Utilization of microbial induced calcite precipitation for sand consolidation and mortar crack remediation

Peer review under responsibility of Housing and Building National Research Center.

Figures & data

Fig. 1 XRD diffractogram of sand.

Table 1 Chemical composition of sand and cement, wt.%.

Oxide,%	SiO2	Al2O3	Fe2O3	CaO	MgO	Na2O	K2O	SO3	TiO2	P2O5	L.O.I	Total
Sand	97.78	0.88	0.45	0.03	0.01	0.25	0.10	0.01	0.10	0.03	0.23	99.89
Cement	21.09	4.79	3.65	61.78	2.71	0.22	0.12	3.11	–	–	2.50	99.97

Fig. 2 Water absorption of consolidated sand mixed with (1 OD) of bacterial cells and (1 M) equimolar of urea/calcium chloride, calcium acetate or calcium nitrate after four treatments.

Fig. 5 TGA and DTA thermograms of consolidated sand mixed with (1 OD) of bacterial cells and (1 M) equimolar of urea/calcium chloride after four treatments.

Fig. 3 Compressive strength of consolidated sand mixed with (1 OD) of bacterial cells and (1 M) equimolar of urea/calcium chloride, calcium acetate or calcium nitrate after four treatments.

Fig. 8 SEM micrographs of consolidated sand by mixing with (1 OD) of bacterial cells and (1 M) of urea and (1 M) of different calcium sources; calcium chloride (a), calcium acetate (b) or calcium nitrate (c) at two different magnifications [(300 μm for a₁, b₁ and c₁) and (50 μm for a₂, b₂ and c₂)] after four treatments.

Fig. 4 XRD diffractograms of consolidated sand mixed with (1 OD) of bacterial cells and (1 M) equimolar of urea/calcium chloride calcium acetate or calcium nitrate and after four treatments.

Fig. 6 TGA and DTA thermograms of consolidated sand mixed with (1 OD) of bacterial cells and (1 M) equimolar of urea/calcium acetate after four treatments.

Fig. 7 TGA and DTA thermograms of consolidated sand mixed with (1 OD) of bacterial cells and (1 M) equimolar urea/calcium nitrate after four treatments.

Fig. 9 SEM micrographs of bacterial cells (b) present on the surface of calcite crystals.

Fig. 10 Compressive strength of control (C-0), untreated (C-1) and treated (C-2) crack of cement mortar after 28 days.