http://hdl.handle.net/123456789/121 Sat, 04 Apr 2026 14:28:16 GMT 2026-04-04T14:28:16Z http://hdl.handle.net/123456789/2171 DEVELOPMENT OF A REAL-TIME ROAD TRAFFIC ASSESSMENT TOOL FOR KIGALI CITY, RWANDA NYIRAJANA, Jacqueline Traffic congestion is a significant problem in many urban areas, including Kigali City, Rwanda. This problem is associated with augmented fuel wastage, air pollution, financial losses, delays, and risk of accidents, due to poor traffic control and management. Traffic management efforts such as road widening, speed limit devices, and deployment of control measures to mitigate traffic congestion have not yielded expected results. This is largely due to limited availability of tools that incorporate realtime traffic flow parameters in road traffic assessment for metropolitan cities, such as Kigali. This study, therefore, developed a real-time road traffic assessment tool for Kigali City in Rwanda. Purposive interviews were conducted with management officers of national roads in Kigali. Preliminary surveys of five national roads (NR1, NR2, NR3, NR4 and NR5) were carried out. Traffic volume data were captured on NR1 and NR2, between 5.00 a.m. and 8.00 p.m., for 30 days, between November 2019 and December 2019, as specified in the Highway Capacity Manual (HCM). Traffic patterns on NR1 and NR2 were analysed using regression models and Macroscopic Fundamental Diagram (MFD). A Traffic Assessment Tool (TAT) for real-time traffic flow analysis was developed based on MFD and regression models. The algorithm for real-time vehicle detection in TAT was designed and implemented using data captured on NR4. The data were analysed using descriptive statistics and t-test at α0.05. The existing roadway, traffic and control conditions of the five national roads in Kigali City were found to be acceptable in accordance with the Rwanda Transport Development Agency Manual. Average daily traffic on NR1, NR2, NR3, NR4 and NR5, with the same design speed of 60 km/h, were 1030, 914, 867,780 and 885, respectively. Free flow traffic only occurred on NR2, with average flow rate of 645 veh/h. A clear transition between two flow regimes (free and congested) existed on NR1, with average flow rate of 1120 veh/h. Analysis of traffic on NR1 at free flow, yielded maximum flow of 3576 veh/h (5005.7 pc/h ) (regression) and 3348 veh/h (4687.2pc/h) (MFD). These were greater than HCM recommended capacity of 3600 pc /h for two-lane roadways in a direction resulted in congestion. The critical density was 115 veh/km, which increased to a jam density of 230 veh/km in the congested regime. The mean accuracy of vehicle detection and tracking algorithms of TAT for NR4 was 92.7%. The real-time flow and critical density generated by TAT were 3492 veh/h and 106 veh/km, respectively. The highest coefficient of correlation (R2 = 0.2787) between flow and density was obtained with MFD, which exhibited a better accuracy than the regression model. There was no significant difference between the flow parameters obtained from the field data and TAT. The traffic assessment tool developed, provided real-time traffic analysis which could be combined with existing control systems to improve traffic management on national roads in Kigali City. Sat, 01 Jul 2023 00:00:00 GMT http://hdl.handle.net/123456789/2171 2023-07-01T00:00:00Z http://hdl.handle.net/123456789/2169 DEVELOPMENT OF COIR FIBRE CEMENT AND CASHEW NUT SHELL LIQUID BONDED COMPOSITE BOARDS OKE, David Adewuyi There are enormous Agricultural Residues (AR) such as Coir Dust (CD), Coir Fibre (CF), and cashew nut shells, which are sources of environmental pollution in Nigeria. However, these residues can be deployed in Cement Composite (CC) production as alternative building material. Ce0ment composites are however susceptible to unwarranted dimensional instability which can be curtailed by the incorporation of polymeric substances such as Cashew Nut Shell Liquid (CNSL). Literature on properties of CCs produced from AR with the incorporation of CNSL is sparse. Therefore, this study was designed to investigate the properties of CCs made from CD, CF and CNSL. Cashew nuts were collected from a local site at Ogbomoso, milled to about 3.35 mm sizes. The CNSL was chemically extracted from the milled particles using IS methods, while coconut husk were reduced to