What does it mean to cure concrete?

Curing is one of the most important steps in concrete construction, because proper curing greatly increases concrete strength and durability. Concrete hardens as a result of hydration: the chemical reaction between cement and water. However, hydration occurs only if water is available and if the concrete’s temperature stays within a suitable range. During the curing period-from five to seven days after placement for conventional concrete-the concrete surface needs to be kept moist to permit the hydration process. new concrete can be wet with soaking hoses, sprinklers or covered with wet burlap, or can be coated with commercially available curing compounds, which seal in moisture.

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What is the difference between cement and concrete?

Although the terms cement and concrete often are used interchangeably, cement is actually an ingredient of concrete. Concrete is basically a mixture of aggregates and paste. The aggregates are sand and gravel or crushed stone; the paste is water and portland cement. Concrete gets stronger as it gets older. Portland cement is not a brand name, but the generic term for the type of cement used in virtually all concrete, just as stainless is a type of steel and sterling a type of silver.
Cement comprises from 10 to 15 percent of the concrete mix, by volume. Through a process called hydration, the cement and water harden and bind the aggregates into a rocklike mass. This hardening process continues for years meaning that concrete gets stronger as it gets older. So, there is no such thing as a cement sidewalk, or a cement mixer; the proper terms are concrete sidewalk and concrete mixer

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Why does concrete crack?

Concrete, like all other materials, will slightly change in volume when it dries out. In typical concrete this change amounts to about 500 millionths. Translated into dimensions-this is about 1/16 of an inch in 10 feet (.4 cm in 3 meters).
The reason that contractors put joints in concrete pavements and floors is to allow the concrete to crack in a neat, straight line at the joint when the volume of the concrete changes due to shrinkage.

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Can it be too hot or too cold to place new concrete?


Temperature extremes make it difficult to properly cure concrete. On hot days, too much water is lost by evaporation from newly placed concrete. If the temperature drops too close to freezing, hydration slows to nearly a standstill. Under these conditions, concrete ceases to gain strength and other desirable properties. In general, the temperature of new concrete should not be allowed to fall below 10 Celsius during the curing period.


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PROSOCO - Frequently Asked Questions
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Question - CLEANING EIFS
We’re having a difficult time trying to clean the synthetic stucco exterior of our motel. Most of the stains are mold or rust. The scrubbing required to remove the stains also removes the stucco, exposing mesh and styrofoam! High-pressure water-blasting does the same thing. Surely there’s a way to clean the exterior without damaging it?

Answer
Synthetic stucco is also known as an Exterior Insulation Finish System or EIFS. It’s a relatively new building material, so techniques and products for cleaning it are still rare. EIFS surfaces are sensitive, but the stains which attack it are not. As you’ve described, cleaning EIFS can be like trying to scour stains off egg shells. PROSOCO has developed a product specifically for this problem—Enviro Klean® EIFS Clean ‘N Prep. It can be sprayed or brushed on to the pre-wet surface, where it attacks stains. It breaks their grip without any damaging scrubbing. The dissolved contaminants can then be rinsed away with a gentle (but thorough) water rinse. In places where the finish coating has been worn away by scrubbing, high-pressure water or simply time and weather, you’ll want to reapply the coating. Give these spots a preparatory cleaning with EIFS Clean ‘N Prep to ensure your recoat adheres well and looks great.

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Question - DIRTY GROUT
We've got 1-inch ceramic tiles on the floor of the locker room at our health club. The tiles look great, but the grout is black, moldy and getting worse looking despite daily cleaning. How do we get it and keep it clean?

Answer
What's happening is that your daily cleaning isn't removing the dirt. Each cleaning just moves it around and drives it in more deeply. The good news is that there are several cleaners which will get your grout clean. Which one you use depends on the severity of the staining. Stand Off® Grout & Tile Cleaner is the most powerful. Enviro Klean® 2010 All Surface Cleaner and Enviro Klean® EIFS Clean 'N Prep are also effective. In general, use the mildest cleaner possible. Once clean, Stand Off® SLX 100 Water & Oil Repellent will help protect the grout from restaining. Maintenance cleaning with Stand Off® Rinseless Cleaner will get rid of the dirt, since the residual liquid from cleaning is mopped or vacuumed up.

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Question – EFFLORESCENCE ON BRICK
I have a white powder on my exterior brick and mortar. It’s up above the glass window of my storefront. It seems to wash off with a garden hose, but comes right back after the surface dries. What is it and how can I get rid of it?

Answer
That’s a good description of efflorescence. The white powder is actually a kind of salt from inside the brick, block or mortar. When water from rain or other sources penetrates the masonry, it dissolves these salts. Sometimes rain will carry more salts into the masonry. As the force of evaporation pulls the moisture back out to the surface, the moisture carries the dissolved salts with it. Once on the surface, the moisture evaporates, leaving the dissolved salts behind. They build up into those deposits. Washing with a garden hose won’t help, because it puts more water into the masonry. To control efflorescence, first check that water isn’t getting in through failed joints, cracks or other defects. Fix it, if that’s the case. Once you’re sure the masonry is sound, let it dry thoroughly. Then give it a good cleaning. Start by testing Sure Klean® Light Duty Concrete Cleaner. This is usually effective for red brick and gray mortar. For colored mortars and light- or unusually colored brick, test with Sure Klean® Vana Trol®. Once the brick is cleaned, let it dry thoroughly. Then apply Sure Klean® Weather Seal Siloxane PD. This breathable, penetrating water repellent will protect your brick storefront from efflorescence, mold and mildew, freeze/thaw cycles and a host of other water-related problems.

