IJOEST

EFFECT OF REPLACING SHARP SAND WITH STONE DUST AS FINE AGGREGATE IN CONCRETE

 

Ubi Stanley Emmanuel *1Envelope

*1 Department of Civil Engineering, Cross River University of Technology, Calabar

 

DOI: https://doi.org/10.29121/IJOEST.v5.i2.2021.176

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Article Type: Research Article

 

Article Citation: Ubi Stanley Emmanuel. (2021). EFFECT OF REPLACING SHARP SAND WITH STONE DUST AS FINE AGGREGATE IN CONCRETE. International Journal of Engineering Science Technologies, 5(2), 105-123 . https://doi.org/10.29121/IJOEST.v5.i2.2021.176

 

Received Date: 25 March 2021

 

Accepted Date: 19 April 2021

 

Keywords:

Stone

Dust

Concrete

River

Slump
ABSTRACT

Concrete is very variable material, having a wide range of strengths and stress-strain curve. Concrete composite material whose basic properties   are   related to the characteristic of constituent element, especially the aggregate. This research aimed to investigate the effect of replacing sharp sand with stone dust as an alternative to only river sand. Sieve analysis was carried out on the aggregate to determine the size of particle distribution. Slump test was carried out to compare the batches of concrete for the grade, water content between batches of concrete and amount of aggregate. Compressive strength test was carried out on concrete cubes made from sharp sand and   concrete   cubes   made   from replacement of sharp sand with stone dust also concrete made from ordinary stone dust at constant of free water/cement ratio 0.5. To check the properties of concrete produced with different materials, the tests were done for 7, 14, 21 and 28 days. The result obtained indicated that the strength of using sharp sand with stone dust in concrete production was higher than the strength of stone dust in concrete also higher than the strength of using sharp sand in concrete.



 

1.     INTRODUCTION

 

Concrete has been considered to be very durable material requiring a little or no maintenance. The assumption is largely true, except when it is subjected to highly aggressive environments. Concrete structures are built in highly polluted urban and industrial areas, aggressive marine environments, harmful sub-soil water in coastal area and many other hostile conditions where other materials of construction are found to be non-durable (Agbede 2002., Ducatz 1995 and Ubi et al. 2020). For the past decades concrete structures have spread to highly harsh and hostile conditions, the earlier impression that concrete is a very durable material is being threatened, particularly on account of premature failure of number of structures in the recent past. Concrete is the most extensively used man made structural material. It is the product of chemical reaction between cement, sharp sand (fine aggregate), coarse aggregate and water (Fowler and Constantino 1997). The aggregate may make up to three quarters of the volume of concrete. The most durable properties of concrete are workability, high compressive strength and aesthetics. These properties are to a large degree determined by types of material used in concrete mix, especially the type and the size of aggregate. Sharp sand has been used as fine aggregate in concrete work for many years now (Nagaraji and Zahida, 1999). This is because it readily available and there has been no substitute for material. From the confined usefulness of concrete, there exist some proportion of limitations on the use of sharp sand with stone dust as a possible replacement for sharp sand in concrete, this is very important in view of the engineering consideration. Environmental and economic problems arising from increasing volume of stone dust accumulating and taking up space in quarry site (Owoiabi 1996). The problems of environmental degradation caused by the continuous exploitation of sand from marina sources. Hence, this paper sought to investigate the effect of replacing sharp sand with stone dust as fine aggregate in concrete. Rao et al (2002) investigated the effect of replacing sharp sand with stone dust in concrete. The tests showed strength in compression at 3 - 7 and 28 days and also strength in split tension and flexure for 7 and 28 days. The test result showed that concrete with sharp sand as fine aggregate develop a strength of 28mpa on the 28th day while quarry concrete at the same age developed a strength of 32.8mpa indicating a 17% more compressive strength of the stone dust over the sharp and concrete (Prakash and Kumar 2004). In addition, the stone dust concrete had 7% more split tensile strength and 20% flexural strength (modules of mixture) than the concrete produce using sharp sand (Pofale and Kulkarni 1998). The result also shown that under two point loading condition, concrete with stone dust carried 6% more load and developed smaller deflections and strains than concrete, with sharp sand with stone dust. Based on the foregoing, Rao et al (2002), of reducing the cost of concrete by 20%. However, the internet has also provided many experimental facts regarding the use of quarry in concrete works reflecting the large amount of academic and industrial researches in this area. The purpose of this study research is to ascertain the current state of knowledge concerning the use of stone dust in concrete and most importantly to determine the structural and cost implication of replacing sharp sand with stone dust in concrete work and present the information in a form that would be easily understood and accessed by the student and the professional in the Civil Engineering Industry alike.

