Frequently Asked Questions and Answers – EST. 2008

Category: Parking Lot Layout & Requirements
What are the standard requirements for ADA Parking Stalls
Answer:
Standard requirements for ADA parking stalls are as follows:
For standard vehicles stalls: minimum width of 8ft. Length of the parking stall will match that of surrounding spaces, normally 18-20ft.
For van accessible stalls: minimum width of 11ft. Length of the parking stall will match that of surrounding spaces, normally 18-20ft, and an adjacent access aisle with a minimum width of 5ft. Or stalls measuring a minimum of 8ft in width, with an adjacent access isle measuring a minimum of 8ft in width.
ADA parking stalls must be identified with pavement markings, as well as signs depicting the International Symbol of Accessibility. Van accessible stalls shall include the term van accessible on signage. Signs must be at least 60 inches high, measuring from the bottom of the sign to floor, and mounted on post or walls where applicable. If signage is on the accessible route, signage must be at least 84 inches high, measuring from the bottom of the sign to the floor.
What are the standard requirements for vehicle parking stalls?
Answer:
For commercial parking lots, the dimensions for average car parking stalls are approximately: 8.5-9ft wide and 18-20ft long. Compact parking stall dimensions are approximately: 7.5-8.5ft wide and 16-18ft long.
What are ADA parking spaces? Are they required?
Answer:
ADA (Americans with Disabilities Act) parking spaces are designated parking stalls for individuals with disabilities. Yes, by law a calculated number of stalls, depending on the number of spaces within a designated parking area, are required to be designed and designated as ADA accessible parking. A general rule of thumb for the number of ADA stalls required is 1 for every 25 regular parking stalls with at least 1 Van Accesible stall per 8 regular ADA Stalls.
Is there a set minimum for a number of ADA spaces required for any given parking lot?
Answer:
Yes, there is a set minimum for the number of ADA designated parking stalls required in a parking lot. However, that minimum number is based on the number of over all available parking spaces within a parking area. For example, a parking structure with 1-25 parking stalls is required to have a minimum of 1 ADA stall that must be Van Accessible.
Are designated pedestrian walkways required in parking lots?
Answer:
Designated crosswalks/walkways are not required in parking lots unless the original design specified them. Crosswalks are always recommended as they provide a safe crossing area that vehicles can identify upon approach. Crosswalks should typically be placed where safe access to the business or sidewalk is available.

Category: Striping
When can a newly paved parking lot be striped?
Answer:
Asphalt should be given at least 1-2 weeks of curing time before traffic paint is applied. This will prevent paint from absorbing into pavement and appearing thin. In cases where striping needs to be done immediately, paint can be applied in 2 coats or a thicker application rate to combat absorption.
What paint is best for newly seal coated areas?
Answer:
In most cases, especially when asphalt emulsion sealer is used, a waterborne paint should be used to prevent a chemical reaction from occurring which could cause discoloration of paint and premature failing of sealer/paint.
What are the differences in uses and restrictions of oil based paint and water based paint?
Answer:
Generally, Oil based paints are used for striping on concrete surfaces and Waterborne paints are used on newly paved or newly seal coated asphalt lots. Oil based paints typically cost more due to material cost and added clean up cost. Oil based paints must be cleaned using solvents where waterborne paints can be cleaned using water. Due to VOC laws in most states, waterborne paints are being specified and distributed more often then oil based paints.
How soon after a parking lot is seal coated can it be striped? What type of paint is used?
Answer:
Seal coat material normally takes about 24 hours to cure before striping may commence. In warmer weather, striping can be applied in as little as 4-6 hours after final coat of sealer was applied. Newly sealed asphalt pavements are striped with waterborne striping paint.

Category: Concrete
Why do concrete surfaces require joints?
Answer:
Unlike asphalt, concrete is a ridged material that does not flex with movement. Joints allow for expansion and contraction to occur without causing heaving or uncontrolled cracking. Cracking in a concrete surface is inevitable so the use of properly spaced joints will tell the concrete where to crack which results in a cleaner, more uniform appearance.
What options are available for repairing concrete that has lifted, cracked or pitted?
Answer:
There are a couple of different options available to repair the issues listed above. Below are some of the options for repair.
