Estimation of the cementitious properties of various industrial by-products for applications requiring low mechanical strength

This study is a first step in investigating the possibility to create low cost alternative binders by reusing industrial by-products as supplementary cementitious materials. The created binders are dedicated to applications requiring low mechanical strength like waste stabilisation/solidification or mine backfill. A total of 8 by-products are tested: 6 for their pozzolanic proporties (waste glass, 2 kinds of wood ashes, deinking sludge ash, copper slag, and CAlSiFrit®) and 2 as hydration activators (cement kiln dust and fluorgypsum).The results obtained show that the tested pozzolanic by-products participate to the strength development. These by-products are sufficiently reactive to substitute between 20 and 50% of Portland cement. Fluorgypsum can be used as a calcium source but has to be mixed with Portland cement because of its residual acidity. Finally, cement kiln dust promotes the mechanical strength development when added at low amounts (5%).Economical and environmental benefits of using by-products-based binders are discussed. It is estimated that binder supply costs could be reduced by up to 37.5% with interesting environmental benefits including a reduction of greenhouse gas emission.

► Investigation of cementitious properties of eight industrial by-products.
► 20–50% of Portland cement can be substituted by pozzolanic by-product.
► Fluorgypsum and cement kiln dust can be used as hydration activator when mixed with Portland cement.
► Use of both activating and pozzolanic by-product allows substituting between 20 and 75% of Portland cement.
► By-products-based binders could allow savings up to 37.5% of binder supply costs.