Particle size effect of ground granulated blast furnace slag ggbs in cement concrete

Particle Size Effect of Ground Granulated Blast Furnace Slag (GGBS) in Cement Concrete V.Nagendra1, C. Sashidhar2, S. M. Prasanna Kumar3, N.Venkata Ramana4 1

Civil Engineering Department, Nagarjuna College of Engineering and Technology, Bengaluru, Karnataka, India.

2 Civil Engineering Department, JNTUA,Anantapur, A P, India.

3 Civil Engineering Department, Rungta College of Engineering and Technology Bhilai, Chhattisgarh, India.

4 Civil Engineering Department, University B D T College of Engineering, Davangere, Karnataka, India.

Abstract—In the present investigation Ground Granulated Blast Furnace Slag (GGBS) is used as particles of specific size, as replacement to cement. The GGBS is placed in the concrete mix with particles of various uniform sizes of 250µm, 125µm, 90µm, 45µm and 20µm. The dosage of GGBS is varied from 10% to 40% at an increment of 10% for concrete to evaluate the compressive strength.

The results showed that, for particle of size 20 µm, the strength is optimum, which is at 20% replacement level.

Keywords—GGBS, Compressive Strength, Uniform Particle Size.

I. INTRODUCTION Ground Granulated Blast Furnace Slag (GGBS) is a byproduct of Iron industry and which is obtained from during the manufacture of iron. The molten slag is a secondary product of sintering of the raw materials and this is quenched under high pressure of water jets, which results as granulates. The GGBS is obtained when the granulated slag is ground to a very fine powder with a specific surface area of 400-600m2/kg. In the past few research works has been taken place in the area of GGBS as an admixture for the concrete works. Herein few important works are furnished as literature review to know the status of GGBS in the concrete arena. Siddique [1] reviewed the properties of GGBS for partial replacement of cement by weight for strength and durability properties by various researchers.

Luiz Fernandez [2] noticed strength development was slow during the first three days of hydration for concrete containing 40-65% GGBS as replacement for cement by weight. Rafat Siddique[3] covers the properties of GGBS, reaction mechanism and its effect on strength and durability properties of concrete. Amena et.al.,[4] investigated the mechanical properties of compressive strength and flexural strength by partially replacing cement with slag for M 20 grade concrete. The optimum strength obtained for compressive strength was at 20% replacement and whereas for flexural strength it was at 10% replacement. Hogan and Meusel [5] investigated the mechanical properties, abrasion resistance and chloride-ion permeability of concrete using GGBS. Arivalagan [6] evaluated the strength and efficiency factors of hardened concrete, by replacing cement by various percentages of GGBS for M35 grade of concrete. The optimum strength was obtained at 20% replacement. Erhanguneyisi et.al [7] presented an experimental study on combined effects of curing method and high replacement levels of GGBS and mechanical and durability properties of high performance concrete. The partial replacement was varied from 50-80% with W/C ratio of 0.4. The incorporation of slag at 50% and above replacement levels caused a reduction in strength. Bamette [8] conducted the work on replacement of various percentages of GGBS, different W/C ratios and curing temperature on mortar cubes for strength development. Venu Malagavelli and Rao [9] investigated the characteristics of M30 concrete with partial replacement of cement by GGBS and sand with ROBO sand (crusher dust) for compressive and tensile strength. Jenny [10] evaluated the percentage of silica (Sio2) and alumina (Al2o3) in the GGBS for 3,7 and 28 days compressive strength on mortar cubes. From the review it is noticed that no work has been carried out by taking the uniform size of GGBS particle for concrete works. Hence here an experimental work has planned to study the behavior of compressive strength by varying the particle size of GGBS.

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International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 02, Issue 08; August - 2016 [ISSN: 2455-1457]

II. EXPERIMENTAL PROGRAMME To study the effect of particle size of GGBS for concrete, the uniform size particles are taken as 250µm, 125µm, 90µm, 45µm and 20µm. The GGBS was used here as replacement to cement. The percentage of replacement adopted in the experimental work is varied from 10% to 40% with an increment of 10%. A total 240 cubes were cast and tested at 7, 14, 21 and 28 days. The standard cubes were cast with mix proportion of 1:2.65:4.55 and w/c ratio is maintained as 0.5 (the mix proportion and w/c ratio was arrived based on the design mix). The Conplast SP430 used as super plasticizer for the work to achieve desirable workability.

III. MATERIALS For the experimental investigation the following materials were used Cement: The Ordinary Portland cement (OPC) of grade 53 was used. The physical and chemical compositions are presented in Table 1 and 2.

Table1: Physical Properties of Cement Specific gravity Bulk density (kg/m3) Surface area(m2/kg) 3.12 1865 340 Table 2: Chemical Properties of Cement Cao Sio2 Al2o3 Fe2o3 Mgo So3 P2o5 K2o Na2o Tio2 60.84 16.34 6.95 5.38 2.32 1.99 1.67 2.73 1.50 0.28 Fine aggregate: River sand is used as fine aggregate, which is of grade II, based on particle size distribution. The properties are tabulated in Table 3.

Table 3: Physical Properties of River Sand Sl no 1 2 3

Description

River sand

Specific gravity Bulk density(loose)kg/m3 Bulk density(compacted)kg/m3

2.64 1480 1695

4 5

Fineness modulus Grading zone

2.45 II

Coarse aggregate: Crushed granite stone is used as coarse aggregate in the investigation.

