Posts By: Calvac Paving
Recycling is important for our ongoing quality of life. It allows us to reclaim and reuse materials which would otherwise go to waste, clogging up landfills and contaminating our oceans. When most people think of recycling, they may think of cans, bottles, paper or even old computers. But surprisingly, the most recycled material in America is literally right under our feet: asphalt!
Unlike many recyclables, which may have limitations on specific types which can be recycled, any asphalt pavement can be 100% recycled. The American Asphalt Association recently released 2016 data which stated about 79 million tons of asphalt was reclaimed and reused in roadway mix designs and other activities, such as reprocessing into a recycled aggregate base course for use beneath the roadways themselves. In addition, nearly 1.8 million tons of waste and byproduct material from other industries were incorporated into asphaltic concrete mix designs during 2016.
We’ve previously discussed the possible use of plastic bottles and even cigarette butts as elements of asphalt designs which are being explored. By reclaiming these materials into asphalt, it increases their recyclability as part of the mix and helps reduce their impact in landfills. The APA says recycling asphalt saves an estimated 14,664 Olympic-sized swimming pools’ worth of landfill space each year. By adding other recyclable and waste materials to asphalt, this impact will only become greater in years to come.
Recycling asphalt isn’t just good for saving landfill space. It also reduces the environmental impact of quarrying and processing the aggregates and bituminous binders used in the asphalt production process.
Asphalt can be recycled in a number of ways. One of the most popular, and the way which reclaims 100% of the asphalt involved, is to pass chunks of asphalt through a special recycling assembly which raises the temperature to 300℉. Once the asphalt has been processed using this method, it can be laid down on roadways using existing paving technologies and techniques. In this form, it is known as Recycled Asphalt Pavement, or RAP.
Another method of asphalt recycling involves crushing asphalt at a hot mix plant and using the resulting RAP as an additive for “virgin” hot mix. This type of recycling allows for over 30% of the final product to consist of recycled asphalt. By comparison, some brands of paper cups may use only 10-25% post-consumer content, highlighting the recyclable nature of asphalt.
A third way which also reclaims 100% asphalt is to crush the asphalt down into gradations suitable for road base. Rutgers University conducted a study in which RAP was compared to conventional aggregate subbase for use in roadways. The study showed the RAP had more elasticity and stiffness (are you sure they said this, seems contradictory) than the aggregate subbase when the two materials were laid using identical placement methodology. This means RAP is actually stronger, more resilient and better for the environment than regular aggregate road base, while delivering comparable performance as a base material.
If the environmental benefits aren’t impressive enough, consider the potential savings for recycling. That’s right, recycling asphalt costs less than new paving! One estimate places potential savings at a national average of around 55%, or between 30-80%, over virgin hot mix.
It’s up to all of us to do our part to make our world a better, cleaner and healthier place, from the global level to our own homes. At Calvac Paving, we are always on the lookout for ways to perform our work more efficiently and cost-effectively while also remaining environmentally responsible. This means keeping a close watch on new technologies, methods and California State standards which would allow us to deliver comparable or superior results with less environmental impact and greater ROI for our clients. To learn more about Calvac Paving’s commitment to the environment, or to put the four decades of experience we’ve accrued to work for you, please contact us at (408) 225-7700 or www.calvacpaving.com
At Calvac Paving, we support technologies and construction methodologies that offer a more environmentally sound and sustainable way of creating the things we as human beings have come to rely on. From asphaltic concrete recycling to innovations such as self-healing concrete, we are always on the lookout for trends and techniques that change how we operate for a greener, healthier planet. This is why we are so excited about the possibility of roads that actually recharge electric cars as they drive! These specially designed roadways will reduce pollution, increase the performance and range of electric cars to unheard-of levels, and reduce or entirely eliminate the need for charging stations.