Lifted concrete: Depending on the height and cause of the deviation, lifted edges can be grinded down to remove the blunt edge/trip hazard. Surface grinding concrete will expose the aggregate within and will not match the appearance of the untouched areas. If the deviation is caused by a growing tree root for example, the long term repair would be to remove and replace the section of concrete, and extract the tree root.
Cracked concrete: Depending on the extent of the cracking; concrete cracks can be sealed, or caulked to keep out moisture and prevent further damage. Severly cracked concrete should be removed and replaced and additional control joints should be considered to prevent future cracking. Inadequate thickness, concrete strength, or lack of reinforcement can also be the cause of cracking which can only be fixed by removing the concrete and installing new concrete to specifications that are adequate for the use/traffic load.
Pitted/Spalding concrete: Pitted/spalding concrete can be resurfaced using a concrete resurfacing material. Resurfacing materials are typically applied at a thickness of ¼” to ½” depending on site conditions. This will provide a new surface finish. Resurfacing is not considered a permanent solution and may periodicly require maintenance or re-surfacing. Resurafcing material color will vary and typically does not match existing concrete.
What is the usual thickness of concrete sidewalks?
Answer:
Concrete sidewalks are typically 4” thick.
What is the curing time for newly installed concrete?
Answer:
The curing time for concrete can vary. As concrete cures over time, the harder/stronger it becomes. Factors such as weather, concrete strength, and additives/mix design can affect concrete curing time. Foot traffic can typically resume about 24-36 hours after concrete is poured. Vehicle traffic can typically resume within 5-7 days after concrete was placed. Standard concrete mix designs hit their designated strength in about 28 days. “High Early” concrete mixes are designed to hit full strength in a specified amount of time. Standard high early mix designs can hit full strength at 3 or 7 days which reduces the amount of downtime for vehicle traffic.
What is Concrete?
Answer:
Concrete is a mixture of 3 basic components; aggregate (rock, sand, and/or gravel), water, and Portland cement. Portland cement acts as a binding agent when mixed with water and aggregate. The paste (Portland cement/water) coats the surfaces of fine and coarse aggregates, and through a chemical process called hydration, the past hardens to form solid masses known as concrete. Concrete is utilized in a variety of ways, from walk ways to road ways to erecting buildings as foundations or load bearing walls.
What does curing mean for concrete?
Answer:
Remove question.
What are the pros and cons to choosing concrete over asphalt?
Answer:
Concrete, structurally and chemically differs from asphalt cement. Concrete is very rigid and hard and asphalt is flexible and softer. As such, installing concrete pavements, and the capabilities of concrete pavements differ from that of asphalt pavement. Concrete pavements normally carry a higher purchasing expense, though they contain a longer service “life” to that of asphalt pavements. Concrete pavements also usually require less annual maintenance to that of asphalt pavements. Concrete pavements are more durable when compared to asphalt due to its rigidity. In cases where a high amount of movement may occur, concrete will crack or heave where as asphalt would flex to an extent before cracking.
What are the differences in maintenance requirements for concrete in comparison to asphalt?
Answer:
In comparison to asphalt, concrete requires very little maintenance. Joints are cut in concrete to allow for movement, and help control and minimize concrete surface cracks. Should cracks occur, they should be sealed to better reinforce the overall section. Concrete can be sealed to help protect it from overall exposure, however it is not required. Since asphalt does not have joints, cracks that occur should be sealed to prevent water intrusion. As asphalt ages, the oil (binder) begins to dry out causing asphalt to become more brittle and suseptable to cracking. The surface can also begin to come loose causing a rough/uneven surface. Sealer should be applied to asphalt every 3-5 years to preserve the binder and keep the surface intact.
How are concrete structures, such as curbs and sidewalks, made?
Answer:
Curbs and sidewalks are installed by pouring wet mix cement into setting forms. The exposed surfaces are then finsished. Forms are removed once concrete has adequately set.
Can concrete be colored?
Answer:
Yes, concrete can be colored by use of pigment added to cement mixes during the batching process or once cement is placed and cured, the surface on concrete pavements can be stained, dyed or painted a desired color. Color added during the batching process is integral meaning the entire concrete section is colored. Staining and painting are on the surface only so any damaged or wear the surface will expose the gray color of standard concrete underneath.
Are there restrictions on when concrete can or can not be poured?
