A study of Compressive Strength Characteristics of Laterite/sand Hollow Blocks

This paper presents the results of experimental investigations carried out on partial replacement of sand with laterite as it affects the compressive strength of sandcrete hollow blocks. Two mix proportions (1:6 and 1:8) were used with laterite content varying between 0 and 50% at 10% intervals. Hand and machine compaction methods were used. Curing was done by sprinkling water on the specimens. The results showed that for each mix proportion and compaction method, the compressive strength decreases with increase in laterite content. Machine compacted hollow sandcrete blocks made from mix ratio 1:6 and with up to 10% laterite content is found suitable and hence recommended for building construction having attained a 28-day compressive strength of 2.07N/mm2 as required by the Nigerian Standards

Durability of Laterized Concrete Exposed to Sulphate Attack Under Drying-Wetting Cycles.

The study investigated the performance of laterized concrete exposed to drying-wetting cycles of sulphate environments with a view to providing empirical data for laterized concrete specification.  It adopted accelerated ageing method to investigate the effect of sulphate attack on laterized concrete exposed to wetting-drying cycle comprising of 4 days of full immersion and 3 days of drying at ambient temperature at two concentrations (3% and 5%) of magnesium sulphate solution for a total exposure period of 24 weeks.  The test cubes were first cured by complete immersion in water for 28 days and afterward exposed to wetting-drying cycle of magnesium sulphate solution. The compressive strength was determined by using an ELE 2000kN compression testing machine. Data obtained from the experiments were analysed using percentages, mean, ANOVA and regression analysis. The results of the tests carried out showed that conventional concrete had a better resistance (in terms of compressive strength) to sulphate attack than laterized concrete. Conventional concrete exposed cyclically to sulphate solution of concentrations of 3% and 5% lost 18.91% - 30.34% of its compressive strength, after a period of 24 weeks of exposure. Whereas, laterized concrete similarly exposed for the same period; lost 26.54% - 31.79% (at 20% laterite content) and 36.67% - 51.33% (at 40% laterite content) of its compressive strength. It showed that the compressive strength of the tested laterized concrete specimen decreased significantly between 10% and 50%, each at ? = 0.05 with increasing sulphate concentration, laterite content and exposure period. The study concluded that conventional concrete performed better than laterized concrete in intermittently sulphate-laden environments. Keywords: Laterized concrete, Sulphate, Durability, Compressive strength

Effect of Nitric Acid Concentration on the Compressive Strength of Laterized Concrete

Laterized concrete is concrete in which some or all of the fine aggregates is from laterite. In this study, the effects of varying nitric acid concentrations (0%, 5%, 10%, 15%, and 20%), mix proportions (1:1:2, 1:1½:3), exposure period (28, 56, and 84 days) and percentage laterite content (0%, 25%, and 50%) on the compressive strength of laterized concrete were investigated. The tests were carried out with a view to simulating the performance of laterized concrete in contact with soluble nitrate-based substances. 100x100x100mm cubes of laterized concrete were cast and moist-cured for 28 days and the strength of concrete at this age was determined. The cubes were thereafter immersed in 0%, 5%, 10%, 15%, and 20% concentrations of nitric acid for a total of 84 days. Compressive strength tests were carried out at the end of 28 days, 56 days and 84 days of immersion. The results of the tests indicated that the compressive strength significantly reduces with increase in acid concentration, immersion period and laterite content. The effect of richness of mix on resistance of laterized concrete to the acidic aggression becomes more pronounced at the highest (50%) laterite content. Keyword: compressive strength, laterized concrete, nitric acid concentrations, percentage laterite content

Durability of Ternary Blended Cement Concrete in Sulphuric Acid

This study investigated the durability of concrete made of ordinary Portland cement (OPC), bamboo leaf ash (BLA) and pulverized burnt clay waste (PBCW) as binders in sulphate environment. Ternary blending of OPC, BLA and PBCW at ten (10) levels (100:0:0; 90:5:5; 90:10:0; 90:0:10; 80:5:15; 80:10:10; 80:15:5; 70:10:20; 70:15:15; 70:20:10) were used in producing 480 concrete cubes of size 100 mm and cured for 28 days in water. Further exposure to sulphuric acid (H2SO4) of 0, 1, 3 and 5% concentrations was done for a maximum of 120 days. Strength deterioration factors were thereafter calculated as a measure of acid attack resistance for the blended cement concrete. Results show that concrete containing PBCW and BLA performed better in H2SO4 than that of the control. Therefore, it can be concluded that the incorporation of BLA and PBCW in concrete improved its durability in sulphate laden environment. Keywords:durability, sulphuric acid, bamboo leaf ash, pulverized burnt clay waste, strength deterioration

Organisational Culture and Employees Commitment in Public Tertiary Institutions in Lagos State, Nigeria