In the UK, this seeming science fiction is becoming science fact, as the government moves to experiment with charging roads. Operating on the same principle as a wireless phone charger, the roads will charge cars through magnetic induction resonance. Cables implanted in the material of the roadway generate a specialized electromagnetic field that the car can convert into usable energy. The roads will also include communications equipment attuned to the unique energy signature of an electric car, alerting the road that an electric vehicle is present and to initiate the power generation process. This will allow properly equipped electric vehicles to recharge on the go, without needing to stop for extended periods to recharge, one of the biggest stumbling blocks cited in the adoption of electric vehicles thus far.
The roads the UK are experimenting with will be restricted for the time being, ensuring that regular vehicles do not impede the testing process. The government is committing 500 million pounds, or roughly $779 million, to these experimental roads over a five-year span. This technology is already in use in South Korea, powering rail systems with ranges of up to 15 miles, and will be combined with an added initiative to provide charging stations every 20 miles in the UK. The combination of options for drivers will help eliminate so-called “range anxiety,” which one advocate described as a combination of running low on gas and having one’s cell phone be low on battery simultaneously.
Magnetic induction resonance works in much the same way as a powerful operatic voice can shatter crystal. When the voice and the crystal reach a similar resonance, the molecules in the crystal begin to vibrate rapidly and cause it finally to break. Instead of shattering or rupturing the battery, however, the cables the charging roads utilize will create a harmonic resonance within the battery that allows it to transform the signal from the roadway into usable power.
Because many roadways contain metal in addition to the native subgrade, road base and asphalt in the form of rebar, wire-mesh matting and metallic joints between road sections, the cables can use this metal as a part of the transmission system for the power. The metal components of the electric car can be employed as a receiver, directing the transmitted energy to the battery without the driver needing to stop, handle any charging devices or worry about whether or not the car will make it to the next charging station.
Major car production companies such as Audi are leading the research into this technology, which they believe will relegate internal-combustion vehicles to the status of horse and buggy. By working together to create a standardized plug-in system for use in garages, parking structures and ultimately at-home use, these car manufacturers believe they can make charging stations easier to find and thus make electric cars more attractive. The idea of “switching stations,” where a person can simply replace a drained battery with a fresh one and continue on, and the increased range of electric cars to around 250-300 miles per full charge depending on the type of car and battery size, will help expedite this process.
While paved roads are still very much a part of the future landscape, what drives over those roads and what lies beneath them may soon play a more crucial role than ever in our environmental integrity and ability to move people and cargo. Calvac Paving will be watching the trials in the UK with a great deal of interest, because we want to see if this technology truly is feasible and what the implications will be for the paving industry. If everything pans out as the equations and scientists claim, this could be a major breakthrough and a huge tectonic shift in how things are designed in both construction and automotive industries, as well as manufacturing and transportation as a whole. We think that’s a pretty big win, and look forward to this technology here at home!
Portland cement is the basic ingredient of concrete. Concrete is formed when portland cement creates a paste with water that binds with sand and rock to harden.
Cement is manufactured through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients. Common materials used to manufacture cement include limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore. These ingredients, when heated at high temperatures form a rock-like substance that is ground into the fine powder that we commonly think of as cement.
The most common way to manufacture portland cement is through a dry method. The first step is to quarry the principal raw materials, mainly limestone, clay, and other materials. After quarrying the rock is crushed. This involves several stages. The first crushing reduces the rock to a maximum size of about 6 inches. The rock then goes to secondary crushers or hammer mills for reduction to about 3 inches or smaller.
The crushed rock is combined with other ingredients such as iron ore or fly ash and ground, mixed, and fed to a cement kiln. The cement kiln heats all the ingredients to about 2,700 degrees Fahrenheit in huge cylindrical steel rotary kilns lined with special firebrick. Kilns are frequently as much as 12 feet in diameter—large enough to accommodate an automobile and longer in many instances than the height of a 40-story building. The large kilns are mounted with the axis inclined slightly from the horizontal.
The finely ground raw material or the slurry is fed into the higher end. At the lower end is a roaring blast of flame, produced by precisely controlled burning of powdered coal, oil, alternative fuels, or gas under forced draft.
