Not to sound cliché, but you get what you pay for. For many homeowners, budget-friendly services are enticing. Still, you won't want to cut corners on cement. If you end up with a botched job, you might have to correct sloppy concrete work yourself.
Concrete can end up with cracks, spalling, and uneven patches that look rough in places. Here's how to fix these common problems.
What to Look For on Pour Day
There are several causes of faulty concrete, and many of them can be identified and remedied before the first drop of concrete mix falls to the ground. Talk over the pouring process with the contractor, and ask for samples of their work before signing the contract.
Concrete is more complex than cement mud that dries hard. Contractors who work with concrete know that different consistencies, humidity, temperature, and other factors can affect the final product on pour day.
Have a discussion with your contractor about the process, expectations, and finished project before starting. Don't be afraid to ask questions and advocate for your wishes on the project, as you're the one with the funds to complete the vision.
If you're doing a DIY project, you'll want to follow the instructions and avoid adding the wrong ratios and aggregates to the project. Take the time to research the project and how to best mix the correct proportions of cement, water, and aggregate. Pour a couple of small mix batches to find the perfect ratio of ingredients for the texture you want.
Top 6 Ways Cement Can Fail
As cement dries and cures, the water content that made it semi-liquid and viscous begins to evaporate and dry out. If the water leaves the concrete too quickly, it causes contraction that can cause cracks. Further, concrete is porous and can absorb water. When this happens during cold weather, the freezing of the water inside the concrete will cause cracks and crumbling.
2. Ripples and Settling
It's likely to settle as the cement dries hard. Suppose you or your contractor reinforced the structure with a rebar grid or other metal gratings. The concrete dries too quickly or reduces too much water. In that case, your final cement project will be uneven.
Sometimes you'll even see ripples in the cement where it settled between the reinforcement bars. Pouring cement on top of loose gravel or uneven ground can result in uneven settling and even dangerous structure collapse.
Excessive water in the wet concrete mix is forced to the surface as the larger and more coarse aggregates settle to the bottom of the pour mold. Ideally, you would minimize bleed by preventing segregation of the different elements of your concrete by using higher quality fine aggregates and carefully monitoring your mix's water content.
As the water is forced to the surface, it can tunnel out channels through the concrete, making it more porous and susceptible to moisture cracks. Further, water can travel into pockets under and around the reinforcements, causing gaps and a lack of adhesion to the rebar.
If you use chemicals on your concrete (such as deicing agents), the chemical reactions can weaken the adhesion of the top mortar layer that gives the final finish. Deicing chemicals can cause the concrete to be more porous, allowing water to infiltrate the surface.
Once this happens, any drastic temperature change is likely to cause flakes of surface concrete to break away. Bleeding in the surface layer can cause the scaling to become much worse than if your water ratios were more balanced.
Upon removing the pour forms, you will sometimes see a rough rocky section that isn't smooth like the rest of the concrete. This is called honeycombing, and it's caused by the mortar of the mix not adhering adequately to the aggregates.
They create uneven and weakened concrete swatches and should be repaired as soon as possible. Honeycomb sections in your concrete increase permeability and reduce the lifespan of the slab.
Concrete is typically poured in layers. Delamination could result if the final surface layer is not prepared and poured correctly. This is the separation of the surface layer from the base layer of concrete and has more to do with the timing of the final trowel layer than any other aspect. If large non-surface chunks are falling off the poured slab, you're looking at a process called spalling.
When you use a power trowel to smooth the final layer and create a pleasing surface, you can trap air bubbles in that layer. As the air expands and contacts and moves together, it combines and slowly pushes the layers of concrete apart.
In most cases, you can hear delamination before you see it, as the concrete will sound like a drum when tapped or driven on.
Causes of Concrete Weakness and Damage
Many different things cause weakness in concrete, and all of them are avoidable with a little extra caution. First, you can overwork concrete, causing air bubbles, adhesion issues, and breaking down some of the aggregates into particles too small for their purpose.
Improper ratios of cement to sand to water to gravel can also create weakness in a project. Rainy weather can cause disruptions through humidity and temperatures, causing issues with the setting and drying of your concrete project.
How to Avoid Sloppy Cement Install
Like baking and cooking, you can prevent installation stress and sloppy work by being vigilantly observant through preparation, pouring, texturing, leveling, troweling, and drying. If you or your contractor notice an issue, it's much easier to fix it in the project process than to come alone after it's done and try to repair it.
