Effect of Nitric Acid Concentration on the Compressive Strength of Laterized Concrete

Laterized concrete is concrete in which some or all of the fine aggregates is from laterite. In this study, the effects of varying nitric acid concentrations (0%, 5%, 10%, 15%, and 20%), mix proportions (1:1:2, 1:1½:3), exposure period (28, 56, and 84 days) and percentage laterite content (0%, 25%, and 50%) on the compressive strength of laterized concrete were investigated. The tests were carried out with a view to simulating the performance of laterized concrete in contact with soluble nitrate-based substances. 100x100x100mm cubes of laterized concrete were cast and moist-cured for 28 days and the strength of concrete at this age was determined. The cubes were thereafter immersed in 0%, 5%, 10%, 15%, and 20% concentrations of nitric acid for a total of 84 days. Compressive strength tests were carried out at the end of 28 days, 56 days and 84 days of immersion. The results of the tests indicated that the compressive strength significantly reduces with increase in acid concentration, immersion period and laterite content. The effect of richness of mix on resistance of laterized concrete to the acidic aggression becomes more pronounced at the highest (50%) laterite content

Performance of Periwinkle Shell Ash Blended Cement Concrete Exposed to Magnesium Sulphate

The study examined the compressive strength of periwinkle shell ash (PSA) blended cement concrete in magnesium sulphate medium. Specimens were prepared from designed characteristics strength of 25 MPa. The cement replacement with PSA ranged between 0 and 40% by volume. A total of 180 cube specimens were cast and cured in water. At 28 days curing, 45 specimens each were transferred into magnesium sulphate of 1%, 3%, and 5% solution, while others were continuously cured in water and tested at 62, 92, and 152 days. The results revealed a higher loss in compressive strength with the control mix, and that it increases with increased in MgSO4 concentration and exposure period, whereas, the attack on the PSA blended cement concrete was less and the least value recorded by 10% PSA content. Therefore, the study concluded that the optimum percentage replacement of cement with 10% PSA could mitigate magnesium sulphate attack

A comparative study of concrete properties using coconut shell and palm kernel shell as coarse aggregates

The high cost of conventional building materials is a major factor affecting housing delivery in Nigeria. This has necessitated research into alternative materials of construction. This paper presents the results of an investigation carried out on the comparative cost analysis and strength characteristics of concrete produced using crushed, granular coconut and palm kernel shells as substitutes for conventional coarse aggregate in gradation of 0%, 25%, 50%, 75% and 100%. Two mix ratios (1:1:2 and 1:2:4) were used. A total of320 cubes ofsize 100�100�100mm were cast, tested and their physical and mechanical properties determined. The results ofthe tests showed that the compressive strength ofthe concrete decreased as the percentage of the shells increased in the two mix ratios. However, concrete obtained from coconut shells exhibited a higher compressive strength than palm kernel shell concrete in the two mix proportions. The results also indicated cost reduction of 30% and 42% for concrete produced from coconut shells and palm kernel shells, respectively. Considering the strength/economy ratio, it was concluded that coconut shells were more suitable than palm kernel shells when used as substitute for conventional aggregates in concrete production. r 2005 Elsevier Ltd. All rights reserved

Compressive Strength of Volcanic Ash/Ordinary Portland Cement Laterized Concrete

This study investigates the effect of partial replacement of cement with volcanic ash (VA) on the compressive strength of laterized concrete. A total of 192 cubes of 150mm dimensions were cast and cured in water for 7, 14, 21, and 28 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively, while a control mix of 28-day target strength of 25 N/mm2 was adopted. The results show that the density and compressive strength of concrete decreased with increase in volcanic ash content. The 28-day, density dropped from 2390 kg/m3 to 2285 kg/m3 (i.e. 4.4% loss) and the compressive strength from 25.08 N/mm2 to 17.98 N/mm2 (i.e. 28% loss) for 0-30% variation of VA content with no laterite introduced. The compressive strength also decreased with increase in laterite content; the strength of the laterized concrete however increases as the curing age progresses

Effect of Different Sulphate Types and Concentrations on Compressive Strength of Periwinkle Shell Ash Blended Cement Concrete

The study investigated the compressive strength performance of periwinkle shell ash (PSA) blended cement concrete exposed to sulphate environments. Periwinkle shells were obtained from Ikot Ekpene, Akwa Ibom state, Nigeria; and calcined in a furnace to temperature of 8000C at zero soaking time. Concrete mix of design characteristic strength of 25N/mm2 was adopted as the control. The cement component replaced with PSA at five levels of 0%, 10%, 20%, 30% and 40% were cast, and on hardened exposed to varying concentration of sulphates of magnesium, sodium and calcium at four levels of 0%, 1%, 3% and 5% each for three exposure periods of 62, 92 and 152 days after complete immersion in water for 28 days. Using three replicates in all the tests, a total of 630 cubical (150mm) specimens were cast and tested. The results revealed that compressive strength increased with increase in curing age but decreased as the PSA contents increased. The design compressive strength was attained with 10% PSA content at the age of 28 days. The compressive strength reduction in sulphate solutions was noted to increase significantly (p = 0.005, R2 = 0.995) with increase exposure period and concentration, with the most severe caused by magnesium sulphate and the least by calcium sulphate. The least reduction in compressive strength was experienced with 10% PSA blended cement concrete. Based on the test results the study concluded that 10% PSA content is adequate as supplementary cementitious material for structural concrete to be placed in an aggressive sulphate environment

