International Journal of Science, Technology and Society
Volume 4, Issue 6, November 2016, Pages: 80-88

Effects of Using 0.5, 0.55 and 0.6 Water Cement Ratio Separately With a Nigerian Grade 42.5R Portland Cement

Isaac Akiije

Department of Civil and Environmental Engineering, Faculty of Engineering, University of Lagos, Lagos, Nigeria

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To cite this article:

Isaac Akiije. Effects of Using 0.5, 0.55 and 0.6 Water Cement Ratio Separately With a Nigerian Grade 42.5R Portland Cement. International Journal of Science, Technology and Society. Vol. 4, No. 6, 2016, pp. 80-88. doi: 10.11648/j.ijsts.20160406.11

Received: July 3, 2016; Accepted: July 11, 2016; Published: October 28, 2016


Abstract: This research paper is for the purpose of disseminating the results of an investigation into the effect of water cement ratio of 0.5, 0.55 and 0.6 separately while producing most commonly practiced concrete of cement, fine aggregate and coarse by 1:2:4 mixtures. This research study is limited to the use of newly grade 42.5R Portland cement that is being produced in Nigeria recently and of which is readily available. River sand was used as fine aggregate and coarse aggregates used separately were washed gravel, 19 mm and 12.5 mm granites. Nine different concrete mixtures were produced and it is important to note that the results of their slump tests deviated considerably from that of the compacting factor tests correspondingly while considering the degree of workability values. Conducting this research the potential impact derived is that only the use of 19 mm granite with water cement ratio of 0.5 and 0.55 achieved at 28 day flexural strength concrete grade of 4.92 N/mm2 and 4.84 N/mm2 respectively whilst are marginally greater than the standard specification value of 4.5 N/mm2. The significance of this study is that while at when the flexural strength of concrete is satisfied the corresponding tensile strengths values which are 2.684 N/mm2 and 2.590 N/mm2 do not satisfy the required standard specification values which are respectively 3.355 N/mm2 and 3.238 N/mm2. The contribution to knowledge as regards to this research work is in the enlightenment benefit revealed upon the possible prevention of economic loss that can occur due to early rigid pavement failure for roads, petroleum filling station concrete pavements in cities and rural towns or yards for offices and factories due to design of poor concrete proportioning and the use of the new cement.

Keywords: Workability, Flexural, Compressive, Tensile, Strength, Economy


1. Introduction

In Nigeria, construction which involved development of rigid pavements for roads, playgrounds, domestic and factory yards were carried out of which grade 42.5R Portland cement that is relatively new is now most widely used along with 1:2:4 concrete mixtures. The manufacturing of Portland cement grade 42.5R is relatively new in Nigeria but its use is already comparatively high as it is mostly found easily in the open markets and on construction sites. This paper is limited to strength characterization of a Nigerian grade 42.5R Portland cement concrete using three selected coarse aggregates. Portland cement, aggregates and water are the most widely used materials in the production of basic concrete mix design although an admixture may be added for modification of its properties. The problem in the proportioning of concrete using mixtures of cement, fine, and coarse aggregate along with applied water cement ratio is how to get desirable concrete properties such as strength, durability and due economy for the intended structure. Portland cement is a finely-ground powder which, in the presence of water, has a chemical reaction along with hydration during and after setting and hardening forming a very strong and durable binding material. The bulk density of cement normally reflects the volume taken up by the cement plus any air trapped between the particles and the mass of the material whereas the relative density or specific gravity considered only the weight of the cement particles themselves. Cement relative density is considered in the region 3.11-3.15 and that of its bulk density of being general purpose is approximately 1000-1300 kg/m3. Water that is meant for use in the production of Portland cement concrete must be drinkable and free from alkalis, acids, oil and organic matter. Addition of Portland cement with water is the paste and forms active ingredient of the concrete whilst aggregates including sand and stone are inert ingredients. The main aggregates in use for road pavements in combination with a Portland cement material are either natural rock materials, gravels and sands, or slag aggregates. Admixture may also be added to water before the production of the concrete.

