What is Lignin ?
Lignin, a wood waste, can be utilized in the construction industry as a set retarder, water-reducing additive, grinding agent in cement manufacture, cement replacement materials, and other applications after undergoing the required processing.
It strengthens concrete by raising its compressive strength and makes it greener by using less cement throughout the concrete-making process. As a result, there is less wood waste dumped in landfills and less carbon dioxide emissions. There are two types of lignin: lignosulfonate and alkali lignin.
Figure 1: Lignin
How Is Lignin Used in the Production of Concrete?
To Create Greener Concrete: Cement and high-lignin ash byproducts might react chemically. It can therefore be used as a material to replace cement. Because less cement is used, concrete made with cement replacement materials—mostly industrial byproducts—is more environmentally friendly.
This lowers the danger of natural resource depletion during the cement production process and results in a decrease in the amount of carbon dioxide released during the process. Thus, one of lignin’s main benefits is that it makes concrete greener. Additionally, using leftovers in the making of concrete minimizes pollution by reducing the amount of landfill space needed.
Increasing the Compressive Strength of Concrete and Cement Paste
Lignin can be used to replace cement in concrete to increase its compressive strength as well as other crucial characteristics of the concrete construction design. When lignin is added, cement paste’s compressive strength increases significantly—by roughly 30–60% when cured in distilled water and by 2–20% when cured in seawater.
Utilizing Plasticizer
Concrete can benefit from plasticizers made from lignin wastes from pulp mills, which enhance the material’s fresh and hardened qualities. This kind of plasticizer can rival commercially available synthetic and lignosulphonate-based admixtures.
LigniOx, a plasticizer used commercially, can lower the fresh concrete’s water-to-cement ratio and produce more workable concrete.
In the Role of a Grinding Agent
Cement can be ground using lignin at low concentrations or lignin that has been changed. It increases the uniformity and efficiency of cement particle powder grinding while lowering energy consumption during the cement grinding process.
Put Retarder in Place
It also lessens moisture and acid rain damage to the building’s outside walls. Furthermore, the small amount of lignin and modified lignin in cement composition can serve as a set retarder.
Cement particles have increased zeta potential and adsorption capacity thanks to sulfonated lignin. It spreads the cement matrix as a result.
Bolstering Concrete Recycled
Japanese researchers have managed to fortify recycled concrete without the need for additional cement. Rather, to create more rigid concrete than the original, lignin, water, and old concrete were combined and heated under pressure.
Improving Asphalt Mixture
Improving Asphalt Mixture Studies indicate that the addition of lignin amine to heated mixes can alter the surface combination of stone and asphalt material, altering fluidity and lowering manufacturing costs.