Austine Uche | Bayero University, Kano (original) (raw)
Papers by Austine Uche
International Journal of Engineering Research and, 2017
The strength of reinforced concrete elements retrofitted in flexure, deflection and shear by mean... more The strength of reinforced concrete elements retrofitted in flexure, deflection and shear by means of externally bonded Carbon Fibre Reinforced Polymers (CFRP) has attracted the attention of researchers due to many advantages highlighted by a wide set of experimental results. This research presents reliability study on Reinforced Concrete (RC) bridge deck strengthened with externally bonded CFRP subject to corrosion. The deck was subjected to reliability analysis, using First Order Reliability Method (FORM), enhanced with genetic algorithms and the inherent safety was found to yield safety index of 3.8, this agreed with the recommendation of the Joint Committee of Structural Safety Code (JCSS 2001) for structures with moderate consequence of failure. The reliability analysis for the intact and the corrosion affected deck were executed through a developed program, written using MATLAB Simulink and the result showed the detrimental effect of corrosion on reinforcement of steel in the bridge deck. Flexural capacity restoration was also undertaken for the bridge deck using Carbon Fibre Reinforced Polymer (CFRP) with the adoption of adhesive bonding technique. The results of the reliability-based analysis of the strengthened deck with Carbon Fibre Reinforced Polymer (CFRP) yielded a flexural capacity restoration as much as 100%. Sensitivity analysis for the deflection, shear and bending modes of failure were also conducted. It was observed that the stiffness of CFRP and its thickness have influence on the retrofitting capacity of the bridge deck in the deflection mode. However, the critical mode of failure to be strengthened is flexure while the shear mode of failure is not affected much by corrosion.
This paper presents the findings of an investigation on the influence of recycled aggregate concr... more This paper presents the findings of an investigation on the influence of recycled aggregate concrete (RCA) as a substitute for virgin coarse aggregate in the compressive strength of `plain concrete. Recycled aggregate concretes were produced together with virgin coarse aggregates and subjected to empirical tests which include grading, specific gravity, bulk density, water absorption, aggregate impact value (AIV) and aggregate crushing value (ACV) to ascertain their performances. Mix design was carried out for grade 30 concrete according to DoE (1975) and RCA percentages of 0, 25, 50, 75, and 100 were used in replacing the virgin aggregate proportion in the mix. The test results showed that the use of recycled concrete aggregate (RCA) reduces the compressive strength and this reduction increases with the increase in percentage of the RCA. Maximum decrement of about 33% in strength or about 67% of compressive strength development occurs when 100% of RCA was used as substitute to virgi...
Buildings
The world is now focusing on a sustainable environment and reducing the effects of global warming... more The world is now focusing on a sustainable environment and reducing the effects of global warming. One way to achieve such targets is to properly utilize waste and reduce greenhouse CO2 emissions. The cement industry is responsible for almost 10% of global CO2 emission due to the high demand for cement in the construction industry. One of the ways to minimize this effect is the partial replacement of cement by other materials in concrete. Therefore, in this study, calcium carbide residue (CCR), which is highly rich in calcium oxide, partially replaced cement for waste management. Waste tires were grinded to fine sizes in crumb rubber (CR) and partially replaced the fine aggregate. Therefore, this paper investigared the influence of CR and CCR on the durability properties and heat/temperature resistance of self-compacting concrete (SCC). The experiment was designed using response surface methodology to investigate the effects of CR and CCR on SCC properties, design models for propert...
In this study, the findings of an investigation on the effect of partial replacement of cement wi... more In this study, the findings of an investigation on the effect of partial replacement of cement with Waste Tyre Ash (WTA) in cement paste and mortar as supplementary cementing material. The ash was subjected to chemical composition analysis using the X-Ray Fluorescence (XRF) analytical method using the X-Ray spectrometer machine. The consistency of WTA – Mortar indicated that water requirement increases with increase in WTA content. The normal consistency of cement paste was 29.0% while those of WTA – Cement pastes ranged from 35.0 – 45.0%, depending on WTA content. Also, setting times increased with increase in WTA content. It was observed that decrease in linear shrinkage occur with increase in WTA percentage 20% WTA content is recommended for production of structural mortar and as a retarder suitable for the hot weather construction, while WTA content of 25% and above is recommended for non-structural mortar.
