Replacement of Aggregates by Industrial Waste Steel Slag for Sustainable Concrete

Replacement of Aggregates by Industrial Waste Steel Slag for Sustainable Concrete

Ketaki Kulkarni1,

1Post Graduation Student Civil Engineering department,

Trinity College of Engineering and Research, Pune,

AbstractMost of the volume of concrete is aggregates. Replacing all or some portion of natural aggregates with steel slag would lead to considerable environmental benefits. Steel slag is currently used as aggregate in hot mix asphalt surface applications, but there is a need for some additional work to determine the feasibility of utilizing this industrial by-product more wisely as a replacement for both fine and coarse aggregates in a conventional concrete mixture. This paper present results of experimental investigations carried out to evaluate effects of replacing aggregate (coarse and fine) with that of slag on various concrete properties. In this study, concrete of M20 and M30 grades were considered for a replacements of 0, 25%, 35%. 45%, 55%, 65% and 75% of aggregates (Fine) by slag. Various test considered for investigation are compressive strength, flexural strength and Split tensile strength. The workability is measure with the slump cone test. A comparison of results of replacement of fine aggregate concrete with that of control mix concrete showedthe thatslag could be effectively utilized as fine aggregates in all the concrete applications.

KeywordsSlag, GGBS, Industry by-product,

1. INTRODUCTION

   As a construction material, concrete is the largest production of all other materials. Aggregates are the important constituents in concrete. They give body to the concrete, reduce shrinkage and effect economy. Availability of natural aggregates is getting depleted and also its becoming costly. Hence, there has to be an emphasis on the use of wastes and by-products in all areas including construction industry. As 75% of concrete is composed of aggregates it is imperative that we look to maximize the use of waste as aggregate input in concrete making. The increase in demand for the ingredients of concrete is met by partial replacement of materials by the waste materials which is obtained by means of various industries. Slag is a byproduct of metal smelting and hundreds of tons of it are produced every year all over the world in the process of refining metals and making alloys. Like other industrial byproducts, slag actually has many uses, and rarely goes to waste. It appears in concrete, aggregate road materials, as ballast, and is sometimes used as a component of phosphate fertilizer.

   Firstly, slag represents undesired impurities in the metals, which float to the top during the smelting process. Secondly, metals start to oxidize as they are smelted, and slag forms a protective crust of oxides on the top of the metal being smelted, protecting the liquid metal underneath. When the metal is smelted to satisfaction, the slag is skimmed from the top and disposed of in a slag heap to age. Aging material is

   Prof. V. S. Shingade 2

   2HOD

   Civil Engineering department, Trinity College of Engineering and Research

   Pune

   an important part of the process, as it needs to be exposed to the weather and allowed to break down slightly before it can be used.

   Sustainable construction mainly aims at reduction of negative environmental impact resulted by construction industry which is the largest consumer of natural resources. Over a period of time, waste management has become one of the most complex and challenging problem in the world which is affecting the environment. The rapid growth of industrialization gave birth to numerous kinds of waste byproducts which are environmentally hazard and creates problems of storage. Always, construction industry has been at forefront in consuming these waste products in large quantities. The consumption of Slag in concrete not only helps in reducing green house gases but also helps in making environmentally friendly material.

2. LITERATURE STUDY

   A. International Journal papers

   Venu Malagavelliet. al. [1] Their paper focuses on investigating characteristics of M30 concrete with partial replacement of cement with Ground Granulated Blastfurnace Slag (GGBS) and sand with the ROBO sand (crusher dust). The cubes and cylinders are tested for both compressive and tensile strengths. They found that by the partial replacement of cement with GGBS and sand with ROBO sand helped in improving the strength of the concrete substantially compared to normal mix concrete.

   David N. Richardson, [2] for a bridge pier and abutment mass concrete project, three mixes were studied: an ordinary Portland cement (OPC) mix (Type I PC) and two 70% by weight ground granulated blast furnace slag (GGBS) mixes (Type II Low Heat PC). One of the slag mixes contained a high range water reducer (HRWR) and tests for compressive strength, freeze thaw durability, etc. They concluded that although the optimum blast furnace slag proportion for strength was 50%, blast furnace slag replacement levels of up to 70% could be used to achieve moderate strength levels. Strength parity with zero slag mixes is possible with 70 % slag under proper conditions,

3. MATERIALS USED

   1. Material and its properties

      • Cement: PPC. Conforming IS 1489 Part 1 (1991)

      • Sand : fine aggregate conforming to zone II of IS 383

      • Aggregate: coarse aggregate of maximum size 20mm and 10mm.

      • Slag : As per IS 456:2000

      • Admixture used: BASF Glenium

   2. GGBS

   Ground Granulated Blast furnace slag (GGBS) is a byproduct for manufacture of pig iron and obtained through rapid cooling by water or quenching molten slag. If slag is properly processed then it develops hydraulic property and it can effectively be used as a pozzolonic material. However, if slag is slowly air cooled then it is hydraulically inert and such crystallized slag cannot be used as pozzolonic material.

