Topic: Blog

How Long Does Asphalt Take To Dry?

One question we often hear at Calvac Paving is about asphalt cure times. This is a great question because understanding how the asphalt curing process works helps you understand when you can safely stripe, park, walk, and drive on the new asphalt parking lot and what sort of performance you can expect from your asphalt long-term. Let’s take a closer look at how the asphalt installation process works and how this affects the asphalt curing process!

 

Asphalt Surface Installation

 

Most asphalt paving companies prefer not to place a fresh asphalt surface if the ambient temperature is outside the range of  50°F-90°F. If it’s too hot, asphalt will not cure quickly enough.  Paving when it’s too cold can cause the asphalt crack as it rapidly cools. Weather conditions can make a difference as well. If you watch carefully, you’ll notice paving companies rarely place asphalt in heavy rain. While it is possible to pave asphalt outside these parameters, it requires special preparation and oversight.

The rules for hot asphalt patch, resurfaced asphalt sealcoating and cold patch asphalt placement are a little different, so for purposes of this discussion, we’re going to focus on a clean installation on grade for commercial or residential paving like parking lots or a driveway.  

 

 

How Long Does Asphalt Take to Cure?

 

The curing time for asphalt depends on the asphalt mix design, the oil content, the temperature of the mix, the thickness of the paved asphalt layers after compaction, and the temperature and weather conditions when the mix was placed. Generally, you can open new asphalt to public foot and vehicle traffic 48-72 hours after it is placed because this allows time for the asphalt to harden, but you may need to allow a bit more time during hot weather. Asphalt doesn’t fully cure for 6-12 months, so it’s important to keep a close eye on it during this time because it will be less resistant to damage.

The reason we stress the difference between “curing time” and “asphalt drying time,” even though they’re often used interchangeably is that asphalt is designed to be flexible. For it to remain flexible, it has to retain a certain amount of moisture. Water infiltration in paved asphalt driveways, parking lots, roadways, speed bumps, and other asphalt surfaces is the primary factor leading to a blacktop drying out. The water washes away the oil which keeps the asphalt overlay flexible and resilient. You can tell when asphalt dries because you’ll notice cracking, warping, raveling, and loose aggregate appearing on the surface of the matrix, especially sand and other fine aggregates. Fortunately, it takes months to years of asphalt drying time to start noticing signs other than cracking.

 

What Can I Do to Not Allow My Asphalt to Dry Out?

 

Good roadway and parking lot maintenance programs can help prevent a lot of problems. Putting down asphalt seal coating on a regular basis, especially when you freshen up your street or parking lot striping, can help prevent more costly asphalt repairs down the line. This is also a great time to do any basin repairs and crack filling, as catching these problems early, when they’re small, can keep your asphalt fresher and more flexible for a lot longer.

Asphalt sealer drying times vary, but 4-8 hours to dry is usually enough for your sealer to ensure it will keep water out. However, the full drying process for the sealer takes around 24 hours, and it’s important to allow your sealcoating to dry completely before line striping for maximum resiliency and effectiveness. As with any other kind of asphalt sealant, you want to allow crack sealer to cure for at least 24 hours in perfect conditions, and add a day for cool, cloudy, or high-humidity conditions just to be on the safe side.

 

Final Thoughts About How Long It Takes Asphalt to Dry

 

Of course, the best mix design in the world won’t do you any good if it’s improperly placed, if your striping doesn’t meet the latest ADA criteria or if you don’t take proper care of it. For the best possible results and the greatest confidence in your paving job from breaking ground to the final walkthrough and for years of use beyond, click here to contact Calvac Paving. We’ve been proudly serving the Bay Area since 1972 on residential, commercial, and government projects of all types. Our track record for consistent quality, service, and excellence in every aspect of our operations speaks for itself. Put our experience to work for your paving refurbishment, repair, or new construction needs and see why Calvac Paving is the contractor you need for paving that works the first time, every time!

 


Five Reasons the Best Time to Maintain Your Asphalt Is NOW!