In this study, effect of Waste Tyre Ash on the mechanical properties of concrete was investigated... more In this study, effect of Waste Tyre Ash on the mechanical properties of concrete was investigated. The WTA used was obtained by open burning of waste tyre slices to a temperature of about 500oC for about five (5) hours at the local open burning sites in Kano, it was then allowed to cool and sieved through 75 μm and characterized using X-Ray Fluorescence (XRF). The effects of WTA on cement paste and concrete were investigated at replacement levels of 0, 5, 10, 15, 20, 25 and 30%, respectively by weight of cement. The workability of fresh normal concrete and WTA - concrete were determined at fresh state and hardened concrete tested for compressive, splitting tensile and flexural strengths, respectively at curing ages of 3, 7, 28, 56 and 90 days in accordance with standard procedures. The results of the investigations showed that the WTA was of low reactivity with a combined SiO2, Al2O3, and Fe2O3 content of 40.2%. Since the oxide composition is 70%, it cannot be used as a pozzolanic m...
World Academy of Science, Engineering and Technology, International Journal of Civil and Environmental Engineering, 2016
Iran University of Science & Technology, 2017
Reinforced concrete (RC) slabs exhibit complexities in their structural behavior under load due t... more Reinforced concrete (RC) slabs exhibit complexities in their structural behavior under load due to the composite nature of the material and the multitude and variety of factors that affect such behavior. Current methods for determining the load-deflection behavior of reinforced concrete slabs are limited in scope and are mostly dependable on the results of experimental tests. In this study, an alternative approach using Artificial Neural Network (ANN) model is produced to predict the load-deflection behavior of a two-way RC slab. In the study, 30 sets of RC slab specimens of sizes 700mm x 600mm x 75mm were cast, cured for 28days using the sprinkling method of curing and tested for deflection experimentally by applying loads ranging from 10kN to 155kN at intervals of 5kN. ANN model was then developed using the neural network toolbox of ANN in MATLAB version R2015a using back propagation algorithm. About 54% of the RC specimens were used for the training of the network while 23% of th...
This paper presents the findings of an investigation on the resistance of Groundnut Shell Ash (GS... more This paper presents the findings of an investigation on the resistance of Groundnut Shell Ash (GSA)-Rice Husk Ash (RHA) modified concrete to hydrochloric acid aggression and a regression model of the concrete resistance to hydrochloric acid environment. The GSA and RHA used were obtained by controlled burning of groundnut shell and rice husk, respectively in a kiln to a temperature of 600 C, and after allowing cooling, sieved through sieve 75 μm and characterized. A total of fifteen 100 mm cubes of GSA-RHA-Concrete grade 20 mixes at replacement levels of 0, 10, 20, 30 and 40 %, respectively by weight of cement were cast, cured in water for 28 days and exposed to attack from 10 % concentration of diluted solution of hydrochloric acid (HCl) and the concrete resistance was also modeled using Minitab statistical software to establish regression model. The results of the investigations showed that the resistance of OPC concrete against HCl aggression was better than that of blended GSA-R...
This paper presents the findings of an investigation on the effects of Groundnut Husk Ash (GHA) i... more This paper presents the findings of an investigation on the effects of Groundnut Husk Ash (GHA) in cement paste and Mortar as a supplementary cementing material. The GHA used was obtained by controlled burning of groundnut husk to a temperature of 600 o C and sieved through 75 µm sieve after allowing cooling, and characterized. The effects of GHA on cement paste and mortar were investigated at replacement levels of 0, 5, 10, 20, 30 and 40 %, respectively by weight of cement. A total of ninety 40 mm x 40 mm x 160 mm GHA-Mortar prisms made with 1 : 3 (cement : sand) and 0.5 water-cement ratio were tested for flexural and compressive strengths at 3, 7, 28, 60 and 90 days of curing. The results of the investigations showed that GHA was of low reactivity, with a combined SiO 2, Al 2O3 and Fe 2O3 content of 26.06 %. The drying shrinkage decreased, while consistency, initial and final setting times of cement paste increased with increase in GHA content, where as the flexural and compressiv...
The paper aimed at presenting an overview of the potentials of biosilica (silica from rice husk) ... more The paper aimed at presenting an overview of the potentials of biosilica (silica from rice husk) as a new engineering raw material in Nigeria. A study of a large volume of literature on generation of rice husk and its combustion using different types of equipment has been presented. Nigeria is currently the highest rice producer in West Africa, producing an average of 3.2 million tons of paddy rice or 2.0 million tons of milled rice. Rice husk makes up 20% of paddy, therefore Nigeria has the potential to produce about 400,000 tones of rice husks annually. Biosilica is produced from rice husk through chemical and thermal extraction processes. The silica in the ash undergoes structural transformations depending on conditions (time, temperature etc) of combustion. At temperatures of 500-800oC amorphous ash is formed and at temperatures greater than this (>800°C) crystalline ash is formed. The desirable physicochemical and mechanical properties of amorphous silica, notably their high...
