Early-age hydration and autogenous deformation of cement paste containing flash calcined dredging sediments

This paper aims to assess the influence of flash calcined dredging sediments (CFC), having pozzolanic reactivity, on the early-age hydration and autogenous deformation behaviour of blended cements, where cement is replaced by 20, 30 and 40% of CFC. The results indicate that the early-age hydration behaviour of a CFC blended cement is similar to the early-age hydration behaviour of a fly ash blended cement. Furthermore, CFC acts as an SCM that decreases autogenous shrinkage. This is attributed to an increased early-age swelling, and to the dilution effect and formation of different hydration products. The observed swelling is most probably due to the increased ettringite content and higher sulphate to alumina ratio, ensuring a crystallisation pressure as a result of supersaturation of the pore solution towards ettringite formation. Besides its pozzolanic reactivity, the decreased autogenous shrinkage that CFC is generating in blended cements, is encouraging for its use as a novel SCM that reduces early-age cracking risk of concrete, hereby improving concrete durability. (C) 2018 Elsevier Ltd. All rights reserved.