Effects of Water cement ratios on strengths characteristics of concrete produced with Recycled Iron and Steel Slag (RISS) aggregates was studied to understand the structural integrity of RISS aggregate in concrete and to determine the veracity of RISS aggregate as alternative aggregate to granite in concrete works. Mineralogical composition of the aggregate showed Silicon oxide (quartz) as the common mineral; both aggregates are well graded, strong and durable. Lower water cement ratios improved both the compressive and flexural strengths of RISS and granite concrete.

Aims:The aim of this research is to verify the suitability of local gravel aggregates obtained from the Southern part of Akwa Ibom State for designed concrete production in place of crushed granite aggregate sourced from distance places at exorbitant cost. This paper assesses the strength characteristics of concrete made from two locally sourced gravel aggregates of 10 mm and 20 mm maximum sizes. Study Design: Three samples of gravels divided into washed and unwashed gravels were used for the research. Concrete mix design of 25 N/mm 2 at 28 days of curing was the target mean strength of the research. Conclusion:The results prove that the size, grading, internal bonding and deleterious material contribute immensely to the strength of concrete made from gravel aggregate.

Titanium dioxide (TiO2) also known as Titanium White, is an inorganic, synthetic pigment used in paint to protect the substrate from harmful effects of ultraviolet light when lead pigments are regarded as toxic. However, its use is being limited since it causes flu-like symptoms, respiratory problem and skin irritation. Calcium carbonate (CaCO3) is a chemical commonly used as an extender pigment in cement to provide bulkiness at relatively low cost. Because of the problem associated with TiO2, it is of importance to regulate and optimize the use of TiO2 relative to CaCO3 and their influence on the physico-mechanical properties of emulsion paints. Nine paint specimens were formulated using 0 – 80 grams per litre of TiO2 and 120 – 200 grams of CaCO3, respectively at 10 gram interval. The following tests were performed on them: specific gravity, viscosity, pH, surface drying time, hard drying time, wash-ability/adhesion and opacity tests, in accordance to Nigerian Industrial Standard (NIS) 278: 1990. The result shows that all samples met specifications of 10 poise maximum, 5%, 7.5-9.0, 20 minutes, 2 hours, and 201 minimum, for viscosity, specific gravity, pH, surface drying time, hard drying time and wash-ability/adhesion properties, respectively. However, six sample specimens only met the requirement of NIS 278:1990 of 2coats for good opacity. In conclusion, TiO2 has no negative effect on the other physio-mechanical properties except the opacity of the paint and so specimens 7, 8 and 9, and ratio 30:170 is considered the threshold values for the paint production.

It has been shown that Concrete increases in strength with age after setting. The strength at a particular age can be further increased by suitable curing of the concrete while it is maturing. Such curing comprises the application of heat and/or the preservation of moisture within the concrete. In this research work, an attempt has been made to study the influence of elevated curing temperature on mechanical properties of concrete. Mechanical properties such as comprehensive strength and pullout strength were investigated. Concrete Specimens were cured under three different temperatures and curing age 30 0 C, 60 0 C and 100 0 C and 7, 14 and 28 days respectively. Compression test and pull out test were conducted on concrete cubes. The results showed strong positive relationship with correlation coefficient 0.779 between number of days and strength of concrete and the P-value 0.004 implies that the relationship is significant at 5% level while the coefficient of Determination (COD) indicates that number of days have 60.75% effect on strength of concrete. Correlation coefficient 0.932 with a P-value 0.013 and COD of 86.79% indicate that temperature has a very strong effect on strength of concrete. The regression analysis showed a unit increase in temperature will lead to 0.062 N/mm 2 increase in the strength of concrete. However the rate of concrete strength at the increase in temperature is lower than the increase in number of days, this implies a tendency for concrete to be weak in future with increase in temperature especially above boiling point.