Correlation between fractal dimension of particle size distribution and strength development in alkanolamine-modified...

This study investigated the grinding characteristics, hydration behavior, and physical properties of cement containing the alkanolamine-based grinding aids (GAs) triethanolamine (TEA) and triisopropanolamine (TIPA). Fractal theory was applied to particle size distributions (PSDs) to determine their correlation with compressive strength. Four GA-modified cements were prepared by adding TEA or TIPA at 300 or 600 ppm, alongside two reference cements without GAs but with different specific surface areas. The addition of 600 ppm TEA markedly increased specific surface area, whereas TIPA produced comparable surface areas at both dosages. For cements containing TEA or TIPA, the proportion of particles smaller than 3 μm increased. X-ray diffraction revealed a distinct monosulfate peak at 7 d in GA-modified cements, indicating accelerated C₃A and C₄AF hydration. TEA and TIPA-containing cements achieved higher 3-d compressive strength; however, after 7 d, all samples except the cement with 600 ppm TIPA exhibited strengths similar to or slightly lower than the cement without GAs. Two fractal dimensions, obtained by dividing PSD into < 3.596 μm and 3.596-38.844 μm size ranges, exhibited strong correlations with compressive strength at 3 and 7 d, respectively. These results confirm that early-age strength is strongly associated with the fractal dimensions of cement particles.