http://ir.mu.ac.ke:8080/jspui/handle/123456789/65 Sun, 28 Jun 2026 05:53:53 GMT 2026-06-28T05:53:53Z http://ir.mu.ac.ke:8080/jspui/handle/123456789/10272 An Evaluation Of The Mechanical And Physical Properties Of Sisal Fiber-Reinforced Alkaline Activated Diatomaceous Earth-Based Geopolymer Concrete Kipsanai, Janet J.; Sofiane, Amziane.; Wambua, Paul M.; Namango, Saul S To achieve sustainability in the manufacturing of concrete, numerous researchers have developed an interest in cutting-edge geopolymer technology and geopolymer composite production. The viability of employing diatomaceous earth from Nakuru, Kenya, reinforced with sisal fiber as a source for geopolymer concrete was evaluated in an effort to create a sustainable geopolymer concrete with acceptable performance attributes. Standard procedures were used to conduct the chemical and physical analysis of diatomaceous earth. The mechanical and physical characteristics of the sodium hydroxide/sodium silicate (NaOH/Na2SiO3) alkaline activated diatomite-based concrete specimens were evaluated using the standard test methods. According to the diatomaceous earth’s chemical analysis, silica (SiO2) made up 88.12 % of the material; Aluminium oxide (Al2O3) was 4.25 % while calcium oxide (CaO) was 4.26 %. Other oxides such as MgO, K2O, TiO2, MnO, Fe2O3, and P205 were also present in trace amounts. The study of particle size revealed that the diatomaceous earth from Nakuru, Kenya, had a fine composition and an average particle size of less than 50.4 µm. The maximum property values for compressive strength, density and water absorption attained by the diatomite-based specimens were, 34.05 MPa, 1.38 g/cm3 and 20.42 % respectively. The diatomaceous earth’s chemical composition suggests that it is comparable to Class F pozzolan. The mechanical, physical and durability performance falls within the acceptable limits as provided in the reviewed literature. As a result of this research, it is possible to successfully use Kenyan diatomite reinforced with sisal fibers as a silica source in geopolymer formulations, opening up new possibilities for utilizing and recycling this resource of natural and industrial waste. Sat, 01 Apr 2023 00:00:00 GMT http://ir.mu.ac.ke:8080/jspui/handle/123456789/10272 2023-04-01T00:00:00Z http://ir.mu.ac.ke:8080/jspui/handle/123456789/10254 Fabrication and Mechanical performance of Bark Cloth/Glass Fiber reinforced Hybrid Polymer composites for Automotive Applications Alibet, Frances; Wambua, Paul; Githinji, David Njuguna; Rwahwire, Samson; Bongomin, Ocident This study developed and evaluated a sustainable hybrid composite based on bark cloth and glass fibers for lightweight automo- tive and semi-structural applications. Hybrid laminates were fabricated via the hand layup technique with varying fiber weight fractions (15–25 wt%), bark cloth-to-glass fiber ratios, and stacking sequences. Mechanical, physical, and microstructural charac- terizations were performed to assess the effects of hybridization and laminate architecture on composite performance. The results demonstrate that hybridization markedly improves the mechanical performance of bark cloth composites. Optimal properties were achieved at a bark cloth-to-glass fiber ratio of 1:3 and a fiber weight fraction of 20 wt%, yielding tensile strength of 43.24 MPa, flex- ural strength of 140.94 MPa, and impact strength of 78.6 kJ/m2 . Laminates with glass fibers positioned in the outer layers exhibited superior flexural and impact resistance due to enhanced surface load-bearing capacity and stress transfer efficiency. Conversely, excessive fiber loading (25 wt%) led to property degradation, attributed to insufficient resin wetting and fiber agglomeration. SEM analysis confirmed that reduced voids and improved interfacial bonding in optimized hybrids governed the observed mechanical enhancements. This work presents the first systematic investigation of bark cloth–glass fiber hybrid composites and demonstrates that an optimized hybrid architecture can achieve a favorable balance between mechanical performance and sustainability. These findings highlight the potential of bark cloth–glass fiber hybrids as promising candidates for lightweight automotive interior components and semi-structural applications, contributing to the development of greener composite materials. Thu, 01 Jan 