This paper presents the findings of an investigation on the compressive strength of concrete cont... more This paper presents the findings of an investigation on the compressive strength of concrete containing Groundnut Husk Ash (GHA) blended with Rice Husk Ash (RHA) and its resistance to acid aggression, as well as regression models of the concrete resistance in acidic environment. The GHA and RHA used were obtained by controlled burning of groundnut husk and rice husk, respectively in a kiln to a temperature of 600 o C, and after allowing cooling, sieved through sieve 75 µm and characterized. The compressive strength of GHA-RHA- Concrete was investigated at replacement levels of 0, 10, 20, 30 and 40 %, respectively by weight of cement. A total of seventy five 150 mm cubes of GHA-RHA-Concrete grade 20 were tested for compressive strength at 3, 7, 28, 60 and 90 days of curing. Also, thirty 100 mm cubes were exposed to attack from 10 % concentration of diluted solution of sulphuric acid (H2SO4) and nitric acid (HNO3), respectively and the concrete resistance was also modeled using Minita...
Analysis and design of inflatable structures made of fibre reinforced composites have been the fo... more Analysis and design of inflatable structures made of fibre reinforced composites have been the focus of many researchers in recent times. As with most designs, sources of uncertainty, variability and bias in the performance of the designed structures exist and should normally be assessed. This paper thus, seeks to identify and quantify levels of uncertainties that are in the design of a typical inflatable fender barrier structure against impact loadings and conducts reliability-based evaluation toward understanding safety levels and factors of safety to be employed for its design and for similar structures. Using a previously validated 3D parametric fluid-structure interaction analysis results of the model, implicit limit state response surface-based performance functions were derived for the structural responses to loads for the complex stresses and strain modes of failures. The First Order Reliability Method (FORM) was used to evaluate the influence of the uncertainties in materia...
This paper presents the findings of an investigation on the compressive strength of Groundnut Hus... more This paper presents the findings of an investigation on the compressive strength of Groundnut Husk Ash (GHA)-Concrete and its resistance to acid attack. The GHA used was obtained by controlled burning of groundnut husk to a temperature of 600 oC and sieved through 75 μm sieve after allowing cooingl. The compressive strength of GHA-Concrete was investigated at replacement levels of 0, 5, 10, 20, 30 and 40 %, respectively by weight of cement. A total of ninety 150 mm cubes of GHA-Concrete grade 20 were tested for compressive strength at 3, 7, 28, 60 and 90 days of curing and the microstructure of GHA-Concrete samples at 0 and 10 % replacements were examined at 28 and 90 days of curing. Also, thirty six 100 mm cubes were subjected to attack from 10 % concentration of diluted solution of sulphuric acid (H2SO4) and nitric acid (HNO3), respectively. The result of the investigations showed that the compressive strength of concrete decreased with increase in GHA content. However 10 % replac...
The paper aimed at presenting an overview of the potentials of biosilica (silica from rice husk) ... more The paper aimed at presenting an overview of the potentials of biosilica (silica from rice husk) as a new engineering raw material in Nigeria. A study of a large volume of literature on generation of rice husk and its combustion using different types of equipment has been presented. Nigeria is currently the highest rice producer in West Africa, producing an average of 3.2 million tons of paddy rice or 2.0 million tons of milled rice. Rice husk makes up 20% of paddy, therefore Nigeria has the potential to produce about 400,000 tones of rice husks annually. Biosilica is produced from rice husk through chemical and thermal extraction processes. The silica in the ash undergoes structural transformations depending on conditions (time, temperature etc) of combustion. At temperatures of 500-800 o C amorphous ash is formed and at temperatures greater than this (>800°C) crystalline ash is formed. The desirable physico-chemical and mechanical properties of amorphous silica, notably their h...
This paper presents the findings of an investigation on the resistance of Groundnut Shell Ash (GS... more This paper presents the findings of an investigation on the resistance of Groundnut Shell Ash (GSA)-Rice Husk Ash (RHA) modified concrete to hydrochloric acid aggression and a regression model of the concrete resistance to hydrochloric acid environment. The GSA and RHA used were obtained by controlled burning of groundnut shell and rice husk, respectively in a kiln to a temperature of 600 o C, and after allowing cooling, sieved through sieve 75 µm and characterized. A total of fifteen 100 mm cubes of GSA-RHA-Concrete grade 20 mixes at replacement levels of 0, 10, 20, 30 and 40 %, respectively by weight of cement were cast, cured in water for 28 days and exposed to attack from 10 % concentration of diluted solution of hydrochloric acid (HCl) and the concrete resistance was also modeled using Minitab statistical software to establish regression model. The results of the investigations showed that the resistance of OPC concrete against HCl aggression was better than that of blended GSA...
