Case Studies on Durability of High Volume GGBS Concrete Used in Marine Structures

Lopamudra Sengupta, Ph.D Scholar, V P Technical Services, Abhijeet Landage, M-Tech, Concrete Technologist, Dr L R Manjunatha, Ph.D, Zonal Head, Yogananda MV, M-Tech, Concrete Technologist

Introduction

General

Durability and strength are two most important criteria and requirements for the long-term performance of concrete structures against weathering action, chemical attack and abrasion. Any deficiency in any of the two i.e. durability and strength, could make the structure unfit for the intended purpose. If the structure is not durable, but has sufficient strength, then the strength of the structure reduces with age due to deterioration of concrete and reinforcement due to surrounding conditions.

Environment plays an important role while selecting durable materials for concrete structures. For coastal environments where the rate of corrosion is very high, precautions should be taken for the corrosion allowance of reinforcement, epoxy painting of reinforcement, required cover to reinforcement, grade of concrete to be used, minimum cement content, water-cement ratio, quality of water for construction, alkali content of the aggregates, proper placement and compaction of concrete.

In addition to above precautions fine Pozzolanic/Cementitious materials such as Fly ash (FA), Ground Granulated Blast Furnace Slag (GGBS) and Ultrafine Pozzolanic materials such as Silica fume (SF), Rice Husk Ash (RHA), Metakaolin (MK), Ultrafine Slag (UFS), Ultrafine Flyash (UFFA) were used in concrete to improve the particle packing which in turn reduces the porosity and restricts the movement of moisture, air & carbon dioxide into the core of concrete [1]. In the United States, Secondary Cementitious Materials (SCMs) are usually added to concrete rather than blended with clinker, and currently more than 60% of ready-mixed concrete uses SCMs [2].

Many research scholars across the globe are involved in investigating the potential use of carbon-based nano material Graphene Oxide (GO) and Carbon Nano Tubes (CNT) as nano reinforcement in concrete. Use of Nano materials improves the micro structure of concrete especially nano pores in high strength concrete. The addition of 0.05% graphene oxide (GO) nanosheets (by weight of cement) can effectively increase the compressive strength and flexural strength of ordinary Portland cement paste by 15% to 33% and 41% to 58% respectively [3]. Probably Nano technology will be adopted as one of the solution for durable concrete structures in future.

Background to High Volume GGBS Concrete
Mineral additive like GGBS enriches the performance of concrete against Chloride attack, Sulphate attack, Alkali Silica reaction [4,5] also helps in low heat of hydration, reduced permeability, Higher long-term strength and improved workability. Blast furnace slag has both filling and dispersing effect in mortar and concrete [6]. With all above benefits of GGBS in concrete it was decided to use High volume in sea structures.

Micro level Studies
Scanning Electron Microscope (SEM) and Particle size analysis studies were done on GGBS to understand the morphology at micro level. Particle size and shape influences the strength gain and packing efficiency [7] and hence reduces permeability and increases strength of concrete. Particle shape and size on 20-Micron scale shows surface area and bond area of GGBS is better compared to fly ash. In Fly ash, spherical shaped particles have less bonding surface.

Micro-Photographs of Cement, GGBS and Fly ash at 20X MagnificationFigure 1: Micro-Photographs of Cement, GGBS and Fly ash at 20X Magnification

Real Time Study on Marine Structures
One of the greatest discoveries of 20th century was oil and its exploration initially was concentrated on land. As the need for oil expands in an explosive rate, oil industry moves into deeper water in the search for additional supplies of oil and gas with the construction of offshore platforms and Jetty. Depending on the water depth and environmental conditions the type of offshore structure is designed with structural steels and concrete members. In order to resist aggressive environmental conditions precaution is taken in both steel and concrete to achieve durability which will be explained in below case studies.

Background for Case Studies
In the case studies below, Offshore Platform structure and Jetty is exposed to severe coastal conditions near to Mumbai, India. Other than Gravity loads, Environmental loads and Seismic loads, structure will also be subjected to chloride attack, Sulphate attack, Corrosion of Reinforcement, Penetration of sea water and erosion during its construction and service life. Based on literature, material availability, consistent quality, similarity in physical and chemical properties with cement and compatibility with chemical admixtures it was decided to use GGBS in concrete as per IS 16714 – 2018 [8] in conjunction with ordinary Portland cement.

