Topic: Blog

Latest Bay Area Asphalt Repair Project From Calvac Paving

Modern technology and paving practices have revealed faster, more cost-effective solutions to problems that once would have required expensive tear-out and repaving operations. One of the best examples we at Calvac Paving have ever seen was the rehabilitation of the Redwood Shores parking lot we recently undertook. This project mixed new technology with time-tested techniques to deliver a great result for the client, faster and more efficiently than conventional paving methodology.

 

The parking lot itself was old, cracked and weathered from years of use, but not so bad as to need a complete removal and replacement. Age and oxidation from poorly placed asphalt atop moisture-sensitive base material had caused the asphalt to crack and dry out, reducing its flexibility and its resilience. The parking lot was in need of a major face-lift, and Calvac Paving had the perfect product and the years of specialized talents to make it happen. This was a very unique project in that it perfectly fit the criteria for a very specific application: a Petromat overlay.

 

Petromat is a non-woven reinforcing fabric that is applied using a liquid asphalt binder known as RS1, which works as a penetrating adhesive and moisture barrier. The Petromat fabric helps to retard the existing cracks from reflecting through the new asphalt surface and gives the finished surface a higher tensile strength, thereby distributes the weight of heavy truck traffic over a greater area. After that, a full two-inch placement of hot ½”fine asphalt is placed with self-propelled paving machines.  Once the asphalt has been placed, the compaction equipment follows immediately behind the paving equipment. These very large and heavy smooth drum rollers compact the hot asphalt to a dense, smooth and uniform finish.Day 2 of the project

Once the compaction process is completed and the hot asphalt has cooled, we then apply a fog seal mixture of 50% SS1 and 50% water. This is designed to help bond the top layer of new asphalt and give it that black shiny “new pavement” look. After the Petromat overlay is 100% completed to our satisfaction, we can proceed with striping and stenciling operations.

Because of the unique considerations and time constraints of the job, Calvac Paving recommended a 2” Petromat overlay over the entire parking lot, measuring approximately 63,500 square feet. This offered the best results for the budget and gave them similar benefits to getting a brand-new parking lot for years to come, without the hassle, expense and lost time of a complete remove and replace. This project also had some very unique parking design restrictions, offering a perfect opportunity for Calvac Paving to design a new layout for the regular and ADA stalls. This redesign included larger stalls, which helped prevent unnecessary dents in car doors, making both the tenants, and owners happy with their new parking lot investment.

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Please feel free to drive by and see what a truly professional paving project should look like, and what your commercial parking lot can look like too! From a private roadway rebuild to a complete parking lot rehabilitation and much more, there are very few jobs Calvac Paving cannot do. We’ve been serving the Bay Area for more than 40 years. Now let us serve you! To find out more about Petromat or how we can help with your next project, contact us by email or by phone at:

(408) 225 – 7700

(650) 694 – 7944

(831) 375 – 7944

When you need the best, don’t leave the results to chance. Contact Calvac and have the job done right the first time, every time!

 


The Lost Art Of Concrete

Cement Contractors

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 45 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:

Calvac Paving
2645 Pacer Ln
San Jose, CA 95111
(408) 837-9021


Maintenance Mondays -Your Sealcoating Matters-

Calvac Paving Slurry Seal

Helpful Tips sign Sealcoating is an important process in the maintenance of your all too expensive parking lots.  We all know that the costs for paving repairs have increased.  This makes it all the more important to protect and preserve your asphalt surface.  Calvac Paving has been applying sealcoat for over 45 years, longer than most Bay Area Suppliers have been making asphalt based sealcoats.  Each successive generation of sealcoats has provided greater protection from premature wear, moisture intrusion and oxidation.  Even with these improvements we strongly recommend the addition of latex and sometimes sand to the existing asphalt sealcoats to extend the life expectancy of these applications.  It is also vital for you to have your contractor apply two coats of sealcoat to your property.  The first coat, with the added sand and latex, is the filler coat and allows placement of a second coat with added latex only or wear coat.
Preparation of the existing asphalt surface is a very important process in sealcoating your parking lot.  Calvac Paving will spend the time necessary to clean and prepare your asphalt to assure a durable and attractive product. We will remove all vegetation, and apply herbicide if appropriate.  We will use Power blowers, scrapers, wire brushes and brooms to thoroughly clean the existing asphalt.

