Thesis Abstract

<p>&nbsp;            <b>ABSTRACT&nbsp;</b></p><p>An enormous gap exists between the production capacities of the Cement Manufacturing Plants and the demand for cement in Nigeria. Prior to 2010, Nigeria could only produce between 4 and 6.5 million tons annually as against the domestic demand of about 18 million tons. There is the need therefore to augment the local cement production by the introduction of Natural Pozzolans of volcanogenic origins as partial replacements of the Ordinary Portland Cement (OPC) in concrete mixtures. The study thus focused on experimental works on the pozzolanic characteristics of Jos Plateau volcanic deposits as potential pozzolans for partial replacements of the OPC in concrete mixtures. The laboratory experimental studies evaluated the chemical characteristics of the volcanic materials and the pozzolanic characteristics of concrete made with the volcanic materials in partial replacement of the Portland cement in the concrete mixtures. The results of the chemical analysis indicated that the oxides of SiO2, Al2O3 and Fe2O3 are substantially present in all the samples tested. The sum of these oxides varied from 71.45 (JP14) to 95.31% (JP3). The average sum of the minor oxides obtained was 3.16%. However ASTM C (2001) recommends that sum of the minor oxides should not be more than 5% by weight. The average values of CaO, MgO, and SO3 were 0.29 %, 1.81 %, 0.53 % respectively of the 20 samples of materials tested. Furthermore alkalis (Na2O and K2O) average values were 0.25 % by weight of the samples tested. All the materials samples studied have no trace of carbon in any of the samples investigated. The results of test indicated that the LOI and the MC of the 12.3 and 2.3 % respectively. The MC values were within the ASTM C 109/C 109M (2001) maximum recommendations of 3%. While those of the LOI were slightly above the 10% recommendation of ASTM C 618 (2005).The result of the study further indicated that the Initial Setting and Final Setting Times were 2 hours 35 minutes and 3hours 30 minutes respectively. The result of soundness test tests of the Portland pozzolan cement paste showed the changes in volume varied from zero to 0.40%. ASTM C 618 (2005) recommended a maximum of 0.80%. The control cube had compressive strengths of 26.0 N/mm2 at 28 days curing. The results of the partial replacements of 5, 10, 15 and 20% of OPC with the volcanic materials were all above 75% of the control strength. The investigation established that Pozzolanic Activity Index with Portland Cement (PAIC) at 28 days for 5% to 20% replacement of OPC showed a sliding from an average index of 105 to 81.ASTM C 595(2006) minimum specification is an index of 75 for a pozzolan to be used Portland Pozzolana Cement in concrete mixtures. The volcanic materials can be used for cement Type IP Type P and (ASTM C 595 (2006).It is conclusive that the volcanic deposits possess pozzolanic characteristics as natural pozzolans for use in concrete. <br></p>

Thesis Overview

<p><b>1.0 INTRODUCTION&nbsp;</b></p><p><b>1.1 BACKGROUND TO THE STUDY&nbsp;</b></p><p>Concrete globally, is a crucial material for infrastructural development due to its versatility and flexibility in usage and application making it superior to other building materials such as wood and steel (Hossain et al, 2011).The versatile nature of the concrete makes its universal usage in construction next only to water. Altwair and Kabir (2010) averred that though concrete is superior to other materials, the production cost of its main constituents (cement) is excessive. European Commission (EC, 2001) stated that the average energy cost on the production of one ton of cement is 50% the total cost of the production; with the electricity demand at about 90-1300Kwh per ton of cement produced. Horst (2001) asserted further that about 1 barrel of fuel or ¼ ton of coal is needed for the calcinations of the limestone alone to produce 1 ton of cement. Jha and Prasad (2004) affirmed that low-cost or large scale housing can best be achieved by the replacement of costly conventional cementitious materials such as Portland Cement (PC) with innovative and sustainable materials such as the pozzolans. Hashmi (2008) stressed that even though the various cementitious alternatives may not be capable of replacing totally the PC at the moment, but they can however partially be replaced in a variety of construction applications such as in mortar and concrete mixtures. In line with the concept of producing cheaper alternative cementitious materials, an assessment of pozzolans of volcanogenic origins for partial replacements of the OPC in the concrete mixtures is earmarked. Thus the object of this study is to investigate the potentials of the volcanic deposits from Jos Plateau as pozzolanic materials for partial replacements of Portland cement in concrete mixtures. Wright (1989) had established that the Jos Plateau is within the historic