Case Study 1: An Offshore platform structure exposed under Severe Coastal Condition
As shown in Figure 2 and Figure 3, a composite Offshore structure of fixed platform type shows Concrete Gravity Platforms and Steel Template Structures which is under construction. Deep studies were done in material selection & proportion to manufacture high performance concrete against severe aggressive condition. Each and every ingredients of concrete were tested for its physical and Chemical properties as per Indian Standards (IS) codes to check its suitability for trials mixes and construction. Initially, various combinations of Cement - Fly ash, Cement - UFS were tested for its fresh & hardened properties and later OPC 53 is partially replaced by GGBS at various percentages in concrete starting from 0,10,20,30,40,50,60 & 70 and based on the results GGBS is used up to 60% in M-45 grade concrete for Pile & Pile Cap works. Many mix proportions were carried out for various grades of concrete and tests were done to ascertain the selected concrete for its fresh properties, Hardened properties and durability.

Images of Offshore Platform under ConstructionFigure 2 & 3: Images of Offshore Platform under Construction

Keeping all the parameters same, a Comparative durability studies were carried on Actual Concrete sample (ACS) (40% OPC 53+ 60% GGBS) and Standard Laboratory sample (SLS) (100% OPC+ 0% GGBS). Three durability tests namely Chloride Migration Coefficient Test (CMCT) as per NT Build 492 [9], Chloride Ion penetration test (RCPT) as per ASTM C 1202 [10] and Water Permeability Test (WPT) as per DIN:1048 Part 5-1991[11] were carried on test specimens.

Durability Tests:
Test 1: Chloride Migration Coefficient: The chloride migration coefficient method is a measure of the resistance of the tested material to chloride penetration. Non-Steady-state migration test is carried on the test specimens and the results achieved is less than 2 x 10-12 m2/s for Actual Concrete sample compared to Standard Laboratory sample of 9 x 10-12 m2/s. As per Table 1, Actual Site sample showed ‘very good’ concrete quality compared to Standard Laboratory sample and it was decided to use it for Substructure Works. For superstructure, concrete which showed Chloride migration coefficient (2 - 8)*10-12 m2/s is used.

Table 1: Criteria for Chloride Migration Coefficient Test as per project requirements
Non-Steady state migration coefficient (x10-12 m2/s) Concrete Quality
<2 Very good
2-8 Good
8-16 Normal
>16 Poor
Test 2: Chloride Ion Penetration Test: This test method covers the determination of the electrical conductance of concrete to provide a rapid indication of its resistance to the penetration of chloride ions. Rapid Chloride Penetration Test (RCPT) result achieved is less than 800 Coulombs for Actual Concrete sample compare to Standard Laboratory Sample of 1800 Coulombs.

Table 2: Chloride Ion Penetrability based on charge passed as per ASTM C 1202
Charge passed (Coulombs) Chloride Ion Penetrability
>4000 High
2000-4000 Moderate
1000-2000 Low
100-1000 Very low
<100 Negligible
Above table provides a qualitative relationship between the results of this test and the chloride ion penetrability of concrete. From Table 2, we can clearly say that the presence of GGBS around 60% of total cementitious material in concrete reduced the chloride Ion Penetration to “Very low” extent. Based on results ‘Very low’ Chloride Ion Penetrability concrete is used in substructure and ‘low’ Chloride Ion Penetrability concrete for superstructure in the project.

Test 3: Water Permeability Test: This test determines the true resistance of concrete against the penetration of water under hydrostatic pressure. WPT were carried on Actual Concrete Sample and Standard Laboratory sample and the mean depth of water penetration is 7mm and 20mm respectively. As per DIN: 1048 Part 5-1991 and MORTH 5th revision, the mean of maximum depth of penetration shall not exceed 25mm.

