Experimental Study and Analysis of the Effect of Natural Microbial in Expansive Clayey Soil

In the construction fields, the main characteristic required for the soil is their capacity to resist the super imposed loads safely by a control in stresses and deformations. Among the different types of soils, the construction activities on expansive soils requires adequate care since it was a fine grained soil that shows large volume change when exposed to varying water content.According to various studies, sub grade stabilization in roads can provide significant improvement in engineering properties. Microbial stabilisation is a new and alternative treatment method in geotechnical field by the use of bacteria in soil improvement, which are already naturally present in soils to develop more by providing the nutrients as an energy source. So far the researcher's has been carried out with Microbial induced calcite precipitation MICP bacteria for the production of calcium precipitates by biological method and have practiced only on the sandy soils. These researches were done on the Experimental Study And Analysis Of The Effect OF Natural Microbial In Expansive Clayey Soil forming a cementious soil matrix.Totally 405 samples were prepared under varying bacterial concentrations of 106, 107 and 108 cfu ml, incubation periods of 1, 3, and 4 days with increasing curing periods of 1,7,14, 28 and 60 days. For each set of test 3 specimens were tested to evaluate the accurate value.For the volume changing nature of clay soil were analysed by conducting the Free Swell Index FSI tests. From the FSI test, the swell got decreased from 85 to 30 for Acetobacter treated soil. Similarly the free swell values are also decreased to 20 for soil treated with Acetobacter and 35 for the soil treated with E.coli at 60 day age curing, 108 cfu ml concentration and 4 day incubation period, as compared with untreated soil.The peak stresses for the 60 days curing period for Acetobacter, Bacillus and E.coli bacteria are410 kPa, 521 kPa and 341 kPa respectively. As the curing period increases the UCS value of Bacillus improved more than Acetobacter and E.coli at 60 day age and with 108 cfu ml concentration. The UCS strength of Bacillus bacteria treated soil was 4.5 times greater than the untreated soil strength when compared with Acetobacter and E.coli.For the CBR tests on treated soils, Acetobacter, Bacillus and E.coli were mixed with soil in varying concentrations ie, 106, 107 and 108cfu ml with incubation periods 1, 3, and 4 days and tested after curing the samples for 60 days to know the effect of long term treatment. California Bearing Ratio of soil increases to 6.7 , 8.2 and 5.9 respectively after 60 days curing from a value 2.3 with Acetobacter, Bacillus and E.coli and the concentrations of 108cfu ml and 4 day incubation period Rishav Sharma | Prof. Nitesh Kushwaha "Experimental Study and Analysis of the Effect of Natural Microbial in Expansive Clayey Soil" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-4 , June 2021, URL: https://www.ijtsrd.compapers/ijtsrd42332.pdf Paper URL: https://www.ijtsrd.comengineering/civil-engineering/42332/experimental-study-and-analysis-of-the-effect-of-natural-microbial-in-expansive-clayey-soil/rishav-sharma