Advanced Materials Research, 2015
This paper investigates the effect of Groundnut Husk Ash (GHA) blended with Rice Husk Ash (RHA) i... more This paper investigates the effect of Groundnut Husk Ash (GHA) blended with Rice Husk Ash (RHA) in cement paste and concrete with a view to improve its suitability as a supplementary cementing material. The GHA and RHA used were obtained by controlled burning of groundnut husk and rice husk, respectively in a kiln to a temperature of 600 °C, and after allowing cooling, sieved through sieve 75 μm and characterized. The effects of GHA admixed with 10 % RHA on cement paste and concrete were investigated at replacement levels of 0, 10, 20, 30 and 40 %, respectively by weight of cement. Fresh concrete grade 20 of mixes made with partial replacement with GHA admixed with 10 % RHA in the order as above were tested for workability and hardened concrete tested for compressive, splitting tensile and flexural strengths at curing ages of 3, 7, 28, 60 and 90 days in accordance with standard procedures. The result of the investigations showed that GHA was of low reactivity and RHA was more reacti...
This paper presents the findings of an investigation on the influence of recycled aggregate concr... more This paper presents the findings of an investigation on the influence of recycled aggregate concrete (RCA) as a substitute for virgin coarse aggregate in the compressive strength oplain concrete. Recycled aggregate concretes were produced together with virgin coarse aggregates and subjected to empirical tests which include grading, specific gravity, bulk density, water absorption, aggregate impact value (AIV) and aggregate crushing value (ACV) to ascertain their performances. Mix design was carried out for grade 30 concrete according to DoE (1975) and RCA percentages of 0, 25, 50, 75, and 100 were used in replacing the virgin aggregate proportion in the mix. The test results showed that the use of recycled concrete aggregate (RCA) reduces the compressive strength and this reduction increases with the increase in percentage of the RCA. Maximum decrement of about 33% in strength or about 67% of compressive strength development occurs when 100% of RCA was used as substitute to virgin c...
ABSTRACT The paper is aimed at optimizing bearing thrust block design for thrust restraint using ... more ABSTRACT The paper is aimed at optimizing bearing thrust block design for thrust restraint using Genetic Algorithm. The design was achieved by calculating the bearing Area from the design equation and then breaking the area in to the corresponding bearing width and height (b and h). The optimization was achieved by obtaining optimum values of the design variables (bearing width and height) that would give minimum volume of the truncated pyramid concrete block at the minimum bearing Area.Optimum values of the design variables obtained from genetic algorithm were successfully compared with the different values of the design variables obtained using the traditional Iterative approach. Five different iterates were compared with the Genetic Algorithm result for different soils. The volume was found to increase up to 95%, 90.97%, 74.55%, 59.72%, 33.77% and 119.05% for soft clay, silt, sandy silt, sand, sandy clay and hard clay respectively in contrast to Genetic Algorithm result. Optimum solution was found when the block height (h) varied between one and two times the block width (b) except for hard clay in which the block width was between one and two times the block height (h).
American Journal of Civil and Structural Engineering, 2014
ABSTRACT This paper presents the findings of an investigation on the strengths of concrete contai... more ABSTRACT This paper presents the findings of an investigation on the strengths of concrete containing Groundnut Husk Ash (GHA) and strength prediction models of the concrete. The GHA used was obtained by controlled burning of groundnut husk to a temperature of 600 o C and sieved through 75 µm sieve after allowing cooling. The compressive, splitting tensile and flexural strengths of GHA-Concrete grade 20 were investigated at replacement levels of 0, 5, 10, 20, 30 and 40 %, respectively, at curing ages of 3, 7, 28, 60 and 90 days in accordance with standard procedures. The strengths of GHA-Concrete were also modeled using Minitab statistical software to establish regression models. The result of the investigations showed that the compressive, splitting tensile and flexural strengths of concrete decreased with increase in GHA content. However 10 % replacement with GHA was considered as optimum for structural concrete. The regression models of GHA-Concrete for compressive, splitting tensile and flexural strengths were developed with R 2 values of 0.934, 0.905 and 0.910, respectively and are considered to be good for prediction of concrete strengths.