Marotta [1] claimed that determining concrete quantities for a construction project requires volumetric calculations with addition of appropriate waste factor ranging from 3 to 8 percent. However, Hebhoub et al. [2] resolved that some of the factors which may affect the workability of concrete are the grading and shape of sand, the proportion of fine to coarse aggregates, and the characteristics of the aggregates. They have given useful information about concrete proportioning to achieve desired amount of concrete production and workability. Ukpata and Ephraim [3] investigated flexural and tensile strength properties of concrete using lateritic sand and quarry dust as fine aggregate and concluded that the proportion of lateritic sand content should be kept below 50% for structural works. Therefore, they have subjected their investigation to defined limitation of which a desired strength for road pavement may not be achieved. According to Ilangovana et al. [4] aggregates size distribution is one of the most important properties that influence several concrete characteristics that include workability, mechanical strength, durability and water absorption. Traditionally, concrete has been accepted to be a durable material but this view is no longer strongly held. Falade [5] claimed that inadequate design, care and supervision during construction and wrong choice of construction materials are among the reasons for concrete incapability to satisfy this requirement. Aggregates size distributions and water cement ratios are given considerations in this study in order to determine the strength and durability characteristics of the concretes produced and their worth.

The study in this research paper aims at investigating the characterization of concretes produced using grade 42.5R Portland cement along with three selected coarse aggregates separately with the same river sand regarding concrete strength developed for worthy highway pavement. Specifically the objectives of this research are to:

a. Define the specific chemical and metallic composition properties of the cement used together with the determination of its initial and final setting times;

b. Determine the particle size distribution for both the fine and coarse aggregates along with their fineness modulus, coefficient of uniformity and coefficient of curvature;

c. Define and compare different concretes made of the cement, river sand and granite or gravel with varying water-cement ratio of 0.5, 0.55 and 0.6 while using 1:2:4 mixture individually;

d. Determine and compare the workability of the fresh concretes prepared through the slump test and the compacting factor test and;

e. Carry out laboratory tests to destruction of hardened concrete specimens prepared in order to determine flexural, compressive and tensile strengths.

The main scope of work in this study therefore includes using 19 mm granite, 12.5 mm granite and washed gravel individually in the production of concretes for city and rural street pavement construction with strength comparison considerations where the materials are readily available. Significantly, this study provides information upon the use of grade 42.5R Portland cement alongside the local content resourceful reliability. The justification for this research work is in the enlightenment on the economy associated to the failure of concrete commonly produced locally in Nigeria for the construction of highway pavement for petroleum filling stations in cities and rural towns or office and factory yards.

2. Materials and Methodology

The design mix for the hardened concrete produced for this research work contained the following four ingredients which are water, cement, fine aggregate and coarse aggregate. The kind of water used is the drinkable water found in the concrete laboratory of the department of Civil and Environmental Engineering, University of Lagos. The type of cement used for this investigation is relatively new in the Nigerian markets and it is the grade 42.5R ordinary Portland cement Type I whose properties conformed to AASHTO M 85 [6] and also being produced in Nigeria. Type I Portland cement is suitable for general concrete construction and where no special properties are required. The cements were supplied in 50 kg per bag and were well protected from dampness by placing them on planks to avoid lumps in the laboratory. Each bag of cement opened was used within 30 minutes. The relative density or specific gravity of cement used was determined according to ASTM C 188 [7] whilst the bulk density was determined as its weight per unit volume. The fineness of the cement used was measured by determining the percent passing the 0.045 mm sieve in accordance to ASTM C 430 [8] procedure. The cement was subjected to initial and final setting time tests based on measurements by the Vicat apparatus according to ASTM C 191 [9]. In the process, the time when a penetration of 25 mm occurred was determined and recorded as the initial setting time while the final setting time was when the needle did not penetrate visibly into the paste. Atomic absorption spectrometer methodology with high performance of low detection limits and accuracy was adopted in the laboratory to carry out the cement chemical elements composition and metallic components using the absorption of optical radiation by free atoms in the gaseous state.