volcanic deposits of Nigeria (Appendix ‘D’).The utilisations of the volcanic deposits from the Jos Plateau as raw materials for the production of alternative cements will reduce the OPC contents in concrete mixtures and also improve its engineering properties. Neuwald (2004) affirmed that pozzolans are such materials that can be used in partial replacements of Portland Cement (PC) in concrete mixtures or in cement blending. The word “pozzolana” according to Jackson (2003), is derived from the Latin words “Pulvis Puteolamus”, meaning the powder from Puteoli or the dust of Puteoli. These were a direct reference to the unconsolidated pyroclastic (ash) deposits of Campi flegrei and Vesuvius volcanic fields were the Romans first discovered the unique characteristics of the Natural Pozzolans. Wilson and Ding (2007) stated that, the Romans, while mixing lime and the volcanic ash quarried from Pozzuoli (believing it was sand) found out that the mixtures produced much stronger end results, than the previously mixed materials.&nbsp;</p><p>This discovery significantly altered the use of construction materials by Builders of the famous Roman historic structures such as the Theatre at Pompeii (seating 200,000 spectators), the Romans walls, aqueducts and several structures. Pozzolanas are thus cements of antiquities. Shetty (1982) positioned that this pozzolanic reactivity of the natural Pozzolanas accounts for the existence of ancient structures such as The Wharf of Caligula constructed with volcanic ash from Mt Vesuvius in Pozzuoli. The American Society for Testing and Material (ASTM) C 618 (2005) defined the pozzolans as siliceous or siliceous and aluminous materials, which in themselves possess little or no cementitious values but when, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties. Parhizkar et al (2010) has also defined Pozzolanas as materials containing reactive silica and/or alumina, which, alone have little or no binding property, but when mixed with portland cement, react with calcium hydroxide (produced from the hydration of the cement) to form a strong gel. Pozzolana cement is widely used in countries such as Europe, America, China and India for massive structures such as dams, bridges, roads and high rise buildings; and the volcanic materials in particular has been used in Europe, North America for partial replacement of the OPC in concrete mixes or for the production of a Blended Cement (Detwiler et al., 1996). Day (1990) reported that 32 countries (Appendix ‘AE’) have so far officially permitted the use of the pozzolans in partial replacement of the Portland cement; a replacement varying from 10% (Ice Land) to 50 % (Argentina, China and Indonesia).&nbsp;</p><p>But on the African continent, the report indicated that only South Africa and Morocco made the list with each allowing a replacement up to 15 % of the OPC. Citifmonline (2011) reported recently that the Ghana Standard Board has specified the use of pozzolan cement as a building material; and its use is compulsory for all government infrastructural projects. A growing economy such as Nigerian needs enormous amount of this cement to prop up its housing and other infrastructural developments. Armstrong (2009) reported that in 2008, Nigeria was third largest importer of cement in the world. Fiakpa (2008) reported that Nigeria imports about 11 million tons of its cement demands annually to meet up the domestic demand of the commodity. The Jos Plateau volcanic deposits are accordingly potential pozzolanic materials for cement blending or partial replacement of the PC in concrete mixtures. The prerequisite to the application is the assessment of the pozzolanic characteristics of the deposits with Standards such the ASTM C 618 (2005): Specification for Fly Ash and Raw or Calcined Natural Pozzolana or Use in as a Mineral Admixture in Portland cement Concrete.&nbsp;</p><p><b>1.2 THEORETICAL FRAMEWORK&nbsp;</b></p><p>The Theoretical Framework of this study is based on the assertions of researchers such as Detwiler (1996) and Day (1990) that primarily, the natural pozzolan originates from volcanogenic activities resulting from violent eruptions and ejections of melted magma from the molten earth; and that these rocks of volcanogenic origins posses cementitious properties once in finely divided form. Neuwald (2004) explained further that these materials react chemically with the calcium hydroxide Ca(OH)2 to form the compound possessing cementitious properties through what is referred to as the pozzolanic activity of the pozzolan. Further theory is that the chemistry of natural pozzolans varies from deposit to deposit because of the variable proportions of the constituents and the variable mineralogical and physical characteristics of the reactive oxides of silica, alumina and iron; and additional constituents, such as alkalis [sodium oxides (Na2O) and potassium oxides (K2O)] and other trace elements in varying degrees [ACI (2000), Intermediate Technology Development Group (ITDG, 2000)]. In addition to this theory, Day (1990) and Detwiler (1996) affirmed that virtually with all pozzolans; there has always been no clear correlation between the chemical characteristics of the pozzolan and the respective Pozzolanic Activity of the material.