Dr. Surendra P. Bhatnagar, Chairman & Managing Director–Tech-Dry (India) Pvt. Ltd.,Bangalore

Concrete is supposed to be the most versatile material used in modern construction. It is a very durable material, but its properties and performance depend on so many factors like selection of mix ingredients, mix design, placing, compaction, curing conditions, design and detailing and environmental factors.

It is an irony to note that inspite of the above statement that concrete is a durable material, these benefits of concrete are not always achieved in practice and we would analyse this factor in this paper.

Concrete is a composite material and therefore its quality would largely depends on the basic constituents that are used like coarse aggregate, fine aggregate and/or sand cement and water.

The quality of concrete is generally related to its strength and permeability which in turn, are broadly governed by the amount of water used in the mix.

Thus, for high strength and low permeability, a low water/binder ratio is often required. Careful selection of mix constituents, including chemical and mineral admixtures, proper mix design practices, placing and adequate curing are significant contributory factors to the overall quality of concrete.

Unfortunately, even RMC in India are unable to maintain low water–cement ratio on account of the fact that they use rather very cheap type of plasticizers and the retention of slump loss is not optimum.


Water in excess of that needed for cement hydration is retained in pores within the concrete mass and can be detrimental to concrete durability. Loss of surplus water occurs with the drying of concrete, which leads to an increase in porosity and reduced concrete strength.


Curing is the most important factor because it is necessary to retain required water by the concrete, which is not always available, and therefore cement hydration is affected.

Correct curing significantly enhances strength and durability. The builder or the client is always in a hurry and therefore correct curing is not achieved which is required for strength and durability.

The durability influenced by the transport of water containing dissolved substances and gas through pore networks and along cracks.

Compaction of the concrete is a key factor, which is normally not properly supervised. The solution contained in the pore structure of concrete is normally highly alkaline as a result of cement hydration, with a pH of about 13 for Portland cements. The alkaline pore solution is particularly beneficial to steel reinforcement as it provides a chemical protection against corrosion.

However, the carbonation if not checked makes the reinforcement vulnerable to corrosion.
  • Alkali-silica (alkali-aggregate) reaction
  • Sulfate attack
  • Carbonation
  • Effect of Chlorides

Protective and Remedial Systems

Protective and remedial systems may be applied to concrete in a structure to protect it against chemical or mechanical effects. In principle, such systems are designed primarily to enhance structural durability and extend service life performance. However, improvements or repairs to damaged structures may also be driven by the need to improve aesthetics. Technical considerations are essential to sound decision-making in all cases. To successfully implement a repair or protective system, it is essential to arrest causes, which favor the observed deficiency.

Symptoms often have more than one cause. Therefore, the key to success or failure of a repair system is the proper diagnosis of the problem. This is followed by developing a cost-effective repair or remedial plan, which ensures long-term serviceability and integrity of the structure. Professional expertise is required at every stage of a repair process. This includes design, planning, material selection, placement, installation and inspection of protective systems. As such, it is important that economic considerations do not solely dominate system selection at the expense of performance and eventual structural serviceability.


Restraint to deformation is the basic cause of concrete cracking. It is essentially the lack of freedom of concrete members to respond to movements or volume changes.

The primary concerns with cracks are whether they affect structural integrity, whether they have been caused by inappropriate design detailing, or are simply unacceptable aesthetically.

Cracks vary in dimension. Small micro cracks arise from stresses or strains due, for example to restraint of movements as in shrinkage cracking of concrete. There can be fine hairline cracks that may have no apparent durability consequences.

It must be recognized that concrete has an inherent potential to crack, and that crack control is an integral part of reinforced concrete design and construction techniques. In respect of concrete durability, crack patterns can be helpful in diagnosing potential causes of deterioration. Thus, to enable proper repair of cracks, their causes must first be identified.

What kind of cracks can occur and how can they be avoided?

Both plastic and settlement cracking are associated with bleeding of fresh concrete, i.e., water rising to the top of the concrete shortly after compaction. This can be avoided by using 4th generation plasticizers.

Plastic Shrinkage Cracks

Plastic shrinkage cracks occur when moisture from the concrete surface evaporates faster than the rate of bleeding. This can be avoided by using crystallization and curing products.

If the final finishing of the concrete is not good a random, forming a map pattern is created as show in the figure below.

Plastic shrinkage which are sometimes induced by temperature differences as cement hydration are typical.

Some fine cracks occur due to drying shrinkage. These cracks are referred to as ‘surface crazing,’ Crazing is identified as a series of minute closely spaced shallow cracks. This can be avoided by spraying water on the concrete and keeping control of the ambient temperature.

Alkali aggregate reaction can be avoided by washing the jelly and by using alkali aggregate admixtures.

It is important that the reinforcement is coated by repellency products like Silane Cream, which would help the concrete. There are admixtures, which can increase the compressive strength of concrete.


Normally efflorescence is noticed in concrete and it can be controlled by using anti efflorescence products.
  • The quality of water is vital and any chloride content in the water can be dangerous.
  • Placing of concreting, selection of reputed RMC suppliers, using your own waterproofingcompounds like admixtures or Salt Retarder can be very useful.
  • The proper compaction is required to avoid any voids and honey combs. How to rectify the problems of concrete before waterproofing?

