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Browsing by Author "Kabiru Mustapha"

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Clay Mixtures and the Mechanical Properties of Microporous and Nanoporous Ceramic Water Filters
(Journal of Materials in Civil Engineering, 2016) Ebenezer Annan; Kwabena Kan-Dapaah; Salifu T. Azeko; Kabiru Mustapha; Joseph Asare; M. G. Zebaze Kana; Wole Soboyejo
This paper presents the results of an experimental study of the effects of clay mixtures on the mechanical properties of mixed clays with controlled levels of plasticity, prior to the firing of porous ceramic water filters for water filtration. Two clays with well-characterized initial compositions (Iro and Ewuya clays) are mixed with varying proportions to control their plasticity. The mechanical properties of the mixed and fired clays are then studied using a combination of experiments and theoretical models. These include the flexural strength, fracture toughness, Young’s modulus, and thermal shock resistance of fired clay mixtures. The results show that clay mixtures with 45–60 vol.% of Iro clay and 40–55 vol.% Ewuya clay can be used to produce clay composite filters with robust mechanical properties. The thermal shock resistance of a mixed clay filter (containing 50% Iro clay and 50% Ewuya clay) is also explained using a combination of elastic and viscoelastic crack-bridging models. The regimes for effective viscoelastic crack bridging are identified by comparing the relaxation times to the thermal shock durations. The implications of the results are then discussed for the mixing of locally available clays into robust micro- and nanoporous materials for applications in clay ceramic water filters.
Development of unfired earthen building materials using muscovite rich soils and alkali activators
(Case Studies in Construction Materials, 2019) Emeso Beckley Ojo; Kabiru Mustapha; Ronaldo S. Teixeira; Holmer Savastano
Most studies have focused on the alkali activation of thermally activated kaolinitic clays for the production of innovative building materials. Whilst the widespread use of these minerals may be hindered due to geographical availability; a combination of thermal activation and alkali activator solutions yields a material with high embodied energy with implications on eco-friendliness. This study presents an eco-friendly approach for the development of a low environmental impact building material using a low molarity alkali activator solution for the stabilisation of uncalcined muscovite rich soil. Influence of curing conditions on the physical, mechanical, microstructural and mineralogical properties were evaluated. Results show that alkali activation of uncalcined muscovite in the soil significantly improved the physical and mechanical properties of extruded earthen materials. Samples tested yielded compressive strength values between 9–11 MPa for varying curing regimes. The binding was mainly attributed to the formation of amorphous sodium aluminosilicate gels as a result of the partial dissolution of muscovite. These results show that low environmental impact building materials may be developed with uncalcined muscovite rich soils in developing regions around the world where these minerals are predominant for the provision of sustainable low-cost housing solutions.
Effect of Pullout on Mechanical Behavior of Natural Fiber-reinforced Earth-based Composites
(Proceedings of 13th Nigerian Materials Congress (NIMACON 2014), 2014) Kabiru Mustapha; Annan E.; Azeko, S. T.; Zebaze Kana, M. G.; Soboyejo W. O.
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.
EFFECTS OF SAWDUST PARTICLES REINFORCEMENT ON THE MICROSTRUCTURAL, PHYSICAL, AND MECHANICAL PROPERTIES OF CEMENT-BASED COMPOSITES: AN EXPERIMENTAL STUDY
(Annals of the Faculty of Engineering Hunedoara, 2024) Kabiru Mustapha; Sikiru Ottan Abdulraman; Moyosoreoluwa O. King-Okuneye
This study investigates the effect of varying sawdust reinforcement volumes on the physical and mechanical properties of Portland cement composites. Sawdust from a local sawmill in Moro, Kwara, Nigeria, was incorporated into cement composites at volume fractions from 40% to 90%. Composites samples were produced for physical, mechanical and microstructural characterizations. Results showed that water absorption increased with higher sawdust content, peaking at 41.78% for 90% sawdust composite, and bulk density also rose, reaching a maximum of 193.33 g/m³ at 90%. Apparent void volume generally decreased with increasing sawdust content. Optimal mechanical properties were observed at 60% sawdust content, with the highest compressive strength of 20.32 MPa, flexural strength of 8.36 MPa, and fracture toughness of 0.85 MPa.m, while hardness decreased with increasing sawdust, peaking at 42.99 HRBS at 40% sawdust. Microstructural analysis using scanning electron microscopy (SEM) revealed a uniform distribution of sawdust particles within the cement matrix, with improved interfacial bonding observed at the optimal 60% sawdust content, contributing to the enhanced mechanical properties of the composite. In conclusion, 60 vol.% sawdust reinforcement is optimal for enhancing the mechanical performance of Portland cement composites, offering a balance between strength and sustainability, suggesting its potential as a cost-effective, eco-friendly reinforcement for cement-based materials in sustainable construction practices.
