Questions & Answers

Each month, we will post answers to your frequently asked questions on concrete, sealants, water repellents, and other construction chemicals on this page. We continually gather and respond to the questions you submit. If you have a question, please e-mail us or contact us at our corporate office.

Cleaning & Maintenance ~ Fundamentals ~ Grouting ~ Polished Concrete
Highways & Bridges ~ Industrial/Commercial ~ Residential

Cleaning & Maintenance

We came across your web site while we were trying to find some information on cleaning concrete. We purchased a home with the front steps covered with indoor/outdoor carpeting. We pulled the carpeting off with no problem, but we are having a hard timer removing the old adhesive used to hold down the carpet. Could you suggest an easier way to remove the adhesive, besides true grit and determination?
How do we get oil spots off of our driveway? We hired a painter to paint the walls in our finished walk out basement. His van leaked black oil on our driveway. We called him back and asked him to clean it off. He hired a company to clean the concrete and their truck leaked more oil on the driveway. We asked them to stop cleaning our driveway and decided to clean it ourselves. What should we do?
We are always fighting the same fight at the end of every concrete floor project. Dirt, mud stains, rubber tire marks and sometimes rust stains sticking to our once clean concrete floor. Our crew pours the concrete and gives it a smooth and clean finish, as soon as we leave the other workers dirty the floor so bad, we have to clean the floor at our expense before receiving our final check. What can we put on the floor to minimize this problem?
My neighbor was trying to be helpful and assisted our daughter in changing the oil out of her ancient "hand me down" car. The oil catch pan was as old as the hand me down car and we have a huge, dark oil spot on our nice clean driveway. What can we do?

Fundamentals

Occasionally, we are called to repair spalled and scaling concrete on either new or old concrete placements. We've tried mixing our own repair material, mostly “moose milk” (acrylic latex) with Portland cement and fine sand and have had some success, but not always. We are looking for a more reliable way to repair eroded surfaces in concrete work. Call backs are eating up our profits. Any suggestions?
What's the effect of deicers and salts on concrete? How can I make concrete more resistant to salt and deicer damage?
We have a problem with surface crusting on our fresh concrete slabs. Our sites are almost always exposed to sun and wind. Even though we know that "blessing" the concrete surface with a sprinkle of water by the finisher is not the best answer, we have little else to fall back on. What else can we do?
We recently installed a large flat concrete floor in a large metal building. The floor project turned out great; however, we had one major difficulty with a long lane of concrete floor along the north side of the metal building's wall. We observed that large areas of the fresh concrete were not setting for hours, while other areas set within a normal time given the conditions of the project. What caused the spotty setting of the concrete?
We are an international development company. We specialize in buildings with large areas of concrete floors. Joints in the floors have become a major problem for us. We have a maintenance company on retainer but the repair patch never lasts. Is there a long lasting repair for broken joints
We want to improve our concrete curing standards. I have heard that there is now a new standard, ASTM 1315, which addresses our concerns. Can you tell me more about it?
What is the purpose of a "vapor barrier" under a concrete floor, does it make the bottom weak?
What is concrete dusting? Why do concrete floors dust? This is a major problem to our company, we hope you have some answers.
Our firm needs a prescriptive standard for our cure and seal contract language. We used to call out Federal Specification TT-C-800. We liked it because it had a minimum solids specified and a specific water retention minimum. We are very aware TT-C-800 has been discontinued as an active standard. What can we replace it with?
What causes hardening in cement or concrete?
What was the earliest use of Portland cement?
We are hearing and reading a lot of terms for placing and finishing concrete. We do not understand some of these terms. See the list attached and please enlighten us as to the meaning of the "terms."
What is a "slump test" for concrete?
We were told by our concrete contractor the weather is getting cold and he will have to charge more for his work in cold weather, is this true?
We have varying or mottle color areas on the surface of our smooth, new concrete floor. We do not like this appearance. How did it happen? What can we do about it? Also, who should we blame?
What is a general definition for lightweight concrete aggregate?
What can we do to prevent the problems we are experiencing with our concrete in hot weather?
We poured a concrete slab and did it ourselves. We followed a handbook from the local lumber store and it was helpful in getting the area ready for the concrete. Some of the people did not show up as they had promised and we had to pour the concrete with three people, only. The concrete was real "soupy" and flooded into the forms from the truck. We leveled it and had to wait to smooth it. The breeze dried the water off the top and we finished the top with hand tools. Now we have a hump in the middle and the ends of the slab are bent up and there are cracks running through the slab. What did we do wrong? We did not want wavy, cracked concrete.
Could you please inform me on how much it would cost to put concrete on a 36 ft. by 78 ft. piece of land, and 40 ft. by 80 ft. piece of land? You may use whatever type of concrete you like, just make it as least expensive as possible.
Our concrete contractor and his concrete supplier offered us a lower cost concrete if we allowed them to make the concrete out of the waste from a blast furnace. Do I want to say yes to this offer? The savings were attractive to us.
Is there a way to color my concrete in a permanent way and not spend the money for colored concrete mixed in a concrete truck?
We cannot seem to overcome surface crusting on our fresh concrete slabs. Our sites are almost always exposed to sun and wind. What can we do, it has become a real problem?