Answer:
There are only a few restrictions as to when concrete can or can not be poured. Concrete can typically be performed in all seasons. Restrictions include pouring concrete during rain/snow and or when temperatures are below freezing. In colder temperatures, the use of insulated blankets can keep the temperature of concrete above 45 degrees during the curing process. During curing, when the concrete temperature drops below 40 degrees the curing process essentially stops which can delay curing time and cause premature failures. In hot climates, measures should be taken such as water curing or the application of curing compound to ensure the moisture within concrete does not evaporate to quickly.

Category: Asphalt
Why is asphalt maintenance important?
Answer:
There are many factors that can affect the longevity and structural integrity of asphalt pavement. Routine maintenance helps to not only preserve the surface condition of the pavement, but has also shown to aid in extending the life of the structure further. Saving on the expense of having to remove and replace the area before it can be utilized to its full potential. Periodic maintenance will also address any safety hazards (i.e. pot holes, cracks) that often occur as a result of normal wear and tear.
Why does existing asphalt not match the color of newly patched areas? Is there a way to color match them?
Answer:
With prolonged exposure to natural elements, sunlight/UV light and traffic, the oils and aggregates that make up asphalt begin to break down. With constant exposure to oxygen, a process called oxidization occurs which results in a change in the color of asphalt from its initial charcoal black color to gray. When asphalt is patched, new asphalt is applied to existing asphalt and as a result there are often noticeable visual differences between the existing asphalt and the newly applied asphalt.
Sealing or Seal Coating asphalt is a standard process of maintenance for all asphalt pavement. Seal coating helps preserve the oils in asphalt and protects the surface from exposure to natural elements, UV light and traffic. It also gives asphalt a “new” charcoal black color again which can provide a uniform color across the pavement even if areas have been patched.
Why do pot holes occur? How are they repaired?
Answer:
Pot holes occur from moisture penetration or sub-grade settling. Moisture penetration will result in erosion of the base layer causing undermining, where as settling is an effect of base failure due to improper compaction or unsuitable materials. Whether caused by moisture or settling, the proper way to repair a pot hole is by a full depth asphalt patch, in which the asphalt is cut away to clear margins, i.e. no cracks, no settling, and removed. The base, or layer below, is then removed to an appropriate depth, depending on conditions, and gradually added and compacted until appropriate grade is met. The asphalt section is then replaced with new hot mix asphalt and compacted flush with adjoining edges of existing asphalt. Asphalt binder is applied to saw cut edges of existing asphalt before installation of new asphalt to aid in bonding of new pavement to existing.
When is it appropriate to seal coat a newly paved area?
Answer:
For newly paved areas, the asphalt must cure for at least 1 year before sealer can be applied. Applying sealer prematurely can cause issues with the asphalt curing and may keep the asphalt from hardening at the surface.
What maintenance techniques are utilized to properly maintain asphalt?
Answer:
There is a number of repair methods and techniques utilized to maintenance asphalt pavement. The type of repair, or technique, used at any given time is dependent on the condition of the asphalt. The most common repairs conducted are:
Crack Sealing: The application of hot rubberized sealant into asphalt cracks.
Asphalt Patching: There are a effectively two types of asphalt patches.
1.) “No Cut” asphalt patching: includes removing all loose material, applying an emulsion based tack to surface to be patched, and laying and compacting new asphalt to industry standards. This repair is not as effective as a “Full-Depth” asphalt patch. It is intended to be a temporary repair.
2.) “Full-Depth” asphalt patching: entails removing the full depth of asphalt in an effected area, re-compacting base, applying tack coat to saw-cut edges, and laying and compacting new asphalt flush to existing asphalt. “Full-Depth” asphalt patches are permanent repairs, meaning that, unless effected by deteriorating conditions of the surrounding asphalt, the patch should last the life of the surrounding pavement. Sealing saw cut joints with rubberized sealant prevents water intrustion thus extending the service life on the repair area.
Seal Coating: An asphalt emulsion or coal tar based sealer that is applied to the entire asphalt surface. Aids in preserving binding oils and protects the pavement from exposure to the sun, water, oxidation and chemicals.