   Table 1: Physical and Chemical properties of GGBS

   Physical Properties	AS per BS:6699	Test Results
   Loss of ignition (max) %	3.00	0.15
   Moisture content (max) %	1.00	0.31
   Chemical Composition
   CaO + MgO + SiO2 (min) %	66.66	80.31
   Magnesium Oxide MgO (max) %	14	8.72
   Sulphur Tri Oxide SO3 (max) %	2.5	0.19
   Total Chlorides (max)%	0. 1	0.001

4. EXPERIMENTAL WORK

   1. Following testing conducted on Concrete

      1. Workability Slump cone

      2. Compressive Strength

      3. Flexural Strength

      4. Split tensile strength

         Mix design parameters: Mix design for M20 and M 30 grade concrete

   2. Test Set-up

   The 6 in.(150 mm) cubes with a set of 3 cubes, each were cast for compressive strength at 3, 7, 28days and 6 in cylinder with 3 set each were cast for split strength at 28, days time. Beam moulds of size 6in x 6in x 27.56in i.e. (150x150x700mm) for flexure strength time respectively. After the cast, all the test specimens were put into the water tank for curing maintaining temperature of 89.6±35 F (27±2

   ºC) as per IS requirements. The concrete was tested for slump cone test as per the IS-1199 Methods of sampling and analysis of concrete, or each mix of concrete

5. GRAPHICAL RESULTS

   1. Workability

      Fig. 1. Slump in mm comparison graph

      	M20	M30		M20	M30
      Cement(kg)	357.14	409.77	A/C	5.4	4.6
      Water(kg)	189.29	180.30	W/C	0.53	0.44
      CAII (kg)	482.14	527.78	CAII%	25%	28%
      CAI (kg)	482.14	490.08	CAI%	25%	26%
      FA (kg)	964.29	867.07	FA%	50%	46%

      Table 2 : Mix Proportion for control Mix

      Table 3 : Mix Proportion

      Fine aggregate to slag replacement proportions: shown in Table 3 (all weights in kg/cum)

      Grade	M20		M30
      %	FA	GGBS	FA	GGBS
      0%	964.3	0	867.1	0
      25%	723.3	241.1	650.4	216.8
      35%	626.8	337.5	563.6	303.5
      45%	530.4	434.0	476.9	390.2
      55%	434	530.4	390.2	476.9
      65%	337.5	626.8	303.5	563.6
      75%	241.1	723.3	216.8	650.4

      Mix Proportions: The mix proportions were made for a control mix of final slump (10min) 100 ± 10 mm for M40 grade of concrete for w/c ratio of 0.40 by using IS-10262- 2009 method of mix design.

      Fig. 2. Slump in mm % variation comparison graph

   2. Compression strength

      Following is the graphs from results of the Compressive tests performed.

      Fig. 3. Compressive Strength in MPa comparison graph

      Fig. 4. Compressive Strength % increase comparison graph

   3. Flexural Strength

      Following are the graphs from results of the Flexural tests performed.

      Fig. 5. Flexural Strength in MPa comparison graph

      Fig. 6. Flexural Strength % increase comparison graph

   4. Split Tensile Strength

   Following are the graphs from results of the Split tensile tests performed.

   Fig. 7. Split tensile Strength in MPacomparison graph

   Fig. 8. Split tensile Strength % increase comparison graph

6. CONCLUSION

1. Workability : From fig 1 and 2

   With addition of %slagthe Workability variation is as follows:

   %Slag	25%	35%	45%	55%	65%	75%
   M20	12.50	16.67	16.67	20.83	25.00	25.00
   M30	13.64	18.18	18.18	22.73	27.27	27.27

2. Compressive Strength: From fig 3 and 4

   Compressive strength when compared with control mix for 3D, 7D & 28D s goes on increasing .

   With replacement of25% slagthe compressive strength goes on increasing as follows :

   	3Days	7Days	28Days
   M20	4.84	2.53	2.39
   M30	3.36	2.67	1.76

   With replacement of 35% slag the compressive strength goes on increasing as follow :

   	3Days	7Days	28Days
   M20	11.01	4.98	3.02
   M30	9.17	5.78	2.95

   With replacement of45% slag the compressive strength goes on increasing as follow :

   	3Days	7Days	28Days
   M20	18.72	8.14	4.42
   M30	16.60	8.41	3.81

   With replacement of with 55% slag the compressive strength goes on increasing as follow :

   	3Days	7Days	28Days
   M20	8.95	3.44	3.12
   M30	6.58	4.18	2.34

   	3Days	7Days	28Days
   M20	-1.23	-0.56	-0.83
   M30	-2.24	-0.53	-0.90

   With replacement of 65% slag the compressive strength goes on decreasing as follow:

   With replacement of with 75% slag the compressive strength goes on increasing as follow :

   	3Days	7Days	28Days
   M20	-4.32	-6.25	-5.62
   M30	-5.11	-5.30	-5.86

3. Flexural Strength: From fig 5 and 6

   Flexural strength when compared with control mix for 28D s goes on increasing.

