Comparative Analysis on the Strength of Concrete Made With Local Gravel and Granite as the Coarse Aggregate

Comparative Analysis on the Strength of Concrete Made With Local Gravel and Granite as the Coarse Aggregate

Chapter One

AIM AND OBJECTIVES

This research is aimed at finding out whether crushed burnt bricks can be substituted for gravel as coarse aggregates in the production of concrete. The objectives include:

To determine the compressive strength of concrete with gravel and crushed burnt bricks or brick bats as coarse aggregates.
To determine the optimum mix ratio.
To compare the compressive strength of concrete with gravel and crushed burnt bricks as coarse aggregates.
To determine the effect of partial substitution of gravel with crushed burnt bricks as coarse aggregates on the compressive strength of concrete.
To develop a model for predicting the compressive strength of gravel-crushed burnt brick concrete.

CHAPTER TWO

LITERATURE REVIEW

CONCRETE

Concrete is a composite construction material, consisting mainly of a binding material; cement (commonly Portland cement), aggregate (generally coarse aggregate made of gravel or crushed rocks such as granite, plus fine aggregates such as sand), water and sometimes, chemical admixtures. Following a chemical process known as hydration, water reacts with cement to form paste which binds the aggregates together, eventually creating a robust stone-like material called concrete (Shetty, 2010).

According to Jean-Paul (2004), concrete is an artificial material reconstituted from three primary components that are: aggregates (or inert matter: sand, gravels, pebbles, etc.), a binder (lime, tar, cement, etc.), a reactive that can play two roles: that of reactive and binder or a single role as the water which only intervenes as reactive. The fresh concrete forms a wet mass, more or less plastic, that can be poured in moulds or formworks.

In its simplest form, concrete is a mixture of paste and aggregates. The paste, composed of Portland cement and water, coats the surface of the fine and coarse aggregates. Through a chemical reaction called hydration, the paste hardens and gains strength to form the rock-like mass known as concrete.

Within this process lies the key to a remarkable trait of concrete: it is plastic and malleable when newly mixed, strong and durable when hardened. These qualities explain why one material, concrete, can build skyscrapers, bridges, sidewalks and superhighways, houses and dams (Portland Cement Association, 2011).

According to Dvorkin and Dvorkin (2006), twenty-first century concrete has entered as the basic building material appreciably defining level of a modern civilization. The world volume of application of concrete has reached 2 billion m³. They see the advantages of concrete as unlimited raw-material base and low cost, environmental acceptability, application possibility in various performance conditions and achievements of high architectonic-building expressiveness, availability of technology and possibility of maintenance of high level of mechanization and automation of production processes, which cause attractiveness of this material and its leading positions on foreseeable prospect.

CEMENT

In the most general sense of the word, cement is a binder, a material that sets and hardens independently, and can bind other materials together. However, for constructional purposes the meaning of the term cement is restricted to the bonding material used with stones, sand, bricks, building blocks, etc. Cement used in construction fall under two categories, based on cement properties; hydraulic and non-hydraulic (Wikipedia). Non-hydraulic cement cannot harden while in contact with water. It was the first form of cement used by early scientists (Central Asian Cement). Hydraulic cements, on the other hand, have the property of setting and hardening under water. Neville (1995) broadly classified them as natural cements, Portland cements and high-alumina cements.

Of the many varieties of hydraulic cements, the most commonly used today is the Portland cement. It is the basic ingredient of concrete, mortar and plaster. It consists of a mixture of oxides of calcium, silicon and aluminum (Wikipedia). Cement is a hydraulic binder, that is a finely ground inorganic material which, when mixed with water, forms a paste which sets and hardens by means of hydration reactions and processes and which, after hardening, retains its strength and stability even under water(BS EN 197-1, 2000).

CHAPTER THREE

MATERIALS AND METHODS.

MATERIALS.