&nbsp;</p><p>The pozzolan activity of the Jos Plateau volcanic materials is therefore evaluated by assessing the oxides composition and the Pozzolanic Activity Index (also referred to as the Strength Activity Index) of each of the samples of the volcanic deposits in the location to ascertain its pozzolanic characteristics. The philosophy of this study is thus; if the existence of volcanogenic deposits on the Jos Plateau is established, then the deposits would exhibit pozzolanic concrete mix. Consequently it can be predicted that the Jos Plateau volcanic materials would have some levels of pozzolanicity such that its partial replacement of the OPC in concrete mixtures would achieve cheaper cementitious materials which invariably could result in a reduction of the overall cost of housing construction.&nbsp;</p><p><b>&nbsp;1.3 STATEMENT OF RESEARCH PROBLEM&nbsp;</b></p><p>Andrew (2007) stated that the provision of affordable housing has continued to pose a challenge to the developing countries, particularly the Sub-Saharan Africa. Oluwakiyesi (2011) reported that Nigeria for instance has a housing shortfall of between 16 and 18 million units which needs about N60 trillion to remedy deficit. This is so as housing production and its affordability are major challenges Nigeria faces as consequence of deficiencies in primary infrastructures such as roads, water and electricity (Sanusi, 2003). The housing short falls in Nigeria is intense. Okeke (2002) reported that the country can boast of only two to three dwelling units per thousand as against the United Nations recommendations of eight to ten units. The magnitude of the housing deficit in Nigeria according to Ajanlekoko (2001) is enormous and had defied solutions by government; the Federal Government of Nigeria (FGN) between 1979 and 1995 set out four National Housing Programmes to boost housing situation in the country as shown in Table 1.1 but with but to no respire. Okeke (2002) reported that out of the 120,000 units proposed by the FGN to be constructed between 1994 and 1995, only 1,014 were actually built. Table 1.1: National Housing Programmes; 1979 – 1995&nbsp;</p><p>PERIOD HOUSING PROGRAMME REMARKS 1979-1983 Federal Housing Scheme 400,000 units for four years 1986-1991 National Site and Services Scheme Site and Services only 1991-1993 National Prototype Housing Scheme Selected states only 1995 National Housing Scheme –Materials Provision to Contractors Aimed at addressing raising cost of materials Source: Okeke (2002) About two billion additional people are estimated to populate the earth in the next two decades, with 95% of this growth predicted to take place in the developing countries such as Nigeria; it is assertive that this type of growth in population would create an unprecedented demand for Housing and other Basic Infrastructures for the developing countries (Amadei, 2003). Thus the demand for housing will require enormous quantity of cement. The Nigerian Building and Road Research Institute (NBRRI, 2003) asserted that with the exception of doors and windows for a simple residential building, all the building components as shown in Table 1.2 use cement in one form or the other. <br></p><p> 1.4 NEED FOR THE STUDY There is a need for adequate cementitious materials for the infrastructural development of Nigeria in view of its deficits in housing and other basic infrastructures. Amadei (2000) asserted that in the next decade there will an unprecedented demand for basic needs such as health, food, energy, additional housing and other infrastructures particularly in the sub-Saharan Africa. Jha and Prasad (2004) then stressed that large scale housing for example are inevitable; and that to address such housing shortfalls, there is the need for the replacement of the costly conventional building materials such as the PC with alternative cementitious materials for instance the pozzolans for housing construction. The Jos Plateau volcanic deposits are thus potential materials for pioneering the alternative to Portland cement production.