 

2.     MATERIALS AND METHODS

 

The various materials and methods used for the research paper were adopted based on the British Standard (BS). The following materials were used: ordinary Portland cement (type 1), Fine aggregates (Sharp sand and stone dust), crushed aggregates, Sea water.

 

2.1. EXPERIMENT PROCEDURES

 

The grade of concrete used for the experimental project are grade 20N/mm2 and 25N/mm2. The mix design used of various grade and materials were based on weight and not on volume. Firstly, the cubes produced by sharp sand help to control the case of 20N/mm2 and 25N/mm2. Second round, the replacement of a sharp sand with stone dust as find aggregate in concrete. Thirdly, stone dust used to produce concrete cubes.

 

2.2. CURING

 

The purpose of curing was to control temperature and moisture into concrete, which has helped in keeping the concrete saturated as possible until the originally filled space in the fresh cement paste is occupied to the desired product of hydrated cement.

 

2.3. LABORATORY TEST

 

Variation test were carried out in the laboratory and this includes:

 

2.4. SLUMP TEST

 

Slump test is the most commonly used method of measuring consistency of concrete which can be employed in laboratory or construction site. The slump test is not a suitable method for very wet or very dry concrete. It does not measure all factors contributing to workability. However, it is used conveniently as a control test and gives an indication of the uniformity of concrete from batch to batch.  Repeated batches of the same mix, brought to the same slump, will have the same water content and water cement ratio, provided the weights of the aggregate, cement and admixtures are uniform and aggregate grading is within acceptable limits. Additional information on workability and quality of concrete can be obtained by observing the manner in which concrete slump. Quality of concrete can also be further assessed by giving a few tapings or blows by tampering rod to the based plate. The deformation shows the characteristics of concrete with respect to tendency for segregation. The slump test gives fairly good consistent results for a plastic-mix. This test is not sensitive for a stiff-mix, in case of dry-mix, no variation can be detected between mixes of different workability. In the case of rich mixes, the value is often satisfactory, their slump being sensitive to variation in workability. IS 456 of 2000 suggests that in the “very low” category of workability where strict control is necessary for workability by determination of compacting factor will be more appropriate than slump and a value of 0.75 to 0.80 compacting factor is suggested. The bureau of Indian standards, in the past, generally adopted compacting fact or test values for denoting workability. Even in the IS 10262 of 1982 dealing with recommended guide lines for concrete mix design, adopted compacting factor for denoting workability. But now in the revision of IS 456 to 2000 the code has reverted back to slump value to denote the workability rather than compacting factor. It shows that slump test has more practical utility than the other test for workability.

 

2.5. SIEVE ANALYSIS

 

Sieve analysis involved dividing a sample of aggregate into various fractions, each consisting of particles of the sample size. Sieve analysis was conducted to determine the particle size distribution in a sample of aggregate, which we call gradation. A convenient system of expressing the gradation of aggregate is one which the consecutive sieve openings are constantly doubled such as 10mm, 20mm, 40mm etc. under such a system, employing a logarithmic scale, lines can be spaced at equal intervals to represent the successive sizes. The aim of this test was to determine the range of particular size of aggregate to obtain the particle size, in each aggregate sieve analysis was carried out according to the specification in the British standard using BS 410 sieves, to know the grading for the various aggregate. The retained material in each sieve was weighed and expressed as a percentage by weight of the sample passing each of the sieves.

 

2.6. COMPRESSIVE STRENGTH TEST

 

About twelve cube of 150 by 150mm were subjected to compressive strength test to determine their strengths for 7, 14, 21, and 28 days, three cubes were crushing at the age of each day. The cube was weighed to determine the densities after weighing. The cubes were placed on the lower steel platen of the compression test machine. Compressive load was then applied at a constant rate until the sample failed for the recording according to the gauge reading at its failure point.

 

2.7. CONCRETE MIX DESIGN

 

This is the process of selecting suitable ingredient of concrete and determining their relative quantities with the purpose of providing an economical concrete which has certain minimum properties notably workability, strength and durability. The method used in the various mixes was British mix design. The design for the strength of 28 days of 20N/mm2 and   mm2 using ordinary Portland cement with fine aggregate and coarse aggregates. 340kg/mm2 for grade 20 and 360kg/mm2 for grade 25 was cement content and the ratio of water applied in concrete production remained 0.05.

 

3.     RESULTS AND DISCUSSION

 

3.1. SIEVE ANALYSIS

 

3.1.1. SHARP SAND

 

Particle size distribution for the sharp sand is in the percentage shown and is presented in Table 1 and figure 1 indicating the weight at 375g:

Fine                                            -              5%

Medium sand                          -              85%

Coarse sand                             -              8%

Fine gravel                               -              2%

 

Uniformity coefficient

 

Uniform distribution

 

Table 1: Sieve analysis result for sharp sand total weight = 375g

B.S sieve

 (mm)

Weight retained

(g)

Percentage retained

(%)

Percentage cumulative retained

(%)

Percentage passing

(%)

3.35

-

-

-

100

2.36

5.10

4.27

5.63

98.64

1.18

16.00

4.27

5.53

94.37

0.60

18.50

4.94

10.57

89.43

0.425

150.50

40.17

50.74

49.26

0.300

109.60

29.25

79.99

20.01

0.212

58.96

15.72

95.71

4.29

0.150

9.40

2.51

98.22

1.78

0.075

3.50

0.93

99.15

0.85

Pan

3.20

0.85

100.0

0.00

 

Figure 1: Sieve analysis of sharp sand

 

3.2. STONE DUST

 

Particle size distribution for the stone dust in percentage shown in Table 2 and figure 2 with an aggregates of 298g;

Fine                                            -              510

Medium sand                          -              54%

Coarse sand                             -              26%

Fine gravel                               -              10%

 

 

Uniformity coefficient

 

 

The particle are well grade sand with small proportion of the gravel.

 

Table 2: Sieve analysis of stone dust aggregates total weight – 298g

B.S sieve

 (mm)

Weight retained

(g)

Percentage retained

(%)

Percentage cumulative retained

(%)

Percentage passing

(%)

4.76

1.00

0.34

0.34

98.66

2.36

26.70

8.94

9.28

90.72

1.18

50.70

17.06

26.36

73.62

0.60

22.40

7.52

32.88

66.10

0.425

52.00

17.45

51.33

48.67

0.300

43.10

14.46

65.79

32.21

0.212

63.40

21.28

87.07

12.19

0.150

12.20

4.09

91.16

5.82

0.075

24.00

8.05

99.21

0.79

Pan

2.30

0.79

100.00

0.00

 

Figure 2: Sieve analysis of stone dust

 

Coarse aggregate

Particle size distribution shown;

Fine                                            -              8%

Medium sand                          -              8%

Coarse sand                             -              7%

Fine gravel                               -              32%

Medium                                     -              45%

 

Uniformity coefficient

The particle is well grade sand with small proportion of the gravel as indicated in Table 3 and figure 3 with a total coarse aggregate of 1794.2G.

Table 3: Sieve analysis result for coarse aggregate total weight = 1794.2G

B.S Sieves Designation (mm)

Weight retained

(g)

Percentage retained

(%)

Percentage cumulative retained

(%)

Percentage passing

(%)

12.70

59.10

3.33

33.33

96.67

9.50

335.10

18.68

22.01

77.99

4.76

972.20

48.61

70.62

29.38

2.36

202.50

11.29

81.91

18.09

1.18

78.90

4.39

86.30

13.70

0.60

22.50

1.25

87.55

12.45

0.425

31.80

1.77

89.32

10.68

0.300

25.50

1.42

90.74

9.26

0.212

32.90

1.83

92.57

7.43

0.150

33.40

1.86

94.43

5.57

0.075

46.30

2.58

7.01

2.99

Pan

53.60

2.99

100.00

0.00

 

Figure 3: Sieve analysis for coarse aggregate

 

The British mix design method explicitly recognizes the durability requirement in the mix section. The method is applicable to normal weight of concrete made from Portland cement only. From the results obtained in Table 1-3 and figure 1 to 3 of the sieve analysis test, it is was observed that the cost of producing concrete with sharp and stone dust is almost the same. Though this title is different, can make a great deal of change in the overall cost when very large volume of concrete is required. If the site of quarry dust and if you can get the river sand close to the construction site, the price will be less. Hence, the cost of producing concrete with sharp sand with stone dust together is higher than that of river sand only.

 

3.3. COMPRESSIVE STRENGTH TEST RESULT

 

The strength developed by a concrete made with given material and in a given proportion increase for many months under favorable condition, but most specification put the strength at 28 days. The strength development of concrete made with all types of Portland cement depend on temperature and humidity. The strength of river sand (C20) stone dust (SDC20) and replacement of C20 with SDC 20 concrete at 7 days, 14 days, 21 days and 28 days are adequately presented in Table 4-11 respectively.

 

Table 4: Strength of river sand (c20) stone dust (sdc20) and replacement of C20 with SDC 20 concrete 7 day

C20

Sample No

Date

Cast

Date crush

Wt of sample (g)

Size of sample

(mm)

Density

kg/m3

Crushing load (kg)

Strength n/mm2

Cement Content kg/m3

Free water cement ratio

C20A

30-11-10

7-12-10

7950

150

2355

290

18.88

340

0.5

C20B

30-11-10

7-12-10

80.12

150

2373

300

19.03.

340

0.5

C20C

30-11-10

7-12-10

8200

150

2429

300

19.47

340

0.5

Average density =2385, average strength =19.12

SDC 20

SDC20A

30-11-10

7-12-10

8220

150

2435.

310

1,952

340

0.5

SDC20B

30-11-10

7-12-10

8240

150

2442

335

1957

340

0.5

SDC20C

30-11-10

7-12-10

7950

150

2355

320

18.88

340

0,5

Average density - 2410, Average strength = 19.32

Replacement of C 20 with SDC 20

C20/SDC20A

30-11-10

7-12-10

7890

150

2337

220

18.74

340

0.5

C20/SDC20B

30-11-10

7-12-10

8820

150

2613

419

20.94

340

0.5

C20/SDC20C

30-11-10

7-12-10

8300

150

2459

360

19.71

340

0.5

Average density = 2469, Average strength = 19.79

 

Table 5: Strength of river sand) (C25) stone dust (SDC25) and replacement of c25 with SDC 25 concrete at 7 day

Sample No

Date Cast

Date crush

Wt of sample (g)

Size of sample (mm)

Density kg/m3

Crushing load (kg)

Strength n/mm2

Cement Content kg/m3

Free water cement  ratio

C25A

30-11-10

7-12-10

7850

150

2357

280

18.74

360

0.5

C25B

30-11-10

7-12-10

8300

150

2459

270

19.71

360

0.5

C25C

30-11-10

7-12-10

8360

150

2477

280

19.85

360

0.5

Average density = 2424, Average strength =19.43

SDC 25

SDC25A

30-11-10

7-12-10

8545

150

2531

330

1952

360

0.5

SDC25B

30-11-10

7-12-10

8250

150

2442

250

1957

360

0.5

SDC25C

30-11-10

7-12-10

8270

150

2450

320

18.88

360

0.5

Average density = 2475, Average strength = 19.84

Replacement of C 25 with SDC 25

C25/SDC25A

30-11-10

7-12-10

7530

150

2231

270

18.74

360

0.5

C25/SDC25B

30-11-10

7-12-10

8600

150

2548

300

20.94

360

0.5

C25/SDC25C

30-11-10

7-12-10

8700

150

2577

280

19.71

360

0.5

Average density = 2452, Average strength =19.65

 

Table 6: Strength of river sand (C20) stone dust (SDC20) and replacement of c20 with SDC concrete 14 day

Sample No

Cast

Date

Crushed

Wt of sample (g)

Size of sample

(mm3)

Density kg/m3

Crushing load (kg)

Strength n/mm2

Cement content

kg/m3

Free water cement ratio

C20A

30-11-10

14-12-10

7915

150

2345

460

18.79

340

0.5

C20B

30-11-10

14-12-10

8030

150

2379

320

19,07

340

0.5

C20C

30-11-10

14-12-10

8040

150

2382

390

19.09

340

0.5

Average density = 2368, average strength =18.98

SDC 20

SDC20A

30-11-10

14-12-10

8040

150

2382

470

19.09

340

0.5

SDC20B

30-11-10

14-12-10

7915

150

2345

300

18.79

340

0.5

SDC20C

30-11-10

14-12-10

.8030

150

2379

468

19.07

340

0.5

Average density = 2368, Average strength = 18,98

Replacement of C 20 with SDC 20

C20/SDC20A

30-11-10

14-12-10

8213

150

2433

350

19:50

340

0.5

C20/SDC20B

30-11-10

14-12-10

7817

150

2316

380

18.56

340

0.5

C20/SDC20C

30-11-10

14-12-10

8200

150

2429

410

19.47

340

0.5

Average density =2392, average strength = 19.17

 

Table 7: Strength of river sand (C25) stone dust (SDC25) and replacement of c25 with SDC 25 concreted at- 14 day

Sample No

Date Cast

Date crush

Wt of sample (g)

Size of sample (mm)

Density

kg/m3

Crushing

load (kg)

Strength

n/mm

Cement Content

kg/m3

Free water cement ratio

C25A

30-11-10

14-12-10

8132

150

2409

300

19.31

360

0.5

C25B

30-11-10

14-12-10

.

W

2260

290

18.12

360

0.5

C25C

30-11-10

14-12-10

7850

150

2325

300

18.64

360

0.5

Average density = 2331, Average strength = 18.69

SDC 25

SDC25A

30-11-10

14-12-10

8959

150

2651

375

21.25

360

0.5

SDC25B

30-11-10

14-12-10

8850

150

2622

373

21.01

360

0.5

SDC25C

30-11-10

14-12-10

8135

150

2410

362

19,22

360

0,5

Average density = 2561, Average strength = 20.49

Replacement of C 25 with SDC 25

C25/SDC25A

30-11-10

14-12-10

7890

150

2364

300

18.95

360

0.5

C25/SDC25B

30-11-10

14-12-10

8880

150

2631

340

21.09

360

0.5

C25/SDC25C

30-11-10

14-12-10

7620

150

2258

300

18.09

360

0.5

Average density = 24 .18, Average strength =19.37

 

Table 8: Strength of river sand (C20) stone dust (SDC20) and replacement of C20 with SDC concrete 21 day

Sample No

Date cast

Date crushed

Wt of sample (g)

Size of sample (mm3)

Density

kg/m3

Crushing load (kg)

Strength n/mm2

cement

content kg/m3

Free water cement ratio

C20A

30-11-10

21-12-10

8025

150

2377

400

19.06

340    

0.5

C20B

30-11-10

21-12-10

8887

150

2633

430

21.10

340

0.5

C20C

30-11-10

21-12-10

8539

150

2530

400

20.28

340

0.5

Average density =2313, Average strength = 2014

SDC 20

SDC20A

30-11-10

21-12-10

8747

150

2591

450

20.77

340

0.5

SDC20A

30-11-10

21-12-10

8507

150

2520

500

202.0

340

0.5

SDC20A

30-11-10

21-12-10

8992

150

2664

500

21.35

340

0.5

Average density = 2916, average strength = 20.77

Replacement Of C 20 With SDC 20

C20/SDC20A

30-11-10

21-12-10

8200

150

2429

490

19.47

340

0.5

C20/SDC20A

30-11-10

21-12-10

8995

150

2665

450

21.36

340

0.5

C20/SDC20A

30-11-10

21-12-10

8600

150

2548

430

20.42

340

0.5

Average density = 2866, Average strength =20.41

 

Table 9: Strength of river sand (C25) stone dust (SDC25) and replacement of C25 with SDC 25 concrete at 21 day

Sample No

Date Cast

Date crush

Wt of sample (g)

Size of sample (mm)

Density kg/m3

Crushing load (kg)

Strength n/mm2

Cement Content

kg/m3

Free water cement ratio

C25A

30-11-10

21-12-10

7835

150

2321

340

18.60

360

0.5

C25B

30-11-10

21-12-10

8100

150

2400

400

19.23

360

0.5

C25C

30-11-10

21-12-10

7640

150

2263

390

18.14

360

0.5

Average density = 2328, Average strength = 18.65

SDC 25

SDC25A

30-11-10

21-12-10

g365v

150

2378

450

19.86

360

0.5

SDC25B

30-11-10

21-12-10

7890

150

2338

495

18.73

360

0.5

SDC25C

30-11-10

21-12-10

 

150

2596

500

20.81

360

0.5

Average density = 2440, Average strength =19.08

Replacement of C 25 with SDC 25                                                    

C25/SDC25A

30-11-10

21-12-10

8539

150

2530

400

20.28

360

0.5

C20/SDC25B

30-11-10

21-12-10

7743

150

2294

360

18.39

360

0.5

C20/SDC2C

30-11-10

21-12-10

8887

150

2633

440

21.10

360

0.5

Average density = 2485, Average strength =19.92

 

Table 10: Strength of river sand (C20) stone dust (SDC20) and replacement of C20 with SDC 20 concrete 28 day

Sample No

Date Cast

Date crushed

Wt of sample (g)

Size of sample

(mm3)

Density

kg/m3

Crushing load (kg)

Strength

n/mm

Cement content

kg/m3

Free water cement ratio

C20A

30-11-10

28-12-10

8580

150

2542

510

20.39

340

0.5

C20B

30-11-10

28-12-10

8630

150

2557

520

20.40

340

0.5

C2Q.C

30-11-10

28-12-10

8430

150

2497

500

20.02

340

0.5

Average density =2532, Average strength =20.29

SDC 20

SDC20A

30-11-10

28-12-10

8600

150

2548

610

20.42

 

0.5

SDC20A

30-11-10

28-12-10

8730

150

2586

620

20.73

340

0.5

SDC20A

30-11-10

28-12-10

8700

150

2577

610

20.66

340

0.5

Average density =2570, Average strength. = 20.60

Replacement of C 20 with SDC 20

C20/SDC20A

30-11-10

28-12-10

8500

150

2518

520

20.18

340

0.5

C20/SDC20B

30-11-10

28-12-10

8635

150

2558

530

20.50

340

0.5

C20/SDC20C

30-11-10

28-12-10

8500

150

2518

520

20.18

340

0.5

Average density = 253l, Average strength = 20.28

 

Table 11: Strength of river sand (C25) stone dust (SDC25) and replacement of C25 with SDC 25 concrete at 28day

Sample No

Date

Cast

Date crush

Wt of sample (g)

Size of

sample (mm)

Density

Kg/m3

Crushing load (kg)

Strength n/mm2

Cement Content kg/m3

Free water cement

ratio

C25A

30-11-10

28-12-10

8650

150

2563

500

20.54

360

0.5

C25B

30-11-10

28-12-10

8550

150

2533

598

20.30

360

0.5

C25C

30-11-10

28-12-10

8550

150

2533

597

20.30

360

0.5

Average density =2543, Average strength =20.38

SDC 25

SDC25A

30-11-10

28-12-10

8580

150

 2542

630-

20.37

360

0.5

SDC25B

3041-10

28-12-10

8680

150

2571

590

20.28

360

0.5

SDC25C

3d4i4&

, 284&-W-

g63a.

150

2561

620

20,54

360

0.5

Average density = 2549, Average strength = 20.39

Replacement of C 25 with SDC 25

C20/SDC25A

30-11-10

28-12-10

8580

150

2542

598

20.38

360

0.5

C20/SDC25B

30-11-10

284240

8680

150

2571

600

20.71

360

0.5

C20/SDC25C

30-11-10

2842-10

8660

150

2565

598

2.057

360

0.5

Average density = 2551  Average strength =20.55

 

3.4. DENSITY OF THE CONCRETE CUBES

 

This can be expressed as the ration of weight to volume in mathematical form.

 

This is the factor that affect the strength of concrete. The higher the density the higher the compressive strength, as indicated in Table 12.

Stone dust has normal weight because their densities are comparable to that of sharp sand concrete according to Neville (2003) ranges from 2200 to 260Qkg/m2. The result obtained was that density of quarry dust higher than that of sharp sand.

 

Table 12: The average density and strength for C20

CURING AGE

Days

DENSITY    C20

(Kg/m3)

DENSITY

SDC20

(Kg/m3)

DENSITY

C20/SDC20

(Kg/m3)

7

2385

2410

2469

14

2368

2368

2392

21

2513

2916

2866

28

2532

2570

2531

 

Figure 4: Average density for C20

 

 

Table 13: The average density and strength for C25

7

2424

2475

2452

14

2331

2561

2417

21

2328

2440

2485

28

2543

2549

2551

 

Figure 5: Average density for C25

 

Table 14: The average strength for C20

Curing Age

Strength

C20

(N/mm2)

Strength

SDC20

(N/mm2)

Strength    with

SDC20

(N/mm2)

7

19.12

19.32

19.17

14

18,98

18.98

19.17

21

20.14

20.77

20.41

28

20.29

20.60

20.28

 

Figure 6: Average strength for C20

Table 15: The average strength for C25

7

19.43

19.84

19,65

14

18.69

20.49

19.37

21

18.65

19.08

19.92

28

20.38

20.39

20.55

 

Figure 7: Average strength for C25

 

3.5. STANDARD DEVIATION

 

The account of the deviation of every value from the distribution has been taking by using the standard deviation. The value which is higher shown that there was a high level of consistencies during the laboratory work.

Standard deviation (SD) = 

Where xi = x1, x2, x3, the value of the compressive strength for the cube produced.

x     =   mean of number of value

n       = Total number of value

The standard deviation for the various mixes designed are to be calculated at 7, 14, 21 and 28 days to know the strength.

 

For C2O at 7 days curing strength

 

 

For SDC2O 7 days strength

 

=0.105n/MM

 

 

For C20 at 14 days 1 strength

 

 

For C2O at 14 days 1 strength

 

 

For SOCO20 at 14 days strength

 

 

For X20 with SDC2O at 14 days strength

 

SD2 (19.50 – 19.17)2 = + (18.56 – 19.17)2 + (19.47 – 19.17)2

0.19N/mm2

 

For C20 at 21 days strength

 

 

For SDC2O 21 days strength

 

 

For C20 at 14 days 1 strength

 

 

For C2O with SDC20 21 days strength

 

 

 

For C20 at 28 days strength

 

 

For sdc25 at 7 days strength

 

For C25 with SOC25 at 27 days strength

 

 

For C25 at 14 days strength

 

 

For SDC25 at 14 days strength

 

 

For C25 with SDC25 at 14 days strength

 

 

For C25 at 21 days strength

 

 

For SDC25 at 21 days strength

 

 

 

For C25 with SOC25 at 21 days strength

 

 

For x25 at 28 days strength

 

 

For SDC25 at 28 days strength

 

 

For C25 with SDC25 at 14 days strength

 

 

For C25 with SDC25 at 28 days strength

 

 

3.6.  TARGET MEAN STRENGTH

 

Variation of concrete in production, is the amount by which the produced concrete strength is greater than the characteristic strength. Margin for design takes care of the variation of concrete, in production, it is the amount by which the produced concrete strength is greater than the characteristic strength. From the results shown in Table 16 and figure 8, comparative analysis of the concrete produced replacing stone dust with sharp sand in each case was examined. The formula used are:

FM =             fe + Ks where

Fm =             the target mean strength

Fe   =             specified characteristic strength

Ks   =             the margin, which is the product of

S     =             standard deviation and

K     =             a constant

 

The K is device from the mathematics of the normal distribution and increase as the proportion of detective is decrease thus:

K for = For 10 percentage defective = 1.28

K for 5 percentage defective = 1.64

K for M percentage defective = 2.33.

A value of 5% defective is however, permitted in cp 110, 1985 for instance; the target mean strength of gate 20 concrete is Fm = fe + ks

= 20+ (1.64 x 8) = 33N/mm2.

Table 16: Target mean strength

Age day

Strength (N/mm2)

Target  mean strength

7

C20:19.12

57%

14

C20:18.98

62%

21

C20;20.14

64%

28

C20:20.29

68

 

7

SDC20: 19.32

72%

14

SDC20;18.98

66%

21

SDC20:2,14

74%

28

SDC20: 20.60

77%

 

 

Target mean strength

 

7

C20/SDC20: 19.79

58%

14

C20/SDC20: 19.17

60%

21

C20/SDC20: 20.41

68%

 

7

C25:19.43

54%

14

C25: 18.69

60%

21

C25: 18.65

64%

28

C25: 20.38

70%

 

Target mean, strength

 

7

C25/SDC25: 19:65

56%

14

C25/SDC 25: 19.37

62%

21

C25/SDC 25 :19.92

68%

28

C25/SDC 25: 20.55

72%        

       

Figure 8: Target mean strength gradient

 

4.     CONCLUSION AND RECOMMENDATION

 

From the research work carried out on the effect of replacing sharp sand with stone dust in concrete work, many inferences have been deduced from the results of the investigation, some of the conclusion based on this investigation are summarized thus:

1)     If the proper design procedures are followed, stones dust as fine aggregate does not have any detrimental effect on the overall properties of concrete, rather it helps to improve on the properties, if sharp sand could be added with stone dust it will help the concrete to be detrimental.

2)     Sharp sand with stone dust concrete develop 6 -12% more compressive strength than sharp sand (fine aggregate) while stone dust concrete develops 6 - 14% more compressive strength also than river sand, it attains higher strength at early age than sharp sand concrete.

3)     The cost implication replacing stone dust with sharp sand in concrete   is   within   the   acceptable   margin   of   price differentials. Economical to consider replacing sharp sand with stone dust for use when a cheaper means of transportation is devised or the construction site is closer to the site were the material can be obtained.

4)     Concrete with replacement requires more water than river sand concrete that's why it's develops higher strength. In this case, when replacing sharp sand with stone dust, in concrete, you must know that enough water is supplied to the concrete.

 

4.1.  RECOMMENDATION

 

In view of the foregoing engineering advantages of replacing sharp sand with stone dust in concrete, the following recommendations are presented to stakeholders:

1)     In construction industry professionals should come up with more information regarding the replacing of sharp sand with stone dust in concrete by investing in research into replacing and how it can be used to obtain concrete with must higher strength than that form river sand or that of stone dust

2)     Government should make the transportation section more efficient so as to reduce the cost of transporting good and materials for construction and other constitutions of concrete from one place to another.

3)     Awareness campaigns should be organized by professional in Civil Engineering way of seminar and workshop to enlighten the general public on the cost and strength consideration for replacing sharp sand with stone dust in concrete work, by so doing more and more people will come to embrace the replacing of sharp sand with stone dust instead of using only sharp sand in the construction site they will use both the sharp sand with stone dust. By so doing stone dust will give more strength together with the strength of river sand and the strength will be higher than that of sharp sand only. For that, many people will like to use both the sharp and with stone dust for the construction of their own structures.

 

SOURCES OF FUNDING

 

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

 

CONFLICT OF INTEREST

 

The author have declared that no competing interests exist.

 

ACKNOWLEDGMENT

 

None.

 

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