Frequently Asked Questions
Q. What is concrete?
A. Concrete is basically a mixture of two components, aggregate and paste. The paste being cement and water, then aggregate, sand and rock. A basic mix using air entrainment would be for our stamped concrete mixes. It is 15% cement, 18% water, 8% air, 28% sand and 31% rock.
Q. How should concrete be placed?
A. Two things need to be considered:
- Strength, which means the ability to carry loads imposed.
- Durability, which means the ability of the concrete to resist the environment in which it is placed.
Q. Do you reinforce your concrete?
A. Yes, in most jobs it is on two-foot centers and number four rebar. For stairs and other jobs, more is used along with larger size rebar.
Q. Will my concrete crack?
A. Yes, concrete will crack. We do everything we can to prevent or minimize the cracks. We saw cut within 24 hours or use different borders to act as control joints. The subgrade must also have proper compaction as well as proper drainage. For driveways, we do not recommend driving on them for at least seven to 10 days.
Q. What is concrete finishing of flatwork?
A. Finishing concrete is the operation of consolidating, leveling and creating a concrete surface of desired texture and hardness. The finish should be strictly functional or decorative. Finishing makes the concrete attractive and serviceable. The final texture, hardness and joint pattern depend on the concrete's end use.
Q. When should concrete be cured?
A. You should wait until all bleed water has evaporated and concrete is firm enough to leave only 1/4 inch deep footprints. Early finishing can cause crazing, dusting, blistering and scaling. Outside concrete should not be steel troweled. Bull float and broom finish is recommended. Use air-entrained concrete (5 to 8%) for freeze-thaw protection. Never sprinkle water or cement on concrete while finishing it because it may cause dusting or scaling. Never use a jitterbug. Fog spraying is also effective during hot weather and windy weather, but also impractical in most cases. Evaporation Retardant is an effective alternative. Saw cut joints as soon as practical, especially during hot weather.
Q. What is a control joint?
A. Control joints create weakened sections to control crack locations and accommodate movements, caused by temperature changes and drying shrinkage, to prevent vertical but permit slight horizontal movement.
Q. How much water should be added to a load of concrete?
A. Adding one gallon of water to a cubic yard of concrete will increase the SLUMP about one inch. Decrease COMPRESSIVE STRENGTH about 200 to 300 PSI. Increase SHRINKAGE potential about 10%. Waste AS MUCH AS 1/4 bag of cement and it proportionally affects DURABILITY.
Q. What are the common causes of surface scaling?
A.
- Excessive slump, overworking of wet concrete, premature finishing operations, inadequate or improper curing.
- Little or no entrained air due to failure to use air entrainment admixture agent, air worked out by overworking overwet concrete, or premature finishing.
Q. What is the solution of the surface scaling?
A. Always use air-entrained concrete for outside work and indoor surfaces exposed to vehicular traffic. Five to eight percent is right for most mixes. Use low-slump concrete (4 inch max.) and a water/concrete ratio of no greater than 0.50.
Q. What are the two basic causes of cracks in concrete?
A.
- Stress due to drying shrinkage or temperature changes. These types of cracks are an inherent, unavoidable property of concrete. However, unavoidable, they can be controlled.
- Stress cracks due to applied loads. These are settlement cracks and can be avoided by having a proper sub-grade, slab design, and proper concrete mix designed for the load.
Q. What tests should you know about for proper concrete placement?
A. Slump test (ASTM C-1431), air content (ASTM C 231) or temperature test (ASTM 1064), Call or write for a booklet of 40 pages concerning concrete placement procedures.
Q. Should concrete be cured?
A. Yes, by curing the concrete moisture is maintained in the early stages which allows for maximum hydration and a more durable product with increased surface strength.
Q. What is stamped concrete?
A. Concrete is poured and placed using ACI guidelines then when in a somewhat plastic stage, a rubber imprinting mat is aligned and pressed into the concrete creating impressions of slate, stone, tile, brick, cobblestone and more.
Q. How can color be achieved?
A. Two main methods.
- Integral color. By this method preweighed dissolvable bags are placed into the concrete trucks at the rate of one bag per yard of concrete thereby tinting the entire load.
- Color hardeners. By this method concrete is placed when the bleed water has left. It is then cast upon the surface of the concrete and floated into the concrete. The top is colored to the depth of 1/8 inch to 3/16 inch.
Q. How are different color shades achieved?
A. A method called antiquing which is a secondary color put on top of the base color to highlight the stamping impressions.
Q. Should my decorative concrete be sealed?
A. Yes, we recommend that all concrete be sealed. By doing this, popouts, scaling and water penetration are greatly reduced and stains such as oil spots can be repelled.
Q. Does my company do staining?
A. Yes, we can stain cured concrete from one color to several colors. We can achieve many patterns and color combinations. With our knowledge of the Engrave-A-Crete saw, circles and many geometrical patterns can be achieved.
Q. What is stenciled concrete?
A. Stencilled concrete is another option to do with new concrete. There are many patterns of stencils and they can be used to do more precise grout lines and and can be done with color hardeners. With color hardeners you can do several colors in one pour. A colored-release powder can also be added to the top of the color hardeners to make a secondary color. A textured roller can be rolled over the top of the concrete to make a texture in the concrete which allows you to have a textured look or you can have a flat finish.
Q. How many stamping and stencil patterns do you have?
A. We offer 22 stamping patterns and 30 stencil patterns.
Q. How many colors do you offer?
A. Seventy colors and 20 release colors.