Browsing by Author "Kabiru Mustapha"

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    Effects of fibre reinforcements on properties of extruded alkali activated earthen building materials
    (2019-12-10) Emeso B. Ojo; Kabirat O. Bello; Kabiru Mustapha; Ronaldo S. Teixeira; Sérgio F. Santos; Holmer Savastano
    The reaction between clay minerals present in soil and an alkaline solution has the potential to develop in situ binders, which can be harnessed in the development of earth based construction materials. To ascertain the efficacy of this stabilisation mechanism in conjunction with fibres which are commonly used in earthen construction, this study presents a comparative analysis of the reinforcing effect of different fibre types (sisal, Eucalyptus pulp microfibers and polypropylene) in an alkali activated stabilised soil produced using extrusion technique. An evaluation of flexural properties in oven-dry and saturated conditions was conducted to simulate mechanical response in ideal and extreme conditions to evaluate effect of fibre type and content (0–2 vol%). Physical properties were also studied and optimum fibre contents evaluated. Results show that with respect to lignocellulosic fibres, sisal fibre reinforcements yielded the most remarkable result with the highest statistically significant improvement in flexural strength (79% relative to the unreinforced matrix) compared to composites reinforced with Eucalyptus pulp micro-fibres. Improved packing density and attendant reduction in water absorption associated with sisal fibre reinforced composites was attributed to synergistic interactions between sisal fibres and alkali activated matrix. On the other hand, synthetic fibre reinforcement (polypropylene), which had no statistically significant effect on composite flexural strength, transformed brittle unreinforced matrices to deflection hardening composites due to weak fibre-matrix interactions. Sisal fibres have thereby demonstrated a significant reinforcing potential in extruded alkali activated earth-based materials and presents a satisfactory balance of strength, density and ductility for the development of eco-friendly building materials for low cost housing solutions.
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    Mechanical performance of fiber-reinforced alkali activated un-calcined earth-based composites
    (2020) Emeso B. Ojo; Kabirat O. Bello; Odette F. Ngasoh; Tido T. Stanislas; Kabiru Mustapha; Holmer Savastano; Wole Soboyejo
    This paper presents the results of a multi-scale study of the mechanical properties of model earth-based composites. The composites are produced by the alkali activation of in-situ clay minerals within an earthbased matrix that is reinforced with two different fibers (sisal and polypropylene). The local mechanical properties of the fibers, binder and matrix materials are characterized at the nano- and micro-scales using nano-indentation and statistical deconvolution techniques. The macro-mechanical properties are also elucidated using a combination of flexural strength testing, and resistance-curve experiments. The underlying strengthening and toughening mechanisms are explored using a combination of in-situ/exsitu observations and micro-mechanical models. The implications of the results are then discussed for the design of strengthened and toughened earth-based composites that are reinforced with natural fibers (such as sisal) and synthetic fibers (such as polypropylene fibers).
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    Mechanical properties of calcium carbonate/eggshell particle filled polypropylene Composites
    (MRS Advances, 2020) Kabiru Mustapha; Rashidat Ayinla; Abdulraman Sikiru Ottan; Tunji Adetayo Owoseni
    Calcium carbonate is widely used as a filler material in the production of polymer matrix composites and studies have shown that eggshell contains about 94% calcium carbonate. The effect of calcium carbonate from eggshell particles in polypropylene was studied in this work and the result compared with unreinforced polypropylene. Industrially synthesized calcium carbonate/eggshell particles were used as filler in polypropylene matrix with varying mass fractions from 5 to 20 wt. % at 5 wt. % increment. The produced samples were mechanically characterized for indentation hardness and uniaxial tensile properties using a Rockwell hardness tester and universal mechanical testing machine respectively. These properties were measured at different compositions to determine its compositional dependence. Microstructural analysis of the composites top and fracture surface was also carried out using scanning electron microscope to examine possible failure mode. The results were compared to measure the effect of reinforcement and the replacement criteria for the conventional calcium carbonate. The results obtained showed that calcium carbonate reinforced polypropylene has its highest tensile strength, elastic modulus and modulus of rupture at 5 wt. %, ductility and modulus of resilience at 10 wt. %, and hardness at 15 wt. %. The results also showed that granulated eggshell can provided appreciable improvement in the mechanical properties of polypropylene as obtainable in mineral calcium carbonate reinforced polypropylene.
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    Reinforcement of cement mortar with recycled polyethylene waste for construction applications
    (2021) Moses K Flomo; Salifu T Azeko; Emmanuel K Arthur; Jamal-Deen Kukurah; Kabiru Mustapha; Ebenezer Annan; Benjamin Agyei-Tuffour
    This current research work combines both experimental and theoretical study of the impact of cement mortar reinforced with recycled polyethylene waste for applications in the construction industry. The work explores incorporating low density polyethylene (LDPE) waste into cement mortar to improve its fracture toughness and flexural strength with balanced compressive strength. Different volume fractions (0, 5, 10, 15, 20, 30, and 40%) of the powdered LDPE were mixed with cement and the density, compressive strength, flexural strength, and the fracture toughness were observed under different testing conditions. All specimens were tested after curing of 7, 14, and 28 days. The results show that there was [Formula: see text]6% increase in the fracture toughness at 5 vol. %, [Formula: see text]7% increase at 10 vol. %, and 24% increases at 20 vol. % of LDPE. Also, it was observed that the weight and compressive strength decreased with increasing volume fraction up to 40 vol. % of LDPE waste. The results for the survival/failure probability show that the PE-mortar composites with PE volume percentages up to 20 vol. % had the highest survival probability. The composite with this volume percentage can withstand crack up to 6 mm, with a survival probability of 0.6.