Case Study 2: An Offshore Structure with Jetties
As shown in Figure 4, a composite Offshore structure and Jetty is in under construction stage. Mix proportions were carried with different percentages of Cement and GGBS (75% OPC 53 + 25% GGBS, 65% OPC 53 + 35% GGBS, 50% OPC 53 + 50% GGBS) and tests were done to ascertain the selected concrete for its fresh properties, hardened properties and durability. Based on preliminary test results, GGBS is used up to 50% in M-40 grade concrete for Pile, Pile Cap and Precast works.

Image of Offshore Structure platform and JettieFigure 4: Image of Offshore Structure platform and Jettie

Table 3 shows the mix proportion of M40 Grade concrete with Compressive Strength result and Workability of concrete in terms of Slump and Flow.

Table 3: Mix proportion for M40 Grade Concrete
Grade of Concrete Binder Content in Kg/m3 Water/Cement Chemical Admixture Dosage in % Compressive Strength in Mpa Workability in Flow/Slump
in mm
OPC 53 GGBS Initial 60 Min 120 Min
M-40 240 240 0.37 1-1.5 52.8 600/
Collapse
580/ Collapse 550 / ≥ 180
Durability Tests:
1) Test 1: Chloride Ion Penetration Test: RCPT test is carried as per ASTM C 1202 on cores from the structure which is cured for 12 days and tested after 28 days. Result achieved is less than 1000 Coulombs with GGBS replacement of 50% in M-40 Pile, Pile cap & Precast work at project site. From Table No 2, we can clearly say that 50% of GGBS in total cementitious material in concrete reduced the chloride Ion Penetrability to ‘Very low’ extent.

2) Test 2: Water Permeability Test: The Mean of Maximum depth of penetration of three test specimens is 7 mm. Obtained test result is within the permissible limit as mentioned in DIN: 1048 Part 5-1991 and MORTH 5th Revision.

Thus, it is an established fact that in order to build environmentally sustainable structures, the 21st Century construction practices must be driven by considerations of durability and sustainability. Being the most important infrastructure players and major consumers of natural resources on the earth, the concrete industry will have to be reshaped through the adoption of environment friendly technologies. The owner, developer, designer and contractors can demonstrate that by using concrete wisely, they will be contributing to sustainability and by incorporating some of the benefits of concrete, save both money and resources during the life of the structure.

The Blast furnace slag products have been included as “designated procurement items.” in Japan for public works under the law concerning the promotion of procurement of eco- friendly goods and the services by the state and other entities (Green purchasing Law) which took effect in 2001 in Japan.

We need to further focus specifically on concrete’s role in the provision of sustainable structures, sustainable architecture, sustainable roads and sustainable human settlement

Conclusion
Following are the few conclusions drawn from above two case studies:
  1. Chloride Migration Coefficient value decreases with increased percentage of GGBS upto 60% in concrete.
  2. Comparing both the case studies, we can clearly say that higher the content of GGBS in concrete reduces the Chloride Ion Penetration which in turn reduces the corrosion of reinforcement.
  3. The presence of GGBS in concrete reduces the water permeability in to the core of concrete this is mainly due to pore refinement and grain refinement.
  4. Thus in order to achieve durability of concrete Secondary Cementitious Materials and Ultrafine materials to be used in addition to primary binders in concrete at appropriate quantity.
Reference
  1. Malhotra, V.M and Mehta, P.K. (1996), “Pozzolanic and Cementitious Materials”, Overseas Publishers, 191.
  2. S.H. Kosmatka, M.L.Wilson, Design and Control of Concrete Mixtures, 15th ed. Port.Cem. Assoc, Skokie, Illinois, 2011.
  3. T. Manzur and N. Yazdani, “Strength enhancement of cement mortar with carbon nanotubes: early results and potential,” Transportation Research Record, no. 2142, pp. 102–108, 2010.
  4. Kulkarni, V.S. (1998), “Use of ground granulated blast furnace slag for strength and durability”, Indian cement review, No.12, 3-16.
  5. Wang Ling, Tian Pei and Yao yan, “Application of ground granulated blast furnace slag in High performance concrete in China”, International workshop on sustainable Development and concrete technology, Beijing, China, 2004, 309-317.
  6. Mehta P K and Richard W Burrows (2001), “Building durable structures in 21st century, The Indian concrete journal”, v. 34, No.7, 437-443.
  7. Huiwen Wan, Zhonghe Shui and Zongshou Lin, (2004), “Analysis of Geometric Characteristic of GGBS particles and their influences on Cement Properties”, Cement and Concrete Research, V. 34, No. 1, 133-137.
  8. IS 16714-2018, “Ground Granulated Blast Furnace Slag for use in Cement, Mortar and Concrete”, Bureau of Indian standards, New Delhi, India
  9. NT Build 492, Nordtest Method “Chloride Migration Coefficient from Non-Steady-State Migration Experiments”.
  10. ASTM C1202, “Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration”, American society for testing and materials.
  11. DIN 1048 (Part 5), “Testing Concrete: Testing of Hardened Concrete Water Permeability”.
  12. IS 456-2000, “Plain and reinforced concrete-code of practice”, Bureau of Indian standards, New Delhi, India
  13. MORTH, Specifications for Road and Bridge Works, Fifth Revision 2013.
NBM&CW September 2021
Accelerated Building & Bridge Construction with UHPC

