RECENT DEVELOPMENTS IN THE INDIAN CONCRETE INDUSTRY IN THE USE OF GGBS IN CONCRETE AT RMC BATCHING PLANTS AS PARTIAL REPLACEMENT TO OPC CEMENT AND ITS EFFECTS ON CONCRETE DURABILITY AND SUSTAINABILTY IN THE INDIAN CONTEXT

L.R. Manjunatha 1, Sandhya. R. Anvekar 2, M.V. Yogananda 3

1AGM-Marketing, JSW Cement limited, Bharatiyar University India,

2VTU, Bangalore, India 3JSW Cement limited, India

ABSTRACT Sustainability, or sustainable development in concrete and construction industry, is aimed at improving the quality of life for everyone, now and for the next generations. It encompasses environmental, economic and social dimensions, as well as the concept of stewardship, the responsible management of resources we use in construction and particularly concrete production in India being the second largest producer of cement in the world. The future challenge for the construction industry in India is clearly to meet the growing needs for infrastructure development and housing while at the same time limiting the impact of its burdens in CO2 emissions due to construction by drastic improvements in the use of alternative materials in construction and supplementary cementing materials as partial replacements to OPC. Cement and steel production accounts for almost 19-20 % of CO2 emissions in India. Due to exponential growing in urbanization and industrialization, byproducts from the steel industries such as GGBS are becoming an increasing concern for recycling and waste management. At same time, studies have revealed usage of GGBS in concrete as a partial replacement for OPC have increased the compressive strength, tensile strength, durability and decreases the permeability, embodied energy and cost per cubic meter. By knowing the numerous advantages of industrial byproducts, Ready-mixed concrete (RMC) industries have partially replaced the cement with Fly Ash, GGBS, ultrafine GGBS or Silica Fume, which are by-products of other industries. Currently over 40-45 % of the concrete supplied by RMC companies in India has a replacement of Fly ash and GGBS. The acceptance level for blended cements and concretes in India is increasing because of inherent mechanical properties of mineral admixtures and easy availability in southern and western markets. GGBS blended concrete have been used successfully in concrete for many years in many countries throughout the world were structures have to be designed for durability requirements in very aggressive environment.

The research paper deals with how the RMC and concrete industry in India is progressively using GGBS, how the growth and the adoptability is happening through RMC way, case studies which have revealed durability and permeability of concrete in presence of GGBS.

KEY WORDS: GGBS, OPC, RMC, fly ash, silica fume

INTRODUCTION Ready Mixed Concrete Industry in India The Ready mix concrete business in India is in its infancy but it is having a steady growth in the last 2 decades. For example, 70% of cement produced in a developed country like Japan is used by Ready Mix concrete business there. In Europe and USA it is about 60% [1]. Here in India Ready Mix concrete business used around just 2 % in the beginning of the 90’S and presently the commercial RMC is at 9 -10 % of total cement production with another 10% estimated to come from project based captive RMC plants totally taking the mechanized RMC Production to 20 % of the cement production in India and there is still a lot to catch up in terms of growth and conversion of Site mix Concrete(SMC)to Ready mixed concrete [2]. The Indian cement industry is the second largest in the world with an installed capacity of 340 million tonnes and the production for the year 2013-14 was around 260 million tonnes and presently the commercial RMC alone consumes around 9-10 % of the total cement production and producing approximately 30-32 million cubic meter of commercial ready-mixed concrete annually. Captive RMC plants which are set up at project sites in metros and cities have been estimated to produce around another 35 million cubic meter of ready -mixed concrete annually, which in turn taking the total production of mechanized concrete (production of concrete from RMC batching plants) in India to about 65-67 million cubic meter annually. In the developed countries the cement consumption through RMC route is about 70-75 % (USA) and 65-70 % (Europe and Japan). [3] As a testimony to the growth of RMC industry in India, as per best of the knowledge, currently there are more than 900 commercial RMC plants present and operating in about 95 to 100 cities and towns across India including metros, tier 1 and tier 2 cities and in total there are more than 2600 ready-mixed concrete batching plants in operation in many metros, cities, and various project locations across the country. An added advantage of RMC is quantity of OPC usage can be reduced in Ready Mixed Concrete by replacing a good portion of cement by supplementary cementing materials like Ground granulated blast furnace slag(GGBS), Fly ash, Microsilica with are industrial by products which otherwise would have been solid waste products and caused serious environmental issues. In the present scenario, cost of cement have been increased abruptly which leads to increase of cost of concrete. To overcome the inflation, supplementary cementitious materials are used in conjunction with OPC. So that the, durability, Sustainability and cost effective can be achieved with the usage of mineral admixtures.

