Full Project – Comparative analysis of strength characteristics of concrete produced from different coarse aggregates sourced in Aba, Abia state

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CHAPTER ONE

INTRODUCTION

BACKGROUND OF THE STUDY

Concrete is a major component of infrastructural facilities in the 21^st century because of its versatility in use. It is used more than any other man made material in the world (Anosike, 2011). Base on its properties i.e. strength, rigidity and easy formability coupled with the easy availability of the component materials have made concrete the materials of choice for Architects, Engineers, Builders and developers. Concrete as a composite construction materials is made up of three basic component, cement,aggregate and water and if not provided in a required proportion will greatly affect the quality of the concrete (Duggal, 2008).

Concrete aggregate and paste are the major factors that affect the strength of concrete (Shetty, 2005), the properties of aggregate greatly affect the durability and structural performance of concrete as aggregate with undesirable properties cannot produce strong concrete (Neville, 2011), Although it is not necessarily true that aggregate whose properties all appear satisfactory will always make a good concrete, and this is why the criterion of performance in concrete has to be used. According to Mehta and Monteiro (2001), the aggregate exercise a significant influence on strength, dimensional stability, and durability of concrete. Therefore, concrete strength is govern by aggregate size, type and source (Hassan, 2014; Agimam et al., 2013; Jimoh and Awe, 2007; Abdullhi, 2012).

The most significant mechanical property of concrete is the compressive strength of concrete. It is obtained by measuring concrete specimen after curing for 28days.Some of the factors that influence the concrete strength include aggregate quality,cement strength, water content and water/cement ratio(Noorzaei et al.,2007).According to Ayininuola and Olalusi (2004) and Ede (2011), the use of substandard materials for concrete is the leading cause of building collapse in Nigeria. Therefore, an examination of the strength of concrete made from coarse aggregates obtained from different sources within the construction area is required to overcome the problem of building collapse due to concrete failure. This problem has let many researchers on concrete strength and the various test solutions to getting a better and workable concrete so as to saves occupants from the danger of structure failures which is mostly as a result of non-standard materials used in the concrete.

Aggregate as defined by UNESCO-NT and VERP II, (2008) are “materials comprising of percentage required from gravel,crushed stone and natural sharp sand of their specific size of particle mixed together at a required ratio to form part of concrete mortar.”The Council of Registered Builders of Nigeria (CORBON) and Nigeria Institute of Building (NIOB),(2014), stated that aggregates are the granular filler material such as sand, stone dust, gravel,crushed stone, crushed blast-furnace slag, etc. that are used with binder such as Portland cement to produce concrete. Bert-Okonkwo, (2019) as citing Ezeokonkwo, (2014) also described aggregates as inert or chemically inactive materials which form the bulk of cement concrete and are bounded together by means of cement as a binder.

Aggregate used in construction basically comes in two different sizes-the bigger ones known to be coarse aggregate (grit) and the smaller ones – fine aggregate(sand),(Ezeokonkwo, okolie and Ogunoh, 2015), Furthermore, Ezeokonkwo, Okolie and Ogunoh, (2015) stresses that coarse aggregate form the filler matrix between the coarse aggregate. Since up to 70-80 percent of the total volume of concrete consists of aggregate. Therefore, aggregate characteristic significantly affects the performance of fresh and hardened concrete and also have impact on the cost effectiveness of concrete (Quiroga and Fowler, 2003). Aside the aforementioned, aggregate characteristics such as shape, texture, and grading influence workability, finishability, bleeding,pumpability, and segregation of fresh concrete also affect the strength, stiffness, shrinkage, creep, density, permeability, and durability of hardened concrete.

In our society today, some of the cement brands that are being sold are not up to standard and this may be traced to negligence on the part of the manufacturers by paying very little attention to the quality of the cement. Also the regulatory body has failed to put strict measures to enforce the required standard. This problem has resulted to the production of poor quality cement that has led to the production of low strength of concrete.Cement as we know was first developed by Joseph Aspdin, an enterprising 19^th century British stonemason, who heated a mix of ground limestone and clay in his kitchen stove, then pulverized the concoction into a fine powder. The result was the world first hydraulic cement (one that hardens when water is added). Aspdin dubbed his creation Portland cement due to its similarity to a stone quarried on the isle of Portland, off the British coast. In 1824, this brilliant craftsman obtained a patent for what would prove to be the world most ubiquitous building material, laying the foundation for today global Portland cement industry.