As the material moves through the kiln, certain elements are driven off in the form of gases. The remaining elements unite to form a new substance called clinker. Clinker comes out of the kiln as grey balls, about the size of marbles.
Clinker is discharged red-hot from the lower end of the kiln and generally is brought down to handling temperature in various types of coolers. The heated air from the coolers is returned to the kilns, a process that saves fuel and increases burning efficiency.
After the clinker is cooled, cement plants grind it and mix it with small amounts of gypsum and limestone. Cement is so fine that 1 pound of cement contains 150 billion grains. The cement is now ready for transport to ready-mix concrete companies to be used in a variety of construction projects.
Although the dry process is the most modern and popular way to manufacture cement, some kilns in the United States use a wet process. The two processes are essentially alike except in the wet process, the raw materials are ground with water before being fed into the kiln.
Concrete is not a ductile material-it doesn’t stretch or bend without breaking. That’s both its greatest strength and greatest weakness. Its hardness and high compressive strength is why we use so much of it in construction. But concrete does move-it shrinks, it expands, and different parts of a building move in different ways. This is where joints come into play.
Although many building elements are designed and built with joints, including walls and foundations, we’ll limit this discussion to joints in concrete slabs. Here’s an overview of the types of joints, their function, and tips for locating and installing joints.
Concrete Joint Information
As concrete moves, if it is tied to another structure or even to itself, we get what’s called restraint, which causes tensile forces and invariably leads to cracking. Restraint simply means that the concrete element (whether it’s a slab or a wall or a foundation) is not being allowed to freely shrink as it dries or to expand and contract with temperature changes or to settle a bit into the subgrade. Joints allow one concrete element to move independently of other parts of the building or structure. Joints also let concrete shrink as it dries-preventing what’s called internal restraint. Internal restraint is created when one part of a slab shrinks more than another, or shrinks in a different direction. Think how bad you feel when part of you wants to do one thing and another part wants to do something else! Concrete feels the same way.
If you have a question for Calvac Paving, please contact us at
2645 Pacer Ln
San Jose, CA 95111
From India to Indiana, from Cumbria, England to Corpus Christi, Texas, everyone agrees the amount of free-floating plastic in the environment is an ongoing problem. With an estimated 5 trillion pieces of plastic adrift on the surface of the ocean alone and uncountable more tons of the material in landfills and vacant lots all over the world, plastic both makes our current standard of living possible and poses one of its most dire threats.
At Calvac Paving, we make a point of keeping current on the latest breakthroughs and experiments in building and paving technologies, and new processes for repurposing plastic as a paving material is very much in our wheelhouse. Several different processes are in the testing stage, including using plastic to coat paving aggregates and reduce the amount of bitumen necessary for traditional asphalt; adding pellets of recycled plastic as part or all of the aggregate portion of the asphalt; and a Lego-like process of building roads from paving blocks of recycled plastic.
Apart from the obvious advantages of reducing the environmental impact of discarded free-range plastic, the primary benefit of utilizing plastic-impregnated asphalt is twofold. First, using plastic seems to increase the tensile strength of asphalt significantly, up to 60% in certain mixes.
Second, by reducing the amount of bitumen, or tar, used as the binding agent in most industrial asphalt mixes, it may also cut the cost of paving by up to 15%. The higher tensile strength potentially increases the size and mass of traffic which can use these roadways, meaning it may be possible to move more freight and larger vehicles in areas where existing paving and statutes would simply not permit them. In turn, this could substantially reduce transportation costs and thus the costs of everything from steel to gasoline to milk.
In addition, plastic-impregnated asphalt may lend itself more readily to hybridization with innovations such as the self-charging roads which we’ve discussed recently. As the costs of developing and deploying these technologies shrink, the likelihood of incorporating multiple technologies into a single roadway increase at a similar rate.
