Production of low fines SCC with increased robustness in a highly flowable, less viscous condition meeting true SCC specifications is now a reality to help realise the architect’s and engineer’s dream of various complex profiles and shapes in various structures across sectors. Nilotpol KAR, Managing Director, Master Builders Solutions, South Asia, and Amol Patil, Sr. Specialist- General Manager (Admixture and Specialty Products) Master Builders Solutions, India, present the concept, which has been validated through a few case studies where huge possibilities of its application exist in various civil engineering sectors.

Classical Self-Consolidating Concrete (SCC) has its pitfalls in stability and rheology with high cementitious content in the mix owing to the ever-changing concrete constituents. In grades of concrete around the 35 – 50 MPa, the cementitious content and the costs thereof are highly uneconomical to sustain.

In developing economies of Asia Pacific, use of classical self-consolidating concrete is still low and comprised in terms of evaluation. Also, nearly 75% of concrete is still below 40 MPa. Any SCC supplied by a concrete producer for these grades leads to an over design.

For the last decade, low fines SCC has evolved with special tailor-made Poly Carboxylate Ether (PCE) based hyperplasticizer coupled with special focus on the mix design to give a stable and fluid mix to conform to SCC specifications and is referred to as Smart Dynamic Concrete. With the further innovation and evolution of chemistry, tailor-made formulations incorporating special polymers aid in significant improvement in rheology to give better passing ability and segregation resistance. With the climate change policies, this enables better binary and ternary binder compositions to reduce CO2 emissions and result in improved durability. It is thus a dream come true of a higher performing and versatile concrete – in terms of Ecology, Ergonomy, Efficiency, and Economy.

Introduction
Use of high slump mixes as well as high flowable mixes existed since the 1980s. To activate dispersion in concrete, apart from focus on concrete mix design, optimum water binder ratio, powder type and content optimisation, a suitable comb type polymer – poly carboxylate ether (PCE) – based chemistry to maximise dispersion has been used.

While introduction of flowable mixes changed the dimension in concrete, it did not impact the construction industry in concrete pours except for dense / congested reinforcement. So, while we traverse from 1990s to 2010s less than an estimate of 2 – 4% of all ready mixed or site mixed concrete as an average is used as flowable mixes which typically fulfil all properties of Self Consolidating Concrete (SCC) as per
  1. 1. The European Guidelines for Self-Compacting Concrete - Specification, Production and Use.
  2. 2. ASTM C1611, the Slump Flow of Self-Consolidating Concrete; ASTM C1621, the Passing Ability of Self-Consolidating Concrete by J-Ring; and ASTM C1610.
Surprisingly, in Japan where the invention of SCC took place, the use is still < 20%.

Figure 1 provides an idea of the self consolidating concrete volume as a part of the total concrete volumes done in that country.

Classical Self-Consolidating Concrete (SCC)Figure 1: Estimated total concrete volumes and % of Self Consolidating Concrete (SCC) as % of total concrete volumes

Amongst the challenges to produce a perfect SCC in practice, it is designed for its rheology. It is important to have a perfect balance and homogeneity between flow and cohesion to avoid segregation and bleeding, so the placement and self consolidation happens perfectly in tune inside the confines of the structural sections especially in conditions of dense or congested reinforcement. In normal SCC mixes anything in excess of 500 kg/m3 is required where no less than 450kg is made up of cementitious content. The resultant mix is that the compressive strength is very high in the order to 60 to 75MPa. In many cases, this is an over design especially in the Indian context. Majority of concrete class required is less than 40 MPa and nearly more than 75% is between 30 – 45 MPa for the most commonly used grades of concrete in construction practice.

To make a justifiable point here is a case of a concrete structure falling in the category of R2 reinforcement (as per JASS) and strength class 30 MPa requiring joint-less concrete. The viable option here is SCC; however, the binder or cementitious fines to have a classical slump flow (spread) of > 600 mm and other limits of T500, L-Box, J-ring values would require somewhere to the tune of 450 kg/m3 of cementitious fines with standard poly carboxylate ether based admixtures. This would result in “overkill” in the concrete mix design – this is probably one of the biggest reasons why such a concrete, despite the immense benefits never grew popular across India owing to exorbitant costs.

