A View of Concrete Technologies and Required Related Research for Materials of Construction and Their Testing Methods

Dr. Y. P. Gupta, Consultant, Allahabad Bypass Project; BCEOM-LASA JV Chairman, ICI UP Centre Professor (RTD.) Civil Engineering, MNNIT, Allahabad

Introduction

In the past 60 years, significant changes have taken place in the type, properties of concrete and its constituent materials. During the 1940’s to 2000’s substantial basic research was conducted in the United States and many other Countries which produced a thorough understanding of the properties of concrete materials, such as cement and aggregates, and the effect of these materials on the green and hardened properties of concrete. Material standards and specifications, concrete mix design and ingredient proportions, test procedures, and construction techniques were developed extensively on the basis of this knowledge.

In recent years, Construction Industry has been placing strong emphasis on high-strength and high-performance concrete and on shorter construction times. In response to this challenge, research has been focused on producing changes in the properties of the basic ingredients of concrete, such as cement, and on developing new ingredients to achieve better-quality, higher-strength, and more-durable concrete.

Admixtures: Needs and Challenges in Concrete Technologies

For several generations, concrete admixtures have been developed with the aim of altering a wide range of green and hardened concrete properties to achieve high-early-strength and high-performance concrete. Use of admixtures has allowed a dramatic reduction in the water-cementitious materials ratio (w/cm) in the concrete mix, which in turn has resulted in higher-strength and more-durable concrete. Significant research has also been done on the development and use of cementitious and pozzolanic materials, such as fly ash, silica fume and slag to replace or supplement the cement content in the concrete mixture. These materials have significantly improved the durability of concrete by reducing its permeability.

Today, it is quite common for admixtures and cementitious / pozzolanic materials to be included in concrete in addition to the standard concrete ingredients. Such complex concrete mixtures are significantly different from the simple Concrete mixes produced in the 1960’s to 2000’s in India. Yet many specifications and construction practices developed in accordance with basic research of the 1950s are still being applied to today’s concrete materials and construction industry, especially on small scale projects.

In addition, there are still unresolved problems and many unanswered questions associated with today’s concrete. For example, excessive shrinkage and shrinkage cracking are being observed in many of the high-performance and high-strength concrete. These unintended consequences impact the durability of the concrete and thus tend to defeat the purpose of using such concrete mixes. Another important set of issues with today’s concrete relates to the timing, duration, and type of curing, and the balance between curing time and speed of construction.

Still another issue is the knowledge gap among many practitioners with regard to the properties of individual concrete ingredients, how the various ingredients interact in the concrete mix, and how to arrive at the optimum mixture for the type of application and level of exposure to adverse environments. An effective technology transfer plan is needed to convey to practitioner’s state-of-the art information and the latest research findings on materials and concrete properties should be informed to field Engineers & implemented.

Testing Methods

Current testing methods for concrete and its ingredients are another challenging issue. Some of these methods are simple but time-consuming and tend to slow the pace of construction. New or improved tests for determining the properties of concrete and its materials need to be developed like Concrete strength is known after 28 days which is too long. These test methods should combine speed, accuracy, and precision. Technologies from other fields, such as medicine or the military action that can be non-intrusive should be considered in determining the concrete strength.

Research for New Concepts

The challenge to the research community in this millennium is to promote and develop a thorough and comprehensive understanding of the properties of concrete and of its multiple ingredients. This challenge can be met through a well-planned basic research program. This program should include the development of new and improved methods for testing concrete and its materials. Another program should focus on the best and most effective means of transferring the knowledge and methods thus developed to concrete practitioners for implementation. The following are some specific directions which these programs might take.

a) Cement
Many changes have occurred in the sources and production of cement, including the raw materials, fuel used and the grinding of the clinker. Today’s cements are much finer than those of the 1950’s and 1980’s. Research in the basic properties of cement is needed to evaluate the effect of such properties as fineness, chemical composition on the heat of hydration, and on shrinkage characteristics.

b) Admixtures and Pozzolanic / Cementitious Materials
There is a need to evaluate all the properties of the various admixtures and cementitious or pozzolanic materials. Issues associated with the use of these materials in concrete, including setting time, plastic and hardened concrete shrinkage, and the need for extensive curing should be investigated. The research should produce ready to use tables of the types and dosage or proportion of these materials in concrete, and the specific level of performance and strength achieved with each. The research should also focus on developing a new family of admixtures that would improve the tensile strength of concrete and facilitate the fast construction of concrete structures. For example, new admixtures now being produced help in the self-compaction of concrete in structures. This must be simplified.

c) Curing Materials
The industry has moved away from moist curing toward the use of curing compounds which are more convenient to use. However, the use of high cement content, higher fineness of cement, silica fume, and low basic research and emerging Technologies related to concrete w/cm ratio has made the concrete more prone to shrinkage and thermal cracking. Curing compounds are not effective in preventing shrinkage or cracking. New curing compounds are needed not only to prevent evaporation, but also to replenish lost concrete mix water. For example, the curing compound might include chemicals that could condense ambient moisture on the concrete surface to provide much needed moisture. Further, Concrete ingredients like aggregates, Admixtures are to be developed which can help in self- curing of Concrete without the use of water or curing compound and not giving rise to shrinkage cracking.