Almost as interesting as what plastic asphalt can do is the story of the various ways in which its applications came to be. In India, a chemistry professor, annoyed with the potholes of his city, remembered seeing people in Mumbai patching similar potholes by filling them with empty plastic bottles
and then heating them to a liquid state. In Scotland, an engineer built on the India protocol by using pellets of recycled plastic, aggregate and a very small amount of bituminous binder to create a roadway surface which causes less wear on tires. Meanwhile, a company in the Netherlands backing the block paving strategy was inspired by the idea that using interlocking blocks would allow for easier infrastructure placement and damaged section replacement.
By reducing the amount of “trash” plastic in the open environment and repurposing it in new ways, these innovators are also challenging accepted notions of what is possible in large-scale construction. These changes in turn may serve to make not only the final product of construction initiatives, but the processes and techniques by which they are created, more efficient, effective and environmentally friendly.
Calvac Paving takes our role in environmental sustainability and finding better ways to accomplish the tasks we undertake more effectively and safely very seriously. It is the entire reason we keep such a close eye on how construction technology is changing and evolving. When and where possible, we make it a point to adopt and implement these changes ourselves, because while we know the “tried and true” methods have survived and been used as long as they have for very good reasons, we also understand there’s almost always a better way to do just about anything if you’re willing to look hard enough for it.
We at Calvac Paving believe we can best serve the communities we live and work in by emphasizing the fastest, safest and most c
ost-effective means available to do our jobs, while striving to reduce the impact our industry can have on the global as well as local environment. It’s all part of Calvac Paving’s commitment to not just doing the job, but doing it right. We do it for our clients/stakeholders, for our community and for a better, cleaner, healthier world. To learn more about Calvac’s commitment to the environment, or to put the four decades of experience we bring to every project to work for your job, please contact us at (408) 225-7700 or https://www.calvacpaving.com/contact-us/
The saying “They don’t build ‘em like they used to” is literal truth in the concrete industry. For decades, modern science has struggled to work out how ancient societies such as the Romans were able to create buildings, monuments and roadways which are still visible and even in use today, when the average lifespan of modern concrete tends to be far more modest. Now, a team of scientists from the University of Utah believes they may have found the surprising answer to this centuries-old mystery.
Modern concrete uses Portland cement as its base, which is a fine powder created from lime, chalk, sandstone, iron and other materials and then combined with aggregates of varying sizes. However, the Romans used a type of cement created from the ash of certain volcanoes. These volcanoes’ emissions contained a rare combination of mineral elements which only occurs naturally in very specific areas with particular geological profiles. What’s most surprising is that the minerals which make Roman cement different from Portland cement appear to react to seawater, which encourages the crystalline structure of the minerals to continue growing. This actually makes the concrete self-healing and impedes cracking, a feat modern science is still trying to replicate.
This discovery of how Roman concrete was made is important because it could lead to greener and more eco-friendly concrete production and paving technologies, as well as structures with higher strength, structural integrity and longevity under adverse conditions than modern concrete allows for. In addition, Roman concrete did not use reinforcing steel such as a wire mesh mat or rebar, both of which Portland cement will corrode and degrade over time. This may lead to significant cost reductions for new construction on structures like bridges, building footings and other applications.
However, the research team warns it’s too early to get too excited about Roman concrete. First, Roman concrete relies on very specific minerals, namely tobermorite and phillipsite, being present in certain quantities. The researchers say the composition of Roman concrete was largely a matter of luck and being in the right place, at the right time, with access to the right materials. Second, we don’t yet know exactly how the Romans made their cement or what the process was for mixing it with aggregate and placing it. This by itself may leave us several years, or even decades, away from being able to use Roman concrete effectively.