Grouting

What is your experience with anchor bolts and anchor bolt installation?
We have a number of penetrations through a below grade wall. The penetrations are for electrical and mechanical conduits and pipes. There is the possibility of the exterior of the wall being flooded with water due to ice and snow melt. The cored holes for the conduits and pipes are larger in diameter than the conduits and pipes. What can we fill the annular spaces with to prevent water from leaking into the interior mechanical space?
We use the L&M grouts to anchor our drilled and grouted reinforcing bar. We use it in concrete and rock. Does the reinforcing steel differ? We get concrete or rock failure when we pull the rebar to test the bond. Sometimes the bar "stretches" a little more before we get a cone shaped pull out failure. What is happening?
Our rail car unloading track is owned and maintained by our tank farm corporation. We are in the gulf coast of the US and our rail yard is flooded by cloudbursts of rain. We used to have our rails near ground level on a layer of ballast. This proved to be a series of low laying dams following the downpours. We elevated the rails on mounds of cement grout and allowed the water to drain freely away. The problem is, our pedestals of grout are crushing under the tank car traffic. We do not want to bed on the ballast again, what can we do?

Polished Concrete

What's the best way to maintain our new FGS/PermaShine polished concrete floor? I am interested in making the bare concrete surface last as long as possible and continue to look good over time.

Highways & Bridges

We have a bridge division in our construction company. We need a product to prevent the rapid crusting and rying of the high strength concrete mixes we use to cast the bridge decks and the approaches to the bridge. What do you have?
What is available to protect our clients' bridges and suspended slabs of concrete? There will be car and truck traffic and there will be salt applied during the winter.
In recent years the quality and durability of concrete has come to the attention of the public in the press. Parking structures collapsing, bridges collapsing, "chuck holes" in the spring hatching out like Mayflies. Is our concrete not as good as we think it is?
I was interested in finding out about the possible causes of concrete street expansion, other than heat itself. We have experienced numerous problems of over-expansive joints, causing the individual sections of concrete to force one another to push up and crack. I was wondering if you had heard of any reasons or studies aiding in this phenomenon involving any chemicals in the concrete or anything similar to this. Any information about expansive concrete or street blowups/blowouts would be great.