Ogun River sand from Lagos environs used was air dried in the laboratory for concrete production. The gradation test was performed on the sample that passed through sieve 9.5 mm and retained on 0.075 mm after agitation of nest of the sieves according to AASHTO T 27 [10]. In the process, a nest of sieves with apertures 9.5 mm, 4.75 mm, 2.36 mm, 1.18 mm, 0.60 mm, 0.30 mm, 0.15 mm and 0.075 mm were used for the fine sand grain-size classification. Also, 19 mm, 12.5 mm granites and the washed gravel, obtained from Abeokuta environs in Ogun State of Nigeria were separately air dried in laboratory for the purpose of sieve analysis tests and concrete production. In the process, a nest of sieves with apertures 25 mm, 19.0 mm, 12.5 mm, 9.5 mm, 4.75 mm, 2.36 mm, 1.18 mm, 0.60 mm, 0.30 mm and 0.15 mm were appropriately used for grain-size classification of samples for the purpose of aggregate gradation. The test on size and gradation of coarse aggregates was performed according to AASHTO T 27 [10].

The specific gravity of the fine aggregate used was determined according to AASHTO T 85 [11] specification. Also, the specific gravities of the three coarse aggregates used were determined separately according to AASHTO T 84 [12] specification. The bulk densities for the aggregates 19 mm granite, 12.5 mm granite, washed gravel and fine aggregates used were determined separately according to AASHTO T 19 [13] specification. The specific gravity value of water used in this study is 1 while its bulk density is 1000 kg/m3. The specific gravity value of cement is 3.15 while the bulk density is 1100 kg/m3. The specific gravity value of sand determined is 2.65 while the value of the bulk density of the sand determined for the concrete production is 1600 kg/m3. The specific gravity values obtained for 19 mm, 12.5 mm granites and washed gravel are 2.7, 2.7 and 2.65 respectively while their respective bulk densities are 1560 kg/m3, 1580 kg/m3 and 1620 kg/m3.

2.1. Proportioning of the Concrete Mixtures

Owing to the use of three types of aggregates which are 19.5 mm granite, 12.5 mm granite and washed gravel separately as well as three types of water cement ratio that are 0.5, 0.55 and 0.6 individually, nine batches of concrete were produced. The total volume of nine batches of concrete, Vcb produced in the laboratory with entrainment air of 2 percent and 7 percent wastage is equal to 2.358 cubic metres. Volume of the concrete constituents per batch determined is in Table 1. The proportions of water, cement, fine and coarse aggregates determination was based upon the absolute volume method in order to ascertain the proportion that will give satisfactory strength, durability and economy when used for highway pavement. In the process of the absolute volume method, the specific gravity and bulk density of each ingredient were given consideration while calculating each constituent that produced absolute volume of concrete per 50 kg cement bag in m3. Subsequently, the volume obtained is converted into weight for the determination of the batching of the concrete constituents.

Table 1. Volume of the concrete computation constituents per set of specimens.

Label Beam Cube Cylinder Total
Strength Test Flexural Compressive Tensile Splitting  
Size, mm 150 x 150 x 550 150 x 150 x 150 150 x 300  
Testing Days After Curing 7, 14, 21, 28, 56 & 91 7 & 28 7 & 28  
Number 6 x 3 = 18 2 x 3 = 6 2 x 3 = 6  
Concrete Volume V, m3 0.223 0.010 0.016 0.249
Volume of concrete per set of specimens with entrainment air of 2 percent and 7 percent wastage, Vcpss = 0.262 m3; [0.249(1-0.02+0.07)]
Total volume of concrete for nine sets of specimens produced with entrainment air of 2 percent and 7 percent wastage Vct = 2.358 m3

In the process, the mixture to be used was firstly assumed in the proportion of part of cement  that its value is normally 1 to  part of fine aggregate and to  part of coarse aggregate for a fixed water cement ratio which is always less than 1. Also, the already determined bulk densities of cement, fine aggregate and coarse aggregate which are ,  and  respectively were used along with their respective specific gravity ,  and . It is worthy of note that the bulk density of water  is 1 and that of its density  is also 1, Also, in the determination of the concrete production respective weights of constituents of water, cement, fine and coarse aggregates are defined as  respectively.

