The Basics of Concrete Paving
Learning about the benefits of concrete means starting with the basics.
At Michigan Concrete Association, it’s our job to educate the public on the uses and benefits of concrete for your paving project. But learning about concrete means starting with the basics.
Here you will find all you need to garner a basic understanding of what it means to choose concrete for a pavement project, including upkeep, cost planning, and more.
When it’s time to repave or replace your driveway, the most popular choices are concrete and asphalt. While many choose asphalt because it’s more affordable upfront, the two materials are now more competitive in price than ever. It’s also important to look at the long-term benefits rather than just the immediate costs.
When you start to look at the basics of concrete, it becomes clear the upfront cost is one of the only benefits of asphalt. Take a look at some of the benefits of a concrete driveway before making your choice.
A concrete driveway doesn’t just last a little longer than asphalt. On average, it can last 50-60% longer.
The secret behind the strength of concrete lies in the science.
Concrete is made from a paste made of portland cement and water, and large and small aggregates (rocks). When the paste and aggregates combine, a chemical reaction called hydration occurs. This reaction hardens the paste and binds the ingredients together. A tricalcium silicate compound releases calcium ions, hydroxide ions, and heat to speed up the reaction. These ingredients crystalize and more calcium silicate hydrate forms until the water molecules’ path is blocked and there are no longer any empty, weak spaces in the mixture.
This chemical reaction and the lack of empty, weak spaces is what holds concrete together long after asphalt begins to crumble, rut, and fill with potholes. For even stronger concrete, you can adjust the ratio of cement, water, aggregates, and other mixtures. Concrete withstands inclement weather and the elements as long as it’s taken care of properly.
Maintenance is another instance where the upfront cost may seem high but will pay off in the long run.
A month after your concrete has been placed, it should be sealed. A sealer will minimize the amount of moisture and de-icing chemicals (products that can melt ice at a lower temperature than salt) that penetrate the surface, helping to keep your concrete free from stains. Ask your contractor to recommend a sealer or look for one with silane or siloxane. Once the sealer has been applied, it only needs to be reapplied every three to five years, as opposed to asphalt that needs to be resealed every two to three years.
Besides sealing, concrete is relatively hands-off when it comes to maintenance.
Due to its softer consistency, asphalt tends to deteriorate faster. While it’s easy to repair cracks, asphalt needs those repairs more often.
Concrete offers significantly more design options than asphalt, making it a clear choice for homeowners who want more options in order to complement their home’s aesthetic or increase curb appeal.
Here are some ways to take advantage of concrete’s design versatility:
Colored Concrete: A color is distributed completely through the mix, giving you concrete color that resists fading and is still visible even if the concrete chips or becomes scarred.
Stamped Concrete: This method can be used to recreate the look of brick, slate, flagstone, cobblestone, stone, and more, without paying the high price for these products.
Engraved Concrete: Engraving can help update the look of an existing driveway without replacing it completely. Add circles, beautiful designs, or engravings on your driveway that will recreate the look of brick.
These are but a few of the design options that concrete allows for. driveway allows homeowners to match the look of their driveway to their home or other decorative outdoor features. To tie the look of your driveway to the appearance of laid sidewalks or patios, add a decorative border to the drive or entryway.
Concrete is a recyclable, environmentally friendly material that doesn’t emit any harmful chemicals or toxins. When a concrete driveway is removed, the old concrete can be crumbled and reused, saving on transportation costs and emissions, and saving room in landfills.
Given its long life and low maintenance requirements, concrete requires less energy usage overall. Its light color also plays a part in helping the environment by reflecting light instead of absorbing it and keeping temperatures in surrounding areas lower. This helps prevent the occurrence of “heat islands” a problem in many developed cities. The lighter surface of concrete makes such an impact on temperatures that, through LEED programs, incentives are given to buildings that use light colored roofing and pavements.
Concrete can also help the environment by:
Did you know that not all concrete mixes are created equal? The type you choose will depend on the project in front of you.
Surfaces that will be supporting vehicles will need a stronger mix while a patio or sidewalk that needs to be decorative will require a mix with more flexibility. Luckily, due to concrete’s versatility, you can find a mix that’s right for your project by working with a concrete contractor. Let’s take a look at the makeup of concrete and how you can determine the best mix to use.
Concrete is always made up of four main ingredients; cement, sand, aggregate (a mix of sand, gravel, stone, slag, and recycled concrete), and water. It's the ratio of sand to cement that determines the strength of a mixture, and this is what will change based on your project and needs.
There are a few considerations to make when determining what type of concrete mix is right for your project.
Project and Traffic Type
The amount of traffic your concrete will endure will determine how strong your mix should be. Higher traffic areas call for concrete with higher pounds per square inch (psi). Concrete for driveways or highly trafficked sidewalks should have anywhere from 2,500 psi to 10,000 psi. 2,500 psi generally works for home driveways, walkways, and floors. Despite what the area can handle, a contractor might choose a higher psi in order to guarantee the durability of the project.
