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How To Repair Cracks In Concrete Roof Slab

What Is Epoxy Repair Mortar

How to fix or Repair cracks by your self in Concrete Roof /Terrace ? Stop water leakage.

Epoxy mortar is simply aggregate mixed with a resin and hardener which, when cured, forms a flexible, waterproof plug which does not shrink.

It is also completely waterproof as it has a resin base and will withstand any temperatures without crumbling. It will accept foot traffic after about 4 hours and is fully cured after 24 hours. Please do however read the instructions on the individual containers as some epoxies vary a little.

Epoxy repair mortars have resin aggregates and a hardener

How Do I Mix Epoxy Repair Mortars

All epoxy repair mortars come in tubs with ready measured amounts of resin aggregate and hardener. The hardener is tipped into the resin aggregate and a mixer paddle is used to get a good, uniform mix. It takes about 4 6 minutes to mix a 20Kg tub of epoxy mortar.

Mixing epoxy repair concrete with a mixer paddle

Supported Poured Concrete Floor Slab Characteristics

As you can see from the Carson Dunlop Associates sketch above, the supported slab is a lot like the floating slab – it claims to have gravel and claims to have compacted soil below the slab.

But the edges of the floor slab rest on a lip built into the poured concrete footing which also supports the building walls.

The good news about a slab with this design is that a little soil settlement below the slab will not cause the floor to tip nor crack provided it has been adequately reinforced.

The bad news about a supported slab design is that if there were significant soil settlement below the slab and if it lacked proper reinforcement at the time of construction, it might collapse.

Where may this occur: if you inspect a garage built on what was originally a sloping hill, you can expect that the interior of the garage foundation was filled with lots of backfill soil. If your builder was the same fellow who hired the author , all of this fill was left un-compacted.

At the low end of the garage where the most fill was added, significant soil settlement can occur. If the slab was also not reinforced and if a lot of soil settlement occurs under this floor, it could collapse suddenly, say when your car is parked there.

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Question: Causes Of Cracking In New Fiber

This question and a detailed reply have moved to a separate article now found

I have a disagreement with our construction companyâs warranty department over the cracks in our garageâs fiber-reinforced floating slab.

8. Several cracks run across length of slab meandering.

9. Some stop and start again a ½ inch over then continues on same direction

10. Some cracks go right through the control point as if it wasnât there

11. Control points are not v-shaped. One inch deep channel. Quarter inch wide.

12. No shrinkage separation space between slab and foundation

13. No water intrusion …

How Do I Clean Everything Up After Making My Concrete Repairs

Concrete Slab Crack Repair Instructional Video

Resin based materials are usually hard to clean and the solvents used to clean them are pretty harsh on the hands. Rizistal however have delivered a solution which you will be able to see in all of the product reviews mentioned above. It is called Safer Solvent, and it is called that because it is!

Dip a rag into the safer solvent and clean your tools easly. The safer solvent can also be used to wipe your trowels down as you smooth over the repair mortars we have mentioned above. As they are all resin based, they tend to stick to the trowels which makes it hard to get the surface smooth.

Use safer solvent to clean tools down after working with epoxy repair mortars

We hope this project has helped you solve a problem that is experienced by thousands of home improvers every year.

Concrete is perishable, it will deteriorate very quickly when it is allowed to crack and the only method of repairing it properly is with epoxy repair mortars. We only recommend Rizistal mortars and concretes because we have worked with them for a couple of years but there are many others out there so please do go and have a look round.

All project content written and produced by Mike Edwards, founder of DIY Doctor and industry expert in building technology.

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How To Repair Wide Cracks In Concrete

Kelly Bacon is a licensed general contractor with over 40 years of experience in construction, home building and remodeling, and commercial building. He is a member of The Spruce Home Improvement Review Board.

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Wide cracks in concrete are best patched and sealed with a concrete patching compound. Smaller cracks, less than 1/4 inch wide, can be repaired with a concrete caulk or liquid filler. Patching compounds typically are mixed with water and applied with a trowel. They have a texture similar to grout and can be smoothed and textured to blend with the surrounding area. However, the color of the patch will look like new concrete and will not match the old concrete. Hiding the patch completely requires painting the surface with an appropriate concrete paint.

Grouting Method Of Crack Repair

i)Portland Cements Grouting

In the case of gravity dam and concretewall large-sized cracks formed. They can be repaired by filling with Portland cement grout.

This grouting method is effective in stopping waterleaks, but it will not structurally bond cracked sections.

The procedure consists of,

  • Cleaning the concrete along the crack.
  • Installing built-up seats at suitable intervals .
  • Sealing the crack between the seats with cement paint, sealant, or grout
  • Flushing the crack to clean it and test the seal and then grouting the whole area.
  • In this method, mixtures of grout may contain cement and water or cement plus sand and water, depending on the width of the crack.

    However, the water to cementratio should be kept as low as practical to minimize shrinkage and maximizestrength. Other admixtures or water reducers may be used to improve the properties of the grout.