For a unit weight of Portland cement, the volume of concrete  produced is given by Equation 1. Table 2 gives expressions for the modalities of using Equation 1 for the possibilities of obtaining absolute volume concrete in m3per 50 kg bag of cement and absolute weight of concrete for batching of Vcb m3 given consideration to bulk densities of the materials used. A useful template for the determination of absolute weight concrete for batching of Vcb m3 is in Table 3 while employing Microsoft Excel Spreadsheet. Table 4 is showing the values of absolute concrete weight for batching of 0.262 m3 in terms of each concrete material constituent for water cement ratio of 0.5 and 19 mm granite.

(1)

Table 2. Expressions for the computation of the absolute volume and absolute weight of concrete per batch. 7.

Table 3. Modelling of absolute volume and absolute weight of concrete per batch.

  B C D E F G
3 Label Water Cement Fine Aggregate Coarse Aggregate Sum
4 Assumed Ratio 0.5 1 1.375 2.821
5 Bulk Density 1000 1100 1600 1560
6 Applied Ratio by Weight =C4 =D4 =E4*E5/D5 =F4*F5/D5
7 Specific Gravity 1 3.15 2.65 2.65
8 Absolute concrete volume per 50 kg cement bag, m3 =C6*50/1000/C7 =D6*50/1000/D7 =E6*50/1000/E7 =F6*50/1000/F7 =SUM (C8:F8)
9 Absolute concrete weight for 0.262 m3 volume =D9*C6 =0.262/G8*50 =D9*E6 =D9*F6 =SUM (C9:F9)

Table 4. Simulation of absolute volume and absolute weight of concrete per batch in relationship to Table 3.

  B C D E F G
3 Label Water Cement Fine Aggregate Coarse Aggregate Sum
4 Assumed Ratio 0.500 1.000 1.375 2.821
5 Bulk Density 1000.000 1100.000 1600.000 1560.000
6 Applied Ratio by Weight 0.500 1.000 2.000 4.001
7 Specific Gravity 1.000 3.150 2.650 2.650
8 Absolute concrete volume per 50 kg cement bag, m3 0.025 0.016 0.038 0.075 0.154
9 Absolute concrete weight for 0.262 m3 volume 42.507 85.013 170.026 340. 052 637.598

2.2. Materials Batching and Concrete Specimens Production

Batching of the mixture started through measuring and pouring concrete constituents into the rotating mixer as proportioned in Table 5. The rotating mixer was charged with 10% of the required water followed by 50% of the coarse aggregate, then 100% of the fine aggregate and followed by 100% cement and then the remaining 50% of the coarse aggregate. 80% of water required was added to the rotating mixer and with a minimum total time of mixing time of 4 minutes before the mixture was let out from the rotating mixer. 10% of the water remaining was later pour into the rotating mixer and allowed to rotate for 30 seconds and the water together with the remaining constituent were poured out directly on top of the concrete mixture already on the platform.

Thorough hand mixing was done for uniform concrete colour and there after it paved way for placing of the concrete finally into the required moulds to produce specific specimens. The moulds for concrete casting were duly primed with grease as a lubricator for easy removal of the concrete specimens. Thereafter, concrete were placed in primed moulds to produce specimens based on standard specified layers and compaction to produce 18 numbers of 150 mm x 150 mm x 550 mm beams, 6 numbers of 150 mm x 150 mm x 150 mm cubes and 6 numbers of cylinders of 150 mm diameter with 300 mm height.

Demoulding of the specimens was carried out about 24 hours of casting and then cured. Curing of the specimens was done by placing them into clean water inside a tank having the average temperature of till the day of testing. The remaining 8 sets of specimens based on their concrete constituents were carried out similarly for batching, mixing, handling of the fresh concrete for making samples and curing but not on the same day because of the availability of specimen moulds and space inside the laboratory.

Table 5. Absolute weight of concrete constituents per batch.

