Use of bacterial cell walls as a viscosity-modifying admixture of concrete

This paper reports the rheological and other fresh properties of the cement paste amended with bacterial cell walls (BCW). The major component of BCW, peptidoglycan, resembles commonly used viscosity-modifying admixtures (VMAs) in chemical structures. Our results indicated that the apparent viscosities of the cement paste of W/C 0.36, 0.4, 0.44 and 0.5 amended with BCW of Bacillus subtilis were higher than those of the control cement without BCW. And the viscosities decreased with the increase of shear rates. BCW also increased the yield value of the cement paste. The VMA effects of BCW were comparable to that of diutan gum and dependent on the size of peptidoglycan, as lysozyme and sonication treatment decreased viscosities. BCW also demonstrated resistance to water dilution and resistance to bleeding and segregation. As an abundant material, BCW have the potential to be a new VMA in construction.