American Journal of Civil and Structural Engineering, 2014
International Journal of Engineering Research and, 2017
The strength of reinforced concrete elements retrofitted in flexure, deflection and shear by mean... more The strength of reinforced concrete elements retrofitted in flexure, deflection and shear by means of externally bonded Carbon Fibre Reinforced Polymers (CFRP) has attracted the attention of researchers due to many advantages highlighted by a wide set of experimental results. This research presents reliability study on Reinforced Concrete (RC) bridge deck strengthened with externally bonded CFRP subject to corrosion. The deck was subjected to reliability analysis, using First Order Reliability Method (FORM), enhanced with genetic algorithms and the inherent safety was found to yield safety index of 3.8, this agreed with the recommendation of the Joint Committee of Structural Safety Code (JCSS 2001) for structures with moderate consequence of failure. The reliability analysis for the intact and the corrosion affected deck were executed through a developed program, written using MATLAB Simulink and the result showed the detrimental effect of corrosion on reinforcement of steel in the bridge deck. Flexural capacity restoration was also undertaken for the bridge deck using Carbon Fibre Reinforced Polymer (CFRP) with the adoption of adhesive bonding technique. The results of the reliability-based analysis of the strengthened deck with Carbon Fibre Reinforced Polymer (CFRP) yielded a flexural capacity restoration as much as 100%. Sensitivity analysis for the deflection, shear and bending modes of failure were also conducted. It was observed that the stiffness of CFRP and its thickness have influence on the retrofitting capacity of the bridge deck in the deflection mode. However, the critical mode of failure to be strengthened is flexure while the shear mode of failure is not affected much by corrosion.
This paper presents the findings of an investigation on the influence of recycled aggregate concr... more This paper presents the findings of an investigation on the influence of recycled aggregate concrete (RCA) as a substitute for virgin coarse aggregate in the compressive strength of `plain concrete. Recycled aggregate concretes were produced together with virgin coarse aggregates and subjected to empirical tests which include grading, specific gravity, bulk density, water absorption, aggregate impact value (AIV) and aggregate crushing value (ACV) to ascertain their performances. Mix design was carried out for grade 30 concrete according to DoE (1975) and RCA percentages of 0, 25, 50, 75, and 100 were used in replacing the virgin aggregate proportion in the mix. The test results showed that the use of recycled concrete aggregate (RCA) reduces the compressive strength and this reduction increases with the increase in percentage of the RCA. Maximum decrement of about 33% in strength or about 67% of compressive strength development occurs when 100% of RCA was used as substitute to virgi...
Buildings
The world is now focusing on a sustainable environment and reducing the effects of global warming... more The world is now focusing on a sustainable environment and reducing the effects of global warming. One way to achieve such targets is to properly utilize waste and reduce greenhouse CO2 emissions. The cement industry is responsible for almost 10% of global CO2 emission due to the high demand for cement in the construction industry. One of the ways to minimize this effect is the partial replacement of cement by other materials in concrete. Therefore, in this study, calcium carbide residue (CCR), which is highly rich in calcium oxide, partially replaced cement for waste management. Waste tires were grinded to fine sizes in crumb rubber (CR) and partially replaced the fine aggregate. Therefore, this paper investigared the influence of CR and CCR on the durability properties and heat/temperature resistance of self-compacting concrete (SCC). The experiment was designed using response surface methodology to investigate the effects of CR and CCR on SCC properties, design models for propert...
In this study, the findings of an investigation on the effect of partial replacement of cement wi... more In this study, the findings of an investigation on the effect of partial replacement of cement with Waste Tyre Ash (WTA) in cement paste and mortar as supplementary cementing material. The ash was subjected to chemical composition analysis using the X-Ray Fluorescence (XRF) analytical method using the X-Ray spectrometer machine. The consistency of WTA – Mortar indicated that water requirement increases with increase in WTA content. The normal consistency of cement paste was 29.0% while those of WTA – Cement pastes ranged from 35.0 – 45.0%, depending on WTA content. Also, setting times increased with increase in WTA content. It was observed that decrease in linear shrinkage occur with increase in WTA percentage 20% WTA content is recommended for production of structural mortar and as a retarder suitable for the hot weather construction, while WTA content of 25% and above is recommended for non-structural mortar.
In this study, effect of Waste Tyre Ash on the mechanical properties of concrete was investigated... more In this study, effect of Waste Tyre Ash on the mechanical properties of concrete was investigated. The WTA used was obtained by open burning of waste tyre slices to a temperature of about 500oC for about five (5) hours at the local open burning sites in Kano, it was then allowed to cool and sieved through 75 μm and characterized using X-Ray Fluorescence (XRF). The effects of WTA on cement paste and concrete were investigated at replacement levels of 0, 5, 10, 15, 20, 25 and 30%, respectively by weight of cement. The workability of fresh normal concrete and WTA - concrete were determined at fresh state and hardened concrete tested for compressive, splitting tensile and flexural strengths, respectively at curing ages of 3, 7, 28, 56 and 90 days in accordance with standard procedures. The results of the investigations showed that the WTA was of low reactivity with a combined SiO2, Al2O3, and Fe2O3 content of 40.2%. Since the oxide composition is 70%, it cannot be used as a pozzolanic m...
World Academy of Science, Engineering and Technology, International Journal of Civil and Environmental Engineering, 2016
Iran University of Science & Technology, 2017
Reinforced concrete (RC) slabs exhibit complexities in their structural behavior under load due t... more Reinforced concrete (RC) slabs exhibit complexities in their structural behavior under load due to the composite nature of the material and the multitude and variety of factors that affect such behavior. Current methods for determining the load-deflection behavior of reinforced concrete slabs are limited in scope and are mostly dependable on the results of experimental tests. In this study, an alternative approach using Artificial Neural Network (ANN) model is produced to predict the load-deflection behavior of a two-way RC slab. In the study, 30 sets of RC slab specimens of sizes 700mm x 600mm x 75mm were cast, cured for 28days using the sprinkling method of curing and tested for deflection experimentally by applying loads ranging from 10kN to 155kN at intervals of 5kN. ANN model was then developed using the neural network toolbox of ANN in MATLAB version R2015a using back propagation algorithm. About 54% of the RC specimens were used for the training of the network while 23% of th...
This paper presents the findings of an investigation on the resistance of Groundnut Shell Ash (GS... more This paper presents the findings of an investigation on the resistance of Groundnut Shell Ash (GSA)-Rice Husk Ash (RHA) modified concrete to hydrochloric acid aggression and a regression model of the concrete resistance to hydrochloric acid environment. The GSA and RHA used were obtained by controlled burning of groundnut shell and rice husk, respectively in a kiln to a temperature of 600 C, and after allowing cooling, sieved through sieve 75 μm and characterized. A total of fifteen 100 mm cubes of GSA-RHA-Concrete grade 20 mixes at replacement levels of 0, 10, 20, 30 and 40 %, respectively by weight of cement were cast, cured in water for 28 days and exposed to attack from 10 % concentration of diluted solution of hydrochloric acid (HCl) and the concrete resistance was also modeled using Minitab statistical software to establish regression model. The results of the investigations showed that the resistance of OPC concrete against HCl aggression was better than that of blended GSA-R...
This paper presents the findings of an investigation on the effects of Groundnut Husk Ash (GHA) i... more This paper presents the findings of an investigation on the effects of Groundnut Husk Ash (GHA) in cement paste and Mortar as a supplementary cementing material. The GHA used was obtained by controlled burning of groundnut husk to a temperature of 600 o C and sieved through 75 µm sieve after allowing cooling, and characterized. The effects of GHA on cement paste and mortar were investigated at replacement levels of 0, 5, 10, 20, 30 and 40 %, respectively by weight of cement. A total of ninety 40 mm x 40 mm x 160 mm GHA-Mortar prisms made with 1 : 3 (cement : sand) and 0.5 water-cement ratio were tested for flexural and compressive strengths at 3, 7, 28, 60 and 90 days of curing. The results of the investigations showed that GHA was of low reactivity, with a combined SiO 2, Al 2O3 and Fe 2O3 content of 26.06 %. The drying shrinkage decreased, while consistency, initial and final setting times of cement paste increased with increase in GHA content, where as the flexural and compressiv...
The paper aimed at presenting an overview of the potentials of biosilica (silica from rice husk) ... more The paper aimed at presenting an overview of the potentials of biosilica (silica from rice husk) as a new engineering raw material in Nigeria. A study of a large volume of literature on generation of rice husk and its combustion using different types of equipment has been presented. Nigeria is currently the highest rice producer in West Africa, producing an average of 3.2 million tons of paddy rice or 2.0 million tons of milled rice. Rice husk makes up 20% of paddy, therefore Nigeria has the potential to produce about 400,000 tones of rice husks annually. Biosilica is produced from rice husk through chemical and thermal extraction processes. The silica in the ash undergoes structural transformations depending on conditions (time, temperature etc) of combustion. At temperatures of 500-800oC amorphous ash is formed and at temperatures greater than this (>800°C) crystalline ash is formed. The desirable physicochemical and mechanical properties of amorphous silica, notably their high...
This paper presents the findings of an investigation on the compressive strength of concrete cont... more This paper presents the findings of an investigation on the compressive strength of concrete containing Groundnut Husk Ash (GHA) blended with Rice Husk Ash (RHA) and its resistance to acid aggression, as well as regression models of the concrete resistance in acidic environment. The GHA and RHA used were obtained by controlled burning of groundnut husk and rice husk, respectively in a kiln to a temperature of 600 o C, and after allowing cooling, sieved through sieve 75 µm and characterized. The compressive strength of GHA-RHA- Concrete was investigated at replacement levels of 0, 10, 20, 30 and 40 %, respectively by weight of cement. A total of seventy five 150 mm cubes of GHA-RHA-Concrete grade 20 were tested for compressive strength at 3, 7, 28, 60 and 90 days of curing. Also, thirty 100 mm cubes were exposed to attack from 10 % concentration of diluted solution of sulphuric acid (H2SO4) and nitric acid (HNO3), respectively and the concrete resistance was also modeled using Minita...
Analysis and design of inflatable structures made of fibre reinforced composites have been the fo... more Analysis and design of inflatable structures made of fibre reinforced composites have been the focus of many researchers in recent times. As with most designs, sources of uncertainty, variability and bias in the performance of the designed structures exist and should normally be assessed. This paper thus, seeks to identify and quantify levels of uncertainties that are in the design of a typical inflatable fender barrier structure against impact loadings and conducts reliability-based evaluation toward understanding safety levels and factors of safety to be employed for its design and for similar structures. Using a previously validated 3D parametric fluid-structure interaction analysis results of the model, implicit limit state response surface-based performance functions were derived for the structural responses to loads for the complex stresses and strain modes of failures. The First Order Reliability Method (FORM) was used to evaluate the influence of the uncertainties in materia...
This paper presents the findings of an investigation on the compressive strength of Groundnut Hus... more This paper presents the findings of an investigation on the compressive strength of Groundnut Husk Ash (GHA)-Concrete and its resistance to acid attack. The GHA used was obtained by controlled burning of groundnut husk to a temperature of 600 oC and sieved through 75 μm sieve after allowing cooingl. The compressive strength of GHA-Concrete was investigated at replacement levels of 0, 5, 10, 20, 30 and 40 %, respectively by weight of cement. A total of ninety 150 mm cubes of GHA-Concrete grade 20 were tested for compressive strength at 3, 7, 28, 60 and 90 days of curing and the microstructure of GHA-Concrete samples at 0 and 10 % replacements were examined at 28 and 90 days of curing. Also, thirty six 100 mm cubes were subjected to attack from 10 % concentration of diluted solution of sulphuric acid (H2SO4) and nitric acid (HNO3), respectively. The result of the investigations showed that the compressive strength of concrete decreased with increase in GHA content. However 10 % replac...
The paper aimed at presenting an overview of the potentials of biosilica (silica from rice husk) ... more The paper aimed at presenting an overview of the potentials of biosilica (silica from rice husk) as a new engineering raw material in Nigeria. A study of a large volume of literature on generation of rice husk and its combustion using different types of equipment has been presented. Nigeria is currently the highest rice producer in West Africa, producing an average of 3.2 million tons of paddy rice or 2.0 million tons of milled rice. Rice husk makes up 20% of paddy, therefore Nigeria has the potential to produce about 400,000 tones of rice husks annually. Biosilica is produced from rice husk through chemical and thermal extraction processes. The silica in the ash undergoes structural transformations depending on conditions (time, temperature etc) of combustion. At temperatures of 500-800 o C amorphous ash is formed and at temperatures greater than this (>800°C) crystalline ash is formed. The desirable physico-chemical and mechanical properties of amorphous silica, notably their h...
This paper presents the findings of an investigation on the resistance of Groundnut Shell Ash (GS... more This paper presents the findings of an investigation on the resistance of Groundnut Shell Ash (GSA)-Rice Husk Ash (RHA) modified concrete to hydrochloric acid aggression and a regression model of the concrete resistance to hydrochloric acid environment. The GSA and RHA used were obtained by controlled burning of groundnut shell and rice husk, respectively in a kiln to a temperature of 600 o C, and after allowing cooling, sieved through sieve 75 µm and characterized. A total of fifteen 100 mm cubes of GSA-RHA-Concrete grade 20 mixes at replacement levels of 0, 10, 20, 30 and 40 %, respectively by weight of cement were cast, cured in water for 28 days and exposed to attack from 10 % concentration of diluted solution of hydrochloric acid (HCl) and the concrete resistance was also modeled using Minitab statistical software to establish regression model. The results of the investigations showed that the resistance of OPC concrete against HCl aggression was better than that of blended GSA...