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).
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.
Mechanical properties of calcium carbonate/eggshell particle filled polypropylene Composites
(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.
Overview of Materials Engineering. In Fundamentals of Engineering and Technology
(CCMAS Book Series, 2023) Adeleke, A. A.; Alabi, A. G.; Kabiru Mustapha
Pull-out behavior of natural fiber from earth-based matrix
(Journal of Composite Materials, 2016) Kabiru Mustapha; Salifu T Azeko; Ebenezer Annan; Martiale G Zebaze Kana; Leo Daniel; Winston O Soboyejo
This paper presents the results of a combined experimental and analytical study of the pull-out behavior of natural fiber (grass straw) from an earth-based matrix. A single fiber pull-out approach was used to measure interfacial properties that are significant to toughening brittle materials via fiber reinforcement. This was used to study the interfacial shear strengths of straw fiber-reinforced earth-based composites with a matrix that consists of 60 vol. % laterite, 20 vol. % clay and 20 vol. % cement. The composites that were used in the pull-out tests included composites reinforced with 0, 5, 10 and 20 vol. % of straw fibers. The toughening behavior of fiber-reinforced earth-based matrix was analyzed in terms of their interfacial shear strengths and bridging zones, immediately behind the crack tip. This approach is consistent with microscopic observations that reveal intact bridging fibers behind the crack tip, as a result of debonding of the fiber–matrix interface. Analytical models were used to study the debonding of fiber from the matrix materials, as well as the toughening due to crack-tip shielding via bridging. The results show that increasing the fiber embedment length and the fiber volume fraction (in the earth/cement matrix) increases the peak pull-out load. The debonding process was also found to be associated with a constant friction stress. The combined effects of multiple toughening mechanisms (debonding and crack bridging) are elucidated along with the implications of the results for the design of earth-based composites for potential applications in robust building materials for sustainable eco-friendly homes.
Recycling of Polyethylene into Strong and Tough Earth-Based Composite Building Materials
(Journal of Materials in Civil Engineering, 2016) Salifu T. Azeko; Kabiru Mustapha; Ebenezer Annan; Olushola S. Odusanya; Winston O. Soboyejo
Polyethylene (PE) waste often piles up in the environment for up to 30 to 50 years, without complete degradation. This paper describes how PE waste can be used as a reinforcement in laterite bricks for sustainable building materials. The bricks are produced with different volume percentages (0–30 vol. %) of PE. The flexural/compressive strengths and fracture toughness values of the composite blocks are compared with those of mortar (produced from river sand and cement). The composite containing 20 vol. % of PE is shown to have the best combination of flexural/compressive strength and fracture toughness. The flexural/compressive strengths and fracture toughness values increase with increasing volume percentage of PE up to 20 vol. %, before decreasing to minimum values for composites with 30 vol. % of PE. The trends in the measured strengths and fracture toughness values are explained using composite and crack bridging models.
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.
