relevant micro-concepts of common nigerian civil engineering

v) Temperature for curing also affects concrete strength: a phenomenon amplydemonstrated in experiments by Matawal and Abba-Gana (1998). Lower periods arerequired at lower temperatures to develop a given strength. Although continuedcuring at elevated temperatures results in faster strength development at 28 days, atlater ages the trend is reversed as concrete cured at lower temperatures developshigher strengths.6.0 MICRO-CONCEPTS OF STEEL AS CONSTRUCTION MATERIALSteel is used as reinforcement in reinforced concrete structures and as structural steelwork inframes, towers, trusses (including space tresses), bridges etc. In concrete, it is taken thatconcrete, being weak in tension, does not take such loading so that whenever direct or flexuraltension occurs, then reinforcement must be introduced. As a manufactured material subjected toa lot of quality supervision and specifications, matters related to its uses and applications arerather too technical for a public lecture of this nature: they are macro-concepts to civil engineerstaught rigorously in classrooms. Moreover, it is not a common material to the society who maynever need elaborate reinforcement or structural steelwork for any work related to their housingand businesses. It is then only noteworthy to emphasise that, in use of this type of materials inthe civil engineering industry, certain points must be observed to make optimal application ofsteel. These points are:• They must be free of rust or corrosion and where they have rusted, the scalesshould be thoroughly cleaned.• The dimensions must be comprehensively monitored to ascertain that theyconform to standards of the structural designs.• The yield stresses should be checked because tests by Matawal (1990)revealed that while rods of smaller diameters (12mm and below) tend to giveyield values equal or above specifications, the higher diameter rods (16mmand above) fall grossly below specifications.21