Many homeowners are concerned about their building’s concrete cracks however, the truth is, concrete cracks are very natural, and it can be easily fixed. In this blog, I would like to share some of the key reasons which cause concrete cracks in buildings and how those concrete cracks could be healed without bother.
concrete cracks happen for several reasons and below are the key factors why they occur,
Why Concrete Cracks
- Improper Concrete Ratio
- Not Curing Concretes Properly
- Low-Quality Sand
- Insufficient Vibration
- Excessive Temperatures
Above are the main reasons for cracking in concrete, but apart from that, there are many more reasons, such as lack of control joints, early drying, and so on. let see one by one below,
Improper Concrete Ratio
Cement, sand, and blue metal have to be in good proportion to maintain strong concrete. 1:2:3 is the typical ratio used by most builders in India. Concretes may have more air bubbles when blended by hand that weakens the concrete structure. It is advised to use a concrete mixing system to prevent air bubbles.
Concrete does not require a lot of water to achieve maximum strength. But the vast majority of the concrete used in residential work has too much water applied to the concrete on the job site. This water is added to make it easier to install the concrete. The excess water also significantly reduces the strength of the concrete.
Not Curing Concretes Properly
It is important to cure the concrete for at least 12 days from the date on which the concrete has been poured. During this curing period, the concrete needs to be kept moist and the water must be maintained at least 2 inches in height. This will prevent it from shrinking and cracking. It also helps to remove the air bubbles.
As much as we expel the concrete air bubbles, this makes them stronger. Moisture in concrete will actually allow it to develop long-term strength in the first month after being poured. If the concrete has a dusty surface with small cracks, It is then a sign that there was not enough water sprayed on the concrete during the healing phase.
The method of curing is one that has to be paid close attention. To prevent excessive moisture loss by water, heat, and evaporation, the surface of a freshly-poured concrete structure should be kept damp and protected with plastic sheetings.
Whether you are constructing your own concrete items at home or working on a large building, make sure for the first month that the concrete is fully cured.
The use of lake sand or desert sand and underground sand instead of river sand will cause serious concrete cracks. It is recommended that the bottom layer of the river sand be used because the top layer consists of a lot of dust material that can also cause concrete cracks.
If you can not use river sand then you can go ahead with M-sand (Manufactured Sand). It is manufactured from crushed aggregates formed from hard granite stone which is cubically shaped with grounded sides, washed and graded with consistency to be used as a river sand substitute.
A consolidation or vibration of concrete is one of the most important steps when pouring concrete. If used correctly, concrete vibrators will help consolidate concrete and decrease the number of air pockets inside the concrete mass.
Based on the design, and where the concrete is mounted, you can use internal vibrators or external vibrators. There are however several important factors to consider when buying a concrete vibrator: duration, strength, and height.
A concrete vibrator will normally be acquired knowing you can have multiple uses for it, and that it can be used for a very long time. Internal vibrators are used to hit the middle while the internal vibrator can be used for core consolidation
Thermal cracking is caused by excessive differences in temperature in the concrete structure or surrounding area. The difference in temperature causes the cooler portion to contract more than the warmer portion which limits the contraction.
Thermal cracks appear when the restraint leads to tensile stresses exceeding the tensile strength of the concrete in place. Temperature crackdown
Hydration of cementitious materials in all concrete parts generates heat for several days following installation. This heat easily dissipates into thin sections and causes no problems.
The internal temperature increases and decreases gradually in thicker parts, while the surface quickly cools down to ambient temperature cure. The colder internal concrete that induces the surface contraction due to cooling is limited
Concrete members will expand and contract when the ambient temperatures are hot and cold, respectively. Cracking will occur if the volume of these bulk changes as a result of variations in temperature. This is sometimes referred to as cracking the temperature and is a later age and issue for a longer-term.
However, before you go to repair cracks, you need to know the type of concrete cracks that have occurred and, based on the type, you need to choose the methodology to correct it. Here are the few important approaches that can be used to repair cracks in concrete.
How to fix concrete cracks
- Epoxy Bonding
- Routing and Sealing
- Stitching the Cracks
- Drilling and Plugging
This method involves cleaning concrete cracks with a wire brush and blowing cracks using compressed air to free them from dust.
Apply the bonding agent to the prepared surface and place the mortar on the epoxy bonding agent when it is tacky.
If the bonding agent is dry, you should add a second coat before putting the concrete in place
Advantages of Epoxy
- Weld quality is stronger than concrete
- Works outstandingly well on ground, wood and metal surfaces
- The design process is simple, even though the developer or the landlord can complete it.
Disadvantages of Epoxy
- If the crack is too large it might not fit with the injection process.
- Larger cracks require more pressure to inject epoxy.
- More Expensive
- When base always shifts, gaps between epoxy and mortar can be reformed
- Doesn’t fit well on wet surfaces, the bond power goes way down
Routing and Sealing concrete cracks
Routing is a very popular and easy low-cost approach for isolated cracks.
Extending the concrete cracks along its exposed face and sealing it with an appropriate joint sealant. this method is mainly used for waterproofing by sealing the cracks on the concrete surface where water is stored.
The substance used as the sealant may consist of any material that can handle cyclic expansion and contraction and that does not become brittle over time, including epoxies, urethanes, silicones, polysulfides, asphaltic compounds, or polymer mortars.
Advantages of Routing & Sealing
- Opens small cracks or joints and clean out debris.
- Effective on straight cracks
Disadvantages of Routing & Sealing
- Ineffective to small or wide concrete cracks at random.
- Heavy machinery will spawn new cracks.
- pulling mechanism in downhill is very risky.
- Expensive Device.
Stitching the cracks
This method involves drilling holes on both sides of the concrete cracks to receive stitching dogs and filling holes with non-shrink grout or epoxy.
The crack is bridged with U-shaped metal units called stitching dogs in this method, before being patched with a durable resin material. The dogs ‘ legs should be sealed with a non-shrink grout or an epoxy resin-based adhesive. Stitching is appropriate when re-establishing the tensile strength across major cracks. Stitching dogs should be of variable orientation and length.
Advantages of Stitching
- Used to prevent the slabs from splitting at longitudinal joints.
- Rapid, fast, productive and lasting.
- The use of grouts provides an excellent connection inside the soil.
- Non-disruptive systemic stabilization, without any extra stress
- Masonry is robust enough to withstand the motions of natural structures.
DisAdvantages of Stitching
- Stitching is suitable when tensile strength must be re-established across major concrete cracks.
Drilling and Plugging concrete cracks
This method is primarily used for the repair of vertical cracks.
Drilling and Plugging a crack the process of drilling down the length of the crack and grouting it to form a key. we can use this method only when cracks run in reasonable straight lines or vertical crack.
Advantages of Drilling and Plugging
- Cost-effective method
- Time consumption is less
Disadvantages of Drilling and Plugging
- Used only for vertical cracks.
To summarize, in order to save our time and money, it’s always better to use prevention techniques to avoid concrete cracks in buildings, but at the same time, we can’t guarantee that prevention can overcome a hundred percent cracking. Using the correct crack style technology would definitely help us to achieve effective results.
Thank you for your time in reading this article. please go through “things you need to know before you build your house” would be of great benefit for you…