Statistical Distributions of the Strength and Fracture Toughness of Recycled Polyethylene-Reinforced Laterite Composites
(Journal of Materials in Civil Engineering, 2016) Salifu T. Azeko; Kabiru Mustapha; Ebenezer Annan; Olushola S. Odusanya; Alfred B. O. Soboyejo; Winston O. Soboyejo
This paper presents the results of combined experimental and theoretical studies of the statistical distributions of the strength and fracture toughness of recycled polyethylene-reinforced laterite composites for potential applications in building materials. The composites are produced with different volume percentages (0–30% v/v) and particle sizes (∼300±0.02, ∼600 ± 0.03, ∼900 ± 0.03, ∼1,200±0.02, ∼1,500±0.04, and 1,800±0.03 μm) of powdered polyethylene (PE) in a laterite matrix. The composites with ∼900±0.03 μm and 20-volume percentage of PE are shown to have the best combination of flexural-compressive strengths and fracture toughness. The statistical variations in the flexural-compressive strengths and fracture toughness are well characterized by the Weibull distributions.
Statistics of Flow and the Scaling of Ceramic Water Filters
(Journal of Environmental Engineering, 2014) Ebenezer Annan; Kabiru Mustapha; Olushola S. Odusanya; Karen Malatesta; Winston O. Soboyejo
According to the World Health Organization (WHO), there was an increase in the number of people that have access to safe drinking water between 2006 and 2010. Such trends can be accounted for partly by the increasing usage of ceramic water filters that can remove microbial pathogens from water. However, the initial flow rates in such filters are often limited to ranges between 1 and 3 L/h. In this paper, six frustum-shaped ceramic water filters of the same clay:sawdust composition were tested. Each ceramic water filter was filled with water and allowed to filter 20 times. Each time, the flow rate and water level were measured for a consecutive 12 h. Permeability values were estimated for each run of the ceramic water filters. Statistical analysis was performed on flow rates (in the first hour), mean flow rates, and estimated permeability values. The flow rate values (in the first hour) for the six ceramic water filters were found to be between 1.4 and 3.0 L/h. An effective permeability was obtained for ceramic water filters with a range of microscale and nanoscale pore sizes. The statistical variations in the flow rates and effective permeabilities were elucidated along with the potency of a multiple ceramic water filter system for scale-up studies in serving communities that need portable water.
Strength and Fracture Toughness of Earth-Based and Natural Fiber-Reinforced Composites
(Advanced Materials Research, 2015) Kabiru Mustapha; M.G. Zebaze Kana; O.S. Odusanya; W.O. Soboyejo
This paper presents the results of a combined experimental and theoretical study of the strength and fracture toughness of earth-based materials. They include mixtures of laterite, clay and straw that is stabilized with controlled levels of Portland cement. The compositional dependence of compressive, flexural strength and the fracture toughness is explored for different proportions of the constituent materials. Composites and fracture mechanics models are used to estimate the strength and fracture toughness of the resulting composites. The applications of the results are discussed for the design of earth-based building materials for affordable housing.
Strength and fracture toughness of earth-based natural fiber-reinforced composites
(Journal of Composite Materials, 2015) Kabiru Mustapha; Ebenezer Annan; Salifu T Azeko; Martiale G Zebaze Kana; Winston O Soboyejo
This paper presents the results of a combined experimental and theoretical study of the strength, fracture toughness, and resistance-curve behavior of natural fiber-reinforced earth-based composite materials. The composites, which consist of mixtures of laterite, clay, and straw, are stabilized with controlled levels of Ordinary Portland cement. The compositional dependence of compressive, flexural/bend strength, and fracture toughness are explored for different proportions of the constituent materials using composites and crack-tip shielding models. The underlying crack-microstructure interactions associated with resistance-curve behavior were also studied using in situ/ex situ optical microscopy. This revealed evidence of crack bridging by the straw fibers. The measured resistance-curve behavior is also shown to be consistent with predictions from small- and large-scale bridging models. The implications of the results are then discussed for potential applications in the design of robust earth-based building materials for sustainable eco-friendly homes.