Crack Repair

The key feature for successful crack repair is an understanding of the causes of cracking, whether cracks are dormant or active, and to identify the desired outcome of the repair works.

The objectives of repair work depend largely on the function of the facility. Depending on the nature of the damage and state of the structure, the desired outcome of repair may be structural enhancement, appearance, durability improvement, water tightness, or to prevent the ingress of corrosive substances to reinforcement.

However, in practice it is difficult to repair and therefore we can identify some general methods:

For Wide Cracks/ Thorough Cracks or Cracks in Slab

The best solution is to grout by using injection machine or ordinary grouting depending on the severity of the problem.

For Cracks

The first attempt should be to slow down the rate of seepage or to reduce the void by using products based on natural clays and then use the grouting system. Besides grouting, we should also look into the crack filling products.
Click Here
To Know More or to Contact the Manufacturer
Please let us know your name.
Invalid Input
Please let us know your Designation.
Please let us know your Contact Number.
Please let us know your email address.
Please brief your query.
Our other Value-Added Services:

To receive updates through e-mail on Products, New Technologies & Equipment, please select the Product Category(s) you are interested in and click 'Submit'. This will help you save time plus you will get the best price quotations from many manufacturers, which you can then evaluate and negotiate.

Invalid Input
Invalid Input
Invalid Input
Durability is a key requirement for modern infrastructure projects – highways and roads, bridges, airports and airfields, walkways and plazas, parking structures and stadiums. Miles of concrete must

Read more ...

Buildings have major environmental impacts over their entire life cycle. Resources such as ground cover, forests, water, and energy are depleted to give way to buildings. Today, India has demonstrated

Read more ...

Scour is a natural phenomenon caused by the erosive action of flowing stream on alluvial beds. Failure of bridge due to scour at their foundations, which in this case consisted of abutments and pier, one 1.2 dia

Read more ...

To protect concrete structures like Flyovers, Bridges, Parking areas, Big Commercial and Residential Buildings, the normal decorative exterior paint will not serve the purpose as these paints are not vapour permeable

Read more ...

Repair Strategy of Stoplog Sill Beams During Operation Stage of 510 MW Teesta-V Power Station in Sikkim Running Power Stations serve as a boom to the economy of the country and any generation loss due to construction

Read more ...

Concrete protective liner is a multipurpose solution for waterproofing and protection of concrete surfaces against corrosion and destruction. The product warranties long-term and reliable protection of structures

Read more ...

Sangeeta Pandey, Chief Manager (Civil), Power Grid Corporation of India Ltd., Patna, PVS Sudhakar, Sr. General Manager (Civil), NOFN Works, Power Grid Corporation of India Ltd., Vishakhapatnam & Dr. Achintya, Professor of Civil

Read more ...

Samir Surlaker, Director, Assess Build Chem Private Limited discusses some new joint treatments and injection systems in waterproofing. It is a myth that waterproofing treatments can be carried out by application of single material

Read more ...

Years of research plus decades of practical experience have enabled FAIRMATE to develop detailed solutions to restore and rehabilitate concrete structures with structural rehabilitation, retrofitting and strengthening of RCC structures

Read more ...

Sunny Surlaker, Head Technical Services, Assess Build Chem writes on the selection ideologies, materials and methods for defect remediation in Concrete Buildings. The building façade or the envelope is the primary line of

Read more ...

This article provides some basic information on effects of fire on concrete, various condition evaluation methods, and show findings from a case study of a fire exposed concrete foundation in California, and informs construction

Read more ...

There is considerable controversy within the concrete repair industry regarding the use of bonding agents as a pretreatment method for the repair of deteriorated concrete. This paper examines the use of bonding agents

Read more ...

This paper discusses the effects of fire on concrete and provides a methodology to assess, evaluate and repair concrete structures. Though concrete is among the best fire-resistant building materials, it does get damaged when

Read more ...

The ACI 562 Code Requirements for Assessment, Repair, and Rehabilitation of Concrete Structures and Commentary was first published in 2013 and revised in 2016. Development of ACI 562 was an industry response to variations

Read more ...

The repair industry in India and for that matter, throughout the world, is like the story of an elephant described by seven blind people. Whichever part of an elephant will come in the hands of a blind man, the elephant will be described

Read more ...

The Chamera Hydro-Electric Project (Stage-III) is located on the river Ravi at village Kharamukh (250.0 m downstream of the confluence of river Ravi and Tundah Nala) in Chamba district of Himachal Pradesh. The Project consists

Read more ...

Terex — a diversified global manufacturer of equipment for mining and quarrying industries — is celebrating 10 years of operations in India and has announced expansion plans for its 45-acre manufacturing plant in Hosur, with which it plans

Read more ...

The rapid boom in the construction industry, has tremendously given rise to the demand for sand, causing deficiency of suitable river sand in many parts of India. Besides, river mining causes imbalance in the river bed water flow, and

Read more ...

Regardless of the quality of pavement material and design, increase in vehicular traffic and changing environmental conditions will reduce the service life of pavements and ultimately result in their failure. The causes and

Read more ...

With the increase in construction of buildings in the last two decades, it has been observed that many of the structures are already showing signs of distress. In some cases, repair measures become necessary even within a span

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.