BUILDING A SUSTAINABLE WORLD: ECONOMY INDEX OF GEOPOLYMER CONCRETE

Geopolymer concrete offers a considerable solution not only to the environmental problem but also to the structural deterioration confronting the world. But, limited or no study is found on its cost implications. Consequently, this study evaluates the production cost and the economy index of geopolymer concrete (GPC) and compares it with the Portland cement concrete (PCC). Corncob ash (CCA) and ground granulated blast furnace slag (GGBFS) were used as source materials in the production of geopolymer concrete. Alkaline liquids were prepared to obtain 12 molar concentrations. The concentration was used to activate the source materials. Grade 30 concrete (M30) was adopted as a mix design proportion. GGBFS was replaced by CCA in varying percentages as 0%, 20%, 40%, 60%, 80%, and 100%. The research findings reveal that GPC is 27.71% lesser than the PCC in terms of production cost while the economy index of GPC is higher than the PCC for the same grade of concrete. The results infer that GPC is cheaper and more viable than the PCC. Thus, geopolymer concrete proves to be an innovative product and appears to be a feasible solution not only to the environmental and structural deteriorating problems but also to the problem of high cost of Portland cement in the construction industr

ASSESSMENT OF STRENGTH PROPERTIES OF CASSAVA PEEL ASH-CONCRETE

Basic conventional building materials like cement and aggregates are becoming increasingly expensive due to high cost incurred in their processes, production and transportation. The utilization of locally available materials such as cassava peel ash that can either reduce or replace the conventional ones is being considered. This paper investigated the effect of partial replacement of cassava peel ash with ordinary Portland cement at 5, 10, 15, 20 and 25%. The cassava peel ash was obtained by calcinations of cassava peel to 7000 c temperature. Cube samples of size 150 x 150 x 150 were prepared for concrete grade 30 and cured in water for 7, 14, 28, 90, 120 and 180 days after which they were subjected to compressive strength, tensile strength, durability, porosity, water absorption, slump, compact factor and shrinkage tests. The results showed that partial replacement of 10 and 15% gave compressive strength comparable to the control with 0% replacement and optimum replacement is 10%. It was discovered that the cassava peel ash contains all the main chemical constituents of cement though in lower percentage compared with OPC which shows that it can serve as a suitable replacement if the right percentage is used. However, its durability and sulphric acid resistance improved considerably at 10% replacement of cement with cassava peel ash. The study recommends that concrete made with cassava peel ash can be used for light construction works where high strength is not major requirement but where durability is a major concern

Reliability Assessment of the Nigerian Timber – An Environmental Sustainability Approach in the 21st Century

An important component of environmental sustainability is how we can continue improving human welfare within the limits of the earth’s natural resources. With recent research showing that carbondioxide levels in the air are at their highest in 650,000 years and thus an alarming depletion of the ozone layer, the challenge currently facing many countries is how to respond to the issue of climate change. Steel, reinforced concrete and timber are the most commonly used structural materials worldwide. However, carbondioxide emissions from steel and cement production have been found to be the first and second largest sources of industrial C�� emissions worldwide and this has prompted the inclination towards timber as a structural material. Timber is decomposable or biodegradable as well as renewable and its production does not require the use of high energy fossil fuels as in the production of some other building materials such as steel or even brick. Nigeria is blessed with several timber species in different wood classes but despite the environmentally sustainable and obvious advantages of timber, it is being grossly underutilized as a structural material in Nigeria because there is limited information on the reliability of timber considering the wide property variability between and even within, timber species. This paper addresses the need for reliability analysis of various Nigerian timber species with a view to determining and establishing their structural strength to encourage the use of the Nigerian Timber as a structural material. The need to revise the Nigerian Code of Practice for the structural design of Timber is also emphasized in this pape

Performance evaluation in a construction project: an empirical study of Canaan city housing estate, Ota, Nigeria

Project performance has always been affected by many factors across its lifecycle due to the increasing intricacy and flexibility of construction project. This study evaluated the performance in a construction project with emphasis on Canaan city Housing Estate (CHE). The researchers employed the instrument of main data collection to show the practicability of the cardinal performance indicators (CPIs) with a five-point likert scale for entreating information from the project actors with regard to their perceptions on 50 performance features. The findings showed that the Cronbach's alpha (α) of the data was 0.8942 indicating that the index of instrument reliability was consistent and reliable. Moreover, the empirical finding revealed that performance evaluation in a construction project has gone beyond the traditional approach of quality, time and cost. This study would assist the construction participants in enhancing the project performance and efficient evaluation toward the satisfactory delivery of a construction project

PROBABILISTIC SEISMIC HAZARD ANALYSIS OF SOUTH-WESTERN NIGERIA

For about ten decades, the seismic record of Nigeria has shown the occurrence of several magnitudes of earthquakes. This is contrary to the belief of some people in time past that Nigeria is aseismic. In number and in size, most of the witnessed earthquakes in Nigeria are found to occur in her South-Western region. Researchers have also begun to warn recently that some regions of Nigeria should prepare for devastating earthquakes in years to come. Hence this paper aimed at the probabilistic seismic hazard analysis of the South-Western region of Nigeria using the available historical and instrumentally recorded data. The Gutenberg-Richter (G-R) recurrence law was used to assess the seismicity parameters and to generate a model for calculating the mean annual rate of exceedance and to forecast probable future earthquake occurrence in the South-West. The findings of this assessment established that the South-West region of Nigeria is likely to experience earthquake magnitude as high as 7.2 in the year 2028 with a probability of 36.79%. Hence, this work enlightens on the extent of probable future earthquake magnitude in South-Western Nigeria and it is recommended that the government of Nigeria and inclined agencies begin to look into earthquake in this region

Probabilistic Seismic Hazard Analysis of Nigeria: The Extent of Future Devastating Earthquake.

