FIG 9.

Recovery of watertightness in mortars after 2 months of bacterially based self-healing. Water flow through mortars containing ureolytic (CG7_3 and EM1) or nonureolytic (MM1_1 and RC1_1) bacteria was determined immediately after cracking and following 8 weeks of healing. Reference mortars contained no additives; control mortars contained yeast extract and calcium nitrate, but no bacteria. Recovery of watertightness was determined as a percentage relative to the freshly cracked specimen (0%, no change in water flow; 100%, complete inhibition of water flow). Data are shown for four specimens per condition from two separate cracking/healing experiments.