Current Science

B. Bhuvaneshwari ¹, G. S. Palani ¹, R. Karunya ¹, Nagesh R. Iyer ²

Affiliations
1 CSIR-Structural Engineering Research Centre, Chennai 600 113, IN
2 Academy of Scientific & Innovative Research, Chennai 600 113, IN

Abstract

Molecular dynamics studies towards assessing the bulk properties of the mineralogical array of cement hydrates such as calcium silicate hydrates (C-S-H) and calcium hydroxide (CH) have been conducted. In the case of C-S-H, closely related structures of minerals such as Tobermorite (9, 11, 14) Å and Jennite are taken for MD simulations, as they have similarities with C-S-H in terms of its mineralogical array. COMPASS force field with appropriate set parameters such as cut-off distances, micro-canonical ensembles was employed for the smooth running of simulations. Different supercells for the mineral systems were created and studied further. Results show the calculated mechanical properties of cement hydrates, which form an important input for developing computational model for cement hydrate systems for assessing the physico-chemical and mechanical characteristics.

Keywords

Cement Hydrate, Force Field, Mechanical Characteristics, Molecular Dynamics.

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S. Maheswaran ¹, S. S. Dasuru ¹, A. Rama Chandra Murthy ¹, B. Bhuvaneshwari ¹, V. Ramesh Kumar ¹, G. S. Palani ¹, Nagesh R. Iyer ¹, Sarayu Krishnamoorthy ¹, S. Sandhya ²

Affiliations
1 CSIR-Structural Engineering Research Centre, CSIR Campus, Taramani, Chennai 600 113, IN
2 CSIR-National Environmental Engineering Research Institute, CSIR Campus, Taramani, Chennai 600 113, IN

Abstract

This article presents details of the experimental studies carried out on cement mortar using Bacillus cereus and Bacillus pasteurii in different cell concentrations. Test results showed that the addition of bacterial cultures of both species, enhanced the compressive strength of cement mortar due to the bio-mineralization of calcium carbonate in the cement mortar matrix. The test results revealed 38% increase in compressive strength using B. cereus and 29% increase in the case of B. pasteurii over the control cement mortar. The chloride ingress capacity of B. cereus incorporated concrete found through rapid chloride permeability test confirms the reduction of chloride penetration compared to control sample. Characterization studies have been performed to confirm the calcite precipitation through different experimental techniques, viz. X-ray diffraction, scanning electron microscope, thermogravimetric analysis and Fourier transform-infrared spectroscopy.

Keywords

Bacillus cereus, Bacillus pasteurii, Biomineralization, Cement Mortar, Compressive Strength.

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