EFFECT OF MAXIMUM PARTICLE SIZE OF COARSE AGGREGATES ON THE COMPRESSIVE STRENGTH OF NORMAL CONCRETE Nura Hassan and Ahmed Mohammed B. Department of Civil Engineering Technology, Federal Polytechnic Damaturu E-mail: nura2108@yahoo.co.uk

ABSTRACT: This research work presents the investigation on the effect of maximum size of aggregates on the compressive strength of concrete.  Nominal mix ratios of 1: :3, 1:2:4 and 1:3:6 were prepared using two different water/cement ratios, that is 0.5 and 0.6. Five different sizes of coarse aggregates, that is, 5mm, 12mm, 20mm, 25mm, and 38mm were used. The concrete cubes cast were cured for the period of 14 and 28 days before testing for compressive strength. The research revealed that water absorption of the coarse aggregates increases with the decrease in aggregate size, consequently, the water demand in the concrete mix. It was also found that of the coarse aggregates, size 20mm produced concrete with highest compressive strength in all the mixes irrespective of water/cement ratio and curing age. Concrete’s compressive strength increases with increase in curing age and with richer mixes. Based on the findings of the research, it was concluded that 20mm aggregate is the most suitable for the production of normal strength concrete.

THE USE OF GUM ARABIC AS STABILIZING AGENT FOR SUB-BASE IN ROAD CONSTRUCTION

Yusuf S, Hamza A, and Abdullahi A.B

Department Of Civil Engineering, Kaduna Polytechnic, Kaduna

E-mail:  ibnyusuf2005@yahoo.com

ABSTRACT: There is in need to upgrade the capability of soil, by stabilization instead of throwing it away. In order to find how a black clay soil can be improved, an investigation was carried out to see how an improved black clay soil can be used as sub-base material for road construction. The analysis conducted on the soil; stabilized with 15% Gum Arabic has produced the Liquid Limit of 25, Plastic Index of 8.77, M.D.D of 1.75, O.M.C of 15.92 and CBR of 30%. The results are in line with ASHTO recommendation for soil to be used as sub-base in road construction.

Keywords: Yamaltu Deba, Black clay soil, Gum Arabic, soil stabilization,

Received for Publication on 21 November 2014 and Accepted in Final Form 26 November 2014

DEVELOPMENT OF AN INTELLIGENT TRAFFIC LIGHT CONTROL SYSTEM

A.O. Aleshinloye, A.O. Otuoze and J.B. Ogunsakin

Department of Electrical and Electronic Engineering, University of Ilorin, Kwara, State Nigeria

E-mail: Olasunkanmialesh@gmail.com, otuoze.ao@gmail.com

ABSTRACT: Present Traffic light control systems are based on microprocessors and microcontrollers. These systems have limitations because it uses predefined time settings in switching controls which is not suitable for real life traffic light control system. Efficient traffic controls are based on a real time system and the traffic light to be used must accommodate such flexibility in its operation. Since, each timing signal in the present traffic light control system is fixed, vehicles may be unduly made to spend more time and use up much fuel. To make traffic light more efficient in its operation, development has been focused on “intelligent traffic light control systems”. This paper describes the use of sensor interfaced with the traditional traffic light control system to actualise an intelligent system which gives control based on a real-time monitoring of vehicular flow.

INVESTIGATING THE EFFECT OF SOME LOCAL VEGETABLE OILS AS QUENCHING MEDIA ON MECHANICAL AND METALLURGICAL PROPERTIES OF NST 60-2 STRUCTURAL STEEL

M. ALAGBE

Department of Metallurgical Engineering

Institute of Technology Kwara State Polytechnic Ilorin, Nigeria.

E-mail: alagbemic@yahoo.com

ABSTRACT: The hardening characteristics of NST60 – 2 structural (medium carbon) steel quenched in palm Kernel oil, groundnut oil, palm oil, Shea butter oil, air and water were investigated and evaluated.  This study was conducted on the possibility of improving it wear performance. The investigation was carried out in two parts; the effect of some quenching media on microstructured steel. A micro-structural examination of the quenched specimens was undertaken to ascertain the efficiency of some quenchants on the surface hardening. The results obtained indicate that all the quenching media responded well to all surface hardening with palm kernel oil giving the highest hardness value, being more efficient than groundnut oil, palm oil and shea butter oil.  The Shea butter oil gives the least hardness because; it has higher viscosity which lowers the cooling rate and consequently the lesser the possibility of martensite formation. In general excellent hardening properties were obtained with these vegetable local oils. It is established that surface hardening of NST 60-2 structural steel using palm kernel oil, groundnut oil, palm oil and shea butter oil can be adopted as a heat treatment process for improving its wear performance at less cost.

DETERMINATION OF THERMAL CONDUCTIVITY OF THE ROOTS OF THREE IMPROVED CASSAVA VARIETIES

Oriola, Kazeem Olaniyi

Department of Agricultural Engineering

Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria

E-mail: kazzyoris@yahoo.com, kooriola@lautech.edu.ng.

ABSTRACT: Processing of cassava roots into various cassava based products often involves the application of heat and this is still being done traditionally. Improved methods of processing and handling the roots could be developed for these purposes but it requires a good knowledge of the thermal behavior of the roots as their response to heat treatments is dependent on their thermal behaviour. The thermal conductivity of a crop is particularly useful in this regard as it controls the heat flux during heat transfer processes. However, such information on cassava roots is currently scarce. Thermal conductivity (k) of three improved cassava varieties (TME 419, TMS 30572 and TMS 0326) were determined at moisture contents of 50 – 70% (wet basis) using the KD 2 Pro. The value of k ranged from 0.5284 – 0.5662; 0.4804 – 0.5530 and 0.4660 – 0.5800 W/m⁰K for TME 419, TMS 30572 and TMS 0362 respectively. k of the roots also varied sinuously with increase in moisture content and the relationship was described by polynomial models of the third order with R² values of the plots ranging from 0.7569 – 0.9544. The influence of moisture was not significant (p > 0.05).

AN OVERVIEW ON THE ADVANCES IN CONCRETE TECHNOLOGY

Sani, M.B.¹, Musa, M.¹, and Umar, M.K.²

¹Department of Civil Engineering, Federal Polytechnic Bida, Niger State Nigeria.

²Department of Quantity Surveying, Federal Polytechnic Bida, Niger State Nigeria.

E – mail: informsani@yahoo.com

ABSTRACT: Concrete technology has been practice in the construction industry for over millennia by using cement, sand and aggregate. The compressive strength of about 30-50N/mm² was the maximum strength range achievable which is the limit capture by various codes of practice with the durability estimated on the basis of thickness of concrete cover. In today’s technology, the compressive strength of up to 170N/mm² is achievable with the durability calculated on the basis to time for deterioration. Concrete section could be reduced by more than 1/3 of the conventional thickness of structural components.