LITERATURE REVIEW Need for durability and sustainability As worldwide awareness and concern over increased carbon emissions and its direct impact over global climate change increases, there is intense pressure over all industries to reduce their emissions. The backbone of the construction industry is concrete, which is widely regarded as a high energy material with a current consumption of 1 cubic meter per person per year. Some of the proposed alternatives are Blended Concretes that utilize industrial wastes such as Fly ash and GGBS. [4]

Ordinary Portland cement (OPC) has been used for around 200 years as a binder material. However OPC has high embodied energy of 4.2MJ/kg [5][6]. The contribution of OPC is approximately 5–7% of global man made CO2 emissions [7] high CO2 emissions arising from OPC manufacturing are from calcination of limestone, and high energy consumption during manufacturing. [5] During the recent past many alternatives to OPC concrete have been proposed to reduce green house gas emissions which are Blended Cement Concretes, comprising OPC that has been partly substituted by supplementary cementitious materials, as binders for concrete. Commonly used substitutes include Fly ash, a fine waste residue that is collected from the emissions liberated by coal burning power stations, and ground granulated blast furnace slag (GGBS), a waste by-product from steelmaking. According to Flower and Sanjayan use of blended cements results in reduction of CO2 emissions by 13–22%. These estimates vary according to the local conditions at the source of raw materials, binder quantity, and amount of OPC replacement, type of manufacturing facilities, climate, energy sources, and transportation distances. [8] Scope for research The Indian Ready mix concrete Industry is totally an unorganized sector .The First Commercial RMC plant was started somewhere in the year 1992 at Pune, Since then the industry has gradually grown all over India. There has been the use of green products like Fly ash and GGBS for making the RMC products more durable, Sustainable and Eco friendly and many consumers of RMC are not aware of the new developments in concretes like special eco friendly concretes and concepts.

• Since 1992 there is not much work has been done to estimate the approximate number of RMC plants in India being operated and how much approximate volumes are being produced and what is the scope for green marketing of green building raw materials like Fly ash and GGBS etc

• The availability and usage of secondary cementitious materials (SCMS) like Fly ash, GGBS, etc to make the RMC Concrete products more sustainable and durable and the scope for green marketing.

• To prove the durability and permeability properties of GGBS based concrete in few RMC’S for different grades of concrete at different locations.

Objective of the study

• To study the Indian consumers awareness and knowledge on the use of industrial by products like Fly ash and GGBS which are green and sustainable in Concrete productions as replacement of OPC in RMC Plants.

• To study and estimate the green marketing potential for products like GGBS and Fly ash for use in concrete production in the Indian RMC Industry.

• To study the effect of GGBS on durable properties of concrete in RMC plant. • To compare the durability and permeability properties of GGBS based concrete and

Fly ash based concrete.

