Abstract: At present， the applications of microbial repair materials in engineering are restricted， because the used bacterial solution and calcium source cannot be fixed inside the cracks and the repair process requires repeated grouting. In this paper， the effect of the mass concentration of sodium alginate solution on the performance of repair material and its concrete crack repair effect were studied by using sodium alginate as a carrier for microorganisms. The repair effect of sodium alginate on the concrete cracks was analyzed in terms of the mineral composition and microstructure of repair products. The results indicated that only once grouting repair of concrete cracks using the microbial repair materials based on sodium alginate could seal the cracks of concrete specimens. The 7?day water penetration resistance of this repair material could reach 100 %. Its compressive strength recovery rate reached 63.64 % at a crack width of 1.5 mm.

Key words: concrete, microorganism, sodium alginate, crack, repair effect