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Question - PROTECTION FOR NEW CONCRETE
I just built a new house with a new concrete driveway and sidewalks. With winter coming on, do I need to be concerned about protection -- even on new concrete?

Answer
Even new concrete is subject to the deteriorating effects of moisture, especially in winter. When air temperatures are above 32 F, water can penetrate into concrete. As temperatures drop, the absorbed moisture will freeze and expand. The expansion of the ice crystals can be greater than the available pore space in the concrete, causing spalling. Also, road salts used in deicing can contaminate your concrete as they melt from the under-carriage and fender wells of your vehicle. Absorbed salts cause oxidation of reinforcing steel and can lead to cracking and scaling of concrete. Prevent these problems with Consolideck® Saltguard® WB. This water-based, VOC-compliant treatment stops water penetration and "screens out" damaging salts. It won't change the look of your driveway, or make it slippery. Saltguard® WB is the best insurance that your concrete will stay sound for many winters to come.

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Question - REMOVING MURIATIC ACID STAINS
I hate to admit it, but I tried to save a few dollars by cleaning a new brick building with muriatic acid. I got rid of the mortar smears, but now I have ugly yellow stains all over the brick and the joints. Can you help?

Answer
What's happened is that the bricks and mortar joints have absorbed the acid and the impurities it carries. Once in, even a thorough water rinse can't get it out. As the acid attacks the bricks and mortar, it mobilizes mineral salts within the masonry, creating the stains. PROSOCO carries several products which can help correct this fairly common mistake, including Sure Klean® 800 Stain Remover and Sure Klean® Ferrous Stain Remover. Which one is right for you depends on the type of brick and mortar you're cleaning.

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Question - REMOVING GRAFFITI FROM CONCRETE
The 10-foot-high concrete wall adjoining the alley at the back of our apartment complex is a popular target for graffiti. Removing it is labor-intensive, and it usually comes right back anyway. If I leave it alone, it seems to attract more graffiti. It’s a frustrating situation. Can you help?

Answer
Rapid removal is the key to breaking the graffiti cycle. Studies show graffiti vandals move on from sites where their “work” isn’t left on display. The problem is that spray paint and other graffiti are hard to get out of porous concrete. Also, the wrong cleaning method can damage your wall or lock in the stains. Sure Klean® Heavy Duty Paint Stripper or Sure Klean® Fast Acting Stripper are both more than a match for cleaning off graffiti attacks. Heavy Duty is your choice if the graffiti has built up over time. Once cleaned, apply penetrating, breathable Weather Seal Blok-Guard & Graffiti Control to your wall. It protects cast-in-place, precast and pigmented block. The treatment fills the pores so graffiti can’t get a grip. Normally, Blok-Guard & Graffiti Control won’t change your wall’s appearance. Graffiti slides off when washed with Defacer Eraser® Graffiti Wipe and rinsed with water. Graffiti Wipe is a mild, citrus-based maintenance cleaner specifically designed to work with Blok-Guard & Graffiti Control. Together, these products provide a system that makes it easier for you to remove graffiti than for the vandals to apply. Under those conditions, your vandals will most likely choose to move on.

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Question - WHY MURIATIC ACID IS BAD
A mason I know uses muriatic acid to clean brick. When I tried to tell him it was a bad idea, he responded by showing me several websites and magazine articles that recommend muriatic acid! Where does the idea that muriatic acid cleans brick and block come from? Is there anything to it?

Answer
Use of muriatic acid as a masonry cleaner predates World War II. Then it was the only product available. Since then, developments in the kilning process of clay products, plus changes in types and number of additives in brick and concrete made muriatic acid obsolete and even harmful for masonry cleaning. Relatively recent advances in the overall construction industry such as colored mortars, aluminum windows and stainless steel trim have made muriatic acid even more undesirable for cleaning masonry. Don't use it.

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How Much Manufactured Stone Do I Need?

Answer:
Just follow these easy steps to determine how much stone you will need.

1. Measure the width and the height of the area to be covered and convert to square footage;
width x height = total square footage

2. Figure the square footage of any windows and doors and subtract this amount from the first figure (total square footage – windows and doors).

3. Determine how many linear feet of corner pieces you’ll need. Measure the linear footage of outside 90° corner pieces and convert to square feet. One linear foot of corners will cover about 1/2 square foot of flat area – ie, 20 linear feet of corners = 10 square feet of flat area. Subtract this flat area amount from the total square footage to determine how much total stone you will need. You should allow an extra 5 -10% more stone for cutting and trimming on both corners and flats


 

Natural Stone
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