The climate will play a large part in determining your concrete mix. High temperatures or extreme variations might call for an entrained air mixture — a mixture that holds tiny air bubbles — that allows it to expand and shrink in a changing climate.
Surface Area and Design
If you’re working with tight spaces or areas that will need to be worked into specific designs, a mix with a plasticizer will make the concrete more fluid and easier to fit into hard-to-reach areas.
Concrete Mix Facts:
Concrete may be pricier, but when it comes to choosing concrete for your parking lot, “good investment” is a better phrase than “most expensive.” Today, concrete is more comparable in price to asphalt and can last twice as long.
Concrete is a good investment for many reasons, but let’s break it down.
ways to price a concrete parking lot
There are a few ways you can price out a concrete parking lot.
Per Square Foot
Depending on the specifications of your project, a concrete parking lot can range between $4 and $7 per square foot. This price typically includes the cost of material and labor.
Per Parking Spot
You can also estimate your project’s cost by the number of parking spots instead of square footage. For small projects, a lot with six spots would range from $5,000-$14,000. On the larger side, a 200-spot lot would range from $174,000-$490,000.
Additional costs for a parking lot come from maintenance. Over time, the maintenance costs of concrete are almost zero, whereas asphalt parking lots need to be recoated every few years and completely resurfaced every ten years.
The increased durability of concrete means less pitting or surface spalling, which could be a hazard to your customers or employees. If you look at the life of a parking lot over 20 years, the maintenance of an asphalt lot can cost as much as 80% of the initial construction cost.
additional cost considerations
When considering how much your concrete parking lot will be, it’s not just the price of labor and materials you need to factor in.
Scope of work: Will you be removing and replacing an existing lot or starting from scratch? Laying a lot in an unprepared area (like a field) requires much more work.
Location: The cost of your materials will vary state-by-state but also city-by-city.
Distance: The distance between the supplier and the location will affect the cost.
Drainage requirements: Every municipality will have different drainage requirements.
When properly maintained, a concrete driveway will require very little maintenance and will last for decades. Let’s take a look at how to properly maintain this investment.
Concrete doesn’t require a lot of maintenance if you keep it clean. Cleaning your plain concrete surface mostly requires keeping it clear of debris and dirt, either with a broom or a leaf blower. You can rinse it with a hose or a power washer to remove stubborn dirt.
Cleaning instructions will vary based on the type of concrete surface you have.
Here are a few examples:
Stamped concrete: Rinse this concrete well with a garden hose on high pressure, scrub with a push broom and a small amount of dish soap, and rinse to remove all soap residue.
Stained concrete: If indoors, dry dust mopping and occasional wet mopping with a neutral-pH cleaner will do the trick. If outdoors, follow the instructions for stamped concrete.
reseal when needed
While resealing your concrete surface is not necessarily required, it is recommended in order to keep it in the best shape possible for longer. Follow a regular sealing schedule of every two years if the concrete is exposed to heavy traffic or weather extremes. Regular resealing protects your concrete from moisture penetration, freeze-thaw conditions, and de-icing chemicals. While you can reseal a driveway yourself, it’s recommended that you set up a schedule with your concrete contractor.
avoid de-icing chemicals
It is generally a best practice to avoid these de-icing chemicals on your concrete surface when possible. De-icers can cause surface damage, and products containing ammonium nitrates and ammonium sulphates will attack the concrete’s chemical makeup.
While it’s rare for concrete to crack, when it does it’s important to figure out why and get it repaired before more damage is done.
Proper installation and maintenance play a huge part in minimizing large cracks in your concrete driveway or parking area.
some reasons concrete cracks
There are a few reasons your concrete surface might crack, and all should be addressed as soon as possible to avoid further damage.
Too much water in the mix: Concrete doesn’t require much water to begin with, but often too much water is added on the job site to make the concrete easier to work with. This temporary “fix” reduces the strength of the concrete. When there is too much water, the concrete dries that water and evaporates, leading to shrinkage that pulls the concrete slab apart.
Pouring more malleable mixes is easier and might cost less because less manpower is required, but eventually this trick will lead to costly cracks.
Improper strength for use: If the use of the concrete surface is not taken into consideration when mixing the concrete, cracks will eventually appear. The higher the traffic in the area, the more psi your concrete mix needs.
Lack of control joints: Control joints are planned cracks. These cracks allow for any movement caused by temperature changes or shrinkage. If the concrete cracks, a control joint helps it crack in a straight line rather than at a random angle. The joints should be the depth of the slab and no more than two to three times (in feet) the thickness of the concrete (in inches). So, four inches of concrete should have joints 8 to 12 feet apart.
types of cracks
Some cracks cause more problems than others. Here are the types of cracks you can expect to see in concrete:
what can you do about concrete cracks
Not all cracks require repair, but there is no specific formula for deciding when they should be fixed. There are a few steps you can take to avoid cracks.
