Unconfined Compressive Strength and Visualization of the Microstructure of Coarse Sand Subjected to Different Biocementation Levels

Geomechanical Behavior of Bio-Cemented Sand for Foundation Works

“…The rate of expansion then drops as pronounced shear bands develop. In general, these results are typical of the behavior of artificially cemented specimens prepared with a range of cement types [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Figure 14 shows the response and changes of G max with p′ for typical gypsumcemented samples and comparison with the response for uncemented sand.…”

“…For example, strengths of up to 30 MPa [20] were obtained from small-scale experiments, and even at larger-scale (100 m 3 ) strengths of up to 12 MPa [21] have been reported. Other results show maximum compressive strengths obtained for bio-cemented sand of about 14 MPa [22]. As much as UCS strength increase can be related with individual soil particle strength, factors like roundness, size, and shape too may reduce the strength [20].…”

“…As sands with similar gradings were used and samples were prepared to similar densities in both studies, the different responses point to the sample preparation method as Geomechanical Behavior of Bio-Cemented Sand for Foundation Works DOI: http://dx.doi.org/10.5772/intechopen.88159 being the key difference. Several studies [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] have shown that regardless of the injection process, obtaining uniform calcite precipitation is difficult, and it is also difficult to control, especially for small amounts of cement. The results from the mixing method of preparation show that this can lead to more homogenous cementation at low calcite contents and mixing can achieve calcite contents of nearly 10%.…”

Plasticity characteristics of lateritic soil treated with Sporosarcina pasteurii in microbial-induced calcite precipitation application

“…The MICP research area is multi-disciplinary in nature and involves microbiologists and civil engineers who aim to provide a soil improvement method that is environmentally friendly and sustainable. MICP is a gentle alternative to the conventional soil improvement methods currently in use which have been adjudged to be environmentally unfriendly [22,23,30,43]. Although recognition has been given to laboratory studies on MICP, the lack of understanding the long-term mechanical properties of biocemented soil and its field upscaling has delayed its extensive acceptance for practical engineering applications [28,42].…”

“…Because of their varied ecology, microorganisms exhibit various functional characters that are beneficial in nature and it is fair to say that bacteria can be found almost everywhere, from the friendliest environments to the most hostile setting [32]. One of the processes that MICP relies upon which has also attracted the interest of researchers is bio-cementation which occurs naturally through biochemical processes to produce calcite which is a key parameter on which MICP revolves [43].…”