Mix design of concrete with calcined dredging sediments as novel SCM

Maintenance dredging works in the port of Antwerp generate each year about 450.000 tons dry matter of dredging sediments, for which suitable disposal solutions or applications are required. Mechanical dewatering of the sediments results in dewatered filter cakes, rich in clay minerals. When flash calcination is applied to activate the clay minerals, the sediments show pozzolanic properties superior to siliceous fly ash. Replacing 30 wt.% of cement by dredging sediments leads to a strength development equivalent to that of a reference mix with ordinary Portland cement (OPC) at 28 and 90 days, as a result of pozzolanic reactions. Therefore, calcined dredging sediments have a great potential to be used as a novel supplementary cementitious material (SCM) for the production of sustainable cement and concrete. This paper presents concrete mix design, compatibility of the dredging sediments with different types of superplasticizer and examines both fresh and hardened concrete properties.status: publishe