Noticing the consistency of the concrete is easily fixed by adjusting the ratios while it's mixing. You or a contractor can reinforce a leaking form before a catastrophic blowout causes a massive mess and delay.
Trapped air pockets can be popped and released, and the surface smoothed before the concrete sets and dries. None of these preventative options are available after the concrete is dry.
Solutions to Fix Sloppy Cement Projects
Mistakes and failures are harder to correct once the concrete has been set and dried. The project will need to be ripped out and redone in some cases. However, in some cases, you or a contractor will be able to fix the issue relatively quickly.
In the case of uneven surface settling, grooves or ripples, finish texture discrepancies, or honeycombing, you can grind a thin surface layer off and pour a new layer of fine mortar and sand. The smaller the aggregates for the top layer, the smoother your restoration pour will be.
Suppose just a section of the concrete pad has been damaged from chemical exposure, a hard impact, or thermal shock. In that case, you may be able to cut the damaged section away and relay that portion of concrete.
In almost all of these situations, you'll need to carefully consider the origin of the damage and how the surrounding areas will affect the repair process. If in doubt, get a second opinion from a trusted contractor.
When to Restore
If the damage is relatively small or shallow, you can likely repair or restore the concrete. This is often the course of action for indoor concrete floors and relatively low-traffic areas like concrete patios. You can patch cracks, reinforce weak points, and then resurface the slab.
Resurfacing is an option when you want to prevent damage and choose preventative maintenance instead of responsive maintenance. Additionally, you can restore concrete with cosmetic resurfacing when looking for a new aesthetic for your driveway, walking path, or patio.
When to Replace
Repairs can be difficult or ineffective if cracking or another form of damage is significant. When cracks are recurring or expansive, you will want to break up and remove the current concrete and lay a new slab. You can use this replacement as an opportunity to take preventative measures and increase the longevity of your concrete.
Use this project to level the ground under the slab, lay in reinforcement, and create stress scores.
When you lay a large slab of concrete and cut scores into the slab, any settling, expansion, or contraction will cause the crack to form under the score point and reduce the level of damage. Imagine building a levy to redirect a river around a town.
The scores in the concrete create a levy to turn the cracks where you want them. Reinforcing with rebar means that when the ground settles under the slab, the concrete isn't holding itself up, because there's a layer of extra structure.
Tips for DIY Cement and Concrete Projects
Watching the concrete dry doesn't speed up the process and can cause issues when you continuously check on the progress.
Concrete projects aren't fast, but they last a very long time when they're done correctly. Mix, pour, finish, and let rest. Move on to a different project if you have one, and come back the next day (at least).
If you're pouring concrete, think ahead about how the project will change routines for pets, family members, and your community. Gather all your supplies before you begin the project. Needing to run out of more sand in the middle of your mix process can cause issues in your final set.
If you have a neighbor who uses your driveway to turn around frequently, you'll thank yourself for communicating with this neighbor long before they pull onto your wet cement project.
The same could be said for your dog, who doesn't understand that damp concrete can cause cuts and chemical burns to their paws if they don't stay out of it.
If you repair the damage, you'll want to understand how that damage occurred. For example, if you've got crazing (fine surface cracks), your slab dried too fast; you can prevent this by covering the workspace with plastic while it's drying in order to slow evaporation.
Another example of researching the issue is to look at where your water flows in a storm. If you need to, you can divert it away from your concrete slab and prevent further recurring cracks and settling.
Concrete vs Cement
Many people use the terms "Cement" and "Concrete" interchangeably. However, if misunderstood, some differences can lead to project failure, shortened longevity, and costly damage. There's a common idea among artisans and tradespeople—the right tool makes the job easier and more sound.
It's not that you can't do a task with the wrong tool; you're more likely to get it done correctly and with a minimum of issues when you use the tool designed for the job.
Cement is the binder used with other materials to create solid structures. You rarely see straight cement used unless it is for aesthetic projects. More commonly, you'll see it mixed with sand or gravel to create concrete or fine aggregate and pigment to create mortar for masonry projects.
Sometimes, you'll see these concoctions mixed and used on the same project for different effects. You can use concrete and mortar the same way you would use grout in mosaic projects and many DIY home improvement projects, such as making stepping stones or planters.