Toughening Behavior in Natural Fiber-reinforced Earth-based Composites
(MRS Advances, 2016) Kabiru Mustapha; Martiale G. Zebaze Kana; Winston O. Soboyejo
This study presents a combine experimental and analytical investigation of the toughening behavior in natural fiber-reinforced earth-based composites. A specially designed single fiber pullout apparatus was used to provide aquantitative determination of interfacial properties that are relevant to toughening brittle materials through fiber reinforcement. The parameters investigated included a specially designed high strength earth-based matrix comprising of 60% laterite, 20% clay and 20% cement. The toughening behavior of whisker-reinforced earth-based matrix is analyzed in terms of a whisker bridging zone immediately behind the crack tip and interface strength. This approach isconsistent with microscopy observations which reveal that intact bridging whiskers exist behind the crack tip as a result of debonding of the whisker-matrix interface. Debonding with constant frictional stress was obtained and this formed the basis for the analytical model considered and the underlying crack-microstructure interactions associated with Resistance-curve behavior was studied using in situ/ex situ optical microscopy to account for the bridging contribution to fracture toughness. The effect of multiple toughening mechanisms (debonding and crack bridging) was elucidated and the implications of the results are considered for potential applications in the design of robust earth-based building materials for sustainable eco-friendly homes.
UNTRADITIONAL SYNTHESIS OF BORON-CONTAINING SUPERHARD AND REFRACTORY MATERIALS - A REVIEW
(Global journal of Engineering, Design & Technology, 2013) B. Agyei-Tuffour; E. Annan; E. R. Rwenyagila; E. Ampaw; E. Arthur; Kabiru Mustapha; S. Kolawole; W. O. Soboyejo; D. D. Radev
Boron-containing ceramics find large application in production of superhard and high-temperature materials with application in nuclear and aerospace techniques, military industry etc. The synthesis methods are decisive for the complexity of chemical, morphological and technological properties of these materials. The traditional high-temperature synthesis methods have some disadvantages leading to inconstancy of the product composition due to the boron evaporation, degradation of the furnace materials and contamination of the products, high energy losses etc. Here we show the advantages of some untraditional synthesis methods like direct mechanical synthesis and self propagating high-temperature synthesis (SHS) in the production of titanium diboride (TiB2), zirconium diboride (ZrB2) and production of dense boron carbide (B4C) based materials. Using SEM, TEM, XRD and analytical chemical methods, it was shown that diborides of titanium and zirconium have appropriate properties for production of dense ceramic materials. Using the method of mechanically-assisted sintering high-dense B4C-based ceramic materials was obtained. It was shown that the mechanical properties of materials obtained by pressureless sintering are close or overcome the corresponding properties of boron carbide densified by the method of hot pressing. The possibility to produce B4C-based ceramics with controlled properties was also shown.
Untraditional synthesis of Ni-based alloys for medical application
(ARPN Journal of Engineering and Applied Sciences, 2013-04) B. Agyei-Tuffour; E. Annan; E. R. Rwenyagila; E. Ampaw; E. Arthur; Kabiru Mustapha; S. Kolawole; W. O. Soboyejo; M. I. Marinov; D. D. Radev
Due to the combination of excellent mechanical properties, high chemical stability and appropriate biocompatibility, the Ni-based alloys find large application in implantology and dentistry. The traditional metallurgical synthesis methods of these alloys have some difficulties leading to inconstancy of the composition, degradation of properties and escalation of the product price. Here we show how to overcome the disadvantages of the traditional methods of synthesis and production of Ni-based alloys for medical application using combination of mechanochemical and powder-metallurgical routes. The structural properties of the products were studied using SEM/TEM and XRD methods. It was shown that the mechanically assisted synthesis allows obtaining nanosized Ni-Ti alloy with mean particle size of 20-30 nm at significantly lower temperature in comparison with the traditional metallurgical high-temperature alloying. It was also shown that after 40 hours of intense mechanical treatment of the starting Ni and Ti powders, a direct synthesis of Ni-Ti alloy proceeds. The product has excellent sinterability which allows producing bodies with controlled structural properties appropriate for application in implantology. Using standard mechanical tests and structural examinations it was demonstrated that the Ni-Cr dental alloys obtained by mechanically assisted sintering and casting possess excellent mechanical, technological and aesthetic properties. These alloys are suitable as dental restoration materials and production of porcelain veneered constructions like crowns and bridges using the so called metal-to-ceramic technique.

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