obtain CF and CD using IS and ASTM methods. Cement composites were produced at four levels of CF (5.0, 7.5, 10.0 and 15.0%), four levels of CD (5.0, 7.5, 10.0 and 15.0%) and four levels of CNSL (2.5, 5.0 7.5, 10.0%) based on cement weight at 2:1 cement: water ratio following the preliminary tests. A CC board machine was developed and tested for the production of CC boards using Schaum’s Machine Design methods. The physical and sorption properties such as density, Water Absorption (WA), Thickness Swelling (TS) were determined using ASTM standards. The mechanical properties such as, Compressive Strength (CS), Modulus of Rupture (MOR), Modulus of Elasticity (MOE), and Impact Strength (IS) were evaluated using ASTM standards. Data were analysed using ANOVA at 0.05. A 5.5 kW electrically operated CC board machine developed has an amplitude of 2 mm; frequency of 350 rpm; CC size of and capacity of 360 CCs per hour. The densities, WA and TS of CF composites without CNSL ranged from 1350.00 to 1690.00 kg/m3, 33.1 to 69.5% and 1.1 to 3.2%, respectively. Their respective CS, MOR, MOE and IS in Nmm-2 were 5.72–11.43, 4.37–5.34, 813.24– 1428.85, and 1.19–4.35. The densities, WA and TS of CD composite without CNSL ranged 1030.00–1480.00 kg/m3, 27.5– 69.1% and 1.9–5.1%, respectively. Their respective CS, MOR, MOE and IS in Nmm-2 were 0.9–11.16, 1.6–3.79, 330.64– 1916.31 and 0.86 – 2.18. However, composites with CNSL had densities, WA and TS that ranged from 1310.00 to 1510.00 kg/m3, 7.1 to 17.8% and 0.9 to 2.7%, respectively. Their respective CS, MOR, MOE and IS in Nmm-2 were 2.18–7.25, 1.71– 2.36, 306.01 - 1054.09 and 1.09 to 2.57. The incorporation of CNSL significantly affected the physical, sorption and mechanical properties of the manufactured CCs and can be utilised in both indoor and outdoor applications. There was significant differences in the properties of CC produced from CF, CD and those treated with CNSL. Cashew nut shell liquid enhanced the properties and performance of cement bonded composites made from coconut coir fibre and dust for indoor and outdoor applications. Thu, 01 Jun 2023 00:00:00 GMT http://hdl.handle.net/123456789/2169 2023-06-01T00:00:00Z http://hdl.handle.net/123456789/2167 DETERMINATION OF FRACTURE PARAMETERS OF HIGH STRENGTH CONCRETE DERIVED FROM RICE HUSK ASH CEMENT BLENDS BUCKNOR, Anthony Olusegun Concrete, a conventional building material is prone to fracture crack propagation, due to temperature and shrinkage stresses development, resulting in strength loss. Efforts in recent times have been directed at improving the resistance of concrete to crack propagation using pozzolanic materials such as Rice Husk Ash (RHA). However, information on fracture characteristics of High Strength RHA blended High Strength Concrete (HSC) are limited. This study was designed to investigate fracture characteristics of modified RHA-HSC using Crack Tip Opening Displacement (CTODc) and Stress intensity factor (KSIC). Rice husk obtained from Ire-Ekiti was calcined for six hours at 700°C in a closed furnace and cooled over a 48-hour period. The RHA produced was milled to 5 µm, and the chemical and microstructural properties were determined using ASTM C 618 and Xray Diffraction (XRD), respectively. The BRE/DoE mix design method was used to determine the concrete mix for targeted compressive strength of 60 MPa. Portland limestone cement was replaced with RHA at 0, 10, 20, 30, 40 and 50% by weight of cement. Seventy-six (milled and unmilled each) 150 mm RHA-HSC cubes were cast and tested for compressive strength at 7, 14, 21 and 28 days. Based on the preliminary results 78 beams of milled (0, 10 and 20%) RHA-HSC blends were prepared to obtain CTODc and KSIC using Reunion Internationale des Laboratoires et Experts des Materiaux method. The CTODc and KSIC for 60 MPa were modelled using numerical analysis, while Scikit-learn statistical method was used to model varying RHA-HSC blends. Adequacy of the model was determined using coefficient of Regression (R2). The RHA comprised of SiO2 (87.3%), Al2O3 (3.1%), and Fe2O3 (1.1%). This satisfied the ASTM C 618 70% minimum requirement for oxides. The observed pattern of peak broadening, smaller grain size and distinct peaks in RHA-HSC blends, implied the presence of a periodic crystal lattice structure. The compressive strengths of