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Recent developments in concrete research have considered the possible advantages related to the use of seawater as mixing water for concrete production. Specifically, the SEACON-INFRAVATION project investigated the performance of seawater concrete for the construction of sustainable and durable reinforced concrete structures. Besides laboratory activities aimed at characterizing the performance of seawater concrete and corrosion behavior of various types of embedded reinforcements, a demonstration project was executed in Italy. The prototype consisted of a concrete culvert built along the A1 motorway, close to the city of Piacenza, Italy. The demonstration activities led to testing of the on-site use of seawater and assessment of the corrosion conditions of the embedded reinforcements, allowing a thorough understanding of long-term durability and sustainability. For this purpose, the prototype culvert was divided into six segments; each segment was representative of a combination of type of concrete (reference, seawater, and recycled-asphalt-pavement concrete) and type of reinforcement (carbon steel, austenitic and duplex stainless steels, and glass fiber–reinforced polymer). This article presents concrete mix designs, materials characterization, embedded probes used to monitor the corrosion of the reinforcements, and test results obtained at various stages of execution and service conditions. In addition, a sampling campaign, one year from construction, is included. Finally, mention is made of the life cycle assessment and life cycle cost analyses performed to quantify the long-term benefits of seawater concrete combined with corrosion-resistant reinforcement.

In recent years, worldwide research has been facing the challenge of finding solutions able to decrease the environmental impact of cement and concrete production. Many strategies could be adopted in order to reach this goal, such as reducing the clinker factor in cement or producing alternative clinkers to portland clinker, in addition to the adoption of efficient water recycling processes in concrete production, thus reducing the consumption of natural resources. An interesting approach to implementing the different strategies is to develop concretes combining the use of cement and seawater, permitting a significant saving in fresh water consumption and offering an important benefit to countries that are facing a water shortage. Thanks to the recent technological improvement in the composite material sector, corrosion-free reinforcements have been successfully developed, thus proposing an alternative to steel rebars in concrete, especially in exposure conditions that are critical because of the presence of chloride, or even in combination with seawater. The use of a specialty binder based on an intrinsically low pH and a high sulfate resistance can be beneficial for the stability of the concrete and of the embedded glass-fiber–reinforced polymer rebars. This article compares the mineralogical and mechanical behavior of pastes and mortars containing (1) limestone portland cement, (2) sulfoaluminate cement and (3) a blend of the two, when mixed with seawater. Compressive strength and drying shrinkage tests were performed, and the results were interpreted on the basis of the microstructural data obtained through X-Ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC). The results suggest that the phase assemblage of the systems and, in particular, the equilibria among the different Al2O3-Fe2O3-monovalent anion (AFm)/Al2O3-Fe2O3-trivalent anion (AFt) minerals play a key role in the strength development mechanism.

Controlled low-strength materials (CLSMs) are engineered, cement-based mixes that are of growing interest in all trench backfilling and bedding applications in which low stiffness, strength, and density are required. Although 50 years have passed since its first application, CLSM technology has been the focus of continuous innovation. The challenge today concerns the excessive long-term gain in strength of current CLSMs that leads both to difficulties in the event of future removals and to unbalanced stress-strain behavior with surrounding soils. In this investigation, the authors present a long-term laboratory study aimed at the creation of new CLSM formulations for pavement applications with the objective of avoiding or limiting any gain in stiffness and resistance over time. For this purpose, a rapid-hardening cement that presented distinct advantages in rapid-set, high early-strength development, and insignificant long-term gain in strength was used as a substitute for portland cement. All the mixtures studied were subjected to static and dynamic triaxial tests for which the mechanical characteristics of a reference granular soil were taken as the mix design target for new CLSM formulations. The results derived from the use of different admixtures and mixing procedures in mixing time, batching sequence, and mixer type were also investigated.

Controlled low-strength materials (CLSMs) are engineered, cement-based mixes that are of growing interest in all trench backfilling and bedding applications in which low stiffness, strength, and density are required. Although 50 years have passed since its first application, CLSM technology has been the focus of continuous innovation. The challenge today concerns the excessive long-term gain in strength of current CLSMs that leads both to difficulties in the event of future removals and to unbalanced stress–strain behavior with surrounding soils. In this investigation, the authors present a long-term laboratory study aimed at the creation of new CLSM formulations for pavement applications with the objective of avoiding or limiting any gain in stiffness and resistance over time. For this purpose, a rapid-hardening cement that presented distinct advantages in rapid-set, high early-strength development, and insignificant long-term gain in strength was used as a substitute for portland cement. All the mixtures studied were subjected to static and dynamic triaxial tests for which the mechanical characteristics of a reference granular soil were taken as the mix design target for new CLSM formulations. The results derived from the use of different admixtures and mixing procedures in mixing time, batching sequence, and mixer type were also investigated.