DU study investigated the relationship between organizational culture and employees' C0111111ltment in public tertiary institutions in Lagos State, Nigeria. Four hypotheses were tated In this study. The descriptive research design type was adopted for the study. The population of the study comprises all the non-teaching and teaching employees in public tertiary institutions in Lagos State. The simple random sampling technique was first adopted to select four out of the seven public tertiary institutions in Lagos State for the study. The simple random sampling was fUrther used to select 50 employees from each of the four public tertiary institutions comprising a total of 200 samples for the study. An instrument tagged "Organizational Culture and Employees Commitment Questionnaire" was used to collect data for the study. The instrument was validated and a reliability coefficient of 0. 78 was obtained for the instrument. Data collected were analyzed using descriptive and inferential statistics. Results from the data analysis indicated that significant relationship exist between organizational culture and employees' commitment in public tertiary institutions in Lagos State. It was fUrther found that significant difference exist in the commitment of employees of different sex, ages and length of service to their institutions in Lagos State should Management improve on the cu"ent rewards system in their institutions to enhance employees' commitment levels as well as output among other

An Analysis of Factors Influencing Hiring/ Placement of University Graduates in Nigeria

1bia study notes the alarming rate of graduate unemployment and analyses the factors iaftuencing labour market demand for University graduates in Nigeria. A total of II 0 Labour Orpnizations was randomly sampled within Lagos metropolis. The study adopts a descriptive survey design. With the aid of a structured questionnaire and unstructured interview questions, relevant information was collected. Four hypotheses were postulated and tested at 0.05 level of significance using the chi-square. Finding shows that there are significant relationships between the experience, Government's economic policies, Quality of degree, Area of specialization and hiring I placement of Labour by Employer. The study concludes by suggesting the way out for the endemic state of unemployment in general and graduates from Nigeria Universities in particular

Urbalization and the transitional Economy: Impacts and Effects On Africa Regional Growth

• lltctwDhtg trend of international trade and investment are primary economic activities """M'Ye as the engine of the world economic growth. We discover that the volume of goods IIWIIedln Nigeria since 1950 has tremendously improved as a reflection of lower tariffs. An lllctwDe In tariff by one country usually triggered retaliatory changes by trading partners ~«~ding to tariff wars with the attendant effect of less trade and employment inhibition. But with Intense trade openness to the world, economic activities have witnessed a significant transition. The geographical spread of the growth has generated controversial debate. The paper Is a discourse of globalization, and the transitional economy. It also reviews the definition of Globalization and examines the impact and effect of the transitional economy on the regional growth with particular reference to Africa, using Niger Delta in Nigeria as a case study. African countries, therefore, should rise to the challenges of globalization as the new Asian Tige

An empirical study of the factors influencing Industrial Conflicts in Nigeria (1980-2010)§

The study examined empirically the factors that influence industrial conflicts in Nigeria during the period 1980-2010. Earlier studies have isolated the economic and non-economic determinants of conflict in developing countries but the impacts of the identified factors have not been estimated The work attempted to bridge the gaps that exist between the theoretical and empirical analyses. The study employed simultaneous equation model techniques (SEMT) in which strikes and wage rates were made endogenous .As a descriptive study which made use of three research questions and three hypotheses, 400 staff across six selected companies in the six geo-political zones of Nigeria, after stratification, were chosen randomly through simple random techniques. Secondary data were obtained from the Federal Ministry of Labour, Employment and Productivity, Lagos and the National Bureau of Statistics (NBS) Lagos. Results show that changes in wage rate, price expectation and union membership concentration influence industrial conflicts in Nigeria. Also the simultaneous equation model revealed that wages were significantly affected by strikes activity. Strike activities were not affected by wages only during the period under stud

The impacts of Policy and Strategic Management on Macroeconomic Indicators in Corporate Governance

Although pockets of cases of resistance, hesitance, and foot-dragging are still recorded with respect to the exposure of top public and private sector personalities to continuous policy/strategic management executive development programmes, it is most worrisome that ,, corporate governance void and missing links have continued to deflate concerted efforts ·• towards improving key macroeconomic profiles in the Nigerian nation. The paper examines the policy and strategic development in political and economic governance and its implications for macroeconomic performance. The paper seeks to awaken the sensibilities of government as policy makers I managers and productive corporate institutions as movers I drivers to blend and collectively ~ptimize various monetary and fiscal intervention mechanisms for sustainable redefinition of strategic macroeconomic indicators in the millennium

A Review of Pozzolana in Nigeria: Current State and Exploratory Assessment for Commercialization in Construction

Many researches have been conducted on pozzolanic materials in Nigeria, mainly from agricultural and industrial wastes, and calcination of natural deposit material as clay. Many conclusions on these researches indicate they can improve the quality of concrete produced with them, resulting in the production of sustainable concrete. They possess the potential for more affordable construction and reduce the ill reputation concrete has garnered over the years due to its growing carbon footprint. The utilization of these wastes in concrete also reduces the pressure on landfills, an environmentally friendly process. The outcome of these researches has remained on shelves and have not been harnessed to develop a footprint for its commercial application in construction. This review seeks to address this problem. Of the agricultural wastes studied, pozzolans from rice husk, palm oil wastes can be harnessed locally for processing and local utilization in locations unique to their generation source. Wastes from coconut shells and sugar cane are not viable in their current quantity to explore commercially. The waste from corn-cob and clay processed to pozzolana in concrete applications is commercially viable to meet the Nigerian demand. However, the cement manufacturing companies in Nigeria need to adopt these wastes to produce the cheaper corresponding blended cement alongside their regular cement. The Nigerian populace needs to be educated on the benefits of utilizing these pozzolans for ease of patronage