The potential of cement stabilized shale quarry dust for possible use as road foundation material

Abstract This research investigated the potential of cement stabilized shale quarry dust for possible use as road foundation material. From the results, the shale consists mainly of SiO2 (27.7–60.1%), Al2O3 (7.30–17.9%), CaO (3.91–32.3%) and LOI (4.93–18.8%). The shale quarry dust (SQD) in its natural state had an average liquid limit (LL) as 38%, plasticity index (PI) as 24% and fines fraction as 14%, which is regarded as poor material according to American Society for Testing and Materials recommendation. The plasticity, compaction, California bearing ratio (CBR) and unconfined compressive strength (UCS) of the SQD were evaluated in its natural state and when mixed with varying percentages of cement. When stabilized with 3% cement, the strength parameters such as CBR and UCS showed improvement by about 20 and 25%, respectively, while the swellability indicators; plasticity and shrinkage limit reduced by about 56.2 and 46.6%, respectively, suggesting substantial improvement in the volume stability, strength and stress–strain properties and continued strength gain with time of the cement treated materials. The presence of the carbonate minerals contributed to the improved strength of the SQD for a given cement type and dosage. The beneficial changes in geotechnical properties of SQD when treated with 6% Portland cement, indicate that treated shale material satisfy most Nigerian specifications for highway fill and embankment, base and sub-base material. Their use, in heavy traffic highway, however, may be handled with caution as the continued high LL may likely imply some swelling on moisture influx

Analysis of sky conditions using solar radiation data over a tropical station

Radiation data in Nigeria are very sparse because radiation is not routinely measured. The data used for this work are from the physics Department of Obafemi Awolowo University, lle-lfe which is one of the few stations that collect radiation data in Nigeria. The daily, global and diffuse radiation measurements have been used to characterize the atmosphere of lle-lfe (70 14` N, 40 35` E) during January to December 1994. The clearness index ky (=H/H0) which gives the percentage depletion by the sky of the incoming global radiation and the relative sunshine (s/s0) gives the measure of cloud in the atmosphere has been adopted for use in this study. Also investigated are the diffuse radiation Kdiff (=Hdiff/H) and the diffuse coefficient Kcoef (= Hdiff/H0) that mirror the effectiveness of the sky in the scattering of the incoming radiation. Results show an average Kt value of 0.57 for year 1994 with maximum clearness index occurring in June (Kt= 0.68) and minimum in Dec (Kt =0.42). This present study also shows that the relative sunshine s/s0 has its minimum in August which indicates reduced hours of sunshine and solar insolation during the monsoon month of August in the tropical Nigeria station. Keywords: Daily, global and diffuse radiation, clearness index, diffuse coefficient, relative sunshine [Global Jnl Pure & Appl. Sci. Vol.9(3) 2003: 387-392

Effect of Deficit Irrigation Levels on Yield and Water Productivity of Some Maize Varieties in a Semi-arid Environment

The aim of this research is to determine the appropriate irrigation scheduling under three different maize varieties in Northern Guinea Savanna agro ecological zone of Nigeria. The trial was conducted during the 2015 and 2016 dry seasons at the Institute for Agricultural Research (IAR) field in Samaru (Latitude 11.11° N and Longitude 7.38°E). The experiment was laid out as a split – plot design replicated three times. Planting dates and supplementary Irrigation levels were in the main plots while maize varieties formed the sub-plots with the planting dates at 10days interval starting from March and February respectively. Three levels of irrigation were imposed based on levels of cumulative pan evaporation (Epan ) values of 1.0 Epan  (EI1), 0.70 Epan  (EI2) and 0.40 Epan  (EI3). Results from the two trials, revealed more efficient utilization of soil moisture by crops irrigated with 70 CU irrigation regime (6.91 and 6.97 kg grain/mm water respectively for the two seasons) while the least efficient water use was recorded by the full CU treatment (6.63 and 6.93 kg grain/mm water respectively) with relatively higher grain yields of 14% and 20% more than the 70 CU and 40 CU regimes respectively in 2015. Similar trends were recorded in the case of cob weight, 100 seed weight, seed/cob, shelling percentage and harvest index. In 2016 season, the similar trend was observed indicating the highest grain weight (3348.0 kg/ha) recorded by the full irrigation treatment which was statistically higher than (2724.0 and 2072.0 kg/ha) respectively for the 0.70 and 0.40 CU regimes. The best performing variety in terms of efficient water use and relatively high yield was the medium maturing variety (V3)

SPATIO-TEMPORAL TREND OF VEGETATION COVER OVER ABUJA USING LANDSAT DATASETS

Vegetation cover has acted as a source of carbon sinks and air purifier for a long period of time especially in developed cities thereby affecting the global climate change. The study was conducted to spatially estimate the Normalized Difference Vegetative Index (NDVI) which is a vegetation indicator for a period of 28 epoch years for Abuja from 1987 to 2014. The positive signatures of NDVI decrease from 2009 to 2014. Statistical analysis of the observed data samples at 95% confidence interval revealed that the changes observed in Year 2009 contributed most to the changes that was occurred in Year 2014.The modeled NDVI values for the year 2014 based on the regression analysis of the previous three years shows a significant agreement between the simulated values for year 2014 and the observed values. In general, there has been fast transformation of the vegetation cover to other land uses. The study reveals vegetation cover had reduced more significantly. It is also worthy to know that the model generated in this research can be used to predict future changes and trends in the vegetation cover. This will provide policy makers with useful information for the proper planning and design of the city and other capital cities over West Africa