milled and unmilled RHA concrete blends ranged from 54.5 to 60.2 MPa and 11.3 to 44 MPa, respectively. This implied that RHA concrete did not meet the targeted compressive strength of 60 MPa. The corresponding CTODc at 10% and 20% RHA concrete cement blends were 0.02 and 0.32 mm, respectively while that of KSIC were 1.32 and 1.42 MPa√m, respectively. The corresponding CTODc of 10% milled RHA-HSC increased by 20% crack width, while the 20% milled RHA-HSC increased by 58.5%, when compared with the control mix. The KSIC of 10% RHA-HSC samples yielded 7.9% increase, while the 20% RHA-HSC concrete yielded a 16.2% increase, when compared with the control mix. The CTODc and KSIC from varying RHA-HSC blend fracture models yielded 0.02 and 1.24, respectively, and compared favourably with experimental data (R2=0.873). The incorporation of rice husk ash enhanced the fracture resistance characteristics of blended high strength concrete. The adopted model is suitable for predicting the potential failure of high strength concrete derived from rice husk ash cement blends. Fri, 01 Sep 2023 00:00:00 GMT http://hdl.handle.net/123456789/2167 2023-09-01T00:00:00Z http://hdl.handle.net/123456789/2165 PERFORMANCE OF COMPRESSED EARTH BLOCKS STABILISED WITH CEMENT AND PALM KERNEL SHELL ASH COMPOSITIONS AJAYI, Adeola Sarah Cement is the conventional stabiliser used for Compressed Stabilised Earth Blocks (CSEB), which has been in use as a building material over the ages. However, its production causes environmental pollution. Hence, efforts have been directed at finding partial replacements for it with domestic, industrial and agricultural wastes such as Palm Kernel Shell Ash (PKSA). The PKSA has been used to partially replace cement in concrete blocks but information on its use in CSEB is sparse. Therefore, the potential of using PKSA as a supplementary cementitious material in CSEB was investigated. The physical properties (specific gravity, moisture content, liquid limit, plastic limit and plasticity index) of lateritic soil used for the production of the CSEB were determined, as well as the chemical composition of PKSA. The CSEB (100x100x100mm) cubes were produced from lateritic soil, cement, PKSA and water at 11.5% water to mixture of soil and binder. The cement-PKSA mixes were stabilised at 8:2, 6:4, 4:6, 2:8, while the control mix was stabilised at 10.0% cement. The mixes were compacted with a pressure of 6 MPa for the production of 66 Control Mix Blocks (CMB) and 528 Cement-PKSA Blocks (CPB). The blocks were cured at 100% humidity followed by 28 days secondary curing. Wet and Dry Compressive Strengths (WCS and DCS), Block Dry Density (BDD) and Total Water Absorption (TWA) of the blocks were determined according to standards. Data were analysed using a t-test at α0.05. Specific gravity, moisture content, liquid limit, plastic limit and plasticity index values were 3.3, 17.7, 53.4, 59.5 and 6.1%, respectively. The average chemical compositions of PKSA were 46.6 SiO2, 13.5 Al2O3, 11.8 Fe2O3, 0.5 SO3, 1.0 MgO, 1.5 K2O, 1.4 Na2O and 9.8% CaO, while specific gravity was 2.0. The WCS for CMB was 8.99 MPa, while CPB were 9.84, 7.51, 5.29, 3.21 MPa for 8:2, 6:4, 4:6, 2:8 mix proportions, respectively. The DCS for CMB was 9.84 MPa and at 8:2, 6:4, 4:6, 2:8 mix proportions, CPB were 11.79, 9.66, 7.33, 4.61 MPa, respectively. These values fare better than the 3.00 and 4.12 MPa recommended standards for WCS and DCS, respectively. The BDD for CMB was 2128±0.33 kg/m3, while CPB ranged from 2102 to 2132 kg/m3 for 8:2, 6:4, 4:6, and 2:8 mix proportions, respectively, all within the required minimum standard of 2000 kg/m3. The TWA for CMB was 7.5% and ranged from 6.8 to 9.8% for CPB. These values were lower than the 12% maximum standard. A 44% decrease in TWA with variation in cement content from 2 to 8% was attained; with a 2.3% increase in density. An increase in BDD led to an increase in WCS for both CMB and CPB (100% positive correlation). An increase in BDD led to a 44% decrease in TWA for both CMB and CPB (strong negative correlation). Palm kernel shell ash is a suitable partial cement replacement in the production of compressed stabilised earth blocks, with the best performance obtained at 4% PKSA and 6% Cement. Sat, 01 Jul 2023 00:00:00 GMT http://hdl.handle.net/123456789/2165 2023-07-01T00:00:00Z