ACI SP-171. In June 1998, CANMET, in association with ACI, Japan Concrete Institute (JCI), and several other organizations in Canada and Japan, sponsored the Fourth CANMET/ACI Conference on Recent Advances in Concrete Technology in Tokushima, Japan. More than 80 papers from 20 countries were received and reviewed in accordance with the policies of ACI. Sixty-one refereed papers were accepted for presentation at the conference and for publication as ACI SP-179. In addition to the refereed papers, more than 30 papers were presented and distributed at the conference. In July-August 2001, CANMET, in association with ACI and several organizations in Singapore, sponsored the Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology in Singapore. More than 100 papers from 25 countries were received and reviewed in accordance with the policies of ACI. Forty-six refereed and more than 25 additional papers were accepted for presentation at the conference. The proceedings of the conference were published as ACI SP-200. In June 2003, CANMET, in association with ACI and several organizations in Romania, sponsored the Sixth CANMET/ACI Conference on Recent Advances in Concrete Technology in Bucharest, Romania. More than 40 papers presented at the conference were distributed “as received,” and no formal ACI special publication was published. In May 2004, CANMET, in association with ACI and several other organizations in the United States, sponsored the Seventh CANMET/ACI Conference on Recent Advances in Concrete Technology in Las Vegas, NV. Seventeen refereed papers from more than 10 countries were presented and distributed at the conference. The proceedings of the conference, consisting of the refereed papers, were published as ACI SP-222. In addition to the refereed papers, 20 additional papers were presented and distributed at the conference. In May 2006, CANMET, in association with ACI and several other organizations in Canada and the United States, sponsored the Eighth CANMET/ACI Conference on Recent Advances in Concrete Technology in Montreal, QC, Canada. The proceedings of the conference, consisting of 17 refereed papers, were published as ACI SP-235. In addition to the refereed papers, more than 30 additional papers were presented and distributed at the conference. In May 2007, CANMET, in association with ACI and several other organizations in Canada, Europe, and the United States, sponsored the Ninth CANMET/ACI Conference on Recent Advances in Concrete Technology in Warsaw, Poland. The proceedings of the conference, consisting of 10 refereed papers, were published as ACI SP-243. More than 20 additional papers were presented and distributed at the conference. In October 2009, ACI, in association with several organizations in Canada, Europe and the United States, sponsored the Tenth ACI Conference on Advances in Concrete Technology in Seville, Spain. The proceedings of the conference, consisting of 20 refereed papers, were published as ACI SP-261. In addition to the refereed papers, more than 20 additional papers were presented at the conference and published in a supplementary papers volume. In May 2010, the Committee for the Organization of International Conferences (COIC) (formerly CANMET/ACI Conferences), in association with the Chinese Ceramics Society (CCS) and several other organizations in China, sponsored the Eleventh International Conference on Advances in Concrete Technology and Sustainability Issues in Jinan, China. More than 40 papers were presented at the conference. The proceedings of the conference were published by the CCS, Beijing, China. In October 2012, the COIC, in association with ACI, sponsored the Twelfth International Conference on Advances in Concrete Technology and Sustainability Issues in Prague, Czech Republic. The proceedings of the conference, consisting of more than 30 refereed papers, were published as ACI SP-288. In addition to the refereed papers, more than 40 other papers were presented at the conference and published in a supple¬mentary papers volume. In July 2015, the COIC, in association with ACI, sponsored the Thirteenth International Conference on Advances in Concrete Technology and Sustainability Issues in Ottawa, ON, Canada. The proceedings of the conference, consisting of 28 refereed papers, were published by ACI as SP-303. In addition to the refereed papers, more than 40 other papers were presented at the conference and published in a supplementary papers volume. In October 2018, the CCS and the China Academy of Building Research (CABR), Beijing China, in association with the COIC sponsored the Fourteenth International Conference on Recent Advances in Concrete Technology and Sustainable Issues in Beijing, China. The proceedings of the conference, consisting of 19 refereed papers, were published by ACI as SP-330. In addition to the refereed papers, more than 52 other papers were presented at the conference and published in a supplementary papers volume. In July 2022, after a postponement for the Covid-19 pandemic, the ACI Italy Chapter and the University of Bergamo, Italy, sponsored the Fifteenth International Conference on Recent Advances in Concrete Technology and Sustainable Issues in Milan, Italy. The proceedings of the conference, consisting of 44 refereed papers, were published by ACI as SP-355. In addition to the refereed papers, about 20 other papers were presented at the conference and published in a supplementary papers volume. The main topics of the papers presented at the conference include: the deterioration of concrete structures; the corrosion of metallic reinforcement; the repair techniques of damaged concrete structures by using shrinkage-compensating cement-based mixtures; the protection of concrete structures by special materials to obtain watertight concrete; the reduction of the damage caused by alkali-silica reaction; the use of mineral additions such as fly ash, silica fume, and ground-granulated blast-furnace slag to improve the durability of concrete structures; and the production of concrete by reducing gas emissions and energy consumption such as the use of binders alternative to portland cement (alkali activated materials, geopolymers, sulphoaluminate cement) and recycling of wastes coming from different sources. Thanks are extended to the reviewers for the valuable efforts in reviewing all the manuscripts published in the conference proceedings and in the supplementary volume. The guidance from Dr. V. M. Malhotra and Prof. M. Collepardi, the Honorary Chairpersons of the conference, is sincerely appreciated. Also, acknowledged is the support the American Concrete Institute for the publication of the proceedings (ACI SP-355). The Editors Dr. Denny Coffetti Prof. Luigi Coppola Dr. Terence Holland

The new San Giorgio bridge replaced the Polcevera viaduct, built between 1963 and 1967 and collapsed during a storm in summer 2018. The new bridge was designed by Renzo Piano and is made by 19 steel spans supported by 18 concrete pillars. Beside the architectural aspects, special attention was devoted to the mix-design of the pillars, to ensure the production of durable concrete in the marine environment. The use of slag cement combined with limestone filler and polycarboxylate superplasticizers allowed to cast flowable concrete associated with low water to cement ratio and high final compressive strength. A new generation accelerating admixtures, working on the homogeneous nucleation technology, was used to accelerate the cement hydration and gain early compressive strength to speed-up the elevation of the pillars. In the present paper, the advantage of using the new admixture is discussed both in terms of early strength development and microstructure of the cement paste. Beside the improvement of the early strength development, the new admixture reduced the water permeability and the chloride diffusion and improved the resistance to carbonation of the concrete used for the pillars, with further advantages for the durability of this structure.

Supplementary cementitious materials (SCMs) can be effective levers to reduce the environmental impact of concrete. One of the major limitations for high substitution of clinker by SCMs in Portland cement is the loss of strength of the resulting concrete, particularly at early age, compared with similar concrete made with equivalent dosage of pure clinker Portland cement. Furthermore, the possibility to use larger fractions of SCMs requires strongly alkaline activators which pose environmental and safety problems and are not compatible with commercial PCE superplasticizers. A new hybrid additive was synthesized which works, at the same time, as seed for the clinker phase and as an activator for alkali-activated binders. The new product consists of an alkaline suspension of micro-sized particles containing nano-structured CSH seeds, amorphous portlandite, and AFm phases embedded in a polymeric matrix. The structure and the mechanism of action of the new product on slag cements have been investigated by Environmental Scanning Electron Microscopy, X-ray Powder Diffraction, Thermal Analysis, and Isothermal Calorimetry. The new product is fully compatible with PCE superplasticizers and can be used to produce alkali-activated concretes characterized by low-carbon impact.