&nbsp;</p><p>Detwiler et al (1996) reported that a major economic benefit in the use of these alternatives is that it would substantially increase the capacity of a Cement Manufacturing Plant without an installation of a new kiln. The report also explained further that blending of PC with the Pozzolanas saved power and energy as little or no energy inputs are required prior to their utilisations. This is in contrast to the Manufacturing of OPC in which the energy utilisation is intense European Commission (EC, 2001). The applications of the volcanic materials for cement blending or for partial replacement of the OPC would reduce the cement content in the concrete mixtures and invariably reduce the cost of housing in Nigeria. In addition it will lower GHG emissions associated with the Portland cement productions. Therefore the study of the potential utilisation of volcanic deposits from Jos Plateau will not only transform the volcanic materials into an alternative cheaper cementitious material for the production of low-cost housing but will also yield social-economic benefits. Harris (2005) elucidated that cheaper cement, means more construction activities; and that construction activities are an employment generation source, particular in developing countries (second only to agriculture); with emphases that the utilisations of the Natural Pozzolanas for partial replacements of Portland cement would save as further local employment generate where these deposits are located (in mining and processing of the materials).&nbsp;</p><p><b>1.4 AIM AND OBJECTIVES&nbsp;</b></p><p><b>1.4.1 Aim&nbsp;</b></p><p>The study aims at assessing the effect of Jos Plateau volcanic deposits as natural pozzolans on blended ordinary portland cement concrete.&nbsp;</p><p><b>1.4.2 Objectives</b></p><p>&nbsp;i. To ascertain from literature and field survey the presence and the locations of volcanic deposits on the Jos Plateau.&nbsp;</p><p>ii. To determine the chemical and physical characteristics of the volcanic materials.&nbsp;</p><p>iii. To investigate the compressive strengths of concretes containing volcanic materials in partial replacements of the OPC in 5 %, 10 %, 15 %, 20 %, 30 % and 40 % replacements..</p><p>&nbsp;iv. To evaluate the durability of concrete containing the natural pozzolan using Autoclave Standard Test Method.&nbsp;</p><p>v. To evaluate the pozzolanic activity of volcanic deposits in concrete containing the Jos Plateau volcanic materials.&nbsp;</p><p>vi To identity a relationship between the chemical composition of the volcanic deposits and the pozzolanic activity of volcanic materials.&nbsp;</p><p><b>1.5 RESEARCH METHODOLOGY&nbsp;</b></p><p><b>1.5.1 Identification of the Volcanic Deposits</b>&nbsp;</p><p>The study was divided into field and laboratory works. A rigorous literature review was carried out to obtain indebt knowledge in the field of study. The field work consisted of a number of trips to various sites to spot out the locations of the volcanic deposits based on the following;&nbsp;</p><p>i. Volcanic conical hills and outstanding volcanic landmarks.&nbsp;</p><p>ii. Volcanic materials exposed of as results of soil erosion.</p><p>&nbsp;iii. Volcanic deposits exposed of as results of mining activities.&nbsp;</p><p>iv. Volcanic materials exposed due to road construction exploits.&nbsp;</p><p>The number of the volcanic complexes were identified and clustered into nine groups according the Local Government Areas (LGA) which the materials are located as follows:&nbsp;</p><p>Group I: Bassa LGA-three locations.&nbsp;</p><p>Group II: Jos North LGA- one location&nbsp;</p><p>Group III: Jos East LGA- two locations&nbsp;</p><p>Group IV: Jos South LGA- two locations&nbsp;</p><p>Group V: Riyom LGA- two locations&nbsp;</p><p>Group VI: Barkin Ladi LGA - two locations&nbsp;</p><p>Group VII: Bokkos LGA- two locations&nbsp;</p><p>Group VIII: Mangu LGA- five locations&nbsp;</p><p>Group IX: Pankshin LGA- one location&nbsp;</p><p>Pictures of volcanic hills; eroded volcanic soils; and soils exposed by relics of tin mining activities are shown in Appendix ‘H’ to ‘L’. Materials from various locations were thus collected for the study.&nbsp;</p><p><b>1.5.2 Assessing the Pozzolanic&nbsp;Characteristic of the Volcanic&nbsp;</b></p><p>Deposits The pozzolan activity of the Jos Plateau volcanic materials were evaluated by assessing the chemical characteristics and the Pozzolanic Activity (referred to as the Strength Activity) of the volcanic deposits to ascertain its pozzolanic characteristics and consequently the levels of pozzolanicity of each of the volcanic samples.&nbsp;</p><p><b>1.5.2.1 Chemical characteristics&nbsp;</b></p><p>The evaluation of the chemical characteristics of the volcanic materials and Compressive Strength Tests of Portland Volcanic Materials Cement concrete were evaluated to ASTM C 618 (2005) Standard Specifications for fly ash and the natural pozzolan to use in concrete Mixtures. The oxides composition of the volcanic deposits were evaluated by the Wet Chemistry and the Energy Dispersive X-Ray Fluoresce (EDXRF); and the Neutron Activation Analysis (NAA) methods were under taken at the National Metallurgy Development Centre (NMDC), Jos and the Centre for Energy Research and Training (CERT), Ahmadu Bello University (ABU) Zaria.&nbsp;</p><p>The Loss on Ignition (LOI) and the Moisture Content (MC) determinations were also carried out at the NMDC, Jos. The grounding of the volcanic materials and the Specific Gravity (SG) were determined at the Building Department ABU, Zaria. The chemical characteristics (Oxides composition, LOI and the MC) and the SG of the Dangote brand of PC; sieve analysis of the fine and coarse aggregates were also performed.