Effect of Coarse Aggregate Sizes and Replacement Levels on the Strength of Palm Kernel Shell (PKS) Concrete

The maximum coarse aggregate size used in concrete can impact on its strength. An investigation of the effect of coarse aggregate size and replacement level of granite with palm kernel shell (PKS) on the compressive and tensile strengths of PKS concrete were investigated. Mix proportion by weight of 1:1½:2 with w/c of 0.50 were used. All samples were tested at 7 and up to 90 days. Results showed that both compressive and splitting tensile strengths increased with increase in aggregate sizes. Both strengths however decreased with increase in replacement levels of granite with PKS. Optimum replacement level of granite with PKS was 25% with compressive and tensile strengths of 22.97 N/mm2 and 1.89 N/mm2 respectively at maximum coarse aggregate size of 20 mm. However, at 50% PKS content, which results in lightweight concrete, compressive strength was 18.13 N/mm2 which is above the minimum value of 17 MPa for lightweight concrete

Influence of curing Media on the Compressive strength of Palm Kernel Shell (PKS) concrete

The influence of curing media on the compressive strength of palm kernel shell concrete with varying coarse aggregate sizes (5-10 mm, 5-14 mm and 5-20 mm) and replacement level of granite with palm kernel shell (0- 100 % in steps of 25 %) were investigated in this study. The results showed that the compressive strength was significantly influenced by the curing media. Compressive strength of palm kernel shell concrete decreased from curing media CM-1 to CM-3 (CM-1: complete immersion; CM-2: partial immersion; CM-3: no immersion) with increase in percentage replacement of granite with palm kernel shell from 0 % (control) to 100 % in steps of 25 %. However, compressive strength increased from curing media CM-1 to CM-3 with increase in coarse aggregate sizes. The ANOVA showed that the curing medium had significant effect on the compressive strength. The Duncan’s multiple range tests revealed that the mean compressive strengths at different aggregate sizes, replacement levels and curing media were significantly different

Studies on termite hill and lime as partial replacement for cement in plastering

This study investigated the compressive strength and water absorption capacity of 50�50�50mm mortar cubes made from mixes containing lime, termite hill and cement and sand.Two mix ratios (1:4 and 1:6) and varying binder replacements of cement with lime or termite hill amounting to 0%, 10%, 20%, 30%, 40% and 50% were used.Test results showed that the compressive strength of the mortar cubes increases with age and decreases with increasing percentage replacement of cement with lime and termite hill.However, for mix ratio 1:6, up to 20% replacement of cement with either lime or termite hill, all the mortar cubes had the same strength; subsequently, the termite hill exhibited a higher compressive strength.For mix ratio 1:4, mortar cubes made from lime/cement and termite hill/cement mixtures had the same strength at 50% replacement.Generally, water absorption is higher in mixtures containing lime (18.10% and 14.20% for mix ratios 1:6 and 1:4, respectively, both at 50% replacement level) than those containing termite hill (16.10% and 13.02% for mix ratios 1:6 and 1:4, respectively, both at 50% replacement level). Termite hills seem to be promising as a suitable, locally available housing material for plastering. r 2005 Elsevier Ltd.All rights reserved

Effect of granite dust on the performance characteristics of kernelrazzo floor finish

This study is part of an on-going research on the durability performance of kernelrazzo, a type of terrazzo floor finish. It investigated the effect of partial replacement of the coarse aggregate with granite dust on the compressive strength, water absorption capacity and density of kernelrazzo. Two mix ratios (1:3 and 1:4), varying aggregate replacements of marble chipping with burnt palm kernel shells amounting to 0%, 25%, 50%, 75% and 100%, varying percentage replacements of all coarse aggregates with granite dust amounting to 0%, 10%, 30% and 50% were used. Cost comparisons were also made. Test results showed that the compressive strength of kernelrazzo increases up to a maximum of 30% coarse aggregate replacement by granite dust for both mixes for 0–50% replacement of marble chippings with palm kernel shells. For 75–100% marble chippings replacement, the compressive strength increases with increasing amount of granite dust. The water absorption capacity and density (upto 30% of granite dust) decrease and increase, respectively, with increase in percentage of granite dust. The cost of kernelrazo decreases with increase in the percentage of replacement of coarse aggregates with granite dust, except for 100% marble chipping replacement. It was recommended that to produce a good kernelrazzo floor finish in terms of strength, durability, density, water absorption capacity and cost, the overall coarse aggregate should not contain more than 50% of palm kernel shells for 1:4 and 1:3 mix ratios with a maximum of 30% aggregate replacement with granite dust. ? 2004 Elsevier Ltd. All rights reserved