Denver Concrete Company Blog

Magnesium Chloride and Your Concrete Driveway: How a Salt Protector Stops the Damage

If your concrete driveway looks fine in the fall and comes out of winter with a flaking, pitted surface near the garage door, the cause is probably not your concrete. It is the magnesium chloride your car carries home from the street. Here is how road de-icer ends up on your driveway, what it does to concrete, and how a penetrating salt protector or water shield keeps it from doing damage.

How Magnesium Chloride Gets From the Road to Your Driveway

Across the Denver metro, CDOT, counties and cities spray liquid magnesium chloride on roads before and during storms so ice does not bond to the pavement. It works well on asphalt. The problem is that it does not stay on the road.

Every time you drive, your tires, wheel wells and undercarriage pick up slush mixed with mag chloride. When you park in the driveway or garage, that packed snow melts and drips off the car, leaving a concentrated brine in the exact spots where you park. It soaks into the surface, dries, and the next storm adds more. Over a few winters the chloride builds up in the top layer of the concrete, usually in a pattern that matches where your tires sit and the strip just outside the garage door.

What Magnesium Chloride Does to Concrete

Mag chloride damages concrete in two ways at once.

It makes freeze-thaw worse. Concrete is porous. Brine soaks into those pores, and because salt lowers the freezing point, the surface goes through far more freeze and thaw cycles than it would with plain water. Each cycle puts pressure on the top layer until it starts to break loose.

It attacks the cement paste. Magnesium chloride reacts with the cement that holds the sand and stone together, weakening the paste at the surface over time. That is why the damage shows up as scaling and spalling: the smooth top layer flakes off in patches and exposes the stone underneath.

Research backs this up. In a study for the Indiana Department of Transportation, Purdue University researchers exposed concrete to several de-icing solutions and found that calcium chloride and magnesium chloride caused more deterioration than the other solutions tested. The damage from magnesium chloride took longer to appear, but it ended up just as severe.

Once a surface has spalled, a sealer cannot put it back. Small areas can sometimes be resurfaced, but widespread damage usually means replacing the slab. Protecting the surface before the damage starts is far cheaper than either one.

What a Salt Protector or Water Shield Does

A salt protector is a penetrating water repellent, usually a silane and siloxane blend. Unlike a glossy topical sealer that sits on the surface like a coat of paint, it soaks into the concrete and lines the pores so they repel water and the salt dissolved in it. The surface still looks like plain concrete and stays just as slip resistant, but brine beads up and runs off instead of soaking in.

That matters because the damage only happens when brine gets inside the concrete. Keep it out, and freeze-thaw and chemical attack at the surface slow down dramatically.

The Colorado Department of Transportation tested products meant to protect concrete from winter de-icers. In its 2006 report, a silane treatment significantly reduced how easily chloride could get into the concrete, lowering its permeability rating from high to moderate. Silane is the same active ingredient in the penetrating salt protectors used on driveways.

On every new driveway we pour, we wait about 30 days for the concrete to cure, then apply two even coats of a penetrating salt protector. One application protects the surface for roughly 3 to 4 years. We wrote about the product we use in the benefits of using a salt protector on your driveway, and about Colorado road de-icers in using a salt protector on your driveway in Colorado.

Do You Need It on an Older Driveway?

Yes, as long as the surface is still in good shape. A penetrating protector works on any sound concrete driveway, garage apron, sidewalk, porch or patio. It is most valuable where cars park and where snow melts off vehicles, so the strip in front of the garage and the parking pad should be first.

Here is a simple way to check whether your concrete is protected: on a dry day, pour a cup of water on the driveway. If it beads up, the surface is repelling water. If it darkens the concrete and soaks in within a minute or two, salt brine is soaking in too, and it is time to apply a protector.

If your concrete is already flaking, call us before you treat it. A protector will slow further damage on lightly scaled concrete, but a surface that is breaking up badly may need repair or replacement first. Our concrete sealing and rejuvenation service covers driveways, patios and stamped concrete.

New Concrete Needs Extra Care Its First Winter

Concrete keeps gaining strength for weeks after it is poured, so a driveway poured in the late summer or fall is more vulnerable to mag chloride during its first winter. Keep vehicles off it for 21 days after the pour, make sure the salt protector goes on once it has cured, and do not use any de-icing salt on it yourself that first season. Our Denver concrete questions answered guide covers cure times and winter pours in more detail.

Simple Winter Habits That Protect Your Driveway

• Shovel early. Clearing snow before it melts and refreezes cuts down on freeze-thaw cycles.
• Knock snow and slush out of the wheel wells before you park, or sweep the melt off the driveway and garage floor once it puddles.
• On a warm winter day, rinse the parking area with a hose to wash accumulated chloride off the surface.
• Skip rock salt and magnesium chloride ice melt on your own concrete. Use sand for traction instead.
• Re-apply your salt protector every 3 to 4 years, or sooner if the water bead test fails.

