What is Remove and Replace (R & R)? This is the process of completely removing the existingpavement and replacing it. It is the most extreme rehabilitation process there is. When must a pavement be removed and replaced? If the existing pavement system is completely unusable due to age, neglect or change of use, then there is no other option but to remove and replace it. If the asphalt lot or driveway is 60% cracked then it is more cost-effective to remove it all and start over, opposed to continued patching. Won’t all pavements have to be removed and replaced at some point? No. If a pavement is consistently maintained it will never have to be completely replaced. With sufficient planning, a complete rehabilitation project will restore a pavementto as new condition or better. How long does this R & R process take? The entire pavement system must be removed with excavating equipment and hauled to a landfill. New gravel is trucked to the site, graded and compacted prior to paving. So size of the job and distance from the gravel pit and asphalt plant play a big part in the timing, but on average it is less than a week for smaller lots and two to three days for a large acreage driveway. Should a geo-technical engineer be involved with a remove and replace project? Since this is such a large expense, it is wise to seek professional guidance on pavement design and specifications. The existing pavement and sub-grade should be tested and the projected traffic use calculated to determine the best design.
FAQ ABOUT ASPHALT PAVING
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When can we drive on our new driveway? Usually in a day or two unless it is really hot. If you can avoid turning the wheels of your vehicles when it is not moving that will help prevent scuffing. For asphalt resurfacing, depending upon the temperature of the day, one should allow 2 to 6 hours before using the new lot. Sealcoating needs a 24-hour drying (curing) time after work is completed. Do not allow traffic on your lot before the end of the 24-hour drying period. Why are there scuff marks on new asphalt surfaces? Scuffing of newly sealed or paved surfaces are inevitable as it is the nature of asphalt material combined with hot weather. After about a month those scuff marks are rarely noticeable. The scuffs are just the sand being displaced and will wash away. Asphalt requires about 6 months to fully cure. Until that time it is tender and best to be a little careful. Avoid tight turns, and turning the steering wheel when the vehicle is not moving. Avoid sudden stops if you can. What are some of the causes of asphalt failure? Inadequate thickness of the pavement section to support the loads that travel across the asphalt, lack of maintenance, and weak or unstable subgrade components. Asphalt deteriorates when weather and traffic wear “fines” aggregates away. When the “fines” are worn away, there is nothing to bind the larger aggregates together and the surface begins to ravel. This weakens the pavement section and eventually allows water to penetrate the subgrade, which leads to pavement failure. What causes fatigue cracks in pavement? Fatigue cracks are the direct result of excessive bending of the pavement surface. Asphalt will fail if subjected to repetitive or excessive bending as from vehicular traffic. Why doesn’t asphalt stay that nice rich black colour? The UV rays from the sun breakdown the carbon bonds in the asphalt oil thus causing the colour to change from black to gray. It is this oil that binds everything in the asphalt together so when it is depleted erosion starts, some sand particles at first and then larger pebbles to stones then with water infiltration it is all downhill from there. This oil is also what keeps the asphalt flexible. So when the asphalt is gray and oxidized it is less flexible and more prone to cracking. What causes potholes? Possible causes of potholes include asphalt that was too thin, base failure under heavy loads or poor drainage that weakens the subgrade and base. Poor quality (segregation in the asphalt, poor compaction, or asphalt that was burnt or did not have enough oil mixed into it) may be a contributing factor. What causes alligator cracks? Usually alligator cracking is caused by excessive deflection of the pavement due to an unstable base or due to repeated traffic loads heavier than what the road was built to withstand. If this cracking is not addressed then it will expand and cause more damage. Why are there cracks in the asphalt along the edges? Edge cracks are usually caused because there is not enough support next to the road or the base has washed out good if you can avoid driving on the edge. If you do getcracks have them filled with a rubberized crack filler. If the cracking is severe then it may have to be cut out and replaced. When should a parking lot be patched? Patching is a repair operation and can be done as often as needed, until a lot reaches the resurfacing stage (over 35% of the lot is alligator cracked). Damaged areas will get much worse over the winter so it is best to get them done before then. Book the repair work early! How thick should the asphalt be? Asphalt pavements have defined strength co-efficients that determine their service life based on actual traffic conditions. The thicker the asphalt, the longer the pavement will last. For patching we like to put at least an inch more than what was originally installed. In general, we use the following guidelines to determineasphalt depths:• 2” Car traffic only, no truck traffic ever• 3” for driveways that have the occasional delivery orseptic truck• 4-5” Light truck traffic, 1-5 large trucks per day• 6-7” Heavy truck traffic, 5-30 large trucks per day• 8-10” Very heavy truck use (eg: city street or runways)If there are budget constraints, do less area at the appropriate depth, not more area at less depth!
FAQ ABOUT ASPHALT RESURFACING
What is Resurfacing? Resurfacing is the process of installing a new layer of asphalt (generally one and a half to two inches) over the existing pavement (also known as overlaying). When should a parking lot be resurfaced? Resurfacing a lot is ideal when the surface has become heavily oxidized but the base is still stable. Usually when the asphalt is approximately 12 to 15 years old, provided it was paved and maintained properly (correct thickness for the traffic, proper compaction, correct type of asphalt, proper drainage, etc.) Resurfacing when the weather is dry and warm is essential. Paving when it is cold leads to cold “seams” and possibly less than ideal compaction, which can contribute to premature failure. The general rule of thumb is to pave when temperatures are 10° C and rising. How long should a newly resurfaced lot last? Depends on deflection of the original pavement (prior to resurfacing), how many trucks use the pavement and the thickness of the new asphalt layer, but generally you can expect at least 8 to 12 years before more serious maintenance is required. How long before traffic is permitted on a newly resurfaced lot? Rubber tire traffic will not damage the new asphalt but care should be taken to avoid sharp turns (especially power steering marks created by non-moving vehicles).