Spot Speed Study of Vehicular Traffic on Major Highways in Makurdi Town

Spot speeds of vehicular traffic along Otukpo, Gboko, Lafia and Iorchia-Ayu highways in Makurdi town where examined. Manual traffic count was carried out to ascertain traffic volume per hour per lane on each lane of the sampled road segments, and spot speeds of vehicles travelling in both directions of the highways where randomly measured using a Brushel speed gun at different spots for a period of 12 hours (6: 00 am – 6:00 pm) daily. Data analysis using statistical techniques revealed that vehicles travelled at average speed of 51 km/h, 53 km/h, 63 km/h and 50 km/h on the Otukpo, Gboko, Lafia, and Iorchia-Ayo highways respectively. Also, the range of travel pace and corresponding percentages of traffic (in brackets) on highways in Makurdi town were; 46-56 km/h (57%), (47-57km/h (50%), 55-65(32%) and 46-56(49%) for the Otukpo, Gboko, Lafia and Iorchia-Ayu roads respectively. Therefore speed limit ranging between 50-55km/h was proposed for highways in Makurdi town to guarantee safe travel. The study also revealed that highways in Makurdi town operated at a design speed below design specifications of 80–100 km/h required by the Nigeria Highway Design Manual except the Lafia road that has design speed of 80km/h. Speed calming devices, high traffic volume, geometrical layout or highway capacity and possibly pavement condition were identified as factors affecting vehicles speeds on highways in Makurdi town. Road rehabilitation for improved capacity and traffic volume to satisfy design speed, and use of speed limit warning signs to guarantee travel safety were recommended. Keywords: Highways in Makurdi town, spot speed, speed limit, design speed, travel pace

Investigating the Suitability of Coconut Husk Ash as a Road Soil Stabilizer

There is a pressing need to locate cheaper alternatives to traditional stabilizers such as Portland cement and lime which will reduce the cost of stabilized roads and make the practice of treating local soil materials very attractive to road development agencies in poor countries of the underdeveloped world, where deficient soils are often used without treatment, the consequence of which is premature deterioration of roads. This paper presents a study that was conducted to investigate the suitability of coconut husk ash (CHA), a waste product from crop plants, as a road soil stabilizer. The oxide composition of CHA was determined to establish its suitability as a pozzolanic material. It was then mixed with a lateritic soil (classified as A-2-6(1) using the AASHTO system of soil classification) in varying proportions, ranging from 0–20% by dry weight of soil at increments of 2%. The physical and strength properties of each of the soil-CHA blends was then determined in the laboratory. The results show that oxides of K2O, SiO2, Cl, CaO, P2O5, MgO and Al2O3 constitute 92% of CHA, indicating that it is a pozzolanic material. The optimum moisture content (OMC) of the soil increased, while its maximum dry density (MDD) decreased, with increasing CHA content. The CBR and UCS of the mixes increased with CHA content up to 8%, but decreased with a further increase in CHA content. However, the increase in the strength of the soil obtained at the optimum CHA content was not significant enough to warrant its usage as a lone stabilizer for sub-base and base materials, but it can be used for subgrade stabilization. For sub-base and base stabilization, CHA should be admixed with conventional stabilizers for improved performance

The optimum amount of waste glass aggregate that can substitute fine aggregate in concrete

The study that is reported in this paper was carried out to study the effects of glass sand on the properties of concrete and determine the optimum amount of waste glass aggregate that can effectively replace fine aggregate in cement concrete. The objectives of the study were to prepare concrete specimens containing various amounts of glass sand as partial replacement for fine aggregate and to determine the properties of fresh and hardened concrete specimens so produced. It was found that glass sand does not have significant effect on the workability of concrete. The density of concrete containing glass sand was slightly lower than the density of normal concrete by a factor of 1-2%. The presence of glass sand did not alter the established strength-time relation of concrete. The strength of concrete containing glass sand increased progressively with curing time. Glass sand had significant effect on the strength of concrete. A plot of concrete strength and glass sand content was a parabola curving downward. The peak strength, obtained at 10% glass sand content, was 1.2 times the target strength of 25 N/mm2. The study concluded that the optimum amount of glass sand that can effectively substitute river sand in grade C25 concrete is 16% of the proportion of fine aggregate in the concrete. For plain concrete, glass sand alone can be used as fine aggregate. It was recommended that supplementary cementitious materials should be incorporated in the concrete to suppress the deleterious alkali-silica reaction that may take place when glass concrete is exposed to moisture

The Optimum Amount of Waste Glass Aggregate that can Substitute Fine Aggregate in Concrete

The study that is reported in this paper was carried out to study the effects of glass sand on the properties of concrete and determine the optimum amount of waste glass aggregate that can effectively replace fine aggregate in cement concrete. The objectives of the study were to prepare concrete specimens containing various amounts of glass sand as partial replacement for fine aggregate and to determine the properties of fresh and hardened concrete specimens so produced. It was found that glass sand does not have significant effect on the workability of concrete. The density of concrete containing glass sand was slightly lower than the density of normal concrete by a factor of 1-2%. The presence of glass sand did not alter the established strength-time relation of concrete. The strength of concrete containing glass sand increased progressively with curing time. Glass sand had significant effect on the strength of concrete. A plot of concrete strength and glass sand content was a parabola curving downward. The peak strength, obtained at 10% glass sand content, was 1.2 times the target strength of 25 N/mm2. The study concluded that the optimum amount of glass sand that can effectively substitute river sand in grade C25 concrete is 16% of the proportion of fine aggregate in the concrete. For plain concrete, glass sand alone can be used as fine aggregate. It was recommended that supplementary cementitious materials should be incorporated in the concrete to suppress the deleterious alkali-silica reaction that may take place when glass concrete is exposed to moisture