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This preparation may also include Mobile Sweepers, water trucks or buggies and vacuum trucks.  We will burn, scrape and carefully clean the oil spots and apply an oil spot sealer with sand.  We will mask utility covers and other structures to protect against coverage.  We will apply hot rubberized or coldpour emulsion crackfiller as directed.
The consistency of the asphalt sealer is also very important to the durability of your sealcoat project.  Calvac Paving will never exceed the manufacturer’s recommendations for dilution.  This addition of water is necessary for the application and actually improves the bonding to the existing asphalt surface.  We feel the addition of latex and sand to the asphalt sealer extends the life of the sealer, and we include these admixtures in well over 90% of our sealcoat projects. By extendeding the life of your sealcoat surface with added latex, you reduce the number of times you will need to seal coat and stripe your lot as well as impose upon your tenants over the life of the asphalt.
The combination of effective barricading and traffic control with superior craftsmanship and products will provide you with the best result with the least impact upon you and your tenants.

before&afterslurryseal

 


7 Signs Your Parking Lot Paving Needs to be Repaired

Asphalt pavement is one of the most durable and resilient materials currently used in modern construction. It’s easy to place, maintain and recycle when its service lifespan has expired, helping to reduce manufacturing costs and greenhouse gas emissions associated with asphalt paving production. Asphalt surfaces are also very flexible relative to other paving materials, which is just one reason why asphalt parking lots have become so popular. But, like any other construction material, asphalt and concrete paving don’t last forever. A well-placed asphalt surface can last 10-20 years or more with proper pavement maintenance. As we move into the wetter, colder months, you’ll want to be on the lookout for these 7 signs your parking lot needs repair.

 

1.  Look for cracking and crumbling edges.

You’re most likely to see these signs of asphalt deterioration around joints in the parking lot paving and the curb and gutter areas of industrial parking lots and asphalt driveways, although they can occur anywhere. When this happens, it could indicate that people are driving too close to the edge, the asphalt is not properly supported at the edges or the asphalt is beginning to age out of effective service. If not sealed or repaired, the cracks can spread throughout the entire surface. Crack sealing early can help extend the life and performance of the asphalt surfaces.

 

2.  Potholes and sunken areas

These commonly occur when water seeps into cracks in the parking lot’s surface. Over time, the water undermines the subbase, causing the paving in that area to sag and crack. One key symptom of an incipient pothole is the presence of pooling water on the surface. If you notice this, a spot asphalt repair can help prevent larger and more costly problems later.

 

3.  Alligator Cracks

Alligator cracking, named for its distinctive appearance, is a sign of too much stress on the asphalt. If your asphalt surfaces look like the skin of an alligator, it can indicate the subbase was improperly prepared by the original paving contractor and/or the pavement is routinely subjected to heavier traffic than it was designed to withstand, such as parking large trucks on a residential driveway. When you see this, you need parking lot and driveway repair or replacement right away.

 

4.  Oxidization

The binding agents in asphalt which give it its flexibility and strength don’t last forever. In fact, from the moment asphalt is laid, the sun, wind, water, weather, and oil and chemical leaks from vehicles begin to eat away at them. This is why asphalt’s color fades from black to gray and the aggregate begins to peek out of the surface. Depending on the size of the area and whether other signs of damage are present, asphalt seal coat, asphalt milling, and parking lot resurfacing may all need to be considered.

 

5.  Improper drainage

Evidence of improper drainage can be an early sign asphalt repairs are needed. If water can’t drain off your parking lot or driveway it can damage the asphalt surfacing and cause larger problems later. Blocked storm drain inlets can lead to damage as well, so it’s important to inspect them regularly and make sure the runoff from your lot or driveway can go to where it’s intended.

 

6.  Faded or illegible striping

Proper parking stall and line marking make your property look better and more user-friendly. It’s also a requirement of the Americans with Disabilities Act. In addition to directing traffic, striping often works as a sort of visual canary for indicating potential issues which might otherwise go unnoticed. If your parking lot’s striping is looking worn, difficult to read, or hard to understand, you need to take a closer look at the entire area for other potential issues.

 

7.  Time

If you can’t remember the last time you had any repairs or maintenance on your driveway or parking lot, it’s probably time. For best results, your asphalt surfaces should be seal coated at least every 4-5 years to help keep them looking their best and preventing chemicals, motor oil, and water from infiltrating the surface. If there are no major issues with the asphalt surfaces, minor crack sealing and spot repairs can also be made before sealing the surface again. It’s also a good opportunity to update your parking layout and striping to comply with ADA guidelines if they don’t already!  

 

Keeping your asphalt paved surfaces in good repair isn’t just about making your property look and perform its best. Driveway or parking lot problems could also present ADA compliance issues with hefty associated fines and even open your company to workers’ compensation claims or civil lawsuits arising from injuries and vehicular damage. By making timely preventative asphalt repairs you can save time, money, and worry while presenting a more professional face for your business. At Calvac Paving, we know you have a choice of commercial asphalt and concrete paving contractors in the Bay Area, which is why we’re committed to delivering the finest in asphalt repair and driveway and parking lot construction. For your next parking lot repairs or to learn more about how Calvac can help you get the maximum life from your asphalt paving, click here to contact us.

