Dr. S. K. Manjrekar, CMD, Sunanda Speciality Coatings, Mumbai
Size of repair industry in India
In India, the repair industry is not organized, hence, the exact numbers on annual cost to owners/public funding for repair, protection & strengthening are not available. Today, India is placing new concrete to the tune of approximately 1.75 - 2 billion m3/per annum, which of course needs to be protected. If we look at the already placed concrete in the past 50 years, it would be 55 - 60 billion m3 which now needs much more protection.
Essentially, deterioration of concrete takes place due to environmental factors, damage caused to structures due to basic defects in the concrete structures, and change of use, which can take place subsequently. Almost all the concretes are made as per the structural requirement of each structure, and most of its concrete is typically specified. These concretes have to use local material from multiple sources having a different quality, which can be marginal. Sometimes, the mix designs also are not standard and at times one has to work at neck break speed to produce the output, which results in accelerated construction processes, but may sacrifice quality.
These factors lead to malfunctioning and early distress signs in a structure. This has led to the rise of the repair industry, which is likely to become a parallel industry in the construction industry. In India, the repair market, though of a large size and spread over all nooks and corners of the subcontinent, is not organized. Yet, the magnitude can be realistically worked out by intrapolation as well as extrapolation. When intrapolated with regards to the distress and the health of inventory over the past 40 years, the annual cost to owners for repair, protection and strengthening could be estimated between US$ 40 to 45 billion.
Figure 1: R1: http: // www. Concareplus .com/technology.htm, R2: www.indianmirror.com
Why India's repair industry is rising
- India is the second largest manufacturer of cement; hence its total inventory of various structures is also large, with a major part needing repairs after obvious distress signals and based on their health assessment.
- India has transitioned from 15 MPa to 60 MPa in the span of 50 years as a general trend, though till two decades ago, the prevailing strength was 15-25 MPa. This means that inventory of lower grade structures exist as a legacy of the past.
- Low concrete cover, low w/c, site mixing, associated with chloride attack due to advent of traffic jamming number of vehicles and continuous industrialization and carbonation has worsened the scene.
- India is a hot weather country and has a long coastline of 7000 kms with high humidity and tropical climate. Over 35000 square kms of coastal area is under constant attack of airborne chlorides. Fig 1.
Practice and processes of repair include the following:
- To remove deteriorated loose concrete
- Expose corroded reinforcement
- Semblance of cleaning and removal of corrosion products on heavily corroded steel
- Use of chemical, rust removers to remove corrosion products on corroded steel rebars
- Use of bonding agents
- Use of speciality polymer mortars as per global industry norms/specifications.
- Use of protective coatings.
- Design practices
- Installation procedures
- Contracting processes
- QA/QC procedures
- Education and allied several aspects.v
Longevity of Repairs
The short life cycle of repairs is raising questions on the knowledge and awareness about the technical competencies of related personnel and agencies. Rebuilding of older structures is not the general norm; hence, structures are typically repaired and often re-repaired.
Engineering students/working engineers are not taught concrete or the science of steel corrosion with an emphasis on special repair materials like Polymers, Epoxies, Protective Coatings, Nano Materials etc. Since repair is not a subject in engineering schools, many areas remain "grey" due to lack of formal training, education, and hands-on training on the repair materials and processes; this results in short life cycle of the repairs.
Performance of Repairs
One of the largest inventories of concrete structures is with the U.S. Army Corps of Engineers and their experience is given in Fig 2:
That means even in an advanced country like USA, barely 50% of the repairs perform satisfactorily and the remaining repairs fall under the fair, poor, failed categories due to problems in design, installation, materials, and other parameters. What could be the success rate in the repairs in India and why: possible extrapolation of repairs in India is given in Fig 3:
The analysis of re-repairs pattern shown in Fig 4 by Tuutti is very applicable to repairs in India. However unorganized, repairs is a big industry in India and merits judicious attention to control the colossal loss to national wealth by avoiding frequent failures. Repair operations are extremely sensitive and important. Various steps involved in repair projects are dependent on the knowledge level of the specifier. More often, the specifications are copied from one specifier/job to another. As a result, though repairs intended to extend the service life of buildings, the structures often seem to fail prematurely due to the improper strategy of repairs and lack of defined responsibility criterion.
R4: Tuutti Kyosti, (1982) CBI Research Report 4:82, 304 p
Trained personnel are required, but quite often, semi-skilled persons are employed in projects. Realization comes after sub-standard quality of repairs leads to failure and irreversible loss. A small number of engineers charge a nominal fee, which is not the accepted norm of repair industry. However, gullible people succumb to this and awarding the projects, particularly the small-sized projects. There is also a mushrooming of repair chemical suppliers who seem to indirectly advise the small client on using inappropriate chemicals in a wrong way.
Hence, a strategy is presented to increase the accountability of stakeholders in the repairs industry through an understanding of individual and collective responsibilities.
There are several operations needed in any repair job, depending on the type and extent of damage, and involve the stakeholders from the following trades:
- Membranes, Sealants, Coatings
- General Concrete Repairs
- Surface Preparation – Hydro/Shot blasting/chipping
- Grouting/Crack Injection
- Foundation Underpinning
- Underwater Repairs
- Industrial Floor Repairs
- Steel Placement
- Cathodic Protection
Special training courses/certification exams /eligibility criteria must be worked out. This is not a difficult task as abundant reference material is available locally and globally. Otherwise, in the absence of such a unified procedure, every qualified civil engineer will have to wear the several caps of an NDT expert, material specialist, corrosion expert, etc. But this is possible when the engineer is qualified in multiple specialties. More often, the story becomes like an Elephant and Six Blind Men (fig. 5).