&nbsp;</p><p><b>1.5.2.2 Pozzolanic Activity of concrete containing volcanic materials</b></p><p>&nbsp;The pozzolanic Activity of concrete containing volcanic materials from Jos Plateau volcanic deposits was determined according to the Standard Testing Procedure of ASTM 311 C (2005): Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete. The evaluation of the physical characteristics of and Compressive Strength Tests of concrete containing the Volcanic Materials were evaluated to specifications of ASTM C 618 (2005): Standard Specifications for fly ash and the natural pozzolan to use in concrete mixtures. The setting time, the compressive strengths tests and the pozzolanic activity index with Dangote cement were evaluated at the Building Department. While the soundness of the materials and Pozzolanic Activity with lime was investigated at the Chemistry Departments, ABU Zaria.&nbsp;</p><p><b>1.5.2.3 Appraisal of the potentiality of the Jos plateau volcanic deposits&nbsp;</b></p><p>The data obtained from the literature review, field works and laboratory investigations were used in evaluating the pozzolanic characteristics of concrete containing Jos Plateau volcanic deposits as a partial placement of OPC in concrete mixtures or in cement blending.&nbsp;</p><p><b>1.6 SCOPE AND LIMITATION&nbsp;</b></p><p><b>1.6.1 Scope&nbsp;</b></p><p>The scope of the research is to evaluate the pozzolanic characteristics volcanic materials selected from 20 volcanic sites from Jos Plateau by utilising ASTM 311 C (2005) standard tests procedures and other standards. The extents of the tests evaluation is to the recommendation of the Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete of ASTM C 618 (2005). The materials obtained for the study were excavated from the top surfaces of the volcanic hills; and exposed materials resulting from soil erosion, mining and road construction activities. The following laboratory analyses were carried out; Oxides composition, Loss on Ignition and Moisture Content and the Specific Gravity of each sample of the volcanic materials were evaluated. The compressive strengths of the concrete made with Portland Volcanic Material Cement (PVMC) and its respective Pozzolanic Activity Index of the pozzolans with the PC; the Setting Time; Pozzolanic Activity Index with Lime; and the durability checked by Autoclave expansion Standard Test Method (Soundness) of mortar containing the volcanic materials were also studied. The chemical and some physical properties of the Dangote cement used for the study were also investigated.&nbsp;</p><p><b>1.6.2 Limitations&nbsp;</b></p><p>The major limitations were the non-availability of land maps and aerial photographs to depicting specific volcanic areas of the Jos Plateau Volcanic Province. These limitations were also reported by Olowolafe (2000) while evaluating the data for its soil mappings of the Jos Area. The information from literature review land marks Volcanic features and the exposal’s of the volcanic materials, as results of physical activities such as soil erosion, mining and road construction exploits in the area of the study was used. Consequently, the exact or accurate boundaries of the volcanic Sites or locations or grouping would not be definite. The characteristics of historic volcanic eruptions are that they occur in stratified deposits layers depending on the volcanic activity; they are made up of fresher overlying (overburden) materials and other strata. The materials samples were collected from the overburden (top layer) strata in all the locations. Thus results of the samples tested may not reflect the true characteristics of the other layers of the deposits as the other layers may produce varying pozzolanic characteristics. The effect of silica-alkali reaction, freezing-thawing, permeability (porousity) and exposal to other harsh environment (are related to long term related durability issues) on concrete containing the Jos Plateau volcanic materials were not evaluated; first as the ASTM C 618 (2005) limits the assessment of the pozzolanic activity at 28 days; and concept of the study ab initio is to assess the availability and potentiality of the volcanic deposits as Supplementary Cementitious Materials for partials replacement of the costly Portland cement in concrete mixtures. The chemical evaluation of Dangote cement showed that SiO2 and AI2O3 were 49.6 and 43.3 % respectively by weight below the recommended values of ASTM C 150 (2004). CaO were also found in excess 18.6% above the upper limits and the LOI was 8.8 % as against the recommendations of 0.3 % of the ASTM C 618 (2005). These might have affected the compressive strengths of both the control cubes and the cubes containing the volcanic materials.&nbsp;<br></p>