000			04354nam a2200337 4500
003			MY-KuUP
005			20260306122222.0
006			t||||fr|||| 000 0
007			ta
008			260306t20252025my a|||fr|||| 000 0 eng d
020			_aTHE0010424 (Local) _qHardback
040			_aUMPSA _beng _cUMPSA _erda
090			_aFTKA .M37 2025 r Thesis
100	1		_aMaryam Moh’d Subhi Fadil Al Jaber, _eauthor.
245	1	0	_aPeat soil stabilization using gypsum and concrete waste to activate microbially induced calcium precipitation (MICP) / _cMaryam Moh’d Subhi Fadil Al Jaber
264		1	_aKuantan, Pahang : _bUMPSA, _c2025
264		4	_c© 2025
300			_axv, 250 pages : _billustrations ; _c30 cm. + _e1 CD-ROM.
336			_2rdacontent _atext
337			_2rdamedia _aunmediated
338			_2rdacarrier _avolume
347			_2rda _atext file _bPDF
500			_aFaculty of Civil Engineering Technology
502			_aThesis (Master of Science) -- Universiti Malaysia Pahang - 2025
504			_aIncludes bibliographical references
520	3		_aTropical peat soils present significant geotechnical challenges due to their high organic content, excessive compressibility, and low strength. This study investigates Microbially Induced Calcite Precipitation (MICP) as a sustainable stabilization technique, utilizing Magnesium-Rich Synthetic Gypsum (MRSG) and concrete waste as biocatalysts to stimulate indigenous microbial activity. Control soil samples (C1, C2, C3, and C4) were collected from Gebeng, Kuantan, Pahang, Malaysia, at depths of 0.5 m for C1 and C3, and 1 m for C2 and C4. Stabilized samples were prepared by mixing 10% MRSG and 10% concrete waste by dry weight and cured for 7 and 28 days. The stabilization process induced a substantial pH increase, shifting from strongly acidic (3.47–4.0) to near-neutral conditions (6.44–7.35), while simultaneously supplying critical elements required for MICP activity, including calcium ions that facilitate calcite precipitation. This pH modification, combined with the chemical inputs from the additives, altered the microbial community structure, leading to a decrease in overall bacterial diversity but a targeted enrichment of MICP-related bacteria. Deoxyribonucleic Acid (DNA) sequencing of the untreated soils revealed low populations of MICP-related bacteria, with Pseudomonas at 0–0.03% and Bacillus at 0.07–0.09%, while Stenotrophomonas and Brevibacillus were nearly absent. After stabilization, substantial microbial enrichment occurred; Pseudomonas and Bacillus reached 19.23% and 30.63% in S1; Pseudomonas (31.98%), Brevibacillus (21.22%), and Stenotrophomonas (1.28%) in S2; Bacillus (42.80%) and Stenotrophomonas (8.32%) in S3; and Pseudomonas (61.48%) and Brevibacillus (21.55%) in S4. These microbial shifts directly enhanced calcium carbonate precipitation, reflected in substantial improvements in Unconfined Compressive Strength (UCS), with increases of 542.18% in S1, 393.15% in S2, 405.41% in S3, and 207.29% in S4. Dense calcite networks bridging soil particles were identified through Scanning Electron Microscopy (SEM) and elemental mapping. Energy-Dispersive X-ray Spectroscopy (EDX) analysis confirmed significant enrichment of calcium and carbon within the stabilized samples, reflecting the substantial precipitation of calcium carbonate. X-ray Diffraction (XRD) analysis further verified the dominance of calcite as the primary mineral phase, accompanied by minor amounts of vaterite and dolomite, indicating successful mineral transformation through MICP. The presence of strong carbonate and sulphate functional groups detected by Fourier-Transform Infrared Spectroscopy (FTIR) spectra, together with the improved thermal stability observed in Thermogravimetric Analysis (TGA), provided further evidence of extensive microbial mineralization and the formation of stable calcite networks. This study demonstrates that indigenous bacteria can be effectively stimulated to achieve in-situ MICP stabilization of tropical peat soil, offering a cost-effective and environmentally friendly alternative without the need for external inoculation or chemical treatments.
610	2	0	_aFaculty of Civil Engineering Technology _xDissertations
650		0	_aUniversities and colleges _xDissertations
650		0	_aTheses _xDissertations
942			_2lcc _cTHESIS
999			_c104276 _d104282