Crack sealing and water permeability control in cement composites via internal curing with cellulose microfibers

Abstract

This study investigated the effectiveness of internal curing using natural cellulose microfibers (CMFs) in reducing water permeability in early-age cracked cement composites. Saturated CMFs, 5 mm in length, were used as internal curing agents, and mortar mixtures with three different CMF contents (0%, 0.3%, and 0.6% by cement volume) were prepared. To evaluate the effects of internal curing on early-age cracked cement-based composites, constant water-head permeability tests were conducted under cracked and cured conditions at 1, 2, 5, and 19 days after crack formation. Additionally, digital image processing of external crack images and computed tomography analysis on internal cracks were carried out to support water permeability test results. The test results confirmed that internal curing effects of CMFs significantly contribute to sealing and bridging crack surfaces in early age cracked cement composites under limited water supply conditions. Furthermore, the mixtures with both 0.3% and 0.6% CMFs showed superior performance on crack closures compared with the plain mixture without CMFs.