BACK GROUND TO MATERIALS UNDER STUDY

Fly ash Fly Ash is the finely divided mineral residue resulting from the combustion of powdered coal in electric generating plants. GGBS (Ground granulated blast furnace slag) GGBS is obtained by quenching molten iron blast furnace slag in water or Steam, to produce a glassy granular product that is then dried and ground into a fine powder. Various parameters of GGBS and Fly ash are compared and tabulated in Table 1. Table 1 - Comparison of various parameters of mineral admixtures under study

Mineral Admixtures Slag Fly ash

Source Blast furnace quenching of molten material

Thermal Power Plants – fine residue of combustion

Chemical composition Similar to that of Cement high SiO2 and Al2O3, but low in CaO Hydration Hydraulic Non -hydraulic

Permitted replacement to cement 25 – 70 % 15 -35%

Production process Very stringent – stable chemical composition of slag

Not as stringent as in case of Steel / Iron

Impact of using secondary cementitious materials in concrete

• Reduction in the emission of CO2 from cement production plants. • Improved durability. • Reduced potential for cracking. • Reduced permeability. • Reduced corrosion repairs cost nearly by 5% of developed nation’s GDP • Use of waste or by-products reduces the clinker usage. • Increased benefit to cost ratio and Longer service life.

Fly Ash vis-à-vis GGBS Consistency of GGBS v/s Fly Ash

Slag is the co-product of a controlled process from iron production, which results in a very uniform composition from source to source. Fly ash is a byproduct of electric power generation that varies from source to source. This is one reason why Slag can be used in much larger amounts.

Both are used as a replacement for a portion of the Portland cement. Slag replaces as much as 50 percent in normal concrete (and up to 70 percent in special applications such as mass concrete). Fly -Ash is usually limited to 15 or 35 percent.

Indian Fly ash contains about 55 percent SiO2, out of which only 20 to 25 percent are in glassy form. Hence, addition of 100 kg of fly ash (that is, 25 percent of OPC), will consume only about 14 percent of Ca(OH)2; and 86 percent will remain unconsumed.

This calculation is in line with the fact that all of Ca(OH)2 in concrete was shown to be consumed only when 50 percent of Slag or 30 percent of silica fume was used, which is mostly active silica.

Fly ash is not a hydraulic material, hydration will not take place on its own, and it will only harden with the use of activators (e.g. OPC).

GGBS, in contrast, is a hydraulic material, which means that it will set and harden due to a chemical reaction with water.

After hardening, it will retain some strength development and remain stable even under water. Concrete containing GGBS cement has a higher ultimate strength than concrete that uses 100% Portland cement.

Advantages of GGBS over Fly ash on replacement levels

The permitted replacement ratio of Fly Ash in OPC is 15-35% (IS 1489 Part-1), but it’s usually no more than 30% in concrete.

On the other hand, the permitted replacement ratio of GGBS in OPC or concrete is 25-70% (IS 455). It could even be replaced up to 85% in some of the European countries.

With the same content of cementitious material (the total weight of Portland cement plus GGBS), similar 28-day strengths to Portland cement will normally be achieved when using up to 50 percent GGBS.

At higher GGBS percentages the cementitious content may need to be increased to achieve equivalent 28-day strength. GGBS concrete gains strength more steadily than equivalent concrete made with Portland cement.

Typically a Portland cement concrete will achieve about 75 percent of its 28-day strength at seven days, with a small increase of five to 10 per cent between 28 and 90 days.

CASE STUDIES IN INDIA ON THE USE OF GGBS IN RMC INDUSTRY FOR COST EFFECTIVENESS, DURABILITY AND SUSTAINABILITY Compressive Strength Test and Durability test In situ materials such as Aggregates, Cement, GGBS, Fly ash and water is used for mix proportioning in presents of admixtures keeping constant slump and water-cement ratio. Various combination of Cement - GGBS and Cement - Fly ash concrete of different grades were carried and Mix details with compressive strength are tabulated below. Table 2 - Location: Tricon RMC, Pune

Grade Mix design Concrete compressive strength

GGBS mix Fly ash mix 7 days 28 days Cement GGBS Cement Fly ash Fly ash GGBS Fly ash GGBS