Relevance of Self Consolidating Concrete and the path to low cementitious fines self consolidating concrete in India
Post two waves of Covid and the recovery in infrastructure and other sectors, the construction boom in India provides an opportunity for clients, developers, contractors, ready mix concrete and precast concrete companies to higher output without compromising on durability aspects of concrete (matrix, pore structure, permeability, water absorption, shrinkage, modulus of elasticity, recued cracking). For the popular grades of concrete a novel type of a tailor-made PCE based hyperplasticizer enables a practical on-site stable low fines self consolidation concrete (referred to as Smart Dynamic Concrete) taking care of Ecology, Efficiency and Ergonomy in the drive for some key aspects on the balance between “Environmental, Economic and Social” indicators. Fig 2 represents the balance between cost effective and flowability where low cementitious fines self consolidating concrete (also known as Smart Dynamic Concrete or SDC) establishes a definite path to achieving self consolidation in normal grades of concrete with all properties of traditional properties of SCC intact.

Classical Self-Consolidating Concrete (SCC)Figure 2: Smart Dynamic Concrete (SDC) incorporates the economics of regular ready-mix concrete and high performance of SCC

Today, designers are also interested in making complex designs with ordinary concrete as we step into the age of differentiation. All the stake holders are looking for “differentiation” in the market to capture customers’ attention and take a unique position whilst improving their service levels – value engineering. Concrete is a commodity and concrete producers endeavour to move away from the commoditisation of the second largest consumed material in the world (after water). In the quest for Value Added Concrete as a form of differentiation in the very competitive concrete market, there is immense possibility with a sustainable type in form of SDC.

A decade long innovation in making ordinary concrete, extraordinary
Smart Dynamic Concrete (SDC), a low-cementitious fines self consolidating concrete incorporates the ideal properties of cost effectiveness of regular ready-mix concrete and the flowability of conventional SCC as per the testing parameters laid in EFNARC / ASTM. The current challenges of energy efficiency, availability of labour, project delivery on time, speed and return on investment can be overcome with a sustainable and very dense matrix in the cover of concrete offering higher durability and flowable concrete (highly fluid) to save time and money. Reduced energy for consolidation of concrete, repair / rehabilitation issues, placement times and hence concrete placement times are reduced by at least 20 to 40%. Even SDC can flow without aid of vibration for 10 – 15 metres!

The role of construction chemicals gets pivotal here. The stability zone of self consolidating concrete is shown in Fig 3. The fluidity depends on a correlation between yield value and plastic viscosity which can be managed through the unique innovative concept of SDC. This is enabled with a unique PCE based hyperplasticizer tailor-made with a unique viscosity controlling agent to incorporate a perfect balance in a normal grade concrete without increasing cementitious fines and / or powder content. And yet achieve the entire SCC properties a required for an SDC.

Classical Self-Consolidating Concrete (SCC)Figure 3: Correlation in flowable concrete like SCC and SDC between Yield Value and Plastic Viscosity.

Some other salient values include:
  1. (i) Reduction in noise at site (1/5th to 1/10th) and minimal vibration to deliver improved health and safety at construction sites.
  2. Reduced manpower up to 33% compared to conventional concrete
  3. Higher levels of SCMs (supplementary cementitious materials) to delivery quantifiable sustainable benefits towards lower CO2 emissions. EPDs are possible to support in Green Building Certifications.
  4. The structural designer and architect can be emboldened to create more innovative, complex designs as well as exposed fair faced concrete.
  5. Owing to stability of the mix and its segregation resistance the resultant bleeding is lower than limits – this enables reduction of micro-cracking and the ITZ is benefited for a more durable and uniform concrete matrix.
  6. For the same grades of concrete – SDC vs traditional vibratable concrete delivers lower chloride diffusion values and lower permeability values.
A few case studies over the last 10 years
  1. Pashmina Waterfront: Bengaluru, Karnataka
    This project in Bangalore had challenges of high-rise pumping, form finish concrete and cycle time of modular formwork. Approximately 60,000 m3 of concrete was done with SDC concept with a reduction of cement content by 20 kg/m3, enhanced surface finish and reduction in concrete placement time by 25% enabling better cycle of formwork.

  2. Classical Self-Consolidating Concrete (SCC)Figure 4: Concrete Finish with SDC at a Pashmina Waterfront project

  3. Kalinganagar Township Project: Jaipur, Odisha
    The available aggregates for the grades of concrete posed a challenge for a sticky mix and SDC enabled a low viscosity concrete with a V Funnel time of less than 10 seconds creating a better placement situation which improved by 25%. Fig 5 below is a snapshot of the project.

  4. Classical Self-Consolidating Concrete (SCC)Figure 5: Concrete Finish with SDC at a township project in Eastern India

  5. Kalpataru Crescendo: Pune, Maharashtra
    The contractor had to deliver 35,000 m3 and the challenges to have an economical SCC mix to deliver form finished concrete. SDC technology aided with a tailor made hyperplasticizer enabled a concrete which could be pumped at 25% lower pump operating pressure, including 3 slab cycles in a month compared to previous 2and 6 floors were completed in 2 months. Figure 6 provides a good glimpse of the surface finish.

