Volcanic Ash Blended Cement Laterized Concrete

Abstract

The study investigated the chemical and physical properties of volcanic ash, determined the effects of curing age and percentage replacement of cement with volcanic ash (VA) on the compressive, tensile splitting, and flexural strengths characteristics of laterized concrete. It further examined the existing relationships between compressive, tensile splitting, and flexural strengths for granite concrete and its applicability to VA-blended cement laterized concrete with a view to ascertaining the suitability of VA as a pozzolanic material in the production of laterized concrete. A 4 x 4 x 6 x 3 factorial experimental arrangement was used for the study. The volcanic ash was obtained from Dutsin Dushowa, Kerang in Jos Plateau. Four levels of sand replacement by laterite (LAT), 0%, 10%, 20%, and 30%; four levels of cement replacement with volcanic ash, 0%, 10%, 20%, 30%, and six levels of curing ages, 3, 7, 28, 56, 90 and 120 days were adopted with British Method of mix design for 28-day target strength of 25N/mm2. This was taken as control. A total of 288 cubical, 288 cylindrical and 288 rectangular prisms were cast and tested for compressive, tensile splitting and flexural strengths. The test specimens were cured by complete immersion in water. Data obtained were fitted into existing models. Inferential and descriptive statistics were used for data analysis. The result revealed that the chemical composition of the VA sample from the study area met minimum standard requirement for pozzolan. It had SiO2 content of 41.13%; total SiO2 + Al2O3 + Fe2O3 content of 70.99%; and Loss on Ignition value of 8.6. The VA-blended cements up to 30% VA content satisfied the physical requirements of NIS 439:2000, BS EN 196 – 6:2005, and ASTM C618:2008 for pozzolan. The strength properties (compressive, tensile splitting, and flexural) of the VA-blended cement laterized concrete increased with an increase in curing age but decreased as the VA and LAT contents increased. The optimum replacement level was 20%LAT/ 20%VA. At this level, compressive, tensile splitting, and flexural strengths increased with cutting age at a decreasing rate beyond 28days. The target compressive strength of 25N/mm2 was achieved for this mixture at 90days of curing. The relation between tensile and compressive strengths for VA-blended cement concrete was similar to that of granite concrete. The result further showed a strong correlation between compressive and tensile (splitting and flexural) strengths of laterized concrete at various laterite contents 0% (R2 = 0.9558 and 0.7139, p ≤ 0.5), 10% (R2 = 0.9895 and 0.7894, p ≤ 0.5), 20% (R2 = 0.7456 and 0.8970, p ≤ 0.5), 30% (R2 = 0.9895 and 0.7894, p ≤ 0.5). LAT content; VA content and curing age had significant (p ≤ 0.5) effects on the compressive, tensile splitting, and flexural strengths of the VA-blended laterized concrete. The study concluded that 20%LAT/ 20%VA laterized concrete was suitable for low-cost housing, non-reinforced, and low heat concrete works.