M20 200 125 245 85.0 16.8 15.2 30.0 34.0 M25 225 140 265 90.0 20.8 19.9 34.5 40.9 M30 250 150 300 90.0 25.0 22.2 40.0 46.2 M35 285 145 340 80.0 30.0 25.6 44.7 51.0 M40 315 135 370 70.0 34.0 28.4 51.5 58.2 M45 325 135 400 60.0 38.0 32.3 56.3 61.2 M50 337 140 450 50.0 42.4 36.9 61.0 65.0

Figure 1 – Variation of Compressive strength of different grades of concrete with respect to Fly ash and GGBS content From Table 2, it can be observe that, replacement level of GGBS to cement is high compare to Fly ash with respect to any grade of concrete. From Figure 1, we can clearly say that 28 days compressive strength of GGBS based M20 grade concrete is higher over Fly ash based concrete and the similar trend is carried for different grades also. This was probably due to involve of GGBS in both Pozzolanic and cementitious reactions. Long-term strength test

30 34,5

40 44,7

51,5 56,3

61

34 40,9

46,2 51

58,2 61,2 65

0

10

20

30

40

50

60

70

M20 M25 M30 M35 M40 M45 M50

Fly ash

GGBS

Grade of Concrete

Com

pres

sive

Str

engt

h a

t 28

days

were carried for M25 grade GGBS and Fly ash based concrete for 90days which showed 36.2Mpa and 28.8Mpa respectively. Rapid Chloride penetration Test (RCPT) In situ materials such as Aggregates, Cement, GGBS and water is used for mix proportioning in presents of admixtures keeping constant slump and water-cement ratio for M20 grade concrete. Various combination of Cement – GGBS concrete were casted and tested for RCPT as per ASTMC 1202-97 and results are tabulated in Table 3.

Table 3 – Location: RMC Ready mix India, Mangalore plant

GGBS replacement Level in %

Cube ID RCPT, Coulombs Average of RCPT coulombs

0 3-A-1 2196

2220 3-A-2 2186 3-A-3 2279

25 4-B-1 1127

1034 4-B-2 1015 4-B-3 961

40 4-C-1 647

628 4-C-2 608 4-C-3 629

50 4-D-1 549

526 4-D-2 520 4-D-3 510

From Table 3, it is clear that increase of GGBS content in concrete decreases the RCPT value. This may be due to pore refinement by GGBS at microlevel which leads to lesser voids inturn leads to long term strength.

STATUS OF GGBS PRODUCTION, AVAILABILITY AND USAGE IN INDIA. Ready mix concrete industry is slowly and steadily adopting and increasing the usage of secondary cementing materials like Fly ash and GGBS in the production of ready-mixed concretes contrary to the use of pure ordinary port land cement concrete in the ready-mixed concrete productions in the initial stages of RMC Industry growth in the early 90’s. In the late 90’s and early 2000 ready-mixed concrete industry predominantly used blended concretes made with Fly ash as it was abundantly available from various nearby thermal power producing plants and was well received by the customers even though there was very much resistance from customers, structural consultants and builders in the early stage due to lack of awareness.

The year 2006 was the major entry of GGBS to the Indian market by a well known steel company in the south Indian markets having its manufacturing facility at Karnataka, Andra pradesh and Maharastra through their group cement company and later on many new companies have entered the market with manufacturing facility for GGBS due to the increased demand and potential. GGBS is now mainly available in major southern and western Indian ready-mixed concrete markets like Bangalore, Hyderabad, Chennai, Mumbai, Pune, Mysore, Mangalore, Hubli, Vizag, Vijayawada and Coimbatore etc If we look at the ready mixed concrete industry in India today, it has grown exponentially high due to availability and growth of technology, mechanization, resources and demand. As per survey conducted by the Authors during the period from December 2009 to April 2013 on the spread of commercial Ready mixed concrete plants in cites throughout India, and as per Table 4 listed below, there are more than 857 commercial RMC plants run by 5 large RMC companies like Ultratech, RMC readymix (India), Lafarge, ACC Concrete ,RDC Concrete and 445 smaller RMC companies operating in 88 large and smaller cities and towns across India producing approximately 2.25 million cum of commercial RMC monthly and the numbers are growing every year.