  6. Classical Self-Consolidating Concrete (SCC)Figure 6: Concrete Finish with SDC at a premier project in Pune

  7. Shanghai Tower: Shanghai, China
    Classical Self-Consolidating Concrete (SCC)Figure 7: >60,000 m3 of SDC for the raft foundation of Shanghai Tower in China
    Amidst a tight construction schedule for pouring > 60,000 m3 of concrete in a huge raft in a single pour of 6 m thick raft. This was a mass concrete application requiring low cementitious content to control heat of hydration development as well as use of manufactured sand mandatorily due to limited availability of river sand. With a tailor-made PCE for SDC, an amazing record of nearly 60 hours over a weekend was the time taken with nearly 1,000 m3 per hour concrete placement serviced by nearly 7 concrete plants and over 450 truck mixers. All fresh and hardened properties of concrete were maintained including the peak temperature < 65oC in the core, whereas placement temperature was < 23oC. Fig 7 below consist of a site photograph and Table 1 that is the strength progression chart.
 
Conclusions
Classical Self-Consolidating Concrete (SCC)
Low fines SCC (SDC) addresses the needs of the various stake holders across the construction industry and addresses the current challenges of speed, efficiency and durability of concrete structures especially in the common grades up to 40 MPa which constitutes more than 75% of the concrete in India. This type of concrete goes into structures that are not heavily reinforced (everyday RCC structures). This eliminates the extra costs related to fines (material, silos, handling, logistics, etc.) and reduces the binder content for the required strength class. This means less cement or more supplementary cement materials (SCM).

The innovative PCE based hyperplasticizer inbuilt with a special state of the art viscosity modifying admixture is now available in India and almost more than 5 mio cubic metres of concrete have been laid in India alone with this unique SDC concept. It is poised to make a breakthrough for increasing the use of self-compacting concrete in the construction industry as it offers multiple benefits to the various stake holders.

Days 7d 28d 60d 90d
Average (MPa) 39.8 56.9 63.0 66.5
Table 1.  90 days strengths progression for specified C50 concrete
Acknowledgement
The authors wish to thank the project owners, designers, architects, project management consultants, contractors, ready mix concrete companies and its internal staff for their invaluable contributions to make these projects highly successful, utilising SDC technology for a greater value to the construction industry.

References
Lea, F. M., “The Chemistry of Cement and Concrete”, Arnold.

Neville, A. M., “Properties of Concrete”, Pearson

American Concrete Institute, “Self-Consolidating Concrete (ACI 237R-07)” ACI Committee 237, Emerging Technology Series, 2007, Michigan

BIBM, Cembureau, EFCA, EFNARC, ERMCO, “The European Guidelines for Self-Compacting Concrete - Specification, Production and Use” May 2005

Okamura, H. and Ouichi, M. “Self Compacting Concrete”, The Journal of Advanced Concrete Technology, Vol 1, No. 1, 5 – 15 April 2003, Copyright Japan Concrete Institute

Sven M., F., Asmus, Bruce J., Christensen, “Status of SCC in Asia Pacific”, Second International Symposium on Design, Performance and Use of SCC, Beijing, China,2009

Sugiyama, Tomomi, Mastumoto, Toshimi, Ohta, Akira, “Application Study of Viscosity reducing type Super-plasticizers for Low Water-Binder ratio concrete”. Second

International Symposium on Design and Use of Self-Consolidating Concrete, Beijing, China, 2009
Finnish company Betolar expands to Indian concrete markets with a cement-free concrete solution
Betolar, a Finnish start-up, and innovator of geopolymer concrete solution Geoprime®, has expanded its operations to Europe and Asian markets including India, Vietnam and Indonesia. Betolar’s innovation Geoprime® is the next-generation, low carbon

Read more ...

Why Fly Ash Bricks Are Better Than Clay/Red Bricks
It is estimated that in India each million clay bricks consume about 200 tons of coal and emit around 270 tons of CO2; on the other hand, with fly ash bricks production in an energy-free route, there are no emissions. Dr. N. Subramanian, Consulting

Read more ...

Methods & Factors for Design of Slabs-on-Grade
Sunitha K Nayar, gives the grouping of slabs-on-grade based on the design philosophies and a brief overview of the different design methods, the commonalities between design strategies in terms of the input parameters, assumed and estimated parameters, and the

Read more ...

FIBERCRETE®: Synthetic Fibers for Concrete Reinforcement
Kalyani Polymers is offering world-class made-in-India Synthetic Micro & Macro Concrete Fiber Products for the Construction Industry under the brand name FIBERCRETE®. Concrete is an integral part of any construction project, it can be roads, tall structures

Read more ...