The several past seismic occurrences in Nigeria has recently led to warnings from research agencies and the forecast of large earthquake from researchers in Nigeria. Nevertheless, the major forecast from researchers has appeared to be open ended. To this end, this paper aimed at the probabilistic seismic hazard analysis of Nigeria and the limit to probable future earthquake magnitudes in Nigeria. The Gutenberg-Richter recurrence law was majorly employed for the purpose of this research. The Findings of this research established that Nigeria is at the risk of experiencing earthquake magnitudes as high 6.0 in the year 2020; 6.5 between the year 2021 and 2022; 7.0 between the year 2025 and 2026 and 7.1 in the year 2028 with a 36.79% probability.The probability that an earthquake of magnitude 7.1 will be experienced from 2019 to 2028 also ranges from 9% to 36.79%. The findings of this work inform on the sizes of probable future earthquake magnitude and it is recommended that the government of Nigeria pays rapt attention to earthquakes in Nigeria

PREDICTION OF COLLAPSED LOAD OF STEEL COLUMNS USING FINITE STRIP METHOD

The solution of inelastic bifurcation of column is the eigenvalue and eigenvectors which can be solved by many methods such as Power Method and William-Wittrick algorithm which has been proven to be efficient. This study utilised a new method of solution algorithm that utilizes the decomposition of the net assembled structural global matrix into the lower and upper triangles leading to the calculation of the determinant of the decomposed matrix. The product of the squared leading diagonals is the determinant which is the error of the present calculation. This method has been demonstrated to be about 0.02% error. The conventional Finite Strip Method is programmed with the new solution algorithm using an object oriented programming concept (Java). The method is compared with the published work and the agreement between the current work and the reported experimental and numerical work is excellent. Residual stress is successfully implemented with the new solution algorithm

Effects of 12 Molar Concentration of Sodium Hydroxide on the Compressive Strength of Geopolymer Concrete

Geopolymer concrete is an emerging and innovative alkali-activated concrete that has been growingly studied because of its superior mechanical strengths and durability properties. This study, therefore, investigates the utilization of both corncob ash (CCA) and ground granulated blast furnace slag (GGBFS) as source materials activating with both sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions in the production of geopolymer concrete (GPC). Sodium hydroxide was prepared in 12 molar concentration using Grade 30 MPa mix design ratio. GGBFS was replaced by CCA in varying percentages 20, 40, 60, 80, and 100% and cured in ambient conditions. Slump, density, and compressive strength of GPC were determined and compared with Portland Cement Concrete (PCC) of the same grade. The research findings indicate an optimal strength of 100% GGBFS with a compressive strength of 43.17MPa at 28 days curing for GPC compared with 35.12MPa for PCC. The result reveals that GPC has better strength than PCC and, CCA and GGBFS can be utilized as aluminosilicate materials to replace cement in the production of GPC

PSEUDO-DYNAMIC EARTHQUAKE RESPONSE MODEL OF WOOD-FRAME WITH PLASTERED TYPHA (MINIMA) BALE MASONRY-INFILL

This study investigated the design and evaluation of strength property of typha strawbale wall cross section. Assumption were made on edge column acting as axially loaded members that can resist vertical members from the loads acting on the wall. Based on this, the objective of this work is to provide the average design thickness for the cement-plastered typha strawbale that can stiffen the wooden frame. Data on strength and deformation of the structure are the input for the analytical models. Pseudo-dynamic earthquake response tests was conducted on one quarter (¼) scale model in a low rise storey wooden frames stiffened with cement plastered strawbale masonry. The structure was idealized as a plane frame. The analysis utilized the hysteresis models for members’ models as time-independent. The force-displacement relationship of the members’ models was evaluated by the approximate method on the basis of the material properties and structural geometry. The finite element model was designed with straw bale infill panel to determine the hysteretic parameters, stiffness deterioration and strength degradation due to seismic forces

ICONIC STRUCTURES: CASE STUDY OF A HISTORIC MUSEUM WITH NOTABLE SPANS DESIGNED IN CONCRETE

The emergence of iconic structures around the world increased tourism and economic status of the of host cities. Iconic structures stand out and attract the attention of the general public due to their daring structural limits and aesthetic forms. Hence, the design idea of an iconic historic museum is conceptualized in this research. This paper models an art center, analyses and designs the critical elements according to BS 8110,trying to determine the feasibility of a large-cantilevering structure with numerous curves being achieved. The activities carried out in this research involved a systematic modeling of the structure with Building Information Modeling (BIM) tools, analysis and design in reinforced concrete with particular emphasis on the cantilevered wing of about 37.5m. Numerous load combinations were applied, and various member section properties were experimented. The results obtained from the analysis of the designed reinforced concrete model identified the structural efficiency of certain critical members in the west wing of the building and how they were made to adhere to structural limits in the code of practice by ensuring deflections of critical cantilevered members did not exceed the limit. A unique arrangement of structural systems has been combined to solve the problem of deflection of the seemingly impossible cantilever of 37.5m