    For this treatment a manual injection gun may be used in case of smallvolume crack filling and for larger volumes, a pump should be used.

    The good pressure should be maintained for several minutes after the group is filled over a surface to ensure good penetration.

    ii) Dry Packing

    In Dry packing method, the hand placement of a low water content mortar is done by tamping or ramming the mortar into place to make intimate contact between the mortar and the existing concrete.

    Concrete Dry Packing Method

    The repaired surface should be cured by using either water or a curing compound.

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    Home Warranties And Cracked Slabs

    Usually, after cracks appear in your foundation, you begin to wonder if it is covered under home warranties. Home Warranties offer several services in their contracts. Homebuilders, however, provide the assurance for a year after purchase of a new home. Normally, it is builders warranties that cover foundation, bad wiring, plumbing and structural issues. But, in case of keeping your home appliances and systems in working condition, you must have a home warranty.Do take a look at the reviews on home warranty companies to determine which home warranty fits the bill. Take a look at the top home warranty provider companies in the business.

    If you have any doubts, simply send us your questions in the comments section. Were all ears to helping you figure out the best home warranty for you with the a home warranty provider. Do take a look at those companies that have gone out of business to ensure that you sign up for the right one.

    Books & Articles On Building & Environmental Inspection Testing Diagnosis & Repair

    How to Repair Leaking Concrete Roof Slab – Liquid Waterproofing Membranes – Melbourne WATERPROOFING
    • Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews – InspectAPedia.
    • Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from and also See our book review of this publication.
    • The Journal of Light Construction has generously given reprint permission to for certain articles found at this website. All rights and contents to those materials are ©Journal of Light Construction and may not be reproduced in any form.

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    Best For Deep And Hard To Reach Cracks: Expanding Foam

    Another good method for filling up cracks in concrete is to use hydrophobic polyurethane expanding foam. This method is great for filling wide and deep cracks.

    As you can probably tell by the name of it, this material is designed to expand, just like insulation foam for walls.

    When using polyurethane foam for concrete repairs, it will usually come in the form of a special concrete repair kit.

    Always be sure to follow all of the directions on the label of the particular product you purchased.

    When using expanding foam, be sure to put the dispenser nozzle as deep into the crack as possible, and then work your way to the exterior. If you want it to look nice, you can then sand it down and paint over it.

    Plastic Shrinkage Concrete Cracks

    When concrete is still in its plastic state , it is full of water. When that water eventually leaves the slab, it leaves behind large voids between the solid particles. These empty spaces make the concrete weaker and more prone to cracking. This type of cracking happens frequently and is referred to as plastic shrinkage cracking.

    While plastic shrinkage cracks can happen anywhere in a slab or wall, they almost always happen at reentrant corners or with circular objects in the middle of a slab . Since concrete cannot shrink around a corner, stress will cause the concrete to crack from the point of that corner.

    Plastic shrinkage cracks are typically very narrow in width and barely visible. While nearly invisible, it is important to remember that plastic shrinkage cracks dont just exist on the surface, they extend throughout the entire thickness of the slab.

    An excessively wet mix is a contributing factor to shrinkage in concrete. While water is an essential ingredient in every concrete mix, there is such a thing as too much water. When the mix contains too much water, the slab will shrink more than if the correct amount of water was used. Hot weather is another big reason for plastic shrinkage cracks.

    Control joints can be incorporated into the slab to prevent shrinkage cracking. The joints will open up as the concrete slab gets smaller.

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    Is A Crack In A Slab Foundation Bad Can This Be Fixed

    The slab is poured such that it is thicker at the edges, with reinforcing rods used to strengthen the extremities and retain its structural integrity. Depending on the weather and environment, there may also be a layer of crushed gravel underneath the slab to drain excess water, which if not properly attended to can cause cracking. Inserting a wire mesh in the slab at the time of pouring reduces the likelihood of cracking.

    How To Repair Cracks In Concrete Overhang Over Entrance

    Floor Heave Cracks Not Caused By Expansive Soil? Concrete ...

    I have a slab of concrete over the front entrance of my house with some serious cracks in it. I don’t actually know what the proper name for it is, which makes this difficult to Google – so I’ve uploaded two photos to illustrate:

    How do I repair those cracks? Firstly, what’s the best thing to fill them in with? Secondly, how do I get that filler to not fall out while it sets?

    • 1Is there a bunch of water damage there? Is now the time to fix that before you do whatever work you’re planning?Jul 27 ’11 at 14:27
    • Yikes. I’d tear that out and put in something less… heavy.

    You may need to approach this with some caution. It looks like the reinforcing steel is corroding from the picture. When this happens the steel expands and causes the concrete cover over the steel to spall off. Once the reinforcing bar looses its cover the rate of corrosion will increase and the bond between the steel and the concrete is substantially reduced.

