Dredged marine sand as construction material

Abstract

Dredging works are usually required to maintenance activities in many ports all over the world and represents a huge volume of disposal material. The use of dredged aggregates can be considered in several applications as erosive process control, coastal stabilization, beach replenishment, production of construction materials (clay, bricks, aggregates) or construction works (foundation fill, dikes, etc.). Researches revealed the feasibility of dredged marine sand (DMS) in the construction of base and sub-base harbour pavements incorporating this material to hydraulic binder mixes (cement or lime) in order to improve the grading of aggregates and correct the granular skeleton. Its main objective is to improve the packing and to obtain the compressive properties required for geotechnical applications. In this work the study of DMS from the Port of Sant Carles de la Rapita (Tarragona, Spain) as construction material is presented. The analysis of its influence on paste, mortar and concrete production is described. Two experimental phases were carried out once chemical and physical characteristics of DMS were determined. At first, pastes and mortars were made using CEM II/A-M 42,5R cement, different percentages of DMS on replacement of raw sand and plasticizer additive in order to obtain fresh and hardened properties of the mixes studied. After that, DMS was used in the production of concretes as fine aggregates. A pilot experience was carried out with concrete port pavements produced in industrial scale. Fresh and hardened properties of the concretes were determined and compared to the control mix. Results show satisfactory behaviour of DMS as construction material when incorporated in concrete as fine corrective sand.