Start With Concrete Built for Colorado Winters

A protector works best on concrete that was built to resist salt in the first place. That means air-entrained concrete, a proper base and reinforcement, and a dense mix. We pour driveways and garage floors with a 4,500 PSI mix, which is less permeable than the standard 4,000 PSI mix. Read why we use 4,500 PSI concrete and 6 things every Denver concrete driveway needs.

If your driveway is already past saving, see our driveway replacement page and our concrete driveway cost guide. For garages, an epoxy floor coating seals the slab against the brine that drips off your car all winter, and our garage slab page covers replacing a floor that is too far gone. Stamped concrete has its own care routine, covered in our stamped concrete FAQ.

Denver Concrete Questions Answered: 15 Things Homeowners Ask Before They Pour

Most people who call us have already spent an evening searching things like "how long before I can drive on a new driveway" or "is mudjacking worth it in Colorado." The answers online are usually written for Florida or Texas, not for a city that freezes and thaws dozens of times a winter and sits on expansive clay soil. So we pulled together the questions Denver homeowners ask us most, with short, plain answers and links to the longer guides we have written on each topic.

How much does a new concrete driveway cost in Denver?

For a standard residential driveway replacement, our current guideline is about $12.00 per square foot for a 4 inch slab and $13.50 for a 6 inch slab. That includes tearing out and hauling off the old concrete, reinforcement and full cleanup. A brand new driveway with no tear-out costs less per square foot. Total size, the condition of the base underneath and access to the site all move the number. Our concrete driveway cost guide breaks the pricing down by thickness, and the benefits of driveway replacement explains what you get for the money.

How thick should a concrete driveway be in Colorado?

A typical home driveway that sees cars, SUVs and pickups only needs a 4 inch pour, as long as the base is solid and the slab is reinforced. If you park an RV, a trailer or a work truck, or if delivery trucks regularly cross the slab, step up to 6 inches. Thickness alone will not save a driveway poured on a poor base, which is why base prep is on our list of 6 things every Denver concrete driveway needs.

What PSI concrete should I use for a driveway or garage floor?

Most driveway specs call for at least 4,000 PSI. We pour a 4,500 PSI mix on driveways, garage floors and parking areas because the denser mix lets in less water and holds up better against de-icing salts and freeze-thaw cycles. Since switching, we have seen less spalling and fewer hairline cracks. The full reasoning is in why we use 4,500 PSI concrete instead of 4,000 PSI. A good Colorado mix should also be air entrained, around 6 to 7 percent air, which gives water room to expand when it freezes.

Does a driveway need rebar or wire mesh?

Yes. Reinforcement does not stop concrete from cracking, but it holds the pieces together and keeps them level when a crack does happen. Our driveways include either 6 by 6 welded wire mesh or rebar set every 2 feet, plus fiber in the mix to cut down on shrinkage cracks while the slab cures. If a bid you received does not mention reinforcement, ask about it. Strengthening products in concrete explains the difference between rebar, wire mesh and fiber.

Why does concrete crack so much in Denver?

Three things work against concrete here: freeze-thaw cycles, clay soils that swell when wet and shrink when dry, and de-icing salt. Every slab will develop some cracks, which is why control joints are cut in on purpose so the cracking happens in a straight line where you want it. Cracks that widen, heave or leave one slab higher than the next usually point to a base or drainage problem. Those are worth having looked at before they become a trip hazard.

How long after pouring concrete can I walk or drive on it?

You can walk on new concrete after a day or two, but wait 21 days after the pour before driving any vehicle on it, including your everyday car. That gives the slab time to gain the strength it needs to carry the weight without cracking. Cold weather slows curing, so your crew will confirm the exact dates for your pour. Our driveway replacement process walks through each step from tear-out to cure.

Can you pour concrete in the winter in Colorado?

Yes, with the right precautions. Concrete should never be poured on frozen ground, and in cold weather the fresh slab has to be protected so it does not freeze before it gains strength. That usually means insulated curing blankets and watching the forecast closely. Cold-weather work can add cost, which is one reason a winter estimate may include conditions that a summer estimate does not. Spring and fall are the easiest seasons to schedule, and our calendar fills fastest then.

Does de-icing salt damage concrete, and should I seal my driveway?

De-icers are one of the biggest causes of surface damage we see. Salt and magnesium chloride tracked in from plowed streets work into the surface and, combined with freezing, cause flaking and spalling. On every new driveway we pour, we wait about 30 days for the slab to cure and then apply a penetrating salt protector, which protects the surface for roughly 3 to 4 years. Read the benefits of a salt protector on your driveway, and see our concrete sealing and rejuvenation service for existing driveways, patios and stamped concrete.

Should I mudjack my sunken concrete or replace it?