   With replacement of % of slagthe flexural strength goes on increasing as follows:

   slag%	25%	35%	45%	55%	65%	75%
   M20	1.89	5.03	8.18	6.29	2.52	-3.14
   M30	-1.67	4.01	5.35	5.02	0.33	-7.02

   It is observed that flexural strength at 28days increases with increasing quantity of slag.

4. Split tensile strength from fig7 and 8

   Split Tensile strength when compared with control mix for 28D s goes on increasing .

   With replacement of % of slag the Split Tensile strength goes on increasing as follows:

   slag%	25%	35%	45%	55%	65%	75%
   M20	0.9	0.9	3.8	1.9	-8.5	-10.4
   M30	0.6	1.8	3.1	1.2	-9.2	-14.7

   It is observed that Split tensile strength at 28days increases with increasing quantity of slag.

5. Overall Conclusion

1. Workability of Slag replacement concrete is higher than control mix and well as showed the better cohesiveness.

2. The compressive Strength of concrete at 28 days is increased by 4.42% for M20 and 3.81% for M30 when the fine aggregate replaced by slag by 45% and further increase in replacement decrease the strength.

3. The Flexural Strength of concrete at 28 days is increased by 6.29% for M20 and 5.02% for M30 when the fine aggregate replaced by slag by 55% and further increase in replacement decreased the strength.

4. The Spilt tensile Strength of concrete at 28 days is increased by 1.9% for M20 and 1.2% for M30 when the fine aggregate replaced by slag by 55% and further increase in replacement decreased the strength.

5. Hence, it could be recommended that slag aggregate could be effectively utilized as fine aggregate in all concrete applications either as partial or full replacements of normal crushed coarse and natural fine aggregates.

ACKNOWLEDGMENT

We express my gratitude with reverence towards Mr. Shrikant Varpe (Deputy Manager, Ambuja Cements Ltd, Mumbai.) for his constant support in clarifying the all the doubts that our encountered during literature review and while working in the Shree laboratory (Concrete Lab, Chembur).

We are short of words to express our sincere gratitude to all the staff of Concrete Lab. Without their active support it was not possible to initiate the research work.

REFERENCES

1. Frigione G.( 1986): Manufacture and characteristics of portland blast furnace slag cements, American Society for Testing and Materials, Blended cement, ASTM STP 897,G.Frohnsdorff, Ed., Philadelphia , 15-28

2. Dunstan E.R. (1985): A Strength Model for Concretes Containing Fly Ash, Blast-Furnace Slag and Silica Fume, Materials research society proceedings, vol. 65

3. Dubovoy V.S., Gebler S. H. and Klieger P. (1986): Effects of Ground Granulated Blast Furnace slag on some properties of pastes, mortars and concretes, American Society for Testing and Materials, Blended cement, ASTM STP 897,G.Frohnsdorff, Ed., Philadelphia , 29-48.

4. Osborne (1999): Durability of Portland blast furnace slag cement concrete,Cement and Concrete Composites ,vol 21,issue 1, 11- 21,1999.

5. Ganesh Babu and Rama Kumar (2000): Efficiency of GGBS in concrete, Cement and concrete research, vol. 30, issue 7, 1031-1136.

6. Hooton R.D. (2000): Canadian Use of Ground Granulated Blast furnace Slag as a Supplementary Cementing Material for Enhanced Performance of Concrete, Can. J. Civil Eng., vol.27, 754-760.

7. Shun-hu and BAO Xian-cheng (2001-05): Influences of ground granulated blast furnace slag on the performances and durability of concrete, HU Peng-gang Chinal Concrete and Cement Products.

8. Wan, Shui and Lin (2004): Analysis of geometric characteristics of GGBS particles and their influences on cement properties, Cement and concrete research, vol.32, issue 1, 133-137.

9. Gao and Qian (2005): ITZ microstructure of concrete containing GGBS, Cement and concrete research, vol. 35, issue 7, 1299-1304.

10. Wu Xiaand Wang (2006): Study on Strength and Bond Characteristics of GGBS Concrete,Engineering Materials, Environmental Ecology and Technology of concrete, vol. 302-303, 561-566.

11. Oner and Akyuz (2007): An experimental study on optimum usage of GGBS for the compressive strength of concrete, Cement and concrete composites, vol. 29, 505-514.

12. Tamilarasan V.S. and Perumal P. (2012): Workability studies on concrete with ggbs as a replacement material for cement with and without superplasticizers,International Journal of advanced research in engineering and Technology (IJARET), vol. 3, issue 2, 11-21.