Super Plasticizer:The super plasticizer(CONPLAST-SP430) used in the present work , and it is in the form of Sulphonated Naphthalene polymers complies with IS: 9103-1999.

Water:Locally available portable water is used for mixing and curing of the specimens.

Ground Granulated Blast Furnace Slag (GGBS):The GGBS used in the experimental work is supplied by JSW Steel Tornagal, Bellary (dist), Karnataka(State),India. The used GGBS can be viewed in the Figure.1. The physical and chemical properties are presented in the Table 4 and 5.

Figure 1: Ground Granulated Blast Furnace Slag

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International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 02, Issue 08; August - 2016 [ISSN: 2455-1457]

Table 4: Physical Properties of GGBS Specific gravity

Bulk density(kg/m3)

Surface area m2/kg

Insoluble residue (%)

2.90

1220

416

0.14

Loss on ignition (%) 0.19

Moisture content (%) 0.14

Table 5: Chemical Composition of GGBS in Percentage Binde r

Sio2

Cao

Al2o3

Mgo

Mno

Fe2o3

Sulphide sulphur

Sulphite sulphur

GGB S

33.77

33.77

13.24

8.46

0.05

0.65

2.23

0.23

Total chlori des 0.01

IV. RESULTS AND DISCUSSIONS The compressive strength for different dosages and different particle sizes are presented in the table 6 to 9. From the tables, it is observed that the compressive strength increases as the particle size decreases, which is observed for all the days of testing of the specimens. The maximum strength was observed for 20µm particle size and lesser strengths (for all days of testing) are observed for 250µm particle size. For 20% replacement, the strength at 7 days, for 20µm particle size is 18.2 MPa, and the corresponding percentage increase is 25% when compared with control mix. Similarly for 250µm particle size, the strength is less than control mix, and the percentage decrease in strength is 13%. At 14 and 21 days, the percentage increase in strength for 20µm particle size, when compared with control mix is 17% and 24% respectively, whereas for 250m particle size there is an decrease in strength equal to 28% and 7%. At 28 days of testing, the percentage increase in strength for 10%, 20%, 30% and 40% replacements of 20µm particle size is 5%, 12%, 7% and 1% respectively when compared with control mix. The optimum compressive strength is obtained for 20µm size of GGBS particles and effective dosage is noticed at 20% replacement level of cement with GGBS. Hence the present experimental work shown as lesser the size of particles more is the strength for all replacements but effective at 20%, this may due to , GGBS modifies the products and the pore structure in hardened cementations materials and also higher the GGBS content results in denser structure and results more in compressive strength. From the mechanism of admixture usage in concrete, addition GGBS reacts with calcium hydroxide to form extra C-S-H gel in the paste (lesser the particle size increase in specific surface area and leads faster or effective pozzolanic reaction) and this also one of the reasons to enhance the compressive strength of the mix.

Table 6: Compressive strength at 10% replacement of cement by GGBS Sl.No Particle Compressive Strength(Mpa) Size(µm) 7 days 14 days 21 days 28 days Compressive strength 14.65 18.40 21.75 25.90 for control mix 1 20 17.1 19.10 24.30 27.40 2 45 15.8 17.60 22.80 26.00 3 90 14.3 16.00 20.30 24.00 4 125 13.5 15.20 19.30 23.00 5 250 12.0 13.50 18.00 21.00

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International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 02, Issue 08; August - 2016 [ISSN: 2455-1457]

Table 7: Compressive strength at 20% replacement of cement by GGBS Sl.No Particle Compressive Strength(Mpa) Size(µm) 14 days 21 days 28 7 days days Compressive strength 14.65 18.40 21.75 25.90 for control mix 1 20 18.20 21.50 27.00 29.10 2 45 16.80 19.50 25.00 27.20 3 90 15.10 17.10 23.20 25.70 4 125 14.20 15.90 22.30 25.10 5 250 13.00 14.30 20.40 23.90 Table 8: Compressive strength at 30% replacement by GGBS Sl.No Particle Compressive Strength(Mpa) Size(µm) 7 days 14 days 21 days 28 days Compressive strength 14.65 18.40 21.75 25.90 for control mix 1 20 18.90 22.00 27.10 27.90 2 45 17.70 20.00 25.80 27.30 3 90 15.90 17.80 24.30 26.40 4 125 15.30 16.50 23.30 25.70 5 250 14.00 15.30 20.90 23.60

Table 9: Compressive strength at 40% replacement by GGBS Sl.No Particle Compressive Strength(Mpa) Size(µm) 14 21 28 days 7 days days days Compressive strength 14.65 18.40 21.75 25.90 for control mix 1 20 16.2 18.1 24.5 26.3 2 45 15.2 17.3 23.1 25.3 3 90 14.3 16.1 21.5 24.3 4 125 13.6 15.3 20.6 23.6 5 250 12.1 13.2 18.3 21.8 IV. CONCLUSION 1. As the particle size decreases, the strength increases for all replacements of cement with GGBS 2. The 28 day compressive strength is optimum at 20% replacement level and is obtained for 20 micrometer particle size The percentage increase when compared with control mix for 20 micrometer particle size is equal to 12%, whereas for 250 micrometer particle size it is slightly lower than the control mix.

3. The addition of GGBS modifies the products and the pore structure in hardened cementations materials and it results higher compressive strengths at all days.

4. For 20m particle size the strength is maximum at all days of testing, this is because more specific surface area is available for the pozzolanic reaction (chemical mechanism).

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International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 02, Issue 08; August - 2016 [ISSN: 2455-1457]

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