Start with a solid base: Avoiding cracks starts at the beginning of your project. Not only do you need to make sure you have a properly proportioned mix, you also need a properly compacted subgrade and subbase. The subgrade should be properly compacted, and the subbase, the layer of gravel on top of the compacted sub base, should be smooth.
Include proper joints: Joints allow the concrete to crack strategically and in the proper places rather than randomly.
Follow proper maintenance: If you’re cleaning and resealing your concrete surface as often as you should, cracking will be less likely, and the lifespan of your surface will be extended.
If you’re in a northerly climate, your concrete surface will have different needs than one in California or Florida. In states that experience all the seasons, you have to deal with snow and ice accumulation. While throwing salt or deicers on icy surfaces seems like the best way to fight against ice accumulation, some of these products can have a negative effect on your concrete surface.
Here are some guidelines for taking care of your concrete surface in the winter.
Limit chemical use
You should use chemical deicers sparingly and in the first year, you shouldn't use any. During the first year after you pour your new surface, it should be kept clear of all snow and ice. No deicer or any substance used to melt or remove snow and ice should be used. To reduce the risk of slips on icy surfaces during the first year, you can use sand to create traction on the surface.
Deicing chemicals raise the core pressure within the concrete and, if applied early on, can cause scaling distress.
Use common rock salt
After the first year some deicing chemicals may be applied but we recommend using common rock salt (sodium chloride, or NaCl, the same as table salt) rather than deicing salts, such as calcium chloride or magnesium chloride. Sodium chloride is effective to a temperature of approximately 18 degrees Fahrenheit. While other deicers may be effective at lower temperatures, they will harm the concrete over time.
the impact of deicing salts
All deicing salts can cause distress in the concrete over time. Why do deicers cause such a problem for concrete? When deicers are applied to ice, the melting point of the ice is reduced. The ice needs to reach a melting point lower than the temperature of the ice in order to melt. In order to reach this, the energy for melting is pulled from the surface of the concrete, which causes a rapid cooling of the concrete surface. The surface then experiences stress which may cause small cracks.
Water laden with deicer can also build up within concrete joints over time and deteriorate the quality of the concrete.
Sodium chloride achieves the same impact as de-icers, with less harsh results. Sodium chloride is also a much more affordable option in Michigan.
chemicals you should never use on concrete
Besides deicers, here are a few chemicals you should never use on your concrete surface:
While Sodium Chloride is the safer option, you should still use it sparingly and only when absolutely needed.
Your concrete driveway could easily last for your lifetime, but how will you know when it’s time to replace it? You might start noticing changes in your driveway if you’ve never had it replaced or if it was installed before you moved in. Here are a few indicators that will let you know it’s time to either repair or replace your concrete driveway.
Sometimes, the best course of action might be simple repairs.
Cracks that don’t connect: A crack that doesn’t connect to another crack isn’t a huge problem ... yet. Cracks smaller than one quarter inch can be repaired and should be fixed before they spread. If water freezes in the crack, the crack will only get deeper and wider.
A pothole: Potholes are rare in concrete but can be easily repaired if there is only one. You should do so before it causes more damage.
Crumbling edges: If the edge of your driveway is crumbling, it could mean the edges were too thin to begin with. You can add additional edging to prevent more damage or a total driveway replacement.
It’s less than 10 years old: Your concrete driveway should last 15 years at the very least, probably longer. So, if you’re noticing some wear and tear before age 10, make repairs rather than opting for an entirely new driveway.
If you don’t need to replace the driveway, you might choose to resurface. Repaving a driveway can range anywhere between $1 and $3 per square foot and is more affordable than a total replacement.
Sometimes repairs aren’t enough. You should consider a total driveway replacement if you notice any of these signs.
Multiple potholes: One pothole can be repaired; multiple potholes are a sign you might need a new driveway. Multiples potholes can start to impact the foundation of your driveway, and the more you have, the more expensive it gets to repair them.
Spiderweb cracks: Cracks that are all connected and cover a lot of your driveway mean it’s probably time for a replacement.
Drainage issues: Standing water is never a good sign. If water isn’t draining off your drive properly, it could be redirected towards your home’s foundation. This might mean it’s time to replace your driveway and address larger issues.
Multiple areas that need repairs: If you have a number of areas that need repairs, it might be more cost-effective to replace the driveway rather than repair the damage, especially if your driveway is over 20 years old.
The chemical reaction, its makeup, and the materials used in its manufacturing all make concrete a long-lasting choice for your driveway, parking lot or paved project. Whether you’re looking for an aesthetically pleasing option, or one that withstands wear and tear over the years, understanding the basics of this versatile material can help you find the right material in concrete.
Ready to move forward with your concrete project? Find the right contractor for the job with Michigan Concrete.