Unified Vision of Indian Nation for the Concrete Protection, Strengthening and Repair Industry - Vision 2020

Dr. S. K. Manjrekar, Chairman & Managing Director, Sunanda Speciality Coatings Pvt. Ltd., Mumbai

Introduction

Repair industry in India and for that matter throughout the world is like the story of an elephant that is described by seven blind people. Whichever part of the elephant comes in the hands of a blind man, that will be described accordingly. Repair industry also is so huge several having facets and hence it is literally difficult to assess in totality the causes of damage, mapping the extent of damage, proper corrective prescription, prediction of residual life with and without the repair measures, instrumentation and maintaining the health subsequently and most importantly to strike cost benefit ratio of the repair. However, there is substantial amount of "State of the Art" knowledge available today which is based on critical study derived out of past failures and matching R and D work done in the laboratories and successful practical implementation of the same at sites. The consistent results have encouraged the industry, however the daunting task remains to be to corroborate the entire information in a methodic way and thus to provide this ever growing and overgrowing industry an orderly pathway. It is also important to keep the pace with ever dynamic nature of various advances and duly incorporate the same in the set procedures.

Size of Repair Industry in India

Essentially deterioration of concrete takes place due to environmental parameters, damage caused to structures due to external agencies, basic defects in the concrete structures and change in use which can take place subsequently. Almost all the concretes are made as per the structural requirement of each structure and has to be custom made. These concretes have to use local material from plural sources having different quality which can be marginal. Sometimes the designs also are not standard and to top it all, we have to work at neck breaking speed for producing the output which results in accelerated construction processes which may sacrifice quality at some times. Above factors lead to malfunctioning and early distress signs in a structure and have led to an industry which is likely to assume a form of a parallel industry to new construction industry. In India, this market/industry though of a large size and spread over all the nooks and corners of the subcontinent, is not organized. Thus the exact figure of annual cost to owners for repair, protection and strengthening is not available. However, looking at sheer size of this industry as well as the size of country one can safely estimate the cost to be beyond any other country’s expenses including the ones in the advance western world where industry is treated as scientific, organized, the way it deserves. As an indicator, the average annual cost to owners for repairs etc. in U.S. alone is estimated to be $20 billion dollars which equates to approximately `90,000 cores. This is a big industry in India and merits judicious attention to control the loss to national wealth by avoiding frequent failures.

Stakeholders in the Industry and Their Obligations

Repairs industry has several beneficiaries like Engineers, Architects, Equipment suppliers, Material manufacturers, Researchers, Educators, Testing Companies, Contractors, and also Lawyers. As a matter of fact, all these beneficiaries along with owners become a stake holder and thus obliged to put up their best foot forward to share their expertise and be in readiness to accept other’s expertise in a common interest. For example, almost exponential growth of this industry in last three decades has resulted in highlighting several shortcomings and hence the need for many improvements particularly in the field of materials, Design Practice, Installation procedure, Contracting Processes, QA/QC procedures, Education. This would result in service life enhancement reduced costs and importantly avoiding conflicts.

It is also important to note the vital and non-replaceable roles of various organizations mentioned above. It is important to detail what does the industry provide and who provides it as under:

1. Professional Service Companies (architects, engineers and established expert laboratories) - provide forensic evaluation of existing structures.
2. Testing Companies - provide field and laboratory services to analyze materials.
3. Structural Engineers -calculate load capacities and produce design details.
4. Inspection Companies -ensure that installed systems comply with specifications.
5. Material Manufacturers - provide not only specialized materials, but technical support to the specifier and installation contractor.
6. Contractors - integrate the design, specifications, materials, labor and equipment to complete the repair.