Mudjacking is cheaper and faster up front, and it can make sense for minor settling on a small walkway. It does not fix the soil or drainage problem that caused the settling, so slabs often sink again, and the drill holes stay visible. Replacement costs more but lets us correct the base and drainage and gives you a new, reinforced slab built to last decades. We compare both in concrete replacement vs mudjacking in Colorado and the downsides of mudjacking.

Is stamped concrete or pavers better for a patio in Denver?

Both can look great. Stamped concrete is one continuous slab, so there are no joints for weeds to grow through and no individual pieces to settle or shift, and it can be colored and patterned to look like stone, slate or wood. Pavers are easier to patch one piece at a time. We break down cost, upkeep and looks in stamped concrete vs paver patios. For ideas, see enhance your outdoor space with stamped concrete, stamped concrete for your patio and our concrete patio page.

How do I pick colors and patterns for stamped concrete?

Start with your house: pull a color from the roof, brick or trim, then choose a base color and a darker release color to highlight the texture. Lighter colors stay cooler underfoot in the summer sun. Our guide on how to choose colors for a stamped concrete project walks through the process, and you can browse stamped concrete color combinations, the release color chart and stamped concrete patterns. The stamped concrete FAQ answers questions about upkeep and resealing.

Can I tear out my old concrete myself to save money?

You can, but most homeowners underestimate the work. A driveway weighs several tons, breaking it up takes heavy equipment, and disposal fees add up quickly. Damaging a sewer line, sprinkler system or your foundation while breaking concrete costs far more than you would save. Should I tear out my own concrete or hire a professional? covers the tradeoffs, and our concrete removal service handles demo and haul-off.

Is epoxy or polyaspartic better for a garage floor?

Both turn a plain garage slab into a floor that resists oil, chemicals and hot-tire marks and is easy to clean. Polyaspartic coatings cure much faster, so your garage is back in use sooner. Compare them in the benefits of epoxy floor coatings, the ultimate guide to epoxy floor coatings and what is polyaspartic? If the slab itself is cracked or sunken, start with a new garage slab and coat it once it has cured.

Does new concrete add value to my home?

Curb appeal is the first thing buyers and appraisers notice, and a cracked, stained or sunken driveway is an easy reason for a buyer to ask for money off. New driveways, walkways and patios also make the yard more usable while you live there. See boost your home's value with new concrete and popular residential concrete projects in Colorado for ideas.

How do I choose a concrete contractor in Denver?

Get at least two written bids and compare them line by line, not just on total price. A low bid often leaves out tear-out, base prep, reinforcement or cleanup. Ask what PSI mix they use, how they handle drainage, and whether they are licensed and insured in your city. Then read their reviews and look at photos of recent work. Our tips for choosing your concrete provider has a full checklist, and you can see our recent concrete jobs around the metro.

Still have a question?

Denver Concrete Company has poured driveways, patios, sidewalks and stamped concrete across the metro since 2014, including Arvada, Lakewood, Littleton, Wheat Ridge, Westminster and Parker. If your question is not covered here, ask us during your estimate. We would rather answer it before the pour than after.

Boost Your Home’s Value with New Concrete

When it comes to enhancing your property, many homeowners focus on interior renovations, landscaping, or adding new features. However, one often overlooked yet highly effective way to increase your home's value is by installing new concrete surfaces. From driveways and sidewalks to patios and decorative elements, new concrete can significantly improve curb appeal, functionality, and overall property worth. In this article, we’ll explore how investing in new concrete can be a smart move for homeowners looking to maximize their property's value.

Why Choose Concrete for Home Improvements?

Concrete is a versatile, durable, and cost-effective material that offers numerous benefits:

• Longevity: Properly installed and maintained concrete can last decades, making it a long-term investment.
• Low Maintenance: Concrete surfaces are easy to clean and require minimal upkeep compared to other materials.
• Design Flexibility: Modern techniques allow concrete to be customized with colors, textures, patterns, and finishes, enhancing visual appeal.
• Increased Curb Appeal: Well-installed concrete features can instantly upgrade your home’s exterior.
• Enhanced Safety: New concrete can provide slip-resistant surfaces and improve drainage around your property.

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Stamped Concrete: The Durable and Decorative Solution for Your Patio

When it comes to upgrading outdoor spaces, homeowners and contractors alike are constantly seeking versatile, durable, and aesthetically appealing options. Among these, stamped concrete has emerged as a popular choice for patios, driveways, walkways, and more. Combining the strength of traditional concrete with intricate patterns and textures that mimic natural materials like stone, brick, or slate, stamped concrete offers an excellent balance of beauty and durability.

What Is Stamped Concrete?

Stamped concrete is a specially textured and patterned concrete surface that is created by pressing molds into freshly poured concrete. This process imparts the appearance of high-end materials while maintaining the affordability and longevity of concrete. The technique involves pouring a concrete slab, then applying stamps and colorants to achieve a realistic and attractive finish.

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