Industrial/Commercial

The cement surface of our new concrete pavement and building entrance is coming off. The contractor told us we caused it by melting ice with salt. We do not agree. We used sand and cinders, no salt. What is happening to our concrete?
We want to apply one of your membrane sealers on a warehouse floor. The problem is that moisture is visible upon the surface of the concrete in early morning. The floor is six months old and we think the moisture is condensation and not moisture vapor from within the slab... what can we do to tell the difference?
Why are my smooth hard trowel concrete floors always darker than my clients like?
Our Radiant heat floors have cracks in the lightweight cement. Can you recommend a product that we can fill the cracks with prior to painting? We believe that it needs to be flexible as with the heating and cooling most products with continue to crack. (This has happened on some of the floors we have already painted.)
We have problem dusting on the new concrete floor we pumped, placed and finished for our best customer. The floor appears to be covered with white flour. We sweep it and scrub it and it returns the next day. Some areas are showing the surface of the coarse aggregate. We read your "dusting" answer. We did everything right and now we have this awful situation. What do you think happened and what can we do?
We have an expansion adjoining our existing plant. The floor in the existing plant was treated with iron shavings and cement. We can see the iron shavings on the worn parts of the floor. Our existing plant managers told we cannot use it in the new adjoining floor, too much dust from the iron and cement shavings. We have to treat our new floor. What can we do?
We treated our plant floor five years ago with a water proofer and it had the picture of a seal on the label. Can we retreat our plant floor with your Seal Hard? We cannot tolerate an odor because this time the plant is in operation.
We are cast in place concrete contractor. Our clients like our work because the concrete we cast comes out tight in appearance, but we are always trying to do better. How should we reduce our surface voids or "bug holes?"
We are trying to justify coating and rehabilitating the existing concrete floors to a very budget sensitive client, any thing you can share with us to promote nice looking floors?
We own a nationwide automobile tire store and one of our selling points is sparkling clean floors in our display area and in our service bays. We recently had a waste oil receptacle tip over and spread out a nasty black used oil spill on our spotless concrete floor, what can we do to clean this floor?
We have a new concrete slab on grade. The surface is smooth and hard. The surface is beginning to dust or give off a fine white powder. What can we do without removing the slab or installing an expensive overlay? The dust is getting on the inventory and that must stop.
We treated our plant floor five years ago with a water-proofer and it had the picture of a seal on the label. Can we retreat our plant floor with your Seal Hard? We cannot tolerate an odor because this time the plant is in operation.
We have a concrete block wall with a northern exposure, we have insulated and finished the inside and enjoy the improved looks and warmth the insulation and wallboard provide. We have observed the outside of the wall stays wet or damp for days after a rain or snow melt. Can we improve water resistance of the out side face of our wall? We suspect the water will create problems over time.
My concrete contractor failed to coat the finished slab foundation with a curing agent. The next day two hairline cracks appeared that ran from one side of the foundation to the other side. After two weeks, these cracks have not gotten any larger. Should I be concerned about foundation failure later, or are the two cracks simply cosmetic problems?
We have very old and ornate capitals on our building's columns. They are made of stone or a very fine mortar that looks like stone. The capitals are losing their ornate characters from rain and wind. We have been able to work with an art school and they made a sand mold. We tried plaster and the result was beautiful but the plaster is too soft. Do you have a product we can cast our capitals out of?
We have heard and do not know if it is true, is form oil coming under regulation, we use diesel fuel and we do not know if we can continue to use it?
We are always fighting the same fight at the end of every concrete floor project. Dirt, mud stains, rubber tire marks and sometimes rust stains sticking to our once clean concrete floor. Our crew pours the concrete and gives it a smooth and clean finish, as soon as we leave the other workers dirty the floor so bad, we have to clean the floor at our expense before receiving our final check. What can we put on the floor to minimize this problem?

Residential

We have beautiful pigmented concrete. The contractor calls it intregal pigmented concrete. We refused to seal it because sealer turn yellow and ruin the beauty we paid extra to enjoy. What can we seal our colored concrete with that is free of yellowing and free of surface films?
We had a beautiful exposed rock driveway and patio area poured at our home and the first year it was shiny and we could see all the colors of the rocks and it repelled water. Now it is dull and the water soaks in sometimes. What do we do to get the shine and water protection back?
We have a beautiful brick paver driveway, walkway and patio. How do we protect it and not change the colors nor make it slippery?
I have a concrete driveway that is approximately 12 years old. It has some cracks running across it but I have also noticed it is getting rougher?..more porous? I don't know how to explain it but it looks like it will start to crumble a little in spots. Can I put a sealer on the driveway and prevent further breakdown of the concrete? And is this something a female can do on her own? Any information would be greatly appreciated.
Our neighbors have a stucco house. They have never painted it. The color of the stucco was white. They had the white stucco walls sprayed with a rain repellent liquid. Now they have a yellow color house. What happened to their house? We have a nice stucco house, too. We want to seal it and now we are afraid. Do you have something to help us?
We have a very nice broad and long curving driveway. We live in the hottest part of the country and car tires leave black marks on our driveway. How can we get them off, soap and water did not work, and wire brushes leave a dark spot. Hope you have answer.
We are having a very large driveway poured on our property and the contractor said we could save some money if we sealed it our selves. Does this sound like a good way to save money?
This winter I had a pool installed with a concrete deck. About a month later, four of the deck sections began to crack perpendicular to the control joints. The contractor said that cracking was "just one of those things" and that he would not be prepared to do anything unless the cracking became structural in nature. Am I being taken for a ride about the cracking? Is there any route I can take to verify that the contractor workmanship or materials are not at fault?
Please tell us why our concrete contractor insisted upon placing our big wide driveway and patio at or near sunset. We live in the desert southwest and we like it, but it seemed odd to require the placement of concrete at the end of the day.
What would you recommend as the best option to bond flagstone to an outdoor concrete patio in the Kansas City area?
We had a beautiful exposed rock driveway and patio area poured at our home and the first year it was shiny and we could see all the colors of the rocks and it repelled water. Now it is dull and the water soaks in sometimes. What do we do to get the shine and water protection back?