Various processes involved in the industry are:

1. Surface Repair
2. Protection
3. Waterproofing
4. Strengthening etc.
5. and can pictorially be shown as under which is a commonplace knowledge to all professionals

Surface Repair

Protection

Strengthening

Further specific contributions to the trade come through in field installation processes. Though in some underdeveloped or developing parts of the world only one contractor does the job of several specialties, it is more accepted norm now to have specialized contractors or installers to undertake the specific job. Some such heads of specialist contractors can be as under:

• Membrane, Sealants, Coatings
• Surface Preparation – Hydro / Shot blast
• Grouting / Crack Injection
• Foundation Underpinning
• Vertical (High Rise) Repair
• Shotcrete / Guniting
• Industrial Floor Repairs
• Cathodic Protection
• Post Tensioning
• Steel Placement
• Formwork
• Concrete Placement
• General Concrete Repair
• Waterproofing

All above are extremely sensitive and important operations in successful repair work and are required to be done by specialized and highly trained personnel. Often semi-skilled persons replace the trained skillful operators under compulsions from the employers either due to non-availability of skilled person or to save on the cost of a specialist without any information to client. Client will subsequently come to know about such unacceptable replacement only when the jobs do not meet with the success expected or when operation fails totally. In order to avoid such mishaps, some international repair institutions have embarked upon the certification programs. These certifications will assure all concerned that the jobs are in safe hands. The author himself has undergone such maiden certification in "Surface Preparation" in Chicago couple of years ago. This course was conducted by International Concrete Repair Institute USA on the campus of CTL in Skokie-Chicago and the rigorous practical as well as theory examination was held on 10-06-2009.

After discussing about the impact of specialist agencies and certified craftsman is undertaking, it is also important to use State-of-the-Art machinery to be effective time efficient and free of human errors and imprecise judgment.

Spectrum of Repair Jobs

Having discussed about the concurrent participation of several agencies, it is now also in place to discuss the plethora of jobs that can be attended to under this industry. Some of the important types of jobs along with the diagnosis and general corrective measures are given as under:

The Need to Reduce The Failure Rate of Repairs and How?

Today, we are placing new concrete to the tune of approximately 1M3 / person nationally. That is huge quantity. As against if we take the stock of concrete placed in past years then an educated guess is about 25M³/person concrete could be already in place. That is still more huge inventory. A large quantity of this concrete is about 10 years plus old. Most of this concrete was site mixed and without many controls and as a result more susceptible to carbonation, chloride attack, loss of alkalinity and attack of other aggressive chemicals. And in spite of recent developments like low permeability concrete mixes either (insitu or pre-packed), protective coatings, and other repair chemicals, due to reasons cited earlier, the repairs which are intended to extend the service life of structures often seem to fail prematurely.

Concrete Repair and protection projects most times do not satisfy performance criteria. One of the largest inventories of Concrete structures in the world is with U.S. Army Corps of Engineers and their experience is as under.

Performance of Repairs

That means barely 50% of the repairs perform satisfactorily and remaining ones fall into fair, poor, failed category due to the problems in design, installation and materials. In India, due to unorganized nature of the industry and outdated methods of execution the performance would be still marginal and can be vaguely shown as under.


This performance will further get affected depending on aggressive conditions varying from region to region in India.

That means if most of the concerned stake holders in the industry think that there is no improvement necessary or there aren’t any problems which require attention then the industry would remain the same that is at best less than 20% successful performances. At various levels, such attitude of persisting with ongoing age old procedures, equipments and materials is seen galore in India. And now is the time to embark upon some systematic approach so that proper guidelines can be formed for the posterity. Devoted committee having representatives of contractors, engineers, material manufacturers, researchers, educators, owners, material scientists and industry associations need to come together to resolve various problems and find out the solutions. This would be faster and far reaching approach than leaving the improvement issue for few members of the industry to evolve.

This devoted group will look into ‘learning from failures" as well as adopting the ‘State-of-the-Art’ knowledge in holistic way. An attempt is made to show some of the areas that need improvement in the Industry.

Some Areas That Need Improvement

Lack of temporary shoring caused the weakened structure to collapse. The supervising engineer and contractor did not have adequate training and guidance to perform the work safely.