 


Calvac Paving Deploys Trash Capture Devices Inside Catch Basins to Combat Water Pollution

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 

·        Grading

·        Concrete Placement 

·        Asphalt Placement & Compaction

·        Striping

·        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!

Bay Area Asphalt and Concrete

 


Maintenance Monday: 10 Ways to Prepare Your Asphalt for Summer

Calvac Paving Bay Area Asphalt and Concrete Contractor

 

Whether it’s a roadway, a driveway or a parking lot, asphalt takes a pounding over the fall and winter months. The cooler temperatures and more frequent rains can take a toll on even the most robust and well-constructed asphalt pavements. To ensure maximum safety and durability for your asphalt and the people who travel and park on it, Calvac Paving presents ten ways to prepare your asphalt for summer!

 

1.  Take a Closer Look.

Asphalt is very durable and resilient, but there are a number of ways it can fail, so it’s a good idea to have a thorough walkthrough at least quarterly. You should check the condition of your asphalt more frequently in cases of unusually heavy or inclement weather, or if you notice indications of a problem like water flowing down the middle of your lot or roadway.

 

2.  Cracked-Up Asphalt isn’t Funny. 

Surface cracking often indicates that the subgrade beneath the asphalt is failing, this will also allow water penetration into the subgrade. In these cases, depending upon the severity, the affected problems such as potholes, alligatoring, or area(s) need to be removed and replaced.

 

3.  Paint it Black.

If your asphalt looks gray rather than black, has a pitted look or you notice deep cracks which may allow water to infiltrate to the subbase, it’s time to engage in crack filling and sealcoating, to help preserve and protect the asphalt and retard further damage. 

Note: Most unsealed asphalt has a rough and somewhat textured surface, because of the placement methodologies and the type of hot mix used. The larger the aggregate in the mix the stronger the pavement, but you give up the smooth appearance

The solution to this rough surface is twofold. First, an admixture of 2% latex per gallon of raw seal coat is added to both coats of material. secondly, adding one to four pounds of sand to the seal coat on the first coat will add necessary fine aggregate to fill the voids in the asphalt pavement. No sand is added to the second coat. This works to ensure a better looking, longer-wearing surface.

4.  Don’t Stand for It!

Standing water can be a symptom of subsurface issues with a section of your asphalt, usually caused by compaction failure in the subbase. Not only can standing water erode the surface as we’ve already discussed, but it can also undermine the integrity of other sections as the water is forced out of the depression and follows the drainage profile of the area in question.

 

5.  Rainbows Belong in the Sky, Not on Your Asphalt!

If you notice iridescent or rainbow-colored patches, these should be cleaned off as soon as possible. Oil and fuel spills can degrade the asphalt’s surface quickly, creating imperfections which over time can become full-fledged failures, reducing your asphalt’s performance and lifespan. 

 

6.  Clean it Up.

In addition to the fuel and oil spills mentioned above, it’s always a good idea to keep your asphalt clean and clear of debris such as garbage. Food products, in particular, should be cleaned up quickly, because these tend to have a relatively high acid content, e.g., ketchup, hot sauce, salad dressing, which then lingers on the surface, promoting deterioration of the asphalt. Besides, it just looks nicer!

 

7.  Root it Out.

If you have trip hazards such as uneven areas or raised roots, now is an excellent time to get them corrected. Trip hazards can be an expensive liability and can presage surface failure later depending upon the nature, type, and expression of the hazard. If possible, identifying and removing these hazards early can extend the life of your asphalt and help keep your insurance premiums down as well.

8. Traffic Control is Important.

Older and graying pavements make it significantly more difficult to see the traffic markings. This can lead to potential hazardous situations. Often the markings, arrows, crosswalks, stops and bars can become unrecognizable because of “ghosting”. This is the prior striping bleeding into view and confusing the drivers and pedestrians and leading to potential accidents. This condition is usually timely with the need to seal coat the pavement. Seal coat and restripe will solve this for years to come. This will also allow the property to be brought up to the current Building Code.

9.  Time is Not on Your Side.

By the time most people notice a problem with their paving, the damage could be far more extensive than even a detailed site walk can really pinpoint. Frequent examination and correcting areas which show indications of failure as soon as possible after they’re noted can help prevent costly, time-consuming, and unnecessary repairs.

 

10.  Call in the Professionals.

A paving job done poorly can often be worse than no repair at all. That’s why it’s worth your while to bring in pavement professionals with a solid track record of proven results. Calvac Paving has been serving the Bay Area since 1974, and we have the experience, resources and personnel to do the job right the first time, every time. Put our experience and cutting-edge construction technology and methods to work for your project by calling any of our Bay Area locations or clicking here to contact us!


Asphalt: The Most Recycled Material In America!

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

 


The Greenest Mile: How Charging Roads May Make Electric Cars More Efficient Than Ever

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.

Recent Calvac Paving Project

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!


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