Water Cement Ratio Ingredients 19 mm Granite Weight, Kg 12.5 mm Granite Weight, Kg Washed Gravel Weight, Kg
0.5 Water 42.507 43.095 42.440
Cement 85.013 86.190 84.880
Fine Aggregate 170.027 172.381 169.760
Coarse Aggregate 340.112 344.785 339.515
0.55 Water 46.635 46.638 46.015
Cement 84.791 84.796 83.664
Fine Aggregate 169.583 169.591 167.328
Coarse Aggregate 339.224 339.205 334.649
0.6 Water 50.065 50.067 49.409
Cement 83.441 83.445 82.349
Fine Aggregate 166.882 166.891 164.698
Coarse Aggregate 333.822 333.804 329.390

2.3. The Slump and the Compacting Factor Tests

The slump and the compacting factor tests were carried out 10 minutes of finishing concrete mixture. The slump test was carried out in accordance to AASHTO T 119 [14]. Sump test is useful for defining high and medium workability together with the consistency of the fresh concrete. The compacting factor test was also carried out according to BS 1881 [15]. The compacting factor test is useful for medium and low workability of fresh concrete along with its compact ability. The compacting factor value was calculated by dividing the partially compacted concrete weight by that of the fully compacted concrete of which the value is always less than 1. It is pertinent to note that the higher the value of the compacting factor the more workable is the mix and the lesser the hardened concrete strength. The compacting factor test is useful for defining low workability of the fresh concrete mixture.

2.4. Compression Strength Test

Figure 1. Compression strength test machine.

The 150 mm x 150 mm x 150 mm concrete cubes were tested at 7 and 28 days after being removed from the clear water curing tank and dried for few hours in accordance to BS EN 12390-3 [16]. The cubes are tested using a calibrated compression machine inside the laboratory as in Figure 1 under the care of competent personnel. Each cube tested has the face perpendicular to the casting face and the machine exerts a constant compressive progressing force on the cube till it fails at a loading rate of 0.6 ± 0.2 N/mm2/s. The maximum compressive strength of the concrete is based upon the reading at failure.

2.5. Flexural Strength Test

A third point loading with effective spanof 450 mm was achieved on the simply supported specimen as shown in Figure 2 to pave way for flexural strength test according to ASTM C 78 [17].

Figure 2. Flexural strength test machine.

The load was applied continuously and without shock at a rate of 200 m/s and the flexural strength,  or modulus of rupture was then calculated using the following formula.

(2)

P = maximum load, N

L = span length, m

b = specimen width, mm

d = specimen depth, mm

2.6. Tensile Splitting Strength Test

Each hardened concrete cylinder specimen of 150 mm diameter by 300 mm high was subjected to a compressive load for testing at a constant rate of 400 N/s along the vertical diameter until failure occurred in accordance to ASTM C 496 [18] as shown in Figure 3.

Figure 3. Tensile splitting strength test.

Calculating the splitting tensile strength of the hardened specimen tested is as follows:

(3)

Where:

 = splitting tensile strength, MPa

= maximum applied load indicated by the testing machine, N

 = length, m

 = diameter, m

3. Results and Discussions

The results upon the tests carried out on cement, fine aggregate, coarse aggregates, fresh concrete and hardened concrete are presented in this section. Comparisons are discussed regarding the standard specification of the cement requirements, the three types of coarse aggregates used for concrete production individually, tests upon fresh and hardened concrete produced.

3.1. Properties of the Employed 42.5R Cement

Table 6. Compositions of a Nigerian produced 42.5R cement.

The results of this research upon chemical and potential compound compositions while using 42.5R cement in the concrete production are presented in Table 6. CaO and SiO2 that represent more than 80% of chemical composition satisfied the standard specification requirements. Although C3S is of higher percent than the specification requirements for compound composition potential, it is worthy of note that it is an advantage for higher early strength for the Portland cement concrete produced. Other required cement quality parameters such as initial setting time, final setting time, fineness, specific gravity, bulk density, insoluble residue and loss of ignition do complied with the standard specification requirements as shown in Table 7.

Table 7. Other parameters of a Nigerian produced cement.