Insufficient surface preparation around the corroded reinforcing bar. Loose pieces of repair material create a large risk for the building’s owner, the public, the repair contractor, and the engineer.

Shows a failed repair on the side of a water storage tank. What at first appears to be an installation error, poor surface preparation, is actually the result of a design error. The design must take into consideration the water vapor transmission from the tank interior. The water vapor transmission is trapped behind the repair which is very dense and resistant to freeze-thaw damage. With a concentration of moisture trapped behind the repair, the original substrate undergoes freeze-thaw disintegration causing the repair to delaminate. The design requires a strategy to mitigate these factors.

Repair material’s volume change or drying shrinkage properties. Excessive shrinkage restrained by the repair material’s bond to the substrate causes the material to crack.


Poor surface preparation, primer installation or high moisture levels in the substrate.

The repair included an impressed current cathodic protection system. Faulty installation of the cathodic protection system which was improperly balanced and discontinuous reinforcing steel caused accelerated corrosion.


Shows strengthening systems applied to a newly constructed structure. This costly repair was a result of inadequate reinforcing steel across the top of the pier.

Do We Need A Vision?

The need of the day is to have a vision…… "Unified Vision of Indian Nation for the Concrete Protection, Strengthening and Repair Industry – Vision 2020"

A draft vision statement can be as under.

Various improvements that need to be included should result in reducing

• Repair mistakes
• Miscalculations
• Poor performance
• Poor workmanship

And also must look into

• Finding better repair method- ologies that reduce costs while improving quality.

This vision accompanied by the goals related to achieving it, will help industry, client organizations, research institutes and educational facilities to accelerate qualitative progress in the repair Industry. This vision statement can have further subissues and some of them can be as under:

1. Indian industry should establish mechanisms for inter organizational and discipline cooperation to create state of concrete art technology as well as its dissemination.
2. Develop and implement the methodology to hasten documents creation and dissemination within industry stake holder.
3. Create a repair/rehabilitation code to establish evaluation, design, materials, field and inspection practices which raise the level of performance of repair and protection systems, establish clear responsibilities and authorities for all participants and provide the local building officials a means of issue permits.
4. Develop performance-based guide specifications for specific and generic repair designs to improve specifications.
5. Improve repair material design and performance to eliminate cracking, to carry structural loads and to have set and cure properties established by the construction process.
6. Develop environmentally and worker- friendly repair methods, equipment, and materials that will greatly reduce the adverse effects on workers, the public and the earth’s ecosystem.
7. Develop a means for predicting repair system performance to help ensure the use of proper materials, design details and installation methods based upon predictive models validated by experience.
8. Develop and implement a strategic research plan for the repair industry.
9. Increase the number of material-, engineering-, and construction-related professionals interested in and skilled in repair and protection practice to support the growing need for evaluation, design, new materials and construction professionals.
10. Develop selection processes, contractual agreements, procurement methods and relationship arrangements (partnering) that will greatly reduce conflicts, rework, claims and lawsuits resulting from disagreements among contractors, general contractors, engineers and owners.
11. Develop facility owner education that will promote awareness of the effects of deterioration and the means to reduce the risks while protecting their investments.
12. Develop improved means and methods for accurate and thorough condition assessment.
13. Develop specific repair system needs for expanded use, efficiency, and failure reductions.

Conclusion

In conclusion, as a result of this National Conference, a resolution may be passed to bring all the stake holders together and pursue the drafting of all encompassing. Vision documents the knowledge from which to be disseminated up to the grass roots of Indian Nation.

The article is based on studies of last three decades of Indian scenario of repair and exhaustive referencing done from the literature of ACI.

Acknowledgment

This article has been reproduced from the proceeding of 'National Conference on Repair & Rehabilitation of Concrete Structures' organized by ICI western U.P Gaziabad, IA Sructural Engg, and Association of Structural Rehabilitation, with the kind permission of the organisers.