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EFFECT OF CRUDE OIL CONTAMINATED SAND ON THE ENGINEERING PROPERTIES OF CONCRETE
Published 2013-01Call Number: Loading…
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OIL RESOURCE ABUNDANCE AND SECTORAL PERFORMANCES IN NIGERIA, 1970 - 2010
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Page will reload when a filter is selected or excluded.- A considerable fraction of sand in Niger Delta Area of Nigeria is contaminated with crude oil. The contaminated sand is largely utilised by local contractors for the production of concrete. However, there is need to establish its suitability in concreting. Previous works have centered on hardened uncontaminated concrete in crude oil environment but not on concrete made with Crude Oil Contaminated Sand (COCS). This research was designed to evaluate the effect of COCS on some engineering properties of fresh and hardened COCS concrete. Levels of crude oil contamination were determined using gravimetry method of Total Petroleum Hydrocarbon (TPH) test on nine sand samples randomly collected from some oil spill sites in Rivers State. Based on the test results, seven types of artificially contaminated sand were prepared with crude oil levels of 0.0, 2.5, 5.0, 10.0, 15.0, 20.0 and 25.0%. Workability (slump, compacting factor and flow), compressive strength, linear shrinkage, water absorption, and fire resistance were determined using concrete cubes, flexural strength using concrete beams, and surface resistivity using concrete cylinders in accordance with standard methods. Data obtained were analysed using ANOVA at p = 0.05. Eight models were developed using historic response surface methodology to predict the engineering properties of COCS concrete at water-cement ratio (w/c) of 0.5. Also, COCS concrete design mixes with contamination level and w/c ratio suitable for reinforced concrete were formulated. The TPH varied from 8.6 ± 0.2 to 14.1 ± 1.3%. The workability of concrete was improved by the presence of COCS. Slump, compacting factor and flow of the fresh concrete increased with increase in contamination from 30.0 to 200.0 mm, 0.5 to 0.9 and 15.0 to 85.0%, respectively. Compressive strength, flexural strength, linear shrinkage and water absorption of the hardened concrete reduced with levels of contamination from 31.5 ± 2.3 to 3.5 ± 0.0 N/mm2, 5.9 ± 0.8 to 0.1 ± 0.0 N/mm2, 0.1 ± 0.0 to 0.0 cm and 0.2 to 0.0 kg respectively. At a temperature of 200.0˚C, the percentage strength reduction increased from 18.4 to 94.8% for 2.5 to 25.0% contamination. Surface resistivity ranged from 25.1 ± 0.2 to 32.3 ± 0.2 kΩ-cm. The compressive and flexural strengths of COCS concrete were reduced by more than 50.0% at crude oil contamination level greater than 10.0%. The water absorption and surface resistivity values indicated that COCS concrete exhibited greater resistance to water and chloride penetration respectively, it shrank less when compared with the uncontaminated concrete, but exhibited poor fire resistance. Coefficient of determination, R2, of the models developed ranged from 0.823 to 0.999. Concrete design mix ratio of 1part of cement to1.6 part of COCS (10.0% crude oil) to 2.4 part of coarse aggregate was found to be appropriate at 0.45 w/c. This mix gave minimum compressive strength of 21.0 N/mm2 which is acceptable for reinforced concrete structures. Concretes produced with sand contaminated with less than ten percent crude oil were found suitable for use in low strength structures. Mix re-design using lower w/c improved the strength of the concrete. 1 results 1
- Compressive strength 1 results 1
- Concrete properties 1 results 1
- Crude oil-contaminated sand 1 results 1
- Dutch disease 1 results 1
- Macroeconometric model 1 results 1
- Oil Resource Abundance (ORA) has dominated the Nigerian revenue since the 1970s, contributing over 70.0%. Empirical literature have focused on the effects of ORA on aggregate macroeconomic variables (annual average growth in export to import price ratio, agricultural output growth rate, manufacturing output growth rate, public consumption, exchange rate and trade openness), while little attention has been devoted to the multi-sectoral dimension of the effects. This study, therefore, examined the effects of ORA on sectoral investment and output in Nigeria between 1970 and 2010. A macroeconometric model, predicated on the ‘Dutch disease’ theoretical framework was estimated. The framework recognised how a booming sector can hamper growth in the activity sectors (agriculture, services, building and construction, and manufacturing) of the economy. The model considered the linkages between ORA and the activity sectors and ORA was measured as the ratio of revenues from oil to total government revenues. Three Stage Least Squares estimation technique that took cognisance of serial error correlation among the equations in the system, and controlled for endogeneity in the presence of sector-specific effects was employed. Simulation of the model was performed for both ex-post and ex-ante forecasting under different policy scenarios. The data were collected from Central Bank of Nigeria’s Statistical Bulletin, Nigerian National Petroleum Corporation’s Annual Statistical Bulletin and World Development Indicators. Statistical tests for internal consistency using Theil’s inequality coefficients and its decomposition, as well as graphical representations that compared the actual and predicted values of the endogenous variables were carried out to ascertain the model’s forecast accuracy. A 1.0% increase in ORA significantly led to diverse effects on the sectors through public spending channel. Investment dropped in agriculture (4.3%) and services (1.1%) and improved in manufacturing sector (5.2%) and building and construction sector (0.2%). Output declined in agricultural sector (0.5%), services sector (0.3%) and increased in manufacturing sector (0.6%) and building and construction sector (0.5%). For ex-ante forecast of 5.0% increase in ORA, investment declined in agriculture (1.0%), manufacturing (0.5%), services (0.4%), and building and construction (0.4%). Output decreased in services (0.1%) and agriculture (0.1%) and rose in building and construction (0.2%) and manufacturing (0.2%). Under the forecast scenario of 5.0% decrease in ORA, investment increased in all the sectors (services-0.8%, agriculture-0.5%, building and construction-0.2% and manufacturing-0.1%). Output rose in services (0.1%) and agriculture (0.01%) and declined in building and construction (0.2%) and manufacturing (0.04%). Oil resource abundance had negative and positive impacts on the activity sectors of the economy. The negative impact was indicative of the presence of the ‘Dutch disease’ syndrome while the positive implied growth in national earnings through a favourable shift in the production activities of the sectors involved. There is the need, therefore, for the government to diversify the economy in order to enhance investment and output in the activity sectors. 1 results 1
- Oil resource abundance 1 results 1
- Sectoral performance 1 results 1
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