2026 00:00:00 GMT http://ir.mu.ac.ke:8080/jspui/handle/123456789/10254 2026-01-01T00:00:00Z http://ir.mu.ac.ke:8080/jspui/handle/123456789/10252 Physiochemical and thermal characterization of Municipal Solid Waste and Agricultural residue blends for Torrefaction Mpungu, Ibrahim Luqman; Mwasiagi, Josphat Igadwa; Dulo, Benson; Maube, Obadiah; Nziu, Patrick; Bongomin, Ocident Municipal solid waste (MSW), together with other biomass resources, presents a viable feedstock for renewable energy production; however, its direct conversion is limited by high moisture content, ash content, and heterogeneous composition. These challenges can be mitigated through torrefaction, provided that suitable feedstock selection and optimization are achieved. This study investigates the physicochemical and thermal characteristics of MSW, cofee husks (CH), corn cobs (CC), and their blends to demonstrate how biomass quality can be improved through blending. MSW was blended with CH or CC at mass ratios of 25:75, 50: 50, and 75:25 (db/db%). Proximate, ultimate, lignocellulosic, thermogravimetric, and calorifc value analyses were conducted. Proximate analysis showed that MSW had the highest moisture (10.102 � 0.141%), volatile matter (71.115 � 0.759%), and ash content (6.674 � 0.477%), whereas CH exhibited the highest fxed carbon content (18.863 � 0.572%). Ultimate analysis revealed that MSW contained the highest hydrogen content (6.911 � 0.183%), CH had the highest carbon content (50.001 � 0.184%), and CC showed the highest oxygen (44.185 � 0.273%), nitrogen (1.395 � 0.045%), and sulfur (0.057 � 0.035%) contents. MSW had the lowest hemicellulose (11.941 � 0.269%) and cellulose (19.334 � 0.294%) contents, while CC had the lowest lignin content (12.304 � 0.219%). The calorifc value of MSW (17.01 � 0.292 MJ kg�1 ) increased upon blending, reaching up to 17.59 � 0.241 MJ kg�1 . Thermogravimetric analysis indicated enhanced thermal degradation rates with increasing MSW content in the blends. In conclusion, blending MSW with agricultural residues signifcantly improves its physicochemical and thermal properties, enhancing its suitability for torrefaction. The 25MSW75CH blend demonstrated the most favorable characteristics and is recommended as an optimal feedstock for torrefaction-based waste-to-energy applications at industrial scale. Thu, 01 Jan 2026 00:00:00 GMT http://ir.mu.ac.ke:8080/jspui/handle/123456789/10252 2026-01-01T00:00:00Z http://ir.mu.ac.ke:8080/jspui/handle/123456789/9911 Fluoride removal from water using Al(OH)3-surface modified diatomite mixed with brick: optimization, isotherm and kinetic studies Mutai, Isaiah Kiprono; Kiriamiti, Henry Kirimi; M’Arimi, Milton M; Tewo, Robert Kimuta Excess fluoride in drinking water causes both dental and skeletal fluorosis among other problems. As such there is need to develop affordable and easily accessible techniques for fluoride removal from drinking water. This work assessed surface modified diatomite mixed with brick for f luoride removal. Diatomite samples were modified using aluminium hydroxide and the mixture was optimized for fluoride removal through response surface methodology (RSM) using the Box-Wilson central composite design. Batch experiments showed that, individually, a 28 g/L dose of the surface modified diatomite sufficiently removed fluoride to the acceptable level of 1.5 mg/L from an initial concentration of 10 mg/L fluoride while a 300 g/L dose of brick powder was required to remove an equal amount of fluoride in the same water samples. RSM optimization showed that a mixture of surface modified diatomite and brick in the mass ratio 1.8:17.8 grams per milligram of fluoride in water can be used to remove fluoride in water to an acceptable level. Adsorption of fluoride by surface modified diatomite fit better into the Freundlich adsorption isotherm (R2=0.9753) compared to the Langmuir (R2=0.8954), while adsorption by brick better fit the Langmuir adsorption mechanism (R2=0.9804) in comparison to the Freundlich adsorption (R2 =0.9372). Kinetic studies revealed that chemisorption was the main mechanism for both surface modified diatomite and brick adsorbents. Conclusively, an optimal mixture of surface modified diatomite and brick can be successfully used fo Mon, 01 Jan 2024 00:00:00 GMT http://ir.mu.ac.ke:8080/jspui/handle/123456789/9911 2024-01-01T00:00:00Z