Climate Control Concrete
Leading cement and concrete maker ACC has unveiled a revolutionary thermal insulating climate control concrete system in India. Sridhar Balakrishnan, MD & CEO, ACC Limited, discusses its attributes, applications, and benefits for home builders, architects

Read more ...

Innovations in Crack Bridging with Self-Healing Bacteria in Concrete
Dr. Manjunatha L R, Vice President - Direct Sales & Sustainability Initiatives, and Raghavendra, Senior officer, JSW Cement Limited, discuss bacterial concrete that can meet the requirements for strength, durability, and self-healing of cracks.

Read more ...

Sustainable Development Through Use of Self-Curing Concrete
Dada S. Patil, Assistant Professor, Civil Engineering Department, AIKTC, Panvel, Navi Mumbai, Maharashtra; Dr. S. B. Anadinni, Professor & Associate Dean (Core Branches), School of Engineering, Presidency University, Bengaluru; and Dr. A. V. Shivapur, Professor

Read more ...

Developing a Corrosion Resistant RCC Structure
Samir Surlaker, Director, Assess Build Chem Private Limited, emphasizes the importance of a clear cover for a concrete structure since concrete as a porous material needs protection of its reinforcement. Along with the thickness (quantity) of cover, the porosity of

Read more ...

Quest for Higher Strength Concrete From HSC to UHPC
Concrete technology has come a long way since the Romans discovered the material, with a number of ingredients, which include a host of mineral and chemical admixtures, besides of course, the Portland cement, aggregates (coarse and fine), and water. These ingredients

Read more ...

Modelling Methods for Protection of RCC Structures
Anil Kumar Pillai, GM, Ramco Cements, discusses two major softwares (Life 365 and DuraCrete), used in the industry for protection of RCC structures. The common design approach is faulty because we consider only the loading aspect, whereas the environmental aspect is equally

Read more ...

Bajaj Reinforcements LLP - Introduces Fibre Tuff heavy-duty synthetic fibres that offer a range of benefits to concrete
Fibre Tuff, macro synthetic polypropylene fibres, are heavy-duty synthetic fibres that are specially engineered for use as secondary reinforcements, providing excellent resistance to the post cracking capacity of concrete. They are replacing steel fibres in a range

Read more ...

Use of Headed Bars in Reinforced Concrete Design
Reinforced concrete design and construction practice has historically focused on the use of bonded straight or bend rebar as a method for rebar anchorage. This relies on bond integrity between the rebar and the concrete so that sufficient anchorage

Read more ...

Innovation easy, effective and economical tool for asset creation
Innovation and entrepreneurship are essential ingredients in building a successful commercial venture. The ways in which these two concepts fuel enterprise are something entrepreneur's never stop exploring. There is no doubt that innovation were

Read more ...

Reactivity of Alite and Belite towards Sustainability of Concrete
Alite and belite are the predominant phases of Portland cement formulation. Alite is impure tricalcium silicate (C3S) and belite is impure dicalcium silicate (C2S). The impurities are an integral part as cement is manufactured

Read more ...

Innovative, Economic, Durable and Sustainable Concrete to last for +100 years of service life
Concrete is a versatile construction material and day by day its consumption is increasing globally. It is second only to water in the global consumption. No civil engineering structure is feasible without using concrete

Read more ...

Nanospan India Pvt Ltd
The use of Graphene with concrete has been talked about and researched ever since Graphene was invented in 2010 which grabbed its inventors a Nobel prize. Nanospan is the first company in the world to break technological and commercial

Read more ...

Fosroc: Building, Cementing & Supporting
Fosroc is the foundation of the JMH Group. It employs over 1700 employees in 17 operating companies based in Europe, the Gulf & Middle East, India, South Asia, and China. Through FGT, its trading company, it services another 50 countries

Read more ...

Dextra Group
Established in 1983 by French expatriate entrepreneurs, the Dextra Group has a long history of growth and development, driven by strong entrepreneurship and innovation. It has diversified into three main activities: manufacturing, trading and freight forwarding

Read more ...

Ferrochrome Ash Based Geopolymer Concrete
Jyotirmoy Mishra, Ph.D. Scholar, Department of Civil Engineering, Veer Surendra Sai University of Technology, Burla, Odisha, presents his research on the feasibility and compressive strength performance of geopolymer concrete

Read more ...

×
Sign-up for Free Subscription
'India Construction Week'
Weekly e-Newsletter on Construction Industry
Get the latest news, product launches, projects announced / awarded, government policies, investments, and expert views.
Click here to subscribe.
×