A Comparative Analysis of Batching by Weight and Volume towards Improved Concrete Production

Batching of concrete is generally the proportioning of the different constituents of concrete before mixing which could be by weight or volume. Mix-design justified by trial test is the best method to achieve a concrete of desired properties. Standardized prescribed concrete (SPC) mix-design is mostly adopted in mass concreting to high strength concreting applications in most developing nations. British standards accept volume batching for SPC only in mass concrete (<15 MPa) but batching by weight for normal and higher strength concrete. Structural concrete like in storey buildings requires at least a normal strength concrete (>20 MPa) recommended to be batched by weight. Designs batched by volume have been identified as the most commonly used method in concrete production in Nigeria and most developing nations, especially by medium to small scale construction firms due to the very high cost of employing batching plants. This research work developed a modified volumetric batch mix-design that will be equivalent to SPC design mix batched by weight in normal and higher strength concrete. The physical properties of the constituent concrete materials, fine aggregate, 12 and 19 mm sized coarse aggregates were determined. The strength of SPC mix of ST2, ST4, and ST5 to British standard were determined when batched by weight and their volume equivalents mix-design batch determined. The strengths of these SPC mixes were batched by volume and their weight equivalent batch-design determined. A relationship was determined between both batching mixdesign methods for all the prescribed mixes and strengths using the binder-aggregate and coarsefine aggregate ratios, such that the preferred weight batching design mix could be achieved by a modified mix-design batched by volume. This study concludes that concrete mix-design batched by weight is superior to when batched by volume and the desired design batching by weight could be achieved by generating a modified mix-design-batch by volume. This will improve the quality of concrete storey buildings in most developing nations

Data of the properties of rebar steel brands in Lagos, Nigerian market used in reinforced concrete applications

The data presented herein are compilations of the research summary of “Assessment of the Quality of Steel Reinforcement Bars Available in Nigerian Market” (Joshua et al., 2013) [1]. This data article provides information on the properties and cost of steel rebars used in reinforced concrete in Lagos, Nigeria. The data is based on the properties of 12 mm rebar brands which are the most used steel diameter in construction and they include actual diameters, yield strengths, ultimate strengths, ultimate/yield strength ratio, ductility and the cost of each brand. This data also contains the limiting standard properties of the highlighted properties in this data

Geoelectrical Characterization of Coastal Aquifers in Agbado-Ijaye, Lagos, Southwestern Nigeria; Implications for Groundwater Resources Sustainability

Water is a natural resource; its availability depends on climatic and geological conditions, and it is invariably controlled by human activities. Agbado-Ijaye lies within a coastal area, where local communities have been facing incessant water shortages, especially during the dry season. This study investigated the groundwater-bearing geological unit(s) using hydrogeophysical techniques in the coastal environment. The electrical resistivity technique, involving vertical electrical sounding (VES) and two-dimensional (2D) electrical resistivity imaging via Wenner array electrode configuration, was used to characterize the geoelectric distribution. Twenty VES stations were investigated and current electrodes (AB/2 m) spacing expanded from 1–200 m; four 2D electrical resistivity imaging traverses having a length of 200 m each and interelectrode spacing of 10 m (level 1) to 60 m (level 6) was adopted. Four geoelectric units were delineated, namely: topsoil (15–251 Ωm), clayey (28–100 Ωm), clayey sand (125–190 Ωm) and sandy (205–876 Ωm) with thicknesses ranging from 0.7–1.3 m, 4.1–19.0 m, 2.6–15.6 m and undefined depth, respectively. The 2D imaging sections also detected similar geoelectric layers, corroborating the VES-derived sections. The inverted sections delineated two different aquifers: the shallower low-yield aquifer comprising sandy clay/clayey sand units with a maximum depth of about 5.5 m. This layer is adjudged to be the continental plain sand of the Benin Formation. The deeper high-yield aquifer with a maximum depth of 30.4 m is a beach sand unit that belongs to the Tertiary Alluvium of the Dahomey Basin. The study showed that hydrogeophysical investigation is vital in exploring, developing, and managing coastal groundwater resources