Abstract:, a common soil bacterium has been tested for microbial treatment of cement mortar. The present study also seeks to investigate the effects of growth medium, bacterial concentration and different buffers concerning the preparation of bacterial suspensions on the compressive strength of cement mortar. Two growth media, six different suspensions and two bacterial concentrations were used in the study. The influence of growth medium on calcification efficiency of was insignificant. Significant improvement in the … Show more
The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.
The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.
“…Other researchers though using different bacteria such as Mutitu and his co-authors [5], Achal and his co-workers [27] using Sporosarcina pasteurii and Dhamia and his co-workers [36] using Bacillus megaterium bacteria also observed water absorption reduction in the microbial mortars as compared with mortars prepared without microbial media. All these studies attributed the decrease in water permeability and porosity to the calcium carbonate precipitation which seals the pores in the mortar matrix inhibiting water migration [5, 27, 37]. Fig.…”
Cement structures are subject to degradation either by aggressive media or development of micro/macro cracks which create external substance ingress pathways. Microbiocementation can be employed as a self-intelligent solution to this deterioration process. This paper presents study results on the effects of Lysinibacillus sphaericus microbiocementation on Ordinary Portland cement (OPC), normal consistency, setting time, soundness, compressive strength and water sorptivity. Microbial solutions with a concentration of 1.0 × 107 cells/ml were mixed with OPC to make prisms at a water/cement ratio of 0.5. Mortar prisms of 160 mm × 40 mm x 40mm were used in this study. A maximum compressive strength gain of 17% and 19.8% was observed on the microbial prism at the 28th and 56th day of curing respectively. A minimum of 0.0190 and a maximum of 0.0355 water sorptivity coefficient was observed on the OPC microbial prism and OPC control prism, after 28th day of curing respectively. Scanning electron microscope images taken after the 28th day of curing showed formation of vast calcium silicate hydrates and more calcite deposits on microbial mortars. Statistical findings of this study indicate that Lysinibacillus sphaericus significantly retarded both the setting time and normal consistency, but has no influence on the mortar soundness.
“…Adding ne aggregate to the coarse aggregate can reduce the size of the coarse aggregate particles. Provide more bridge contact [8,9] Lvanov and others applied MICP technology to plugging and improving soil strength in geotechnical engineering [10]. Harkes optimized the MICP grouting technology by the clogging of the grouting port and the unevenness of the sample solidi cation that often occurred in the experiment [11].…”
This study solidifies the aeolian sand by microbial induced carbonate precipitation (MICP) technique. The effects of cementation solution with different concentrations, particle size, and grouting batches are examined via the bender element, unconfined compressive test and scanning electron microscope (SEM). The bender element results show that the wave speed of loose aeolian sand is 200m/s; however, after solidify the aeolian sand, the speed of P-wave is about 450-600m/s and S-wave is about 350-500m/s. Additionally, the unconfined compressive strength (UCS) results indicate that when the concentration of cementation solution is 0.75mol/L, the UCS of bio-solidified sand sample is the highest. Then, compared with the aeolian sand with original grade, the particles ranging from 0.1-0.4mm have a better cementation effect. Moreover, the UCS of bio-solidified sand samples increases along with the grouting batch. From the SEM images, it can be seen that when the grouting batch reaches to five times, the particles are almost completely covered by CaCO 3 crystals compared with the three batches and four batches.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
