Kolapo O. Olusola

Assessment of the Quality Steel Reinforcement Bars Available in Nigerian Market

The use of substandard and steel reinforcement rods in the construction of structural steel concrete elements of a building, most especially in floor slabs, has been identified as one of the most important causes of structural failures in buildings in Nigeria. This research investigated the mechanical properties (yield strength, ductility and the ultimate tensile strength) of 12-mm diameter steel bars commonly used in reinforcing floor slabs using an extensometer. Results obtained from the tests showed that only three (3) brands out of a total of nine (9) tested most commonly used brands of sampled rods showed yield strengths greater than 460N/mm2. The yield strengths obtained range between 337.72 N/mm2 and 569.71 N/mm2. The study confirmed that the wide usage of substandard steel reinforcement bars in the Nigerian market is a major contributing factor to increasing incidences of structural building failures in the country when viewed from the angle of variability in material quality.

A Study of Compressive Strength Characteristics of Laterite Sand Hollow Blocks

Soft rock is a term that usually refers to a rock material with a uniaxial compressive strength (UCS) less than 20 MPa. This low strength range might be influenced by physical characteristics, such as size, saturation, weathering and mineral content. A number of uniaxial compression tests have been conducted onto soft rock samples. The results showed that the strength reduced significantly in saturation. The reduction was also caused by weathering, the strength of distinctly weathered rocks were lower than that of partially weathered rocks. In conjunction with the uniaxial compression test, point load strength index tests, IS(50), have also been conducted in order to obtain a correlation between the UCS and the point load strength index IS(50). The results showed that the IS(50) could well be correlated with the UCS. A conversion factor of 14 is proposed for soft rock materials.Cold Asphalt Emulsion Mixture (CAEM) is a mixture of aggregates and asphalt emulsion that is mixed at room temperature. It is relatively simple to produce, but the design procedure provided by the Asphalt Institute and the Ministry of Public Work of Indonesia pose some problems in its practical application. This Technical Note discusses limitations of the current design procedures and presents a simpler and more practicable design procedureKnowledge of the market is a requirement for a successful provision of public transportation. This study aims to explore public perception of paratransit service, as represented by the user and non-user of paratransit. The analysis has been conducted based on the public’s response, by creating several binomial logistic regression models using the public perception of the quality of service, quality of car, quality of driver, and fare. These models illustrate the characteristics and important variables to establish whether the public will use more paratransit in the future once improvements will have been made. Moreover, several models are developed to explore public perception in order to find out whether they agree to the replacement of paratransit with other types of transportation modes. All models are well fitting. These models are able to explain the respondents’ characteristics and to reveal their actual perception of the operation of paratransit. This study provides a useful tool to know the market in greater depth.In recent years, meshless methods have gained their popularity, mainly due to the fact that absolutely no elements are required to discretize the problem domain. This is possible due to the nature of the approximation functions used in this method. Approximation functions used to form the shape functions use only the so-called “nodal selection” procedure without the need of elements definition. The most popular approximation function used is the moving least-squares shape functions. Published works in meshless methods, however, present only the basic formulas of the moving least-squares shape functions. This paper presents the complete and detailed derivations of not only the moving least-squares shape functions, but also their derivatives (up to the second order derivatives), using the exponential weight function. The derivations are then programmed and verified.

Strength Characteristics of Periwinkle Shell Ash Blended Cement Concrete

The study investigated the eect of periwinkle shell ash (PSA) as cement substitute on the strengths of concrete. Specimens were prepared from a mix of designed strength 25N=mm 2 and the replacement of cement with PSA was from 0% up to 40%. A total of 180 specimens were cast and tested for compressive and tensile splitting strength at 7 and up to 180 days. The results revealed that compressive strength increased with the increase in curing age but decreased as the PSA contents increased. The design strength was attained with 10% PSA content at 28 days. The tensile splitting strength with 10% PSA was higher than the control (i.e. mix only having cement as the binder) at ages above 14 days. The relationship between tensile splitting strength and compressive strength of PSA blended cement concrete is similar to that of the conventional concrete. The study concluded that 10% PSA content is adequate as cement substitution for structural concrete.

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.

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.

Pulverized Calcined Clay and Carbide Waste as Alternative Binder in Concrete and Mortar Applications for Sustainable Construction

Portland cement (PC) based concrete is the world’s most consumed man-made material and this consequently puts lots of demand on cement as a binder. The CO2 gas emission during cement clinker production has placed this important material into non-environmental-friendly classification with quest for greener alternatives being on the rise. A recent study showed combination of Pulverized Calcined Clay (PCC) and Calcium Carbide Waste (CCW) as possible alternative for total PC replacement with resulting appreciable mortar strength but delayed setting times and lower strength than PC mortars. This paper reports on effects of PCC-CCW as alternative binder on strength properties of mortars. The mortar mixes had superplasticizers added to reduce water/binder ratio while the CCW was treated to reduce impurities with a view to improving the strength development and a bid to mitigate the observed setbacks of earlier study. The pozzolanic activity indices of the PCC was determined via X-Ray Fluorescence(XRF) and strength determination (strength activity index). The PCC was combined with Purified CCW to determine the binder’s strengths at varying PCC:CCW replacements to determine the prescribed mix combination for optimum strength. Improved optimised mortar strength of 13.11MPa was achieved compared to 11.89MPa in the previous study