Topic: Blog

Maintenance Monday – How Portland Cement is Made

Cement Plant For Calvac Pavings Blog

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.

Old cement dispenser company

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.

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Maintenance Monday – Joints In Concrete Slabs

calvac paving discusses joints in concrete slabs

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

Calvac Paving discusses Concrete Joint Information

Different joints in concrete slabs all have the same bottom-line purpose of preventing cracks

 

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

Calvac Paving
2645 Pacer Ln
San Jose, CA 95111
408-225-7700

sales@calvacpaving.com

 


Paving The Way Forward With Recycled Plastic

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.

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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/


Maintenance Monday: Don’t Let Poor Drainage Take Your Parking Lot Down The Drain!

 

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.

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  1. 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.

 

  1. 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.

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  1. Cracking

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.

 

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  1. 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!


5 Simple Ways To Winterize Your Paving

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!

  1. 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.Recently Complete Project
  1. 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.

Calvac Paving Team

 

  1. 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.

  1. 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.

  1. 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.

 

Calvac Paving
2645 Pacer Ln
San Jose, CA 95111
408-225-7700

 


8 Signs Your Asphalt May Be Failing

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!

 

1.  Alligatoring

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.

 

7.  Raveling

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.

 

8.   Potholes

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!


Bay Area Asphalt Contractor Completes Latest Project

IMG_7684At Calvac Paving, we love a challenge. When St. Francis Retreat in San Juan Bautista needed an overhaul of their existing roadway, we were pleased to lend our experience and expertise to the task. The retreat is in a secluded rural setting just outside the town proper, which created some specific concerns we needed to be cognizant of during the project.

Working in a rural area, we had to plan our work in such a way as to minimize the impact on the environment and existing flora and fauna, as well as ensure we avoided disruption of the operations and tranquility of the Retreat itself as much as possible. In addition, we had to consider the safety of our personnel and the general public. Finally, the historic nature of the Retreat had to be taken into account and treated with respect.

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The roadway is approximately 1 3/4 miles long and required 2,300 tons of hot-mix asphalt. The rehabilitation consisted of pulverizing, regrading and compacting the existing asphalt as additional base material.  Then we laid replacement hot-mix in one 3” lift, compacted.  

We are pleased to report the renovation operation went very smoothly. The local residents, staff and visitors were very patient with the unavoidable disruption a project of this sort involves. We were able to complete the project ahead of schedule and within budget, without injury or harm to the area or anyone involved in or affected by it. Best of all, the Retreat now has a great-looking, high-performance roadway which can be expected to last for years to come.  

IMG_7708Calvac Paving has been serving the Bay Area since 1972. Let us put our craftsmanship and knowledge to work for you on your next project. For quality, safety and efficiency without parallel, we’re proud to be the construction solution for all your paving project needs!

 

 

Calvac Paving


Maintenance Mondays – Drive Lanes Removed & Replaced

Maintenance Mondays: This project was for a Medical Building. This required the crew from Calvac Paving to work on a Sunday to minimize disruption. The bulk of the drive lanes were damaged to the extent that we had to remove and replace approximately 45% of the drive lanes. The crew completed approximately 260 tons of removal and replaced with 260 tons of hotmix asphalt. All of the removed asphalt was hauled to a recycle plant. Our crews were completed and out of our yard and on their way home by 6:30pm.
Calvac Paving – Top Quality. On Schedule. On Budget.

 


Bay Area Golf Course Asphalt Repair

At Calvac Paving, we know a thing or two about asphalt repair and Golf Courses. So when Poppy Ridge Golf Course called us to bid on a project to rehab an extensive areas of failed asphalt encompassing the road leading to the golf course and the parking area itself, and to reseal and restripe the parking area and drive entrance, we were pleased to submit our expertise and cost for consideration. Soon thereafter, we learned we had been awarded the project at 4280 Greenville Road in Livermore.

To achieve the repair, we provided 4” asphalt repairs and two coats of seal followed by restriping. This required excavating the failed asphalt and recompacting the subgrade beneath the asphalt paving. Then the hot mix asphalt needed to be placed in two 2” layers, or “lifts,” using 3/4” asphalt on the base lift and ½” medium asphalt on the surface lift. Covering 4,000 +  square feet of surface area. This ensures strength, flexibility, and density within and between the asphalt layers, while minimizing air voids which can facilitate water infiltration and lead to premature asphalt failure over time. 

Once the subgrade and the lifts had been individually compacted, we provided two coats of Reed and Graham’s OverKote, an asphalt emulsion seal for asphalt which incorporates a latex additive. This step gives a smooth, finished appearance to the asphalt, adds surface resiliency and increases water and dust resistance, extending the operational lifespan of the asphalt.

The staff and patrons of the golf course were extremely cooperative and understanding of our schedule and the project went very smoothly. We’re proud to announce that Poppy Ridge Golf Course has already recommended us for similar projects on the strength of our work here, and we’re excited to be able to demonstrate the quality and efficiency of our work once again.

Calvac Paving has been serving the Bay Area since 1972, and we’re proud to bring the same great results to every project we work on. To learn more about how Calvac can help with your project, call us or send us an email and let us put our experience to work for you!


Calvac Paving And San Harbour South HOA : A New Parking Lot Case Study

 

Calvac Paving recently undertook a paving rehabilitation project for the San Harbour South HOA  association located at 906 Beach Park Boulevard in Foster City, California. The existing pavement was over 45 years old and was starting to exhibit severe cracking and base failures.

Calvac Paving setting up Primary Client Concerns

The primary client concerns included:

  • Continuous access during the milling, repaving and striping operations

  • Cost

  • Schedule and time management

  • Quality surface at the project’s end

Proposed SolutionIMG_1971

After reviewing the jobsite in person, we came up with a range of possible solutions that would meet the client’s needs.

Calvac PavingDue to sub-grade issues. We proposed milling the existing pavement down 2” from the existing surface and laying approximately 2,500 tons of ½” aggregate hot mix, in addition to the replacement of 1,500 linear feet or 90 cubic yards of concrete valley gutter. Our recommendations and proposed fix were accepted by Calvac’s client and HOA Board. The job was undertaken in phases as to not disrupt the community at one time.

Final ResultsFinished Project Piece

The end result of the San Harbour South HOA project looked fantastic! The project went off without any difficulty and was completed within the stated schedule and budget.

Calvac Paving is proud to have served the Bay Area for over 45 years with a wide range of paving, concrete and ADA access planning and implementation solutions. Why gamble with the outcome of your project? Make sure your contractor can get it done right the first time, every time. To learn more about how Calvac Paving can help service your construction job or to obtain a quote for services, please call us at 408-225-7700.

 

Calvac Paving
2645 Pacer Ln
San Jose, CA 95111
408-225-7700