Technical Information Sheet – Concrete
Concrete is the most widely used building material in the world, second only in consumption to water. Why is it used so much? It is relatively inexpensive and can be made from local raw materials. It can be made into almost any shape and is extremely strong and durable.
Properties of Concrete
Due to the wