| 1 |
Author(s):
D.E. Ewa, J.O. Ukpata, E.A. Egbe , G.A. Akeke.
Page No : 1-9
|
Physical Properties of Sandcrete-Laterite Blocks
Abstract
The incorporation of laterite in sandcrete blocks production is a common commercial practice in Nigeria. However, proper calibrations as per optimal mix proportions of these aggregates to give blocks that meet minimum requirements by various standards are lacking. In this study, a mix ratio of 1:8 (cement: aggregates) and a water-cement ratio of 0.5 was adopted at different percentages of laterite replacing sand. Block sizes of 450 x 225 x 150mm were used. Curing was done for 3, 7, 14, and 28 days. A total of 104 blocks were prepared and tested for density, compressive strength, static modulus, water absorption and thermal conductivity. Results showed a decrease in density, compressive strength and thermal conductivity values with the addition of laterite. On the other hand, the water absorption of sandcrete-laterite blocks increased, as the blocks became more permeable. The decrease in thermal conductivity indicates better insulating properties of the Sandcrete-Laterite Blocks. These blocks will therefore reduce the energy requirements in a building. The study recommends an optimal replacement level of 10% of sand with laterite which gave a strength of 1.87N/mm2 and is 6.9% greater than the minimum requirement of 1.75N/mm2 by the Nigerian Building Code for individual blocks.
| 2 |
Author(s):
Michael N. Nwigbo, Umoru E. Lasisi, Youngson N. Ukaru.
Page No : 10-24
|
Comparative Study of Tensile Properties of Hybrid AA6061/SIC/Carbonized Coconut Shell Micro and Nano Composites
Abstract
This study synthesized a hybrid aluminium 6061 matrix composite with particulates of silicon carbide, SiCp and carbonized coconut shell (CCSP as reinforcements), and determined the effect of combining SiCp and CCSp reinforcements of different sizes and weight fractions on the strength properties and microstructure of the developed composite. The hybrid aluminium matrix composites were developed using the stir casting method. Several samples of the composites consisting of AA6061 alloy with 3, 6, 9, 12 and 15% by wt. each of CCSp and SiCp with average particle sizes of 38μm and 42.3nm for SiC, and 63μm and 50.01nm for CCSp were produced and characterized for strength. The microstructures of the developed composite materials revealed uniform distribution of reinforcement particles in the base matrix and excellent bonding between the base matrix and reinforcements after casting. The results obtained showed that addition of CCSp and SiCp reinforcement to the alloy increased the tensile strength and hardness. Also, a mathematical model was proposed for predictive tensile strength of nano-composite and validated by comparison with results of the physical experiment and those of other authors. The proposed model is in excellent agreement with experimental data. The nano-particulates reinforced composite presented maximum improvement in ultimate tensile strength value (53.4% and 8.5% of that for the unreinforced matrix and micro-composite respectively) at reinforcement level of 15wt.% nSiC/nCCS.
| 3 |
Author(s):
Amos Yala Iorliam, Alfred Wilson Opukumo, Benedict Anum.
Page No : 25-38
|
Carbon Capture Potential in Waste Modified Soils: A Review
Abstract
Carbonation of lime modified soil could capture carbon dioxide (CO_2) alongside strength improvement for road pavement materials. Due to large amounts of 〖CO〗_2 emissions and increasing cost of primary soil stabilizers such as lime and cement, the use of lime-based wastes have been encouraged. This paper reviews waste materials based on separate potential for 〖CO〗_2 capture and strength improvement of soils. Such wastes include cement kiln dust (CKD), saw dust ash (SDA), steel slag, basic oxygen steel (BOS) slag, ground granulated blast furnace slag (GGBS), coal fly ash (CFA) and cattle bone powder (CBP). Based on separated considerations of 〖CO〗_2 capture and strength improvement, CKD, SDA, BOS and GGBS have shown to have both high 〖CO〗_2 capture and strength improvement potential for weak soil. Future laboratory studies on lime-based waste (such as CKD and SDA) treated soil for combined 〖CO〗_2 capture and strength improvement need to be conducted.
| 4 |
Author(s):
Amos Yala Iorliam, Robert Ahen Chenge, Dickson Sooter Kuhwa.
Page No : 39-54
|
Treatment of Clay with Oil Palm Fibre Ash and Rice Husk Ash Mixture for Burnt Clay Bricks Production
Abstract
The current study examines the use of oil palm fibre ash (OPFA) and rice husk ash (RHA) mixture in the treatment of A-6 Makurdi clay for burnt brick production. The results show that the compressive strength of 9.4 MN/m2 for burnt untreated brick increased to 10.86 MN/m2 for burnt 2%OPFA+2%RHA treated brick. The corresponding water absorption of 14.9% for the burnt untreated brick increased to 16.2% for burnt 2%OPFA+2%RHA treated brick. The strength value of 10.86 MN/m2 is greater than 10.3 MN/m^2 which is the minimum strength value for negligible weather (NW) conditions. The water absorption of 16.2% is less than 17%, 22% and ‘no limit’ which are the maximum values for severe weather (SW), moderate weather (MW) and NW respectively. Based on combined strength and water absorption criteria, burnt bricks production with 2%OPFA+2%RHA treated A-6 Makurdi clay is adequate for use as a load-bearing brick in wall areas of NW condition.
| 5 |
Author(s):
Amos Yala Iorliam, Ajibola Rasaq Lawal , Rilwanu Ibrahim.
Page No : 55-72
|
The use of X-Ray Computed Tomography for the Assessment of the Internal Structure of Carbonated Soil
Abstract
This study looks at the use of X-ray computed tomography (XRCT) technique to determine the internal structure of carbonated lime treated kaolin. The results show that the formation of calcium carbonate (CaCO_3) along the depth of carbonated kaolin can be determined using XRCT. The carbonate formed shows to be evenly distributed deep down the lime treated kaolin. The air voids of carbonated lime treated kaolin decreased compared to the corresponding non-carbonated lime treated kaolin. CaCO_3 content obtained from XRCT compared favourably with that from TGA and calcimeter technique. XRCT has the potential for the determination of internal structure of carbonated lime treated soil.
| 6 |
Author(s):
Mac-Eteli H.D., Nelson T.A..
Page No : 73-84
|
Modelling Reviewed Hydraulic Indices of Periwinkle Shell Ash Occasioned by Variations in Calcination Temperature
Abstract
Periwinkle shellfish can be found in abundance in the Niger Delta's wetlands. Periwinkle shells are frequently piled in open fields and landfills, resulting in pollution and the development of disease-carrying organisms. Attempts have been made to employ periwinkle shell ash (PSA) as recycled materials in cement-based products in order to manage periwinkle shell by-products, preserve natural resources, and minimize building expenses. A better understanding of results obtained can be established using statistical tools in the analysis and modelling of the trends established with respect to reviewed papers on the PSA production parameters as well as the cement replacement level on the mechanical indices of concrete. This paper, therefore, uses statistical templates to develop analyzed models for a more enhanced understanding of trends and patterns associated with PSA processing variables and cement replacement levels on the compressive strength of concrete.
| 7 |
Author(s):
Sopakirite Somina, Happiness D. Mac-Eteli.
Page No : 85-97
|
Deflection of an Isotropic All-Round Simply Supported Rectangular Plates Incorporating Shear Effect Using Characteristic Orthogonal Polynomial Function
Abstract
The breadth and dexterity with which plates are used in the vast majority of engineering structures necessitates an ever-increasing and deeper study focus on plate strength and stiffness at the ultimate and serviceability limit states of response. From Kirchhoff’s hypothesis, thin plates when subjected to transverse loading, bend and experience transverse deflections that are typically minor in comparison to the plate thickness. However, for thicker plates there is an observed limitation in the application of Kirchhoff’s hypothesis, as this theory ignore the effect of transverse shear on the deformation of plates. This study therefore analytically examines the effect of induced shear on the deflection indices of plates with varying aspect ratios, using the characteristic orthogonal polynomial function. Result obtained shows a close agreement between present study and Kirchhoff’s hypothesis for membrane and thin plates. However, a significant difference was observed for moderately thick plates and thick plates, which clearly shows the effect of transverse shear as the plate thickness increases, which further validates the limitations of Kirchhoff’s hypothesis for moderately thick as well as thick plates. For an aspect ratio of 1.0 – 2.0 at 0.1 interval, results obtained indicated a percentage difference in deflection between the Present study and Kirchhoff’s hypothesis to range between -0.040 – 3.508%, 0.527 – 3.552%, 4.266 – 5.858%, and 13.980 – 17.011% for membrane, stiffened, moderately thick, and thick plates respectively. The validation of the Kirchhoff’s hypothesis for membrane as well as stiffened plates by the present study, indicates the suitability of the application of the characteristic orthogonal polynomial function in the evaluation of the deflection of plates regardless of thickness.
