Effects of Different Sources of Water on Concrete Strength: A Case Study of Ile-Ife

This research investigated the effect of different types of mixing water on the compressive strength of concrete. It analysed the effect of impurities such as salts of sodium, manganese, tin, zinc, copper and lead on the compressive strength of concrete. The effects of the presence of some other impurities like silt and suspended particles on concrete strength were also investigated. Samples of water from six sources in Ile-Ife environ were chemically analysed to ascertain their chemical constituents.  100mm cube samples were cast with these water samples. Compressive strength test was carried out on the cubes and the findings were statistically processed.  The results indicated that sources of water used in mixing concrete have a significant impact on the compressive strength of the resulting concrete. It concluded by suggesting that river water could be used for mixing where tap water is scarce. However, other properties such as durability and shrinkage should be considered before use. Keywords: compressive strength, concrete, mixing wate

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

EFFECTS OF VARYING CURING AGE AND WATER/CEMENT RATIO ON THE ELASTIC PROPERTIES OF LATERIZED CONCRETE

This paper reports the results of investigations carried out on the effect of varying curing age and water/cement ratio on the modulus of elasticity and modulus of deformability of laterized concrete. The test specimens were made with sieved samples of selected grain size ranges of laterite used as fine aggregates to replace sand in normal concrete. Batching was by weight. Three mix ratios of (1:1½:3), (1:2:4) and (1:3:6) were used. Water/cement ratio of 0.5, 0.6, 0.7 and 0.75 were used for each of the mix ratios. The specimens were tested at curing ages of seven to 28 days. The results showed that there was a corresponding increase in both modulus of elasticity and modulus of deformability of laterized concrete due to increase in curing ages. The mix proportion, compressive strength and water/cement ratio were found to have significant effects on both modulus of elasticity and modulus of deformability of laterized concrete