Despite these hurdles, the concepts behind Roman concrete and other green discoveries from the ancient world are constantly being studied, evaluated and applied to our modern understanding of how to build things that last. At Calvac Paving, we’ve been serving the Bay Area for over 40 years in the most environmentally friendly, safe and expedient way possible. We’re always on the lookout for new developments, technologies and ideas which will let us do our jobs more effectively, with less impact on the world we all share. To learn more about our commitment to the environment, or how Calvac Paving can help you with your next project, contact us at:
2645 Pacer Ln
San Jose, CA 95111
With the wetter, cooler conditions of fall upon us and winter in full swing, it’s a good time to check your parking lot and other asphalt applications for signs of poor drainage and damage. It’s much easier and less expensive to catch a problem early and correct it than it is to wait until that small cracked area spreads to half the lot. With this in mind, here are four signs you should look for to check if your parking lot drainage is working as it should.
- Rocks or sand in unusual places
If, after a heavy rain, you notice rocks or sand in low-lying areas, this may be an early warning sign that something’s wrong with your drainage. The water from the rain may actually be eating away at the asphalt and flushing away the solid particles of sand and rock aggregate that make up asphalt. To make sure it’s not runoff from the street or areas higher up, look for consistent ripples or waves in the deposits which are larger at the higher end and taper off toward the lower side of your lot. If you see this, your lot is probably okay, unless you see large areas where the sediment and rocks have gathered. This indicates possible low spots which could cause problems later.
- Pools of water or flow down the middle of the lot
Most asphalt parking lots today are designed along a slight but apparent slope to facilitate runoff. Likewise, they are usually built with an engineered high point called a “crown,” which is intended to direct water away from the middle of the lot and down toward the drain points. Pooling and water flowing directly down the middle of the lot suggests the crown has been compromised or a possible issue with the subgrade, which will need to be addressed before the asphalt begins to buckle.
If you start to see cracks developing, especially in areas where you also see heavy water flow and/or residue such as described above, this is a sign the asphalt is beginning to fail because the water is breaking down the bitumen binder. This may also be a sign of traffic outside the asphalt’s design tolerances being present, such as large amounts of heavy trucks or construction equipment. In either case, once cracking begins, water can infiltrate the asphalt surface and accelerate the rate of failure, making repairing it a priority before it gets out of control.
- Are your drain inlets working as they should?
Periodically, it’s a good idea to check your streetside and in-lot drainage inlets to ensure they’re clear of obstructions and debris which may prevent them from working as expected. In many cases, asphalt failure can be traced back to a blocked drain inlet which hasn’t been corrected. Regular property walkthroughs can help you spot problems like this before they become severe enough to warrant repair or rehab of your parking lot, and keep it working the way you expect it to for years to come.
For more information about drainage or to speak with Calvac Paving about your parking lot or other asphalt and concrete construction needs, click here to contact us!
With winter and its accompanying rainfall on the way, the fall is a good time to take a look at your existing pavement and make sure it’s ready for the weather to come. Calvac Paving has been in the business for over 45 years, and in that time, we’ve learned a thing or two about how to solve small problems before they have a chance to become big ones. Now, we’re pleased to present this list of simple things you can watch for so your pavement lasts longer and looks and performs better in the process, even when the worst of the California winter weather strikes!
Do a routine walkthrough of your paved areas.
Parking lots and other paved areas should be checked at least semiannually for problems. Things to look for include:
- Areas of standing water. Water can break down the asphalt binder and leak down into the subgrade, eroding it over time. This is also an indication that the pavement or subgrade may already be failing, because modern grading techniques are designed to establish a grade that flushes water away from the parking area and toward designated drainage points.
- Oil or other chemicals that leak directly onto the pavement. Just like water, some chemicals associated with vehicles can cause binder breakdown and lead to subsurface problems. Cleaning up oil and other chemical spills as quickly as possible can help prevent this and keep your asphalt in better condition.
- Cracks, divots or uneven areas. These can be caused by weeds growing beneath the surface, freeze/thaw patterns, standing water and oil or ongoing heavy truck traffic. Small cracks and divots are often the first visible sign of possible asphalt breakdown, and it’s more cost-efficient and less intrusive to fix them when they’re small by seal coating or spot patching than it is to do a complete tearout and reinstall of the paving.
- Striping: Old, dull or worn striping and pavement-level signage such as fire lane indicators and other information may be harder to see and read during winter months. Especially in ADA stalls, the striping and signage should always be clearly visible to make sure people know where these areas are.
