Recycling fine sandcrete block waste (FSBW)as fine Aggregate in the production of sandcrete Block

The study investigated the use of Fine Sandcrete Block Waste (FSBW) as fine aggregate in the production of sandcrete blocks with a view of controlling waste and decongesting block molding production sites. Standard sandcrete blocks of size 450mmX225mmX225mm were prepared from a mix ratio 1:6 (cement: fine aggregate) containing sand and FSBW as fine aggregates. The sand was partially replaced by FSBW in the mix within the range 0% - 90% in steps of 10%. The blocks were cured for 28 days and then tested for compressive strength. The physical properties of both the sand and FSBW were also determined. The results of the study revealed that the physical properties of FSBW compares favorably with those of conventional sand with the exception of water absorption. It further showed that the density and the compressive strength of the tested blocks decrease as the percentage replacement of sand with FSBW increases. The density of the blocks varied linearly with the compressive strength. Blocks prepared for mixes having 50% FSBW content or less were found to satisfy the minimum recommended compressive strength of 3.45N/mm2 (NIS 87:2000)

THE TOXICITY OF HEXANOLIC EXTRACT OF Xylopia aethiopica TO LARVAE OF CULEX P. quiuefasciatus

The hexanolic extract of Xylopia aethiopica (Ethiopian pepper) was tested for acute toxicity on the larva of Culex p. quiquefasciatus reared in the laboratory of the Department of Biological Science University of Agriculture Abeokuta, Nigeria. Five concentrations: (50ppm, 100ppm, 200ppm, 300ppm and 400ppm) were evaluated for acute toxicity on the larvae and total percentage mortalities recorded at intervals of 1,12,24,48 and 96 hours in each test. Effects of sunlight and ultra violet radiation on stability of the extract’s potency at 2,4, and 8 hours respectively were equally examined. The mean lethal concentration LC50 was 257ppm. Toxicity of Xylopia aethiopica on Culex p. quiquefasciatus larvae was gradual and persisted throughout the test period. Sunlight exposure has no significant effect on the potency of Xylopia oil while ultra-violet radiation activated its larvicidal properties.Â

Effect of initial catalyst amount on production of bio-diesel from Jatropha Curcas seed using in-situ technique

The effectof initial catalyst amount(0.3 -1.5%) on the in-situproduction of biodiesel from raw Jatropha Curcas seed was studied at a reaction temperature of 600C and reaction time of between 120min. Central composite experimental design was applied to evaluate effect catalyst amount (0.3 –1.5%). Initial catalyst amount was found to have significant (P<0.05) positive influence effects on the yield up to a value of between 0.9 and 1.20 g/g after which there was a significant reduction in the yield of biodiesel produced. Due to formation of by-products (soaps) caused by excessive amount of catalyst there was a general reduction in Jatropha Curcas ethyl-ester as levels of catalyst amount increased. A cubic quadratic model was obtained to predict the yield as a function of catalyst amount. The model predicted well the observed data with a R2 value of 0.939 and a non-significant Lack-of-Fit (P<0.05). The optimal value for initial catalyst amount was obtained as 1.01g/g. The biodiesel obtained at optimal catalyst amount compared favorably with the ASTM D6751-02 standard for biodiesel

Target Output, Extended Output and Site Productivity: Tales of the Expected

Target output, extended output and moderate output are compared for selected construction projects in some selected sites in Nigeria. The objective of this study is to examine the attributes of extended and moderate output, setting of benchmarks for purpose of analysis of worker productivity, determination of derivable benefits, with a view to identifying if the effects are the same for both methods. The study procures the primary data used in this study through the use of questionnaires designed in Likert scale 1 to 5, which are sent to clients, builders and consultants. In all, 120 questionnaires were sent to these respondents who recently completed their housing projects based on the two methods. Results of the study indicate that there is significant difference between both methods in terms of risks of value for money, guaranteed sense of self accomplishment, while a significant difference exists between both methods in job burnt- out effect, timely completion of project, and exhaustion, Moderate target output method demonstrates less risk of timely completion of project than the extended target output. This study concludes that there are various types of risks inherent in use of both methods in housing projects. The study displays characteristics of early completion of project and prospects of getting good value for money. Recommendations of the study are that clients, contractors and consultants should use Moderate target output for execution of their future housing projects job allocations, and also they are at liberty to use any of the two methods as they best satisfy their requirements. Implications of this study to policy makers and other stakeholders in the construction industry is that Moderate labour output method should be explored for use in large and complex projects as considerable cost savings can be achieved, timely delivery of project and good value for money are equally derivable benefits of the method. The outcome of this study serves as a watershed to other peculiar issues inn site productivity and job beats’ allocations

EFFECTS OF PARTIAL REPLACEMENT OF SAND WITH LATERITIC SOIL IN SANDCRETE BLOCKS

Of recent, the attention of most researchers is shifting towards the optimization of building materials by using local contents; the use of indigenous materials; and local industrial by-products unique and abundant in certain localities. This study therefore explored ways in which lateritic soil could be utilised in hollow sandcrete block production in Ota, Ogun State, Nigeria. Sandcrete blocks were made with lateritic soil taken from different sources replacing the conventional fine aggregate (local river sand) in steps of 10% up to 60%. Their compressive strengths determined to check for conformity with standard sandcrete block as specified in the Nigerian National Building Code (2006) with a view to determine the acceptable percentage replacement. Soil tests were performed on the lateritic soil samples to characterise the soils. Classification of the lateritic soil samples within Ota, revealed that the lateritic soils are mostly sandy clay of high plasticity and may replace sand by up to 20%, though an approximate linear decrease in strength with increasing sand replacement with lateritic soil was observed. This percentage replacement can be recommended to the block making industries within Ota with a view to encouraging utilization, though it is encouraged to confirm the percentage before embarking on mass block production

BUILDING INFORMATICS NEURAL NETWORK AND REGRESSION HEURISTICS PROTOCOL FOR MAKING DECISIONS IN BUILDING CONSTRUCTION PROJECTS

Building Informatics is a body of knowledge that uses the ICT computer system, digital systems, building information modeling, and state-of-the-art software in solving technical and management issues in building and construction fields. One of the modern methods used in data forecasting and modeling is Artificial Neural Networks, considering its advantage over traditional regression method. A data sample was taken of 1500 residential building projects’ completion costs. Regression analysis was carried out and model validated with functionality and Jackknife re-sampling technique. 150 Questionnaires were used to capture data on factors influencing application of heuristics protocol for decisions in residential building construction projects and data samples were analyzed using severity index, ranking, and simple percentages. Analysis of data brought up some factors that influence effective application of heuristic protocol in solving decision problems in construction decision process. The linearity analysis was carried out on the model and results indicated high level of tolerance and -0.0876 lowest variation prediction quotients to 0.9878 highest variation quotients. Also, 0.069 regression model fitness coefficient (R-square) was generated with 0.9878 highest variation quotients with standard error of 0.045. The results data attests to the stability of the model generated and the model is flexible in accommodating new data and variables, thus, allows for continuous updating