3.2. Properties of the Aggregates N/mm2

Figure 4 is showing the particle size distribution of fine aggregate used within the total range of sizes as well graded for it is exhibiting a line of constant slope. The fineness modulus of the fine aggregate used in this study is 2.70 of which it could be graded as medium sand for having the size between fine and coarser material based upon the specification limits value of 2.3 to 3.1 in conformity with ASTM specification. The coefficient of uniformity  and the coefficient of curvature  of the sand are 2.67 and 1.04 respectively of which the material is a clean and poorly graded sand SP. The bulk density of the sand used for the concrete is 1600 kg/m3 while its specific gravity value is 2.65.

The fineness modulus of 19 mm granite, 12.5 mm granite and washed gravel are 7.38, 6.31 and 6.9 respectively. The coefficient of uniformity and the coefficient of curvature of the 19 mm granite are 2 and 1.13 respectively as shown in Figure 5. Also, the coefficient of uniformity and the coefficient of curvature of the 12.5 mm granite are 2.94 and 1.76 respectively. Similarly, the coefficient of uniformity and the coefficient of curvature of the washed gravel are 2.90 and 1.06 respectively. It is obvious from the results of the 19 mm and 12.5 mm together with the washed gravel are poorly graded and clean materials. The bulk densities of 19 mm, 12.5 mm granites and washed gravel are 1560 kg/m3, 1580 kg/m3 and 1620 kg/m3 respectively. The specific gravity values obtained for 19 mm, 12.5 mm granites and washed gravel are 2.65, 2.65 and 2.6 respectively. The results of the 19 mm, 12.5 mm granites and washed gravel show that they are normal aggregates for the bulk densities lie between 2400 to 2700 kg/m3 and specific gravities lie between 2.01 to 3.

Figure 4. The fine aggregate grain size distribution curve.

Figure 5. The coarse aggregate grain size distribution curves.

3.3. Properties of the Fresh Concrete Produced

Based upon the values obtained from slump tests and compacting factor tests as shown in Table 8, it is obvious that slump test results contradicted the compacting factor test results. This is because where the compacting factor test gave the results to be plastic state and of medium degree of workability (0.88-0.91), slump test claimed it to be of stiff state with very low degree of workability (0-22) while considering using water cement ratio of 0.50. Obviously relying upon slump test result values according to this study has shown that it could lead to collapse of structures.

Table 8. Fresh concrete slump and compacting factor values obtained.

Water Cement Ratio Slump Values, mm
19 mm 12.5 mm Gravel
0.50 0 21 22
0.55 10 23 24
0.60 15 22 20
Water Cement Ratio Compacting Factor Values
19 mm 12.5 mm Gravel
0.50 0.88 0.89 0.91
0.55 0.91 0.93 0.88
0.60 0.98 0.99 0.95

3.4. Properties of the Cast Hardened Concrete Specimens

Beams, cubes and cylinders are the specimens produced were used to determine flexural, compressive and tensile strengths and the results are respectively presented in Tables 9-13.

3.5. Flexural, Compressive and Tensile Strengths of the Concrete Specimens

Flexural strength of concrete beam specimen results while using 0.5, 0.55 and 0.6 water cement ratios individually for coarse aggregates of 19 mm, 12.5 mm and washed gravel with same type of fine sand are in Tables 7-9. It could be seen that at 28 days of water curing only concrete produced using 19 mm granite with water cement ratio 0.5 and 0.55 mm satisfied flexural and compressive strength standard specification requirements in a highway concrete construction work. However, flexural strength values of 4.92 N/mm2 and N/mm2 respectively marginally satisfied the standard specified value of 4.5 N/mm2. Similarly, compressive strength values of 33.55 N/mm2 and 32.38 N/mm2 respectively also slightly satisfied the standard specified value of 30 N/mm2. Considering tensile splitting test upon values that satisfy flexural and compressive strength, it could be seen that the corresponding values obtained are 2.684 N/mm2 and 2.590 N/mm2 respectively. However, based upon the fact that the expected tensile strength value should be about 10% of the corresponding compressive strength which are 3.355 N/mm2 and 3.238 N/mm2 is showing that the concrete produced does not satisfy the required standard specification requirement for tensile strength.

Table 9. Flexural strength of the concrete specimens using 0.5 water cement ratio.