    The problem is that just covering up the steel with a crack repair mortar may not fix the corrosion problem and either another section of the concrete could spall off or the repair mortar could spall off. I would suggest you get it looked at by a specialist. It doesn’t look like it is in imminent risk of failure but just covering up the cracks may mean that you are hiding a long term problem.

    Then to finish the job properly, once you’ve repaired the cracks, waited at least a further 24 hours:

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    Exposure To The Elements And Weathering

    Most commonly, cracks in the foundation are out of your control and can be attributed almost wholly to sudden and extreme changes in weather.

    A) Snow

    Accumulated snow near the building can melt and create a sudden flood. If the foundation already contains cracks, even thin ones, the water will enter and widen them in time.

    B) Drought

    A reduction in the moisture of the subsoil can cause it to shrink and move further away from the foundation. This creates a gap between the soil and the foundation, leading to possibly dangerous slab movement if the foundation is not adequately supported by other means.

    C) Expansive Soil

    Some soils have a large capacity to absorb moisture and are heavily affected by it. High moisture could expand the soil below the foundation and heave the concrete slab. The damage can vary, and with evenly compacted soil, it could even be negligible.

    D) Consolidating Soil

    This phenomenon is the opposite of expansion in soil. While the result is similar to that of a drought i.e., that the soil cleaves away from the foundation the cause is a property of the soil itself, and can therefore occur even with normal weather patterns.

    E) Storms and Heavy Rain

    Flooding after by a storm can suddenly increase the moisture content of the soil and expand it, forcing the subsoil up against the foundation and causing it to become uneven or crack.

    E) Tree roots

    Cracked Concrete Driveway Repair Prices

    The cost of repairing a concrete driveway depends on the extent of damage and labour charges. To fix cracks, contractors have to assess the damage on the driveway surface. They typically charge based on the area of repair in metres squared.

    The average cost in Australia for repair is $3/m2-$8/m2. The materials mostly used sealant and mixed patching compoundsâmandatory tools to have to include a trowel and a foam backer rod.

    Spoon drains are drain lines with an interior trap that protrude into the pipe enough to create a âspoonâ shape. Here at Specifier, you can read about its use.

    A Besser Block is a hollow, rectangular concrete building block thatâs used to build houses, commercial structures, multi-story apartment complexes, and industrial buildings. For what do we use Besser blocks? Read here.

    This stiffened slab is a structural panel that can be used to build floors or roofs. Itâs essentially a concrete slab with rigid foam attached to the bottom and top for insulation. Read moreâ¦

    Do you have soil moisture conditions? Slab heave is the most common problem in the industry and occurs when excess moisture inside a foundation wall freezes and thaws. Read everything about it!

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    Concrete Cracks Caused By Premature Drying

    There are two common types of cracks brought on by premature drying.

    Crazing cracks are very fine, surface cracks that resemble spider webs or shattered glass. When the top of a concrete slab loses moisture too quickly, crazing cracks will likely appear. While unsightly, crazing cracks are not a structural concern.

    Crusting cracks typically happen during the concrete stamping process, which is a way of adding texture or pattern to concrete surfaces. On sunny or windy days where the top of the slab dries out quicker than the bottom, the top of the concrete surface can become crusty. When the stamp is embedded, it pulls the surface apart near the stamped joints and causes small cracks around the outside edges of the stones. Again, while they dont look great, crusting cracks are not a structural issue to be considered about.

    Its often difficult to determine exactly what caused a particular crack. Proper site preparation, a quality mix, and good concrete finishing practices can go a long way towards minimizing the appearance of cracks and producing a more aesthetically pleasing concrete project.

    We cant stress the importance of a quality mix design in concrete crack controlling. Read our Concrete Checklist: Get The Best Mix For Your Project, which will guide you and your concrete supplier towards creating the best mix for your concreting project.

    Repair Of Ceiling Plaster

    how to repair Concrete roof slab cracks to close NCR #WORLDARCHI

    There are many cases where the steel reinforcements corrode due to various causes such as lack of cover, leakage of roofs, etc. As steel rust occupies very much larger volume than steel, the surrounding concrete cracks and tends to get separated from steel and finally it falls down. This is particularly important in the ceiling plaster under leaking roofs. If we notice any disturbance in this plaster, it should be repaired as soon as possible. There are many cases in which the ceiling plaster has fallen down suddenly.

    The repair for such cases is carried out as follows.

  • Hammer test the area for loose areas and remove all loose particles of mortar, concrete, rust, etc. from the spalled surface and clean it with a wire brush.
  • Apply two coats of polymer modified active corrosion inhibitor to the remaining steel. If additional steel is required, tie the new steel to the old steel by binding wires. Two coats of chromate paint can also be a substitute.
  • Apply one coat of polymer bonding agent over the entire area of steel and concrete to be treated.
  • Apply polymer modified 1:3 cement mortar over the reinforcement and provide necessary cover. Addition of super plasticizer to reduce water and the incorporation of fibres will help to produce strong mortar. If the area is large, guniting with additive for quick setting can be used for better efficiency of the work.
  • Cure the concrete.
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