Driveway sealing 是什么意思？
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How long will my asphalt driveway last?
Well that all depends... A properly constructed and maintained asphalt driveway will probably last 20 to 30 years. “Properly constructed” is a big factor here. Too often a driveway is the last thing on the list when constructing a new home. All to often if there have been overruns in construction costs the driveway will “pay the price”. As contractors it’s not unusual to hear a homebuilder say “we only have $XXX left for paving the drive. What can you do for that much?” Of course that amount is usually less than what is actually needed to do a proper job. Many times premature structural failures in driveways are caused by this scenario or in older homes perhaps the previous owner was only concerned about low price, not high quality, if they had the drive replaced. Unfortunately it’s often impossible to tell how well the driveway was constructed after the fact. One tip would be if a new home driveway was not guaranteed against any structural defects for at least 2 years, or if there are areas that look rough or that hold water. The second part of this is “properly maintained”. If asphalt pavements didn’t need maintenance your city street department would be out of a job as would thousands of pavement maintenance contractors. As we get to answers to some more common questions proper maintenance will become self-explanatory.
Why should I sealcoat my driveway?
Asphalt pavements are made up of stone (aggregate) fine stone or sand, and asphalt cement. The asphalt cement is what gives the pavement it’s black appearance and is the “glue” that holds everything together. Often I joking answer this question in person by asking “why do you paint the wood on your house?” It’s obvious of course; to preserve the wood and protect it from damage from the elements. The same is true of asphalt pavements. Have you noticed that new asphalt is jet black but soon begins to fade and in a year or two has turned gray? That’s oxidation. The effects of the sun and rain/snow oxidizing the asphalt cement in the pavement. Given enough time the pavement becomes brittle and has less resistance to the loads placed on it. This can lead to a multitude of problems. Asphalt is a petroleum product so any other petroleum derivatives that contact it will dissolve into the asphalt, weakening or dissolving the asphalt’s “glue like” properties. These substances commonly include motor oil, transmission/power steering/ or brake fluids, gasoline, and perhaps household solvents like some cleaners. It’s common to see asphalt damaged by concrete cleaning products used on a sidewalk but rinsed onto a driveway. And the other common products mentioned can come from anywhere; a leaking car, oiling the chain on the kid’s bikes, spills while servicing the lawnmower, the list is endless. A good quality sealcoating will protect the asphalt pavement from all these damaging factors while providing the curb appeal of a new-looking black appearance. It’s often overlooked that sealcoating not only seals the harmful elements out but seals the beneficial properties of the asphalt cement in. Many years of research has proven that proper maintenance including sealcoating can double the life of an asphalt pavement. (Sealcoating is not new by any means. The first sealcoating materials were developed in the 1930’s for Standard Oil to help protect the pavement in their service stations.) Because of the scope of this subject there is another article devoted to types of sealers, doing it yourself vs. hiring a contractor, etc. Also see our article on why sealcoating works and how it can save you money.
What about those cracks in my driveway?
Those need immediate attention. A host of problems leading to major failure can result from the small start of a few cracks left unattended. You may wonder why we address this apart from sealcoating. Sealcoating is for sealing an asphalt surface. It does nothing of value for cracks larger than a “hairline” or in layman’s terms the size of a pencil lead or larger. Actual cracks in the pavement require specialized crack sealant materials. Left alone cracks allow moisture to penetrate the asphalt surface. Water expands as it freezes, so moisture in the cracks does the greatest damage in the winter months. But before you breathe a sigh of relief because you live in a warm area, moisture penetration does great damage to pavement no matter what the temperature. It just does more damage faster in freezing conditions. “Homeowner grade” crack sealants are always cold applied and must dry. (Contractors use a superior method with hot-applied materials that set as soon as they cool). The main issue in sealing cracks is that they MUST be clean, dry, and have no vegetation present prior to any sealing. Homeowners should always shop for a sealant containing the highest possible amount of rubber. The rubber allows the sealant to expand and contract with the pavement. Cheaper crack “fillers” are hard when cured and as the pavement moves they will separate from the asphalt, and allow moisture to penetrate again.
What about these ugly stains?
Be careful. One way to prevent stains is to sealcoat the pavement in the first place, but depending on the type of stain the cure can be more damaging than the illness. Be careful to read the label of any “driveway cleaning” product. Many contain solvents. ANY solvent will damage the asphalt pavement and should be avoided, even if the product says it’s for driveways. Often for oily stains the best approach is a biodegradable cleaner (like Simple Green or similar), if those are not readily available plain dishwashing soap will do. Mix a soapy water solution, apply to the stain and let stand for a few minutes, then get a good scrub brush and apply a liberal amount of “elbow grease” and rinse thoroughly. Take note if the scrub brush begins to loosen stones in the asphalt. If this happens, stop and rinse. That is an indication that whatever stained the drive has already weakened the asphalt and you could cause more damage trying to remove it. Contractors have a variety of products made for priming stains before applying sealcoating, however these may not be available to home owners and depending on the type of stain, sealcoating may not adhere to the stained areas. This is a situation where you might want to do a test area if you were sealing yourself to see if the sealer would adhere (apply according to directions, wait 2-3 days, then scuff at the sealer with your shoe or a stiff brush. If it loosens from the stain you may need professional help.
