If you’re reading this, chances are that you’ve spotted some cracks in your concrete and wondering what to do.

Well, first things first – let us assure you that cracks in concrete are fairly normal.

Concrete cracks appear due to a whole range of factors such as temperature changes, structural flaws, poor construction practices, heavy loads and even moisture. They develop when stress builds up and exceeds the overall strength of the concrete.

No one wants unsightly concrete cracks, which is why you want an effective way to repair them and reduce any safety risks too. But further to this, it’s important to address them to prevent these cracks from causing further damage to the integrity and beauty of your property.

So, our team of specialists at Scientific Waterproofing Products (SWP) have prepared a quick guide to help you effectively repair cracking in concrete. 

What are the common types of cracks in concrete?

Concrete cracks are not all the same. 

Some are more noticeable and pose greater risks, while others are less detrimental and only require minor repairs.

To properly fix the cracking problem, the first step is to identify what kinds of concrete cracks you have in your home or premises. This will also help to determine their causes, so you can prevent concrete cracks from re-occurring.

While there are a wide range of concrete crack types, we’ve compiled the 5 most common:

1. Hairline cracks

Hairline cracks are small cracks that are about 0.08mm in width. They are seen in freshly placed concrete often as a result of building negligence and defective practices in construction. Even though they don’t appear threatening, these hairline cracks absorb moisture and can become worse – so it’s important not to overlook them.

2. Plastic shrinkage cracks

Plastic shrinkage cracks develop in a concrete slab when it’s still pliable and drying (just before it hardens). As water evaporates from the concrete, it leaves behind some voids or gaps between particles that then lead to cracking when in solid form.

These plastic shrinkage cracks usually appear around the corners of the structure.

3. Settlement cracks

When the ground settles beneath a concrete slab due to moisture loss, settlement cracks emerge. Settlement cracks also occur in cases where the underlying ground has not been properly compacted or the soil of the subgrade is uneven. 

Because they are often a result of a property settling onto its foundation, settlement cracks appear at the weakest points of a structure such as windows and doors.

4. Expansion concrete cracks and heaving concrete cracks

Expansion concrete cracks happen when concrete expands because of heat. Since concrete is not flexible or bendable, the heat causes it to push against anything in its way – thus, the cracking.

Meanwhile, freezing and thawing of concrete contribute to the formation of heaving concrete cracks.

5. Concrete cracks from overloading the slab

Despite its strength, durability and rigidity, concrete has its limits. Excessive amounts of weight on top of a concrete slab can cause it to crack, especially when the ground is soft and wet due to extreme weather conditions.

It’s important to pay attention to the strength of your concrete mix, so you’ll know the exact pounds per square inch (PSI) that could crush your concrete slab.

What are the best ways to repair concrete cracks?

Now that we’ve discussed the various types of concrete cracks, what comes next is remediating them with the right products and processes that best suit each cracking problem.

At SWP, we have a complete range of Drizoro concrete products that not only strengthen and waterproof your concrete walls, ceilings and floors, but also protect your home against cracks, leaks and foundational decay. 

Here are the most effective ways you can use our waterproofing solutions to repair cracks in concrete:

• How to repair cracks in concrete

1. All cracks should be cleaned out to remove any loose concrete. If it is a hairline crack, then cut it out to open up the crack (minimum requirement of 25mm x 25mm).  
2. Thoroughly wet (without ponding) the void to be filled before applying MAXGRIP.  
3. Next, mix MAXGRIP powder to a pourable consistency according to the product specifications. If working on a vertical surface, mix it to a trowellable mortar then trowel into the channel.  
4. Pour MAXGRIP mixture into the channel.  
5. Leave for 15-20 minutes to set.  
6. Once MAXGRIP has set, proceed on coating with MAXSEAL FLEX, or Maxseal flex M. Remember to follow the product specifications. It’s also recommended to apply two coats to achieve a completely waterproof seal.
7. Embed MAXMESH into the first coat across the crack, then overcoat lightly with MAXSEAL FLEX or MAXSEAL FLEX M to hold in place.   

• How to prevent the transmission of moisture along hairline cracks
  

1. Follow the crack to both of its ends, then mark each end.  
2. Drill a hole into each end, with a minimum size of 20mm diameter to a depth of at least 50mm.  
3. Use MAXPLUG to fill the newly drilled holes. Once set, the MAXPLUG will prevent the transmission of moisture along the crack beyond that point.  
4. Wet the area of the crack along its length to the ends – minimum of 500mm across the crack.  
5. Apply the first coat of MAXSEAL FLEX or MAXSEAL FLEX M onto the wet surface.  
6. Embed MAXMESH into the first coat across the crack, then overcoat lightly with MAXSEAL FLEX or MAXSEAL FLEX M to hold in place.  
7. Allow the first coat to cure (minimum of 14 hours when MAXSEAL FLEX was used, while a minimum of 6 hours for MAXSEAL FLEX M).  
8. Wet the first coat again before applying the second coat of MAXSEAL FLEX or MAXSEAL FLEX. 
   

• How to seal fractures in suspended concrete slabs

1. Prepare the area to be treated by removing any loose materials to ensure a clean and sound surface.  
2. Using a grinding wheel, open the fracture to the desired width (not exceeding 30mm) and a depth not less than half the width. Take note that the minimum width and depth should not be less than 10mm.  
3. Remove any debris from the newly formed void and thoroughly wet it with water (without ponding).
4. Apply MAXJOINT ELASTIC to the void, mixing as per technical bulletin.
5. Where the area is to be exposed to vehicular traffic, it is recommended that the entire slab be coated with MAXSEAL TRAFFIC. If you’d like further guidance about these processes or more information about the best waterproofing products for concrete cracks, speak to us. We’re always here to help!

Choose the best waterproofing solutions for your concrete 

It’s essential to repair cracks in concrete to prevent them from being a passageway of water, as well as to preserve your building’s appearance, safety and overall structure.

Fortunately, you can rely on our team at SWP to provide you with the right waterproofing for your unique situation. We offer a wide range of Drizoro cement-based waterproof coatings for all of your maintenance, repair, and restoration requirements.  

If you’ve got questions or issues around concrete waterproofing or you’d like to find out which product is best for your needs, contact us today!  

You can also check out our list of local Drizoro resellers and applicators here.  

As always, SWP is committed to providing the right waterproofing solution for any water-related problem or application.