Types of Concrete
Concrete is made of cement, water, sand, and stone.
Cement is the main ingredient in concrete.
Cement is a fine powder made from limestone, sand, clay, and iron ore.
To make cement, ingredients are crushed and super-heated in a kiln to form “clinker.”
Clinker is then crushed with gypsum and other ingredients.
When cement mixes with water, hydration activates the chemical compounds and strengthens the material.
Sand and stone are aggregates – they serve to add volume but are not active ingredients.
Schuster Concrete ships “ready mixed” concrete.
We match customer requirements to a specific mix design in our database.
Then, the mix ingredients are sent to batch panels.
All the raw materials are loaded into a drum. The drum mixes the concrete.
By the time the truck arrives at your job site, it’s mixed and ready to pour.
Our batching is done by computer in order to produce accurate and reproducible mixes.
How to Measure Concrete Strength
Concrete gets its strength from the reaction between water and cement.
Thus, the water-to-cement ratio is responsible for fortifying the finished product.
The strength is measured by compressive and flexural strength in Pounds per Square Inch (PSI).
Concrete continues to strengthen over time. Typically, it is measured at intervals of 7, 14, and 28 days. We consider the 28-day strength test to be an accurate measure for the final strength of the product.
Your account representative will help you determine which strength of concrete you need for your project.
Our portfolio includes concrete construction of all types. From tilt-wall to post-tension, concrete floor systems, to large scale laser screed concrete pours. We are well versed in all state-of-the-art concrete placement techniques. From private to public, large to small, we can build it.
Adjusting Concrete for Weather Conditions
Weather conditions affect concrete.
Hot, dry weather causes concrete to set quickly.
Cold weather can cause the top layer to freeze and flake off.
If you’re unprepared, you risk ruining hours of work and thousands of dollars of material. We can substitute ice for a percentage of water during summer months to lower the core temperature of the mix. During winter months, we utilize heated water to increase the core temperature and prevent freezing.
Discuss these options with your account representative.
Concrete typically contains entrapped air of less than 3% by volume.
We can make air-entrained concrete admixtures to protect concrete that is exposed to freeze/thaw cycle.
The air creates space that relieves pressure and protects the concrete.
Air-entrained admixtures contain between 4 and 8% air content by volume of concrete.
We can substitute ice for a percentage of water during summer months to lower the core temperature of the mix.
During winter months, we utilize heated water to increase the core temperature and prevent freezing.
Retarder: Slow the hydration rate. This will give you and your contractor more time to place and finish the product before the concrete sets. Use retarder on hot, dry days to slow the set rate. Consider retarder if you will need more than 30 minutes to unload your truck. Adding retarder to your mix can slow set time by 1.5 to 8 hours depending on dosage.
Water Reducers: Increase workability and strength. Water reducers make concrete “wetter” without additional water. Adding water reduces compressive strength. Using water reducers make the product more workable without compromising the product. The result is a high-strength mix that can be pumped at a 4”-6” slump.
Accelerators: Speed up the setting time. Accelerators are often used in cold weather. In addition, accelerators can be used for projects that need high strength in a short amount of time. High rise projects often use high-early mixes when pouring columns and decks. This facilitates rapid building schedules.