Overlaying/Resurfacing: Depending on the thickness and condition of existing asphalt, the asphalt may be milled, or cut down; removing a percentage of the existing thickness without removing it completely. A minimum of 3.5”-4” of existing asphalt is required to perfrom a mill & overlay. A tack material is applied to aid in the bonding of new asphalt to the remaining existing asphalt. New asphalt is laid on top of remaining existing asphalt and compacted to original grade. If the grade of existing asphalt is accommodating, the asphalt can be applied to the surface with out having to be milled down. Keep in mind that in order to do an overlay or resurface, all problematic areas, meaning cracks, pot holes, alligatoring etc., will first need to be repaired. If not repaired, the newly paved asphalt stands the chance of reflecting the condition of the previous asphalt surface. Eventually the problem areas that were not addressed, will arise in the newly paved surface.
What is the difference between resurfacing (Overlay) and seal coating a parking lot?
Answer:
The primary difference between resurfacing, or overlaying, an asphalt surface and seal coating is: resurfacing, in the terms of an overlay, includes applying new asphalt material to an existing asphalt surface. There are other products such as “Slurry Seal” or “Liquid Road” which are categorized as sealers, however, act as more of a resurfacer than a sealer. They contain solids such as sand and minerals and are fiber reinforced, which in turn reinforce the surface of an existing asphalt surface. Seal coating on the other hand aims to “maintain” or preserve the binder oils in asphalt pavements and protect an asphalt surface from further exposure deterioration. Seal coating does little in terms of reinforcing the strength of the surface itself and will not restore or improve the asphalt surface condition.
What is the difference between an asphalt skin patch (surface patch) and a full depth asphalt repair?
Answer:
Asphalt skin patches are most commonly utilized in temporarly repairing surface defects, such as depressions, or uneven areas, potholes, and alligator cracked areas. Asphalt skin patching is considered a temporary repair, as it does not affect or cure any underlying problems with the pavement structure itself. Skin patching entails applying/laying new material over existing pavement and rolling and compacting. Full depth asphalt repairs entail demoing (saw-cutting/removing, milling, etc.) an indicated area removing the material, re-compacting the underlying base and applying new material in its place. Full depth asphalt repairs are long term repairs aimed to improve and maintain an overall asphalt pavement surface.
What is Asphalt?
Answer:
Asphalt, also known as “Asphaltic Concrete,” is a mixture of dark bituminous pitch with aggregates such as sand or gravel. Asphalt is made to order in a specifically designed plant by mixing heated diluted asphalt cement and heated aggregate together in a drum. Once properly mixed and heated, the asphalt is stored in a silo where it will be dropped from into a transport trailer or dump truck so it can be taken to the project where it will be laid.
What causes asphalt to deteriorate?
Answer:
There are a number of conditions that could result in the deterioration of asphalt. One fact to always keep in mind is that asphalt is typically designed with a 20-25 year service life. Asphalt pavement will always require routine maintenance to ensure that the structure remains sound and in good condition during its service life. Over time, with exposure to the elements, the bonding properties asphalt contains oxidize and wear away, resulting in the segregation of the aggregate material it contains. Other factors that contribute to the deterioration of asphalt are; unstable base and/or sub-base, puddling or stagnant water, exposure to chemicals, natural movement, improper base compaction, improper thickness and/or temperature of asphalt at time of compaction.
What causes asphalt cracking? How are they repaired?
Answer:
There is a number a of reasons as to why cracks in asphalt occur. As such, there are different types of cracks. Types of cracks include Longitudinal, Transverse, Block, Edge, Fatigue, and Slippage Cracking. Asphalt cracking may occur from improper thickness of asphalt, poor asphalt mix, base destabilization due to improper compaction or unsuitable materials, movement and swelling, and the natural flex and compression of asphalt due to pavement temperature changes. Fatigue cracking is usually an indication of base failure or improper thickness of asphalt. Fatigue cracking should not be crack sealed and requires more substantial work to correct the issue. Depending on the width and type of crack, a rubberized sealant can be injected to prevent further spread or deterioration due to water infiltration.
Is there a specific time of year crack sealing should be done?
Answer:
Crack sealing can be done at any time of year. However, for the best result, we do recommend it be done in extremely cold temperatures. Crack Sealing should also not be performed if it’s raining or if moisture is present in the cracks to be sealed. At colder temperatures asphalt cracking tends to expand to its widest point. During the colder month’s asphalt cracks are usually at their largest and can be sealed “fully” at their complete resting size. When sealed during warmer months, when asphalt is at a higher temperature and pliable, cracks have contracted and thus are not being sealed at their widest point which may cause hairline cracks in the sealant when the weather cools down.