The sand used for this project was obtained at the River Benue deposits. The sand was prepared according to the standards specified by BS 882 (1992). The grading was carried out to BS 812: 103(1985). The sand belongs to zone C (Neville, 1995). The gravel, like the sand was obtained from River Benue deposits. The burnt bricks samples were collected at a bricks production site at Ana area of Naka, Gwer West Local Government Area, Benue State. The maximum size of aggregate used was 20mm. Ordinary Portland cement from Benue Cement Company (BCC), Gboko, Nigeria was used as binding agent and water used for mixing was from the Makurdi water works.

METHODS.

SOURCES OF DATA

All the data for this study were obtained from tests carried out at the Concrete Laboratory of the Benue State Ministry of Works and Transport, Makurdi.

CHAPTER FOUR

RESULTS, VERIFICATION AND DISCUSSION.

SPECIFIC GRAVITY

The specific gravity test result of sand, gravel and crushed burnt bricks were respectively determined to be 2.55, 2.71 and 2.17 as shown in Table 4.1. The specific gravities of sand and gravel were within the values reported by (Bowles, 1997). Crushed burnt bricks however, had a low specific gravity of 2.17. Bhattacharjee et al (2011) found the specific gravity of crushed burnt bricks to be 1.71. The difference in value is due the type of soil used in making the bricks as well as the degree to which the bricks were burnt.

CHAPTER FIVE

CONCLUSIONS AND RECOMMENDATIONS.

CONCLUSIONS.

From this study, the following conclusions can be drawn:

Crushed burnt bricks can be used as partial replacement for river gravel in concrete production.

Crushed burnt bricks can be used to produce concrete with lower weight and hence lower dead loads as such can be used on low bearing capacity soils.
The optimum mix ratio for maximum compressive strength of concrete with gravel and crushed burnt bricks as coarse aggregates is 1:1.

Crushed burnt bricks can also be used to produce concrete with higher compressive strength with reduced weights if the bricks are properly burnt.
The models developed can be used to predict the 28^th day compressive strength of gravel-crushed burnt bricks concrete.

RECOMMENDATIONS.

From the forgoing, crushed burnt bricks can be used for both partial and complete replacements for river gravel in normal construction works especially in localities where river gravel is in short supply or too expensive to procure but burnt bricks are available.

Crushed burnt bricks can be used as coarse aggregates in concrete to reduce the overall weight of the structures and hence the sizes of the foundations especially in low bearing capacity soils. This will in turn reduce the overall cost of the structures.

Recycling of crushed waste burnt bricks could also aid in sanitizing the environment.

The use of optimization model is recommended for beforehand prediction of compressive strength.

References

Agbede, I. O. and Manasseh, J. (2008). Use of Cement-Sand Admixture in Laterite Brick Production for Low Cost Housing. Leonardo Electronic Journal of Practices and Technologies. (pp.163-174).
Ahmad, S. and Shabir, Z. (2005). Effect of Different Mix Ratios and Water Cement ratios on Sulphate Attack on Concrete. 30th Conference on OUR WORLD IN CONCRETE & STRUCTURES. Singapore. 23 – 24 August. http://cipremier.com/100030012.
Ahmad, S. and Shabir, Z. (2005). Effect of Water Cement ratio on Corrosion of Reinforced concrete. 30th Conference on OUR WORLD IN CONCRETE &
STRUCTURES. Singapore. 23 – 24 August.
http://cipremier.com/100030013.
Aerican Concrete Institute. (1999). Aggregates for Concrete – Materials for Concrete Construction. ACI Education Bulletin E1-99.
Bhattacharjee, E., Nag, D., Sarkar, P. P. and Haldar, L. (2011) “An Experimental Investigation of Properties of Crushed over Burnt Brick Aggregate Concrete”, International Journal of Engineering Research and Technology. ISSN 0974-3154 Volume 4, Number 1, pp. 21-30.
Bowles, J.E (1997). Foundation Analysis and Design, 4^th Edition. McGraw Hills International. New York.
Bricks, S. (2000). Clay Bricks Specification. Shawberick. New York.

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