So far, there have been researches on concrete strength and the various test solution to getting a better and workable concrete so as to saves occupants from the danger of structure failures which is mostly as a result of non-standard materials used in the concrete.The components of concrete have been examine by many researchers such as Bert Okonkwo, (2012) who discusses the strength of concrete produced in Anambra state using different brand of cement, and he stated that of all cement used in the production of concrete using different brand of cement that SUPASET yielded the highest compressive strength of 31.70N/mm² with slump ranging between 70-140 at 28days strength and a concrete mix ratio of 1:2:4. Anosike, (2011) was able to discuss all the parameters that will be requires for the production of a sound and workable concrete. So far, they have been able to discuss and research among properties yet there have been little or no change in the collapse of structures in which concrete occupies about 70-80% of the aggregate used in the construction. Thus, investigation of the compressive strength of concrete produced from coarse aggregate obtained from the study area is the main focus of this research. This study will use the coarse aggregate of the same size, utilize cement of the same strength, water content and water/cement ratio inorder to determine the influence of aggregate sourced to determine concrete strength produces within the study area.

The outcome of this study would enable the provision of data on concrete strength of coarse aggregate sourced within the study area and also help to avoid the use substandard coarse aggregates source materials that might contribute to low or poor concrete strength. In this project, although concrete is made up of different components, we will be restricted on the component coarse aggregate.

1.2. STATEMENT OF THE PROBLEM

Concrete fail when it can no longer provide the required strength to support its designed load. The failure of Concrete can sometimes be mild with visible cracks and deflections or severe crack, leading to partial or total collapse of the structure either during the construction or post- construction stage. Incidences of failures of structures linked to bad concrete practice are common in Nigeria particularly in our major cities such as Lagos, Port Harcourt, Abuja, Aba, among others.

The findings of the committee of enquiry that investigated the collapsed of four-storey building at Okpuno, Awka, Anambra state capital in September 2008 reported that the building collapsed the same day the casting of the concrete third floor slab was concluded. The incident, took the lives of four persons. The report further revealed that among the causes of the collapse was the use of sub- standard materials’ stating that – poor quality of stone aggregates materials were used for concrete production (Ezeokonkwo,Okolie and Ogunoh,2015).

In order to curb the incidence of building collapse across the globe, several researches has been carried out at different times by different individuals, corporate bodies and civic society to ascertain the strength and/or quality of materials used in concrete production. Attention mainly is placed on reinforcements and cements, with little on the aggregates. However, in Abiastate little research has been made in order to ascertain the quality of the coarse aggregate sourced within the study area.

1.3 AIM AND OBJECTIVES

1.3.1 Aim of the Study

The aim of this research is to comparatively analyze the strength characteristics of concrete produced from different coarse aggregate sourced in Aba, Abia state.

1.3.2 Objectives of the Study

The aim of this study will be achieved through the following objectives:

To determine and compare the strength characteristics of concrete produced using coarse aggregate sourced within the study area.
Discuss concrete materials and strategies for achieving a good concrete strength and also to establish the constituent’s proportion to achieve a better concrete strength.
Determine the difference between the strength characteristics of concrete produced using local coarse aggregate sourcedwithin the study area

1.4 RESEARCH QUESTIONS

What should be the targeted strength of concrete produced using coarse aggregate source within the study area.
What is the compressive strength of concrete produced using coarse aggregate sourced within the study area.
What is the difference between the compressive strength characteristics of concrete produced using the different samples sourced within the study area.

1.5 HYPOTHESIS

There is no significant difference between the concrete produced from coarse aggregates sourced within the study area.

1.6 SIGNIFICANCE OF THE STUDY

This research will be of benefit to the building construction industry, all the professionals in the built environment, government agencies responsible for the implementation and enforcement of the national building code of practice,the National Institute of Building,Council researchers, and the general of Registered Builders of Nigeria, clients and public to help them guide against the strength of concrete production.This research will also serve as a reference and an eye openeron howlocal coarse aggregate use in the production of concrete within the study area and the strength of these concretes.

1.7 SCOPE AND DELIMITATION OF THE STUDY

1.7.1 Scope of the study

Samples for these study will be obtain from Owerintasand and Gravel Cont. (4, Umuoshela Rd., Aba,) and Umunneohi all in Aba Abia State.

1.7.2 Delimitation of the study

Abia state has taken over the led in case of collapse buildings especially non-government owned residential buildings and most of these recent events occurs majorly in Aba, Abia State.

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