Diethanolamine‐Modified Sodium Lignosulfonate Admixture for Early Strength and Water Reduction in Cement Slurry

Abstract Early‐strength cement admixtures often face challenges like poor fluidity, instability, and low compatibility. To overcome these limitations, a novel bio‐based water‐reducing agent (DEA‐SL) was synthesized by grafting diethanolamine (DEA) onto sodium lignosulfonate (SL) under optimized conditions (1:1 molar ratio, 70°C, 4 h). Performance tests showed that adding 1.0% DEA‐SL significantly enhanced cement slurry properties: thickening time decreased from 174 to 56 min, fluidity increased from 190 mm to 210 mm, initial consistency dropped from 15 Bc to 9 Bc, and bleeding stability improved. Additionally, DEA‐SL reduced 14‐day shrinkage by 26% (from 250 × 10 −6 to 185 × 10 −6 ) while regulating hydration kinetics. Spectroscopic analysis confirmed successful DEA grafting and revealed that DEA‐SL controlled hydration product formation without altering phase composition, mildly accelerating Ca(OH) 2 precipitation. Unlike petroleum‐based admixtures, DEA‐SL leverages renewable lignin, offering a sustainable solution with lower carbon emissions. Its performance is highly tunable—adjusting molecular structure or dosage enables tailored optimization of fluidity retention and early strength development. This makes DEA‐SL ideal for time‐sensitive applications like emergency repairs, where rapid setting and high early strength are critical. The mild synthesis conditions and scalable production further enhance its industrial viability. By combining enhanced workability, early strength, and eco‐friendliness, DEA‐SL presents a promising advancement in sustainable construction materials, aligning with global efforts to reduce the environmental impact of cement‐based systems.