Clear debris from drainage channels and curbs.
If water has nowhere to go, it doesn’t matter how good the drainage plan for your lot is. Making sure the drainage channels, storm sewers and other inlets to the runoff system near your property are clear of leaves, branches, garbage and other obstructions will help the water flow better and make it less likely to pool up on your property.
Limit or restrict heavy-vehicle traffic as much as possible.
Large trucks such as semis, garbage trucks and other heavy vehicles can place a lot of stress on asphalt. By itself this shouldn’t be a problem, but when the base course and subgrade are compromised by water or plant intrusion, it could speed up the breakdown process for the asphalt. If at all possible, try to limit, restrict or even out the traffic pattern for such vehicles within your lot to minimize the time they spend on your pavement.
Be sure it’s sealed.
Even if your parking area is free from cracks and other problems, it is a good idea to have it seal coated every 4 to 5 years at the minimum. This is because seal coating helps rejuvenate the asphalt binder at the surface, adding an extra layer of protection against traffic, water and other spills. Even better, it will help make your parking lot and driveways look newer, especially when you redo the striping at the same time. This makes your property more attractive, safer to navigate and less likely to fail for the long haul.
Seek professional help.
If you’re not sure if the paving problems you’ve identified are “big enough,” or if you think your pavement needs a facelift or a complete overhaul, Calvac Paving can help. We’ve been serving the Bay Area for over four decades with quality construction solutions including:
- Curb and gutter remediation, repair and replacement
- Paving rehabilitation, tearout and reconstruction
- ADA access compliance and signage
- And much more!
We take great pride in delivering a great product for your project, within the schedule and budget we agree upon. For more information about how Calvac Paving can help you with your paving or asphalt project, please contact us for a no charge estimate.
2645 Pacer Ln
San Jose, CA 95111
Our water is arguably the most precious natural resource we have, and it’s up to everyone to keep it clean so we always have access to safe drinking water. At Calvac Paving, we’re always looking for new ways to help keep our environment clean and healthy without compromising performance. Recently, we added a new tool to our arsenal in the ongoing fight against water pollution: full trash capture units inside catch basins.
If you’ve been walking down the sidewalk or happened to look at a storm drain in the middle of a parking lot recently, you may have noticed a marker which reads, “No Dumping—Drains To Bay,” such as a stream, lake or the ocean. Other such markers include reminders to be cautious of discarding trash and debris into water sources. All of these markers indicate places where trash capture filter devices may have been installed in storm drains.
The principle behind trash capture units inside catch basins is very simple. They work much like a pool filter to prevent dirt, debris, garbage and other runoff contaminants from getting into the water. Made by REM Filters, these Triton filtration systems are designed for drains which empty to stormwater repositories and water bodies. They have the advantage of being economical, flexible and relatively low-maintenance, while helping keep stormwater runoff cleaner and promoting a healthier environment.
With different filtration media available, property managers, owners and municipalities can design a custom system which works with the primary contaminants in a given area, such as streets, parking lots and garages, food courts, sidewalks and so on. The filters are easy to clean, change and service, allowing for broader application with reduced service and personnel costs versus conventional storm drain clearance procedures. Even better, Triton trash catch basins can be applied to both new and retrofit construction, saving time and money over other stormwater mitigation measures.
Calvac Paving has been serving the Bay Area for over 45 years with the latest and best in paving and stormwater mitigation technology. Some of the services we provide include:
· New Construction
· Concrete Placement
· Asphalt Placement & Compaction
· Pulverizing In Place
· ADA upgrades to existing structures
· Crack Sealing & Repair
· Petromat Overlays
· Parking Lots
· Asphalt Repairs
· And More!
