lignosulfonate used in construction

As an anti-settling agent that also prevents lumping, lignosulfonates are used in concrete mixtures, ceramics, gypsumboard production and for leather tanning. Lignosulfonates provide flowability and plasticity to cement. This is a replacement for more expensive materials that provide set retardation such as superplasticisers, gluconates and gluconic acid. Wet-process Portland cement mills utilise lignosulfonates to increase the solids content of raw slurries. Lignin-based concrete additives are in demand and can be worth as much as $1.05–$1.32/L as an aqueous solution (Holladay et al., 2007). Sulfur-free lignin such as soda lignin has also been shown to improve flowability of mortar (Nadif et al., 2002).

Incorporating a workability agent or plasticiser reduces the chance of large voids and the lower water requirement offsets bleed. Salts of lignosulfonic acids are commonly used, often in combination with a particulate mineral filler. Incorporation of lignosulfonates may give rise to a finer pore system which, whilst causing high capillary absorption and absorptivity actually increases resistance to the passage of water and hence its hydraulic permeability. Air-entraining agents act in a manner similar to lignosulfonates by imparting improved workability to the mix, allowing less water to be used. The cellular network does not give rise to interconnected voids which would otherwise increase the permeability.

Incorporating a workability agent or plasticiser reduces the chance of large voids and the lower water requirement offsets bleed. Salts of lignosulfonic acids are commonly used, often in combination with a particulate mineral filler. Incorporation of lignosulfonates may give rise to a finer pore system which, whilst causing high capillary absorption and absorptivity actually increases resistance to the passage of water and hence its hydraulic permeability. Air-entraining agents act in a manner similar to lignosulfonates by imparting improved workability to the mix, allowing less water to be used. The cellular network does not give rise to interconnected voids which would otherwise increase the permeability.