Action required to improve performance of repairs in India
In India, due to unorganized nature of the industry and outdated methods of execution, the performance of a structure after repairs would be still marginal, as illustrated in figure 5. Individual repair contracts are smaller in value as compared to new projects and hence multi-level supervision is difficult and uneconomical. So, the final responsibility comes on the client's appointed consulting engineer and the contractor. Often times, the entire (360°) approach including the analytical, diagnostic and QC parameters for the contract, both in prescriptive and performance format, are not known to either the consultant or the contractor. This is more because of the multifaceted complexity of the subject and ignorance.
The logical solution is to increase awareness and define responsibilities of all the stakeholders in the repair industry. There are several beneficiaries of the repairs industry:
- Testing companies
- Equipment suppliers
- Material manufacturers
- Most importantly, the Building Owners
At various levels, following age-old procedures, equipment and materials, is still prevalent in India. Stakeholders now need to base their actions on state-of-the-art repair materials and processes. Appointment of specialty engineer, who is by definition a Licenced Design Professional should be retained by the contractor as well as the building owner.
A dedicated group of contractors, engineers, material manufacturers, researchers, educators, owners, material scientists and industry associations needs to be formed to resolve the various problems and seek solutions. Looking at the size of the industry, a nodal federal agency should also participate and bring credibility and authority to the recommendations of the group. This would be a faster and far reaching approach than leaving the improvement issue for the repairs industry to resolve. It must be made a time-bound initiative in the interest of all the stakeholders. The draft of the code will be reviewed by all concerned and then circulated throughout the industry for suggestions.
This task group should develop a 'vision' which will be fluid and change as the repair industry is an ever-growing, dynamic industry. Various improvements would make a qualitative difference and also bring about a 'total responsibility concept' and will reduce mistakes in repair methods and choice of materials; poor performance, and poor workmanship.
The task group must look for better repair methodologies that reduce costs by delaying or avoiding re-repairs and enhance service life. Their vision accompanied by the goals will help the industry, client, research institutes, federal departments like roads, railways etc.….. and all the stakeholders. The vison could encompass sub-issues such as the following:
- Repairs Industry must be made a fully organized sector by forming a federation or trade association.
- Indian repairs industry should have outreach beyond civil engineering to establish mechanisms for inter-organizational and inter-disciplinary cooperation to create state-of-the-art technology as well as its dissemination.
- Indian Concrete Repairs Institute (ICRI) will be formed on a national level which will have affiliations to other such global institutions, and facilitate Technology Transfer.
- Develop and implement the methodology to hasten documents creation and dissemination within industry stakeholders.
- Create a repairs/rehabilitation code to enhance the evaluation, design, materials, field and inspection practices, which raise the level of performance of repairs and protection systems.
- Establish clear responsibilities and authorities for all participants. This should provide the local government officials/authorities a guideline to issue licenses to concerned stakeholders.
- Develop performance-based guide specifications for specific and generic repair designs. This will instill confidence in customer and also will bring a systematic approach to the repairs Industry.
- Improve Repair materials design and performance to eliminate cracking, to carry structural loads, and to define properties of set and cured finished repairs
- Develop environmental and worker-friendly repair methods, equipment, and materials that will greatly reduce the adverse effects on workers, the public and the earth's ecosystem.
- Develop a means for predicting repairs system performance to help ensure use of proper materials, design details and installation methods, based on predictive models validated by experience.
- Develop and implement a strategic research plan for the repairs industry with University, Industry, Government (UIG) partnership.
- Create conducive environments to increase the number of materials, engineering, and construction-related professionals interested in upskilling their repair and protection practices. This will support the growing need of trained and qualified personnel for evaluation of design, new materials, and construction practices related to repairs.
- 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. For eg. a reference of recommendations in ACI 132 for adopting as a guide for repairs industry can be followed.
- Develop client education programs that will promote awareness of the effects of deterioration and the means to reduce the risks while protecting their investments.
- Develop improved means and methods for accurate and thorough condition assessment.
- Develop specific repairs system needs for expanded use, efficiency, and failure reduction.
- Train and assimilate the unorganized sector in the mainstream by knowledge dissemination and inclusion in trade associations. It would be a national program executed all over the country. Skilling is a large initiative undertaken by the Federal Government of India with a special ministry.
- Evolve specifications and standards for the performance criteria of repairs, matching with International Standards in collaboration with Bureau of Indian Standards (BIS).
- Members of the Industry should engage in continuous innovation, based on the conditions of Indian subcontinent as well as training the personnel/applicators on a regular basis and in a structured manner.
The strategy will keep evolving as it is just the beginning of making an incredibly large business more structured and responsible. The vision 2025 will ascertain the improvement in the repairs performance as shown in Fig 7.
Important note: This article is based on studies and experience of authors' 35 years in India's building repairs scenario and exhaustive referencing from published works. However, the conclusions and recommendations are entirely personal and based on experience in national & international projects, which means there can be another viewpoint as well, and together with which, the performances of repairs would improve substantially.