d) Fibers for use in Concrete
Apart from cement, water, aggregate and admixture; different types of fibers are also developed. Fiber Reinforced Concrete has a very high resistance to abrasion and impact loading that means it has good ductility similar to mild steel. It also has a higher tensile strength compared to normal concrete and better abrasion resistance. Apart from high strength, it also has high performance & fracture energy. Following are some of the various types of fibers, which may be used in FRC.
  • Carbon Fibers
  • Steel Fibers
  • Glass Fibers
  • Polypropylene Fibers etc.
Polypropylene Fibers have become very popular these days. Thus concrete mix in green stage should be such that fibers are not collected in pockets and they are well dispersed in the entire concrete matrix. Studies for use of Fiber reinforcement in concrete must be done extensively. This should also be done for Composite concrete Construction using normal concrete and fiber reinforced concrete.

e) Tests For Concrete

1. Tests for Green Concrete
Tests for green concrete properties such as slump, air content, and unit weight have been useful in controlling the quality and consistency of concrete mixtures. However, it can be expected that more emphasis will be placed on shorter construction duration on the roads, bridges, and airports. The present tests for plastic concrete tend to cause delays in construction. New technology is needed to enable testing of the workability, air content, and unit weight of mixtures in a non-intrusive manner. For example, a non-intrusive device similar to a radar gun could be developed for measuring the concrete workability from the concrete chute itself during its discharge.

2. Tests for Hardened Concrete
A better means of predicting the strength and durability of concrete is needed. Tests based on the hydration process, rate of strength development, and other physical and chemical indicators should be developed for predicting the ultimate strength and permeability / durability of concrete. The availability of such tests would allow better optimization of the concrete mixture with respect to the types and proportions of its ingredients. In addition, the concept of 28-day strength may become obsolete as an acceptance requirement. Concrete mixtures of the future may reach their ultimate strength in less than 7 days. This accelerated development of strength may alter the microstructure of the concrete. Research is needed to better understand the physical and chemical properties of hydration process and its related compounds, as well as the extent of micro-cracking and volume change in the mortar matrix.

3. Tests for Permeability
Advances have been made in measuring the permeability of concrete to better predict its durability. Nonetheless, existing devices either are too slow or provide an indirect measure of concrete permeability. Thus a fast, accurate, and repeatable device for determining the permeability of concrete is needed. A procedure should also be developed for predicting the durability of concrete from the automatic analysis of permeability data.

Technology Transfer To Field

Good-quality research in concrete technology and its constituent materials is being conducted at many places. This research is generating new information and technologies. However, effective means of transferring the research findings and products from the research phase to application in field are needed. Many practitioners do not attend conferences, workshops, or meetings. These practitioners often do not receive full information on the properties of new materials and how these materials, individually or collectively, affect the strength, durability, and volume change of the concrete. A detailed plan for transferring the knowledge and new products resulting from completed research in concrete technology and its materials should be developed and implemented. The Concrete making materials & Design handbooks and Internet information should be the centerpiece of such plan.

Summary

This millennium brings challenges and opportunities for research on the basic properties of concrete and its materials. New non-intrusive devices and other test methods should be devised to allow faster, more accurate testing of concrete materials and construction procedures. Performance based specifications should be developed for concrete materials and construction aspects in field. Appropriate tests should be designed to assess compliance with the requirements. An effective technology transfer plan should be developed to translate research results and new products for implementation by practitioners or Field Engineers.
NBM&CW December 2011
Admixture-Cement Compatibility For Self-Compacting Concrete

Admixture-Cement Compatibility For Self-Compacting Concrete

An admixture is now an essential component in any modern concrete formula and plays a significant role in sustainable development of concrete technology. Dr. Supradip Das, Consultant – Admixture, Waterproofing, Repair & Retrofitting

Read more ...

Amazecrete's Icrete: New Age Material for Concrete Construction

Amazecrete's Icrete: New Age Material for Concrete Construction

By maximizing the durability and use of supplementary cementitious materials, Icrete has emerged as a new age material for Concrete Construction V. R. Kowshika Executive Director Amazecrete

Read more ...

Nanospan’s Spanocrete® Reduces Cement & Curing Time in Fly Ash Bricks

Nanospan’s Spanocrete® Reduces Cement & Curing Time in Fly Ash Bricks

Hyderabad-based Ecotec Industries is a leading manufacturer of fly ash bricks and cement concrete blocks in South India under the trademark NUBRIK. Their products are known for their consistency and quality. Ecotec was earlier owned

Read more ...

Ready-Mix Concrete: Advancing Sustainable Construction

Ready-Mix Concrete: Advancing Sustainable Construction

A coordinated approach by the government, industry stakeholders, and regulatory bodies is needed to overcome challenges, implement necessary changes, and propel the RMC sector towards further growth such that RMC continues to play a vital

Read more ...

Advancements & Opportunities in Photocatalytic Concrete Technology

Advancements & Opportunities in Photocatalytic Concrete Technology

Research on photocatalytic concrete technology has spanned multiple decades and involved contributions from various countries worldwide. This review provides a concise overview of key findings and advancements in this field

Read more ...

Self-Compacting Concrete

Self-Compacting Concrete

Self-compacting concrete (SCC) is a special type of concrete which can be placed and consolidated under its own weight without any vibratory effort due to its excellent deformability, which, at the same time, is cohesive enough to be handled

Read more ...

Nanospan's Spanocrete® Additive for Waterproofing & Leak-Free Concrete

Nanospan's Spanocrete® Additive for Waterproofing & Leak-Free Concrete

Nanospan's Spanocrete Additive for Waterproofing & Leak-Free Concrete has proven its mettle in the first massive Lift Irrigation project taken up by the Government of Telangana to irrigate one million acres in the State.

Read more ...

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 ...

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