Origin and industrial applications of lignosulfonates with a focus on their use as superplasticizers in concrete

In concrete technology, superplasticizers (SPs) are commonly used to reduce water content in concrete admixtures. Although most of them are fossil fuel-based, some derive from lignosulfonates (LS), that are sustainable and environmentally-friendly polyphenolic crosslinked polymers. Indeed, LS are an inexpensive and abundant raw material that contains a variety of functional groups including hydroxyls which can be involved in a wide range of chemical modifications to finely tune the physico-chemical properties of the material. This review presents: (1) the current SPs and their mechanism of adsorption and dispersion as admixtures to improve the properties of fresh concrete (e.g., workability, fluidity, setting time and water reducing ability) and that of hardened concrete (e.g., compressive and flexural strength), (2) LS origin and structure, (3) the various LS functionalization methods reported in the literature since 2000, and (4) their corresponding applications in the different fields such as water depollution, dispersant, superadsorbant, antioxidant, material replacement, and more specifically as water reducers for concrete. A special focus is made on the cement-SPs interactions and the impact of the modified-LS structures on the efficiency of concrete. This review aims at demonstrating that, in the context of green chemistry, biorefinery and bioeconomy, sustainable chemical modification of low cost and abundant LS is a worthwhile approach to design materials that find applications in critical industries such as the concrete sector.