Advanced Materials Research, 2015
This paper investigates the effect of Groundnut Husk Ash (GHA) blended with Rice Husk Ash (RHA) i... more This paper investigates the effect of Groundnut Husk Ash (GHA) blended with Rice Husk Ash (RHA) in cement paste and concrete with a view to improve its suitability as a supplementary cementing material. The GHA and RHA used were obtained by controlled burning of groundnut husk and rice husk, respectively in a kiln to a temperature of 600 °C, and after allowing cooling, sieved through sieve 75 μm and characterized. The effects of GHA admixed with 10 % RHA on cement paste and concrete were investigated at replacement levels of 0, 10, 20, 30 and 40 %, respectively by weight of cement. Fresh concrete grade 20 of mixes made with partial replacement with GHA admixed with 10 % RHA in the order as above were tested for workability and hardened concrete tested for compressive, splitting tensile and flexural strengths at curing ages of 3, 7, 28, 60 and 90 days in accordance with standard procedures. The result of the investigations showed that GHA was of low reactivity and RHA was more reacti...
This paper presents the findings of an investigation on the influence of recycled aggregate concr... more This paper presents the findings of an investigation on the influence of recycled aggregate concrete (RCA) as a substitute for virgin coarse aggregate in the compressive strength oplain concrete. Recycled aggregate concretes were produced together with virgin coarse aggregates and subjected to empirical tests which include grading, specific gravity, bulk density, water absorption, aggregate impact value (AIV) and aggregate crushing value (ACV) to ascertain their performances. Mix design was carried out for grade 30 concrete according to DoE (1975) and RCA percentages of 0, 25, 50, 75, and 100 were used in replacing the virgin aggregate proportion in the mix. The test results showed that the use of recycled concrete aggregate (RCA) reduces the compressive strength and this reduction increases with the increase in percentage of the RCA. Maximum decrement of about 33% in strength or about 67% of compressive strength development occurs when 100% of RCA was used as substitute to virgin c...
ABSTRACT The paper is aimed at optimizing bearing thrust block design for thrust restraint using ... more ABSTRACT The paper is aimed at optimizing bearing thrust block design for thrust restraint using Genetic Algorithm. The design was achieved by calculating the bearing Area from the design equation and then breaking the area in to the corresponding bearing width and height (b and h). The optimization was achieved by obtaining optimum values of the design variables (bearing width and height) that would give minimum volume of the truncated pyramid concrete block at the minimum bearing Area.Optimum values of the design variables obtained from genetic algorithm were successfully compared with the different values of the design variables obtained using the traditional Iterative approach. Five different iterates were compared with the Genetic Algorithm result for different soils. The volume was found to increase up to 95%, 90.97%, 74.55%, 59.72%, 33.77% and 119.05% for soft clay, silt, sandy silt, sand, sandy clay and hard clay respectively in contrast to Genetic Algorithm result. Optimum solution was found when the block height (h) varied between one and two times the block width (b) except for hard clay in which the block width was between one and two times the block height (h).
American Journal of Civil and Structural Engineering, 2014
ABSTRACT This paper presents the findings of an investigation on the strengths of concrete contai... more ABSTRACT This paper presents the findings of an investigation on the strengths of concrete containing Groundnut Husk Ash (GHA) and strength prediction models of the concrete. The GHA used was obtained by controlled burning of groundnut husk to a temperature of 600 o C and sieved through 75 µm sieve after allowing cooling. The compressive, splitting tensile and flexural strengths of GHA-Concrete grade 20 were investigated at replacement levels of 0, 5, 10, 20, 30 and 40 %, respectively, at curing ages of 3, 7, 28, 60 and 90 days in accordance with standard procedures. The strengths of GHA-Concrete were also modeled using Minitab statistical software to establish regression models. The result of the investigations showed that the compressive, splitting tensile and flexural strengths of concrete decreased with increase in GHA content. However 10 % replacement with GHA was considered as optimum for structural concrete. The regression models of GHA-Concrete for compressive, splitting tensile and flexural strengths were developed with R 2 values of 0.934, 0.905 and 0.910, respectively and are considered to be good for prediction of concrete strengths.
American Journal of Civil and Structural Engineering, 2014