The last 18 months have been rife with uncertainty and riddled with worry for nearly everyone. With businesses closing temporarily or permanently, the Bay Area’s paving situation has never been as dire as it is now. The fact is, if your parking lot, driveway, and other paving problems aren’t corrected early, they’ll get worse and more expensive to fix later. Here are five reasons the best time to maintain your asphalt is NOW!

 

1. Fluctuating Oil Prices

The price of oil impacts everything, perhaps especially in the construction industry. Asphalt and concrete batching and production processes are uniquely affected by the cost of oil. In July 2020, the cost of asphalt tumbled to a low not seen since March of 2017. One year later, the price has increased by nearly 50%, spurred on by rising oil prices and a concurrent rise in the cost of refining, processing, and batching. With prices going up, now is the best time to lock in current rates for asphalt and concrete before the cost jumps even higher.

 2. Curb Appeal

How can you tell the difference between a closed business and a business that’s open and ready to take care of its customers? The truth is your customers can’t, especially if they’re driving by on the street. Cracked, faded, potholed parking lots with worn-out striping are unattractive to the eye and send an unflattering message to potential clientele. By repairing your parking lot, accessways, and other curb and drive installations, you clearly communicate that you’re open for business, ready to get to work and able to assist your customers with all their needs.

 3. Safety

Did you know that cracked or potholed asphalt, offset sidewalk slabs, and other defects and damaged portions can be a safety hazard? It’s true! If a customer trips and falls because of poorly cared-for paving, your business may be liable for any injuries they sustain. Such hazards can also impede disability access to your business and maybe an ADA violation with a fine of up to $75,000 for the first infraction and $150,000 for each subsequent violation. When you add up the stiff financial and reputation costs of noncompliance and the potential for injury to your staff, customers, and the general public, having your parking lot and sidewalks repaired looks like a pretty good bargain.

 

4. Weatherproofing

When cracks form in asphalt paving, it allows water to infiltrate the subbase. A small trickle of water isn’t a big deal, though, right? Unfortunately, no. As water seeps into the pavement, it wears and washes away the surrounding material and pools within the matrix, allowing plant seeds to take root and start to grow. During colder weather, it may freeze and expand. These erosive processes accelerate cracking and pothole formation as well as undermining the structural integrity and flexibility of the overlying surface. At a certain point, the paving will be beyond repair and will have to be completely removed and redone to work properly. A well-maintained parking lot will perform and look better for years to come.

 5. Increase and Safeguard Your Property Value

Faded, cracked, or faulty paving can be expensive in more ways than you think. It can also drag down the property value, especially if you’re considering selling in the near future. If your paving looks good, it will also perform well for years to come, making the property a better investment for anyone who might end up buying.

 

All in all, maintaining your asphalt paving is a smart investment with a lot of benefits and virtually no downside over time. Whether you need a simple sealcoat and restriping, a spot patch and repair on a faulty section, or a complete tear-out and rebuild of your asphalt and concrete paving, Calvac Paving is here to help with proven, durable results that give you, your tenants, and their customers the great performance and appearance they expect and deserve. For all your Bay Area paving needs and a job that’s done right the first time, every time, click here to contact Calvac Paving today!

 


How Many Parking Spots Will I Need For My Strip Mall?

Happy Monday Everyone! In this edition of Maintenance Monday, one of our social media friends sent us this question.  I own a strip mall in San Jose, we have 10 retail stores, with 75 parking spots. How do we figure out the correct amount of handicap parking spots to have?  The answer is…

Thank you, In this case, 75 stalls. Three would need to be accessible spaces (not handicap), of which one of those would have to be van accessible.  One thing to consider is the current count. If this property has 5 existing accessible spaces, it is best to put back those 5.  The reasoning is that the standards are the minimum and it is not usually a good idea to decrease accessibility on a property.  This is why it is important to plan these layouts with an ADA specialist, you don’t want to create a problem in the future by guessing or overestimating today.

How many parking spots do I need?

 

 

At Calvac Paving, we have ADA Expert(Certified Access Specialists) available. Our ADA Expertspecialists serve the San Jose area as well as the greater Bay Area.


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.

IMG_8848

 

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!

 


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