Is there a restriction as to what time of year asphalt can be seal coated?
Answer:
Yes, a very important factor in the quality and longevity of your asphalt sealer comes down to temperature. Seal Coating should only be done in temperatures that are at least 50 degrees and above for at least a 24-48 hour period for material to properly adhere and cure to asphalt. Failure to follow these specifications provided by the sealer manufacturer will result in premature wear and or failure of the sealer. In New Mexico, the seal coat season typically starts in April and ends in October.
How soon after an area has been patched can it be driven on?
Answer:
Patched areas are safe to drive on once the newly laid material has completely cooled. Rate of cooling depends on the time of year and the temperature throughout the day. Water is often utilized to help expedite the rate of surface cooling which allows vehicle traffic to resume quicker. New asphalt will be vulnerable for up to 45 days meaning sharp turning, hard braking, or hard acceleration will mark or scuff the surface causing permanent blemishes in some cases. New repairs that are not subject to sharp turning or harsh traffic conditions are often opened back up to traffic quicker than areas that are.
How soon after an area has been patched can it be seal coated?
Answer:
It is always best to give new asphalt patches a minimum of 30-45 days of curing prior to applying sealer. The same does NOT apply for a complete new asphalt surface. A newly installed asphalt surface, whether a driveway or parking lot, should be given at least 1 full year before sealer is applied.
How often should a parking lot be seal coated?
Answer:
We recommended that asphalt surfaces be seal coated every 3-5 years after initial 1 year cure time of new asphalt. High volume/traffic commercial lots or roadways may require re-sealing closer to every 3-4 years due to higher volume of wear. Typically, wear begins to occur in drive lanes or entrances where the highest amount of traffic is experienced. Lower volume parking lots, roadways, and driveways can see as much as 5-6 years of service life out of properly applied sealer. A lot of variables affect service life of sealer so it’s best to evaluate your sealer condition between 3-4 years to see if it’s time to re-seal or if more life is left in the existing sealer.
How do cracks in asphalt pavement affect overall life span? Is it possible to keep cracks from occurring or re-opening?
Answer:
Asphalt crack sealing is an important step in maintaining asphalt pavement, as they do affect life and efficiency of asphalt pavement. Cracks in asphalt, when left untreated, allow for moisture to descend past the surface into the underlying layers of base and sub-base. The presence of moisture can cause swelling, softening, and movement of the asphalts foundation and thus movement of the asphalt pavement itself.
Unfortunately, cracks occurring in asphalt pavement is a normal occurrence through the life of asphalt pavement due to constant expansion and contraction caused by temperature changes and the earth’s natural movement. There are no preventative measures, however if regularly sealed, asphalt cracking can be contained and hindered from affecting the structure overall.
Can “alligator” cracked areas be sealed using a rubberized sealant?
Answer:
Alligator areas can be crack sealed; however, we do not recommend it. Alligator cracking usually indicates a structural failure which is usually due to improper base compaction, improper asphalt thickness or lack of water drainage. Crack sealing is not an appropriate remedy for the above listed issues. Crack sealing alligatored areas can also pose a safety risk. Crack fill is a very soft and flexible material. At high temperatures it becomes soft and sometimes “tacky”. Given the amount of crack sealing applied and close proximatey of each crack it is possible for a hot car tire to stick to the sealant if parked on and pull up the cracked chunks of asphalt when the vehicle goes back into motion. High amounts of crack sealant in an isolated area is also not aesthetically pleasing. Full depth asphalt patching ensures any issues occurring below the pavement can be assessed and corrected, with the exception of water drainage. Lack of water drainage indicates a problem with the grade of the overall structure. That of which can only be remedied by removing and replacing the whole structure to correct the slope of the parking lot or area or installing a underground drainage structure to carry the storm water to a designated area.
Are there different ways to patch or repair asphalt?
Answer:
There have been many different types of repairs developed to “patch” or repair asphalt. A good fact to remember is that anything short of saw cutting, removing and replacing the existing asphalt at full depth with new hot mix asphalt, are usually temporary patches and are not meant to last the life of the surrounding asphalt. Asphalt repairs methods include, Skin patching (surface patching), Full depth remove and replace, incremental mill and patch, and infrared patching.