Comparative Analysis of the Compressive Strength of Concrete With Gravel and Crushed Burnt Bricks as Coarse Aggregates
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 composition of material from coarse granular material such as coarse and fine aggregate mixing in a hard matrix of material that is cemented that fills the space of aggregate particles with an additive and bind them together (Saidi, 2007). It has been known widely in function for building foundations, architectural structures, walls, pavements and most of it in the construction industry.
It is important to identify the amount of each material mixing in production of concrete. This is to make certain that the concrete that will be produced is a quality concrete. Furthermore, to produce a high quality concrete it is important to give a careful attention in a technic of mixing concrete. Thus, the quality of each material being used, mixing rate, mixing skills, compaction skills affect the quality of concrete (Hanifa, Komposisi sisa bahan binaan dalam projek pembinaan perumahan, 2008).As what’s been discuss before this, the strength and performance of concrete are very much dependent quality material, mix design and cement ratio. For instance, the higher cement ratio will scale down the durability of the concrete.
Normally, concrete with the minimum compressive strength of 20 MPa or N/mm2 and above is suited for structural use such as shaft, column, shear wall and slab, while concrete with the compressive strength less than 20 MPa or N/mm2 are only suited for non-structural role.
Likewise, when the quality of the concrete does not fulfill such requirements that have been set, and handling is not practiced with care will result in lots of wastage to occur. Since concrete can be applied in various construction works, then it can be categories as follows:
- Reinforced concrete (foundation, structural member and footing done onsite)
- Pre-cast concrete (concrete that’s been already drawn from the mill)
- Concrete masonry units (hollow blocks, concrete form in a mold)
Cement
Cement is a material that has a cohesive and adhesion properties that enable binding chunks of rock into one cohesive body. There are dissimilar cases of cement made at factory for specific purposes and to conform to the specific demands. When the void between the aggregates is minimized, then the need for cement to fill the empty space can be reduced to maintain the workability and the strength of concrete. And so, the optimal mixing ratio of aggregates will produce a concrete with minimal quantity of cement contain. Therefore, the lower water and cement quantity of water and cement ratio (w/c) constant, would result a more durable concrete.
Even though cement is only contributed 10% of the concrete volumes in mixing, it is an active substance and a material that can be controlled scientifically. Cement consists of a mixture of silicate and aluminate compounds of calcium metal in a certain proportion. The ratio of chemical substances in each type of cement influences the properties of the cement. The types of cement that are often used in the construction industry such as:
- OPC, Ordinary Portland cement
- Modified cement
- Rapid hardened cement
- Low heat cement
- Sulfate resistance cement
Cement wills trough a chemical reaction process when it is mixed with water after concreting is done. It then will fill the hollows of the other ingredients so it becomes compact (Neville A. , 2005). Cement is a basic ingredient in concrete, mortar and plaster production. Cement binder that binds that binds the component materials of coarse and fine aggregates to a piece or solid body. The highest chemical materials contain in a Portland cement are Ca02 and Si02 and others consist of A1203, Fe203, MgO, and S03.
CHAPTER THREE
MATERIALS AND METHOD
Materials
The sand and gravel used for this project were obtained at the River Benue deposits. Comparison of Gravel & Crushed Over Burnt Bricks as Concrete Coarse Aggregates
Table 1: Average Specific Gravities of Constituent Materials.
The over burnt bricks samples were collected at a bricks production site at Ana area of Naka, Gwer West Local Government Area of Benue State. 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. The apparatus used are: Specific Gravity Bottle, Balance, Tamping Rod, Ruler, Head Pan, Shovel, 75mm Diameter x 50mm Deep Measuring Cylinder, Timer, Slump Cone, 14mm, 10mm and 2.35mm BS sieves. Others are: Hand Trowel, Compacting Machine, 0.15m × 0.15m × 0.15m Mould, Curing Tank, Scoops, Spanners, Electric Vibrator, Plunger, Base Plate, Compression Machine and Towel as well as stark of BS sieves and sieves Shaker.
Specific gravity (G.S), aggregate impact value (AIV) and aggregate crushing value (ACV) tests were carried according to BS 882, BS 812-112 and BS 812-110 respectively. Aggregate water absorption (AWA) test was conducted in compliance with BS 812-109 [14] while particle size distribution analysis was carried out according to BS 812-103.1. The result of the specific gravity test is shown in Table 1. While that of water absorption is shown in Table 2.
The concrete was batched and mixed according to Awolefe (2016). Slump test was carried out on the fresh concrete to determine the workability of the various proportions of the gravel to crushed burnt bricks in accordance with Philemon (2007). The result of the slump test is shown in Table 3 and Fig. 1.
The cube moulds were cleaned and oiled before each casting. Nine concrete cubes of 150mm were produced for each mix. A mix ratio of 1:2:4 was used. The coarse aggregate was a mixture of crushed burnt bricks and gravel in the proportions of 0:4, 1:3, 2:2, 3:1 and Table 3: Mixed Proportion of Gravel to crushed over Burnt Bricks, W/C Ratio and Slump.
CHAPTER FOUR
Results and Discussions
Sieve analysis
The result of the particle size distribution carried out in accordance with BS 812-103.1 [15] is presented in Figures 2 – 4.
From Fig. 2 more than 90% of the aggregate passed through sieve 4.75mm which places the aggregate as fine aggregate as (BS882) [11], and the assessment of the particle size distribution revealed that the aggre- gate is well graded.
Specific gravity
The specific gravity test result of sand, gravel and crushed over burnt bricks were respectively deter- mined to be 2.55, 2.71 and 2.17 as shown in Table
Table 4: Summary of Compressive Strength Test Results of Cubes Cast Using Various Mix Proportions of Gravel and crushed over Burnt Bricks and Cured for 28 days.
CHAPTER FIVE
CONCLUSION
The following conclusions can be drawn from this study:
- Crushed over burnt bricks can be used as partial replacement for river gravel in concrete production.
- Crushed over 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.
- Crushed over burnt bricks can also be used to pro- duce concrete with higher compressive strength with reduced weights if the bricks are properly and thoroughly burnt.
- Recycling of crushed over burnt bricks could aid in sanitizing the environment.
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