How long will my asphalt driveway last?
Well that all depends... A properly constructed and maintained asphalt driveway will probably last 20 to 30 years. “Properly constructed” is a big factor here. Too often a driveway is the last thing on the list when constructing a new home. All to often if there have been overruns in construction costs the driveway will “pay the price”. As contractors it’s not unusual to hear a homebuilder say “we only have $XXX left for paving the drive. What can you do for that much?” Of course that amount is usually less than what is actually needed to do a proper job. Many times premature structural failures in driveways are caused by this scenario or in older homes perhaps the previous owner was only concerned about low price, not high quality, if they had the drive replaced. Unfortunately it’s often impossible to tell how well the driveway was constructed after the fact. One tip would be if a new home driveway was not guaranteed against any structural defects for at least 2 years, or if there are areas that look rough or that hold water. The second part of this is “properly maintained”. If asphalt pavements didn’t need maintenance your city street department would be out of a job as would thousands of pavement maintenance contractors. As we get to answers to some more common questions proper maintenance will become self-explanatory.
Why should I sealcoat my driveway?
Asphalt pavements are made up of stone (aggregate) fine stone or sand, and asphalt cement. The asphalt cement is what gives the pavement it’s black appearance and is the “glue” that holds everything together. Often I joking answer this question in person by asking “why do you paint the wood on your house?” It’s obvious of course; to preserve the wood and protect it from damage from the elements. The same is true of asphalt pavements. Have you noticed that new asphalt is jet black but soon begins to fade and in a year or two has turned gray? That’s oxidation. The effects of the sun and rain/snow oxidizing the asphalt cement in the pavement. Given enough time the pavement becomes brittle and has less resistance to the loads placed on it. This can lead to a multitude of problems. Asphalt is a petroleum product so any other petroleum derivatives that contact it will dissolve into the asphalt, weakening or dissolving the asphalt’s “glue like” properties. These substances commonly include motor oil, transmission/power steering/ or brake fluids, gasoline, and perhaps household solvents like some cleaners. It’s common to see asphalt damaged by concrete cleaning products used on a sidewalk but rinsed onto a driveway. And the other common products mentioned can come from anywhere; a leaking car, oiling the chain on the kid’s bikes, spills while servicing the lawnmower, the list is endless. A good quality sealcoating will protect the asphalt pavement from all these damaging factors while providing the curb appeal of a new-looking black appearance. It’s often overlooked that sealcoating not only seals the harmful elements out but seals the beneficial properties of the asphalt cement in. Many years of research has proven that proper maintenance including sealcoating can double the life of an asphalt pavement. (Sealcoating is not new by any means. The first sealcoating materials were developed in the 1930’s for Standard Oil to help protect the pavement in their service stations.) Because of the scope of this subject there is another article devoted to types of sealers, doing it yourself vs. hiring a contractor, etc. Also see our article on why sealcoating works and how it can save you money.
What about those cracks in my driveway?
Those need immediate attention. A host of problems leading to major failure can result from the small start of a few cracks left unattended. You may wonder why we address this apart from sealcoating. Sealcoating is for sealing an asphalt surface. It does nothing of value for cracks larger than a “hairline” or in layman’s terms the size of a pencil lead or larger. Actual cracks in the pavement require specialized crack sealant materials. Left alone cracks allow moisture to penetrate the asphalt surface. Water expands as it freezes, so moisture in the cracks does the greatest damage in the winter months. But before you breathe a sigh of relief because you live in a warm area, moisture penetration does great damage to pavement no matter what the temperature. It just does more damage faster in freezing conditions. “Homeowner grade” crack sealants are always cold applied and must dry. (Contractors use a superior method with hot-applied materials that set as soon as they cool). The main issue in sealing cracks is that they MUST be clean, dry, and have no vegetation present prior to any sealing. Homeowners should always shop for a sealant containing the highest possible amount of rubber. The rubber allows the sealant to expand and contract with the pavement. Cheaper crack “fillers” are hard when cured and as the pavement moves they will separate from the asphalt, and allow moisture to penetrate again.
What about these ugly stains?
Be careful. One way to prevent stains is to sealcoat the pavement in the first place, but depending on the type of stain the cure can be more damaging than the illness. Be careful to read the label of any “driveway cleaning” product. Many contain solvents. ANY solvent will damage the asphalt pavement and should be avoided, even if the product says it’s for driveways. Often for oily stains the best approach is a biodegradable cleaner (like Simple Green or similar), if those are not readily available plain dishwashing soap will do. Mix a soapy water solution, apply to the stain and let stand for a few minutes, then get a good scrub brush and apply a liberal amount of “elbow grease” and rinse thoroughly. Take note if the scrub brush begins to loosen stones in the asphalt. If this happens, stop and rinse. That is an indication that whatever stained the drive has already weakened the asphalt and you could cause more damage trying to remove it. Contractors have a variety of products made for priming stains before applying sealcoating, however these may not be available to home owners and depending on the type of stain, sealcoating may not adhere to the stained areas. This is a situation where you might want to do a test area if you were sealing yourself to see if the sealer would adhere (apply according to directions, wait 2-3 days, then scuff at the sealer with your shoe or a stiff brush. If it loosens from the stain you may need professional help.
