Robin Davis

Effect of Nonureolytic Bacteria on Engineering Properties of Cement Mortar

AbstractBacterially induced mineral precipitation is a general phenomenon in nature. Ureolytic bacteria have been used in many studies as an environmentally friendly method for the protection and i...

Investigation of cement mortar incorporating Bacillus sphaericus

ABSTRACT Ureolytic-type bacteria has been used to improve the strength of cement mortar by the precipitation of calcium carbonate. In the present study Bacillus sphaericus has been used to improve the properties of cement mortar such as setting time, compressive strength and sorptivity. The setting time is found to be unaffected by the presence of bacteria. It is found that compressive strength at both 7-days and 28-days of mortar cube increases with the increase of bacteria concentration. At the optimum bacteria dosage of 107 cells/ml, the average compressive strength increases by 58% (at 7 day) and 23% (at 28 day) over the control specimen. The sorpitivity coefficient decreases as the concentration of bacterial cells increases. The mineralogy and morphology of the calcium carbonate precipitation have been tested by XRD and FESEM.

Vertical Irregularity of Buildings: Regularity Index versus Seismic Risk

AbstractThe seismic performance of buildings with irregular distribution of mass, stiffness, and strength along the height may be significantly different from that of regular buildings. Design code...