At Calvac Paving, we are committed to providing the best and most modern paving solutions available, while implementing new ways to make our processes and products greener and more in harmony with our environment. There’s no “Plan B” for our planet; we only have one, and it’s everyone’s responsibility to help keep it green, healthy and beautiful for ourselves and generations to come. New technology and pollution-combating policies, processes and procedures are just one of the many ways we demonstrate our commitment to a greener Earth on every job, every time. To learn more about Calvac Paving’s green initiatives, or to learn how we can help your new construction or retrofit project go more smoothly and be more environmentally friendly, call us at (408) 225-7700 or click here to contact us via email!
Asphalt is a very versatile and durable paving material. Its resilience and flexibility make it an ideal surface for everything from eight-lane superhighways to driveways to parking lots. However, asphalt does require care and maintenance to function at peak performance, and it can fail for a number of reasons. If you see any of these warning signs of failing asphalt, quick action can save you a lot of time, money, and hassle. Here are eight signs your asphalt may be failing—and what you can do to fix them!
Alligatoring is called that because of its appearance: interconnected cracks that look like alligator skin. It is an indication of load-related deterioration which could be caused by a weakened or improperly compacted subbase material, excessive traffic loading, inadequate pavement thickness, or a combination of these factors.
2. Edge Cracks
Edge cracks are found within 1-2 feet of the outer edge of the asphalt surface, running longitudinally, or roughly parallel to the outer edge. These cracks are caused by improper support of the paving surface at the margins.
3. Reflective Cracks
Reflective cracks most typically form in joints or areas of concrete or asphalt paving which have been previously repaired, such as with crack sealing or where a temporary corrective overlay has been placed to relieve stress on deteriorated paving. These cracks form because of continuing movement of the old pavement due to continuing traffic load.
4. Slippage Cracks
Slippage cracks are easily identifiable because of their crescent shape. They occur either due to poorly bonded pavement layers or an asphalt mix design which is insufficient to the demands of the traffic patterns. These cracks appear because of forces applied by turning or braking vehicles, which cause the pavement to move slightly at first but with accelerating damage to the surface the longer the underlying cause goes uncorrected.
5. Rutting and Depressions
Rutting is caused by weakness of the subgrade or base soil layers, instability of an asphalt mix, insufficient pavement thickness, or poor compaction. Rutting is a linear, surface depression of the wheel path caused by deformation or consolidation of any of the pavement layers or subgrade. Depressions, also known as birdbaths, are localized areas of pavement surface failure caused by poor initial construction techniques that undermine the asphalt over time. These may occur on their own or in conjunction with other failure indicators. If left unchecked, depressions can become potholes (see #8).
6. Asphalt Patch Failure
These failures are easy to spot because they’re very localized to the area where a patch was placed, and characterized by unevenness, deflection or stress cracking along the perimeter of the patch. They are caused by either not fully removing the damaged area to be patched, or not allowing a minimum of one extra foot around the perimeter of the patch area to ensure the patch is bonding to an uncompromised surface. The rate of patch deterioration is influenced by materials selection, compaction, and the quality of the surrounding pavement as well as the underlying subbase. While the latter is not typically visible, adding one additional foot around the patch can help patches last longer and function better under load.
Raveling is caused when the aggregate particles in the asphalt cement wear away under traffic forces. This condition suggests either that a poor-quality mixture was used or the asphalt surface has hardened enough to no longer be supple and flexible.
These bowl-shaped holes are caused by localized disintegration of the pavement surface. Potholes are usually the result of another type of distress that has not been properly addressed. Segregation, failed patches and cracks can all lead to a pothole over time. Weak spots and localized areas of improper or insufficient compaction in the subgrade or subbase, or poor asphalt mix designs, can accelerate degradation of the pavement surface and the formation of potholes.
When you notice indications of paving failure, bring in an experienced paving contractor as soon as possible to restore the surface and minimize downtime, expense and the risk of further, more severe failure in the future. Calvac Paving has been proudly serving the Bay Area and beyond for over 45 years, and we’d like to put that experience to work for your next paving repair or new construction project. For more information, or to learn more about how Calvac Paving can deliver the results you need and want, call any of our Bay Area offices or click here to contact us today!