Secondary aggregates and seawater employment for sustainable concrete dyke blocks production: Case study

• Concrete with 50% MRA mixed with 50% SA was the most adequate for dyke block production.
• Concrete employing high % of MRA (without SA) must be in a saturated state.
• Seawater (SW) reduced the concrete’s setting time and its accessible porous.
• SW increased of compressive strength at early age and its Density and Elastic Modulus.
• Laboratory results and technical know-how can be transferred to large scale projects.

The main objective of this research work was to validate the on site real scale production of dyke blocks employing coarse mixed recycled aggregates, steel slag aggregates and seawater. A laboratory experimental phase (Phase 1) was carried out prior to real scale concrete block production within Barcelona’s port (Phase 2). According to the results, the concretes produced with a combined mixture of 50% coarse mixed aggregates and 50% of coarse steel aggregates achieved the most adequate properties for use in dyke block manufacturing. The concrete produced employing high percentages of coarse mixed recycled aggregates (without steel slag aggregates) could achieve adequate properties in its saturated state. The use of seawater instead of freshwater reduced the concrete’s setting time as well as the porosity of the concretes produced, resulting in both the reduction of water penetration and the capillary water absorption capacity of the concretes. The use of seawater increased concrete’s compressive strength at early age. It was also concluded that the results obtained in the laboratory studies and the technical know-how achieved can be transferred to large scale projects.