A. A. Busari

Engineering properties of concrete made from gravels obtained in Southwestern Nigeria

Abstract This study investigates the engineering properties of concrete produced from gravels and also verify the suitability of local gravel aggregates obtained from Southwestern Nigeria in place of crushed granite. Preliminary investigations were carried out in five selected states (Ogun, Oyo, Osun, Ondo and Ekiti) in Southwestern Nigeria to determine the registered gravel mining pits. Fifteen gravel mining pits based on age and scale of mining operations were selected for this study. Appropriate gravel constituents in concrete mix were determined using Gs factor. Concrete cubes 150 mm, 150 × 300 mm2 cylinder modes and 150 × 150 × 750 mm3 beams were cast with collected gravel. 1:2:4 mix ratio was employed. Sieves analysis, density, water absorption were carried out on aggregates, while compressive, flexural and split-tensile strengths of the concrete were determined for 28 days using ASTM and BS methods. High concrete strengths resulted from high FM, low AAV and average Gs of gravels. Gravel location with highest compressive, flexural and split-tensile strengths of concretes had 24.8, 3.5 and 2.8 N/mm2 satisfying the minimum requirement of BS 811:1997 while that with lowest strengths had 9.6, 2.2 and 1.7 N/mm2, respectively. Sources of gravel highly influence compressive, flexural and split-tensile strengths of the cubes and beams.

Mechanical Properties of Dehydroxylated Kaolinitic Clay in Self-Compacting Concrete for Pavement Construction

The high increase in the cost of cement has led to a reduction in concrete production in most developing and under-developed countries. Therefore, the need for a sustainable and cost-effective substitute for cement is necessary. This research focused on the application of dehydroxylated kaolinitic clay in the production of self-compacting concrete for pavement construction. The elemental and oxide composition of the cementitious material (cement and metakaolin) was assessed using atomic absorption spectrometry and a scanning electron microscope was used to determine the particle geometry. Six mixtures of SCC with 0%, 5%, 10%, 15%, 20% and 25% metakaolin replacement were incorporated into this concrete mix. The passing ability, segregation ability and the flowing ability of the fresh concrete were assessed. The strength properties of the various mixtures (compressive and flexural) of the samples were also assessed at 3, 7, 14, and 28 days. The rheological properties showed that the addition of dehydroxylated kaolinitic clay higher than 10% showed poor rheology. However, percentages greater than 15% gave a reduction in compressive strength and flexural strength. In a bid to encourage sustainability in road construction and adopt the use of eco-friendly material, metakaolin is a viable material.

Data on the pozzolanic activity in coconut shell ash (CSA) for use in sustainable construction

The data presented herein are results of the research summary of the investigation for pozzolanic activity in coconut shell ash (CSA) towards a sustainable construction. The data article provides information on the properties of Coconut Shell Ash that are indicative of pozzolanic activity as stated in ASTM C618-15 (2015) [1], BS EN 197-1 (2011) [2] and Joshua et al. (2018) [3]. The data are the physical property of the sand used in determining the binder strengths and the chemical and physical properties (oxide composition and Strength Activity Indices respectively) of the pulverized, calcined and sieved Coconut Shell Ash.

Assessment of Gravel Properties Sourced within Oyo North Senatorial District: Case Study of Ogbomoso

The study evaluated the properties of gravel aggregate sourced within Oyo north senatorial district for concrete production in place of crushed granite crushed at exorbitant cost since characteristic properties show significant reflections on the qualities of gravel aggregate used and also play major role in determining the properties of hardened concrete.Samples of gravel from four commonly used borrow pits: Aroje, Bolanta, Sunsun and Olomi sites were obtained and tested for Aggregate Crushing Value (ACV), Aggregate Impact Value (AIV), Specific Gravity, Water absorption Capacity, Bulk Density, Moisture Content and Particle Size Distribution.On the average the results of the observation for the selected four locations were 22.56 g, 28.17 g, 33.37 g and 40.19 g for Aggregate Crushing Value (ACV), 2.44 g/ml, 2.53 g/ml, 2.57 g/ml and 2.62 g/ml for Bulk density, 0.17 %, 1.43 %, 2.42 %, and 2.48 % for moisture content, 2.02 %, 2.92 %, 2.00 % and 3.15 for water absorption, 2.52, 2.63, 2.60 and 2.55 for specific gravity, 41. 55 %, 45.25 %, 45.59 % and 47.08 % for aggregate Impact respectively.The study revealed that, gravel aggregates from Aroje has superior properties over those of Sunsun, Bolanta and Olomi as compared with coarse aggregate properties in BS 812: 1995 and BS 882: 1992. It is hereby recommended for coarse aggregate in concrete production.