Label 19 mm Granite 12.5 mm Granite Washed Gravel
Days N/mm2 N/mm2 N/mm2
7 4.14 3.24 3.07
14 4.33 3.46 3.41
21 4.63 3.68 3.58
28 4.92 4.10 3.82
56 5.57 4.47 4.03
91 5.59 4.79 4.20

Table 10. Flexural strength of the concrete Specimens using 0.55 water cement ratio.

Label 19 mm Granite 12.5 mm Granite Washed Gravel
Days N/mm2 N/mm2 N/mm2
7 3.88 3.42 2.93
14 4.10 3.73 3.22
21 4.52 4.27 3.28
28 4.84 4.44 3.61
56 5.45 4.46 3.91
91 5.45 4.72 4.15

Table 11. Flexural strength of the concrete specimens using 0.6 water cement ratio.

Label 19 mm Granite 12.5 mm Granite Washed Gravel
Days N/mm2 N/mm2 N/mm2
7 3.01 3.06 2.86
14 3.16 3.14 2.94
21 4.18 3.70 3.19
28 4.24 3.99 3.35
56 4.93 4.11 3.80
91 5.04 4.62 3.98

Table 12. Compressive strength of the concrete specimens using different water cement ratios.

0.50 w/c 19 mm Granite 12.5 mm Granite Washed Gravel
Days N/mm2 N/mm2 N/mm2
7 23.76 16.23 13.01
28 33.55 27.29 20.22
0.55 w/c 19 mm Granite 12.5 mm Granite Washed Gravel
Days N/mm2 N/mm2 N/mm2
7 20.89 14.53 11.89
28 32.38 23.27 18.02
0.6 w/c 19 mm Granite 12.5 mm Granite Washed Gravel
Days N/mm2 N/mm2 N/mm2
7 12.57 12.99 11.32
28 24.88 21.99 15.57

Table 13. Tensile strength of the concrete specimens using different water cement ratios.

0.50 w/c 19 mm Granite 12.5 mm Granite Washed Gravel
Days N/mm2 N/mm2 N/mm2
7 1.901 1.162 1.041
28 2.684 1.862 1.618
0.55 w/c 19 mm Granite 12.5 mm Granite Washed Gravel
Days N/mm2 N/mm2 N/mm2
7 1.671 1.298 0.951
28 2.590 2.183 1.442
0.6 w/c 19 mm Granite 12.5 mm Granite Washed Gravel
Days N/mm2 N/mm2 N/mm2
7 1.006 1.039 0.906
28 1.990 1.759 1.246

4. Conclusions and Recommendations

Specimens of concrete for testing flexural, compressive and tensile strengths were developed using clean and clear water, a Nigerian produced 42.5R Portland cement, one type of river sand and three types of coarse aggregates separately. In the course of the concrete production process, water cement ratio of 0.5, 0.55 and 0.6 were used separately.

4.1. Conclusions

The following are the conclusions proffered based upon laboratory experiments in this study.

a. The 42.5R Portland cement produced Nigeria compared satisfactorily at very good level with ASTM, AASHTO and British relevant standard specification requirements upon its chemical and potential compound compositions. Parameters of the Portland cement such as initial and final setting times, fineness, specific gravity, bulk density, insoluble residue and loss of ignition also compared favourably well with the relevant specification standards.

b. The river sand used as fine aggregate is a clean and poorly graded material SP according to standard and is satisfactorily good in the production of concrete for construction. Also, the 19 mm and 12.5 mm granites together with the washed gravel used are poorly graded clean coarse aggregate materials according to related standards and are useful all useful materials in concrete production for highway structures.

c. Compacting factor test is more suitable for the measurement of workability requirements of the concrete produced in this study than slump test. This is because the fresh concrete described as plastic state with medium degree of workability by compacting factor test is described as stiff state with very low degree of workability by slump test.

d. Only concrete produced using 19 mm granites at 0.5 and 0.55 water cement ratio individually slightly satisfied required strength of at 28 days curing for flexural and compressive strengths. However, tensile strength at same concrete has values of 2.684 N/mm2 and 2.590 N/mm2 respectively which is not satisfying the expected 10% of the corresponding compressive strength which are to be values of 3.355 N/mm2 and 3.238 N/mm2.

4.2. Recommendations

The following are the recommendations proffered based upon laboratory experiments in this study.

a. Table 2 is a useful paradigm of using expressions for the computations of the absolute volume and weight of a batch for concrete production. While the absolute volume methodology is useful at the construction site the weight approach is useful in the laboratory.

b. Table 3 is a useful modelling module that forms a template through the use of Microsoft Excel spreadsheet for actualization of the volume and weight values of a batch for concrete production.

c. Water, 42.5R Portland cement, fine and coarse aggregates used are useful material for the production of concrete but the use of 1:2:4 and water cement ratios 0.5, 0.55 and 0.6 should be discouraged while producing sustainable rigid pavement. This will surely prevent premature failure of public and private highway pavements.


References

  1. Marotta, T. W. (2005): "Basic Construction Materials", Pearson Education, Inc., Upper Saddle River, New Jersey.
  2. Hebhoub, H., Aoun, H., Belachia, M., Houari, H., and Ghorbel, E. (2011): "Use of Waste Marble Aggregates in Concrete", Construction Building Materials 25 (3), 1167-1171.
  3. Ukpata, J. O. and Ephraim M. E. (2012): "Flexural and Tensile Strength Properties Concrete Using Lateritic Sand and Quarry Dust as Fine Aggregate", ARPN Journal of Engineering and Applied Sciences. 7 (3): 324-311.
  4. Ilangovana, R., Mahendra, N. and Nagamani, K. (2008): "Strength and Durability Properties of Concrete Containing Quarry Rock Dust (QRD) as Fine Aggregate", ARPN Journal of Engineering and Applied Sciences. 3 (5): 20-26.
  5. Falade, F. (1999): "Effects of Separation of Grain Sizes of Fine Aggregate on Properties of Concrete Containing Granite Fines", Journal of the University of Science and Technology, Kumasi, Volume 19 Nos. 1, 2 & 3.
  6. AASHTO M 85 (2009): "Standard Specification for Portland Cement (Chemical and Physical)", American Association of State Highway and Transportation Officials, Washington, D. C.
  7. ASTM C 188 (2015): "Standard Test Method for Density of Hydraulic Cement, Density, Hydraulic Cement, Specific Gravity", American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.
  8. ASTM C 430 (2008): "Standard Test Method for Fineness of Hydraulic Cement by the 45-Μm (No. 325) Sieve", American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.
  9. ASTM C 191 (2013): "Standard Test Methods for Time of Setting of Hydraulic Cement by Vicat Needle", American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.
  10. AASHTO T 27 (2014): "Standard Method of Test for Sieve Analysis of Fine and Coarse Aggregates", American Association of State Highway and Transportation Officials, Washington, D. C.
  11. AASHTO T 85 (2013): "Standard Method of Test for Specific Gravity and Absorption of Fine Aggregate", American Association of State Highway and Transportation Officials, Washington, D. C.
  12. AASHTO T 84 (2013): "Standard Method of Test for Specific Gravity and Absorption of Coarse Aggregate", American Association of State Highway and Transportation Officials, Washington, D. C.
  13. AASHTO T 19 (2014): "Standard Method of Test for Bulk Density (‘Unit Weight’) and Voids in Aggregate", American Association of State Highway and Transportation Officials, Washington, D. C.
  14. AASHTO T 119 (2013): "Standard Method of Test for Slump of Hydraulic Cement Concrete", American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.
  15. BS 1881 (2011): "Testing Concrete", British Standards Institution, London.
  16. BS EN 12390-3 (2009): "Testing Hardened Concrete - Making & Curing Specimens for Strength Tests", British Standards Institution, London.
  17. ASTM C 78 (2016): "Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)", American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.
  18. ASTM C 496 (2011): "Standard Test Method for Splitting Tensile Strength of Cylindrical Concrete Specimens, Cylindrical Concrete Specimens, Splitting Tension, Tensile Strength", American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.

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