Table 4: All India Commercial RMC Statistics as on April 2013

Region City locations

Number of companies

Total RMC plants-All India

Approx production of RMC:

Cum/month South India 43 177 314 936147 Western &

Central 18 142 324 753524

North India 18 109 175 457380

Eastern India 9 22 44 99211

TOTAL 88 450 857 2246262 Source: Data compiled by Authors. [9] The usage of GGBS for producing concrete at RMC plants is increasing day by day in the southern and western markets due to the availability of product and technical superiority. As per survey it is estimated that average consumption of GGBS in the southern RMC industry markets is near to one million mt per year and about 0.4 million mt in the western India. CONCLUSION

1. It can safely be concluded that GGBS, which till recent years has been treated as a waste product of steelmaking plant, is in fact a valuable resource material. Its appropriate utilization can provide an economic bonanza worth more than a billion dollars.

2. If we add the value of land which would otherwise be excavated for consumption or for dumping of GGBS, value of agricultural produce from this land area and environmental benefits in terms of reduction in emission of green house gases & reduction in mining activity etc., the total worth of the saving would increase phenomenally.

3. Due to quality, availability, energy effective, low cost, it is widely used for construction purpose which enriches the workability, mechanical properties, durability and sustainability. 4. Because of enriched properties of GGBS, it is widely used for RCC in all types of foundations & Super Structure works, General building construction, Mass Concrete works in dams, spillways, canals, foundations, Underground works, retaining walls, culverts & drainage works, Effluent & sewage treatment plants, Marine work and many more. 5. RMC industry in southern and western Indian market is adopting the use of GGBS in their concrete mixes for giving value addition to their customers in respect of cost effectiveness, sustainability and durability performance. REFERENCES 1. L.R.Manjunatha and Dr.Sandhya.R.Anvekar "Ready-mixed concrete, a boon to modern day’s fast track construction projects and a research study on Customers" Preference ,Perceptions on quality, timely delivery and durability aspects of Ready Mixed Concrete (RMC):”EPC & I Magazine, April 2013 Issue 2. L.R. Manjunatha and Dr. Sandhya R.Anvekar,Dr.Aswath and Mr.Suresh Rao "Innovative special concrete applications using RMC :Some case studies" Universities press—Innovations in concrete for meeting Infrastructure Needs ISBN 978 81 7371 912 7 3. L.R. Manjunatha and Dr. Sandhya R.Anvekar and Mr.Suresh Rao "Innovative applications of concrete for modern day constructions with special focus on Indian concrete industry Examples" Indian Concrete Institute, ISBN 978 -81928912-00 4. Gartner E, Industrially interesting approaches to "low-CO2" cements. CemConcr Res 2004; 34(9):1489–98. 5. L.R. Manjunatha ,Dr. Sandhya R. Anvekar,Savitha and Archana "An Economic and Embodied Energy comparision of Geo-Polymer blended cement and traditional Concretes" Journal of Civil Engineering Technology and Research-Volume 2 Issue 1, Jan-June 2014, ISSN 2349-9575 6. Peng J, Huang L, Zhao Y, Chen P, Zeng L, Zheng W. "Modeling of carbon dioxide measurement on cement plants". Adv Mater Res 2013; 610–613:2120–8.

7. ]Huntzinger DN, Eatmon TD."A life-cycle assessment of cement manufacturing: comparing traditional process with alternative technologies". J Clean Prod 2009;17(7):668–75. 8. Flower DJM, Sanjayan JG. "Green house gas emissions due to concrete manufacture". Int J LCA 2007;12(5):282–8. 9. Suresh Rao and L.R.Manjunatha” Innovative use of concrete for modern day constructions” The master builder,October 2013.PP78-86, ISSN 2249-1228