Accelerated Building & Bridge Construction with UHPC

UHPC, which stands for Ultra High-Performance Concrete, is a testament to the ever-evolving panorama of construction materials, promising unparalleled strength, durability, and versatility; in fact, the word concrete itself is a misnomer

Read more ...

Innovative Approaches Driving Sustainable Concrete Solutions

Innovative Approaches Driving Sustainable Concrete Solutions

This paper explores the evolving landscape of sustainable concrete construction, focusing on emerging trends, innovative technologies, and materials poised to reshape the industry. Highlighted areas include the potential of green concrete

Read more ...

GGBS: Partial Replacement Of Cement For Developing Low Carbon Concrete

GGBS: Partial Replacement Of Cement For Developing Low Carbon Concrete

Dr. L R Manjunatha, Vice President, and Ajay Mandhaniya, Concrete Technologist, JSW Cement Limited, present a Case Study on using GGBS as partial replacements of cement for developing Low Carbon Concretes (LCC) for a new Education University

Read more ...

Behaviour of Ternary Concrete with Flyash & GGBS

Behaviour of Ternary Concrete with Flyash & GGBS

Evaluating the performance of concrete containing Supplementary Cementitious Materials (SCM) like FlyAsh and Ground Granulated Blast Furnace Slag (GGBS) that can be used in the production of long-lasting concrete composites.

Read more ...

Nanospan’s Spanocrete®: nano-admixture for concrete

Nanospan’s Spanocrete®: nano-admixture for concrete

Nanospan’s Spanocrete, a Greenpro-certified, award- winning, groundbreaking nano-admixture for concrete, actualizes the concept of “durability meets sustainability”. This product simplifies the production of durable concrete, making it cost-effective

Read more ...

The Underwater Concrete Market in India

The Underwater Concrete Market in India

India, with its vast coastline and ambitious infrastructural projects, has emerged as a hotspot for the underwater concrete market. This specialized sector plays a crucial role in the construction of marine structures like bridges, ports

Read more ...

The Path to Enhanced Durability & Resilience of Concrete Structures

The Path to Enhanced Durability & Resilience of Concrete Structures

This article highlights a comprehensive exploration of the strategies, innovations, and practices for achieving concrete structures that not only withstand the test of time but also thrive in the face of adversity.

Read more ...

Self-Curing Concrete for the Indian Construction Industry

Self-Curing Concrete for the Indian Construction Industry

The desired performance of concrete in the long run depends on the extent and effectiveness of curing [1 & 2]. In the Indian construction sector, curing concrete at an early age is a problematic issue because of lack of awareness or other

Read more ...

BigBloc Construction an emerging leader in AAC Block

BigBloc Construction an emerging leader in AAC Block

Incorporated in 2015, BigBloc Construction Ltd is one of the largest and only listed company in the AAC Block space with an installed capacity of 8.25 lakh cbm per annum. The company’s manufacturing plants are located in Umargaon

Read more ...

Decarbonizing Cement Industry: Sustainable & Energy-Efficient Measures

Decarbonizing Cement Industry: Sustainable & Energy-Efficient Measures

Dr. L R Manjunatha (VP), Manoj Rustagi (Chief Sustainability & Innovation Officer), Gayatri Joshi (ASM), and Monika Shrivastava (Head of Sustainability) at JSW Cement Limited, discuss new approaches for Decarbonizing the Cement

Read more ...

Concrete Rheology: Technology to Describe Flow Properties of Concrete

Concrete Rheology: Technology to Describe Flow Properties of Concrete

Concrete is a heterogeneous composite complex material, and its hardened property is influenced by its fresh property. Concrete today has transformed into an advanced type with new and innovative ingredients added - either singly or in

Read more ...

Amazecrete ICRETE: Making Concrete Economical & Durable

Amazecrete ICRETE: Making Concrete Economical & Durable

ICRETE offers many benefits apart from reducing cement content and giving high grades saving to ready-mix concrete companies; it helps reduce shrinkage and permeability in concrete slabs, increases the durability of concrete, and also works

Read more ...

UltraTech Cement & Coolbrook’s RotoDynamic HeaterTM Technology

UltraTech Cement & Coolbrook’s RotoDynamic HeaterTM Technology

UltraTech Cement Limited, India’s largest cement and ready-mix concrete (RMC) company, and Coolbrook, a transformational technology and engineering company, will jointly develop a project to implement Coolbrook’s RotoDynamic HeaterTM (RDH)

Read more ...

Plastic Shrinkage and Cracks in Concrete

Plastic Shrinkage and Cracks in Concrete

Plastic shrinkage cracking occurs when fresh concrete is subjected to a very rapid loss of moisture. It is caused by a combination of factors such as air and concrete temperature, relative humidity, and wind velocity at the surface of concrete. These can cause

Read more ...

Dam Rehabilitation With Cutoff Wall for Seepage Control

Dam Rehabilitation With Cutoff Wall for Seepage Control

This paper covers the research work carried out on cement plastering process for internal and external building wall by using spray plastering machine. Objective of study is to experiment and compare the plastering activity by conventional way and

Read more ...

Construction Defects Investigation & Remedies

Construction Defects Investigation & Remedies

In recent years, the speed of construction has increased very fast; buildings which used to take 3-5 years are now getting completed in 1-2 years. There is a race to complete projects faster, but due to this speedy construction, the quality of construction is often

Read more ...

Challenges in usage of Hydrogen in Cement Industry

Challenges in usage of Hydrogen in Cement Industry

With its zero-emission characteristics, hydrogen has become a promising decarbonization path for the cement industry. While there are several issues that need to be resolved in the use of hydrogen, there are also many advantages, so much so that the growth

Read more ...

Enhancing Corrosion Resistance of Steel Bars in Reinforced Concrete Structures

Enhancing Corrosion Resistance of Steel Bars in Reinforced Concrete Structures

Reinforced concrete is a composite material which is made using concrete and steel bars. Concrete takes the compressive forces and steel bar takes tensile forces. Concrete around the steel bar protects it from corrosion by providing an alkaline environment

Read more ...

Moving toward workability retention to rheology retention with low viscosity concrete technology

Moving toward workability retention to rheology retention with low viscosity concrete technology

Amol Patil, Sr. Specialist - General Manager (Admixture and Specialty Products), Master Builders Solutions (India), and Nilotpol KAR, Managing Director, Master Builders Solutions (South Asia), present a paper on the concept of low viscosity concrete in

Read more ...

Cement industry innovating eco-friendly packaging

Cement industry innovating eco-friendly packaging

Cement companies are constantly innovating to meet global sustainability standards and improve logistics, shelf life, and utility of cement, while reducing wastage. Thei aim is to reduce their environmental impact without compromising their product

Read more ...

To get latest updates on whatsapp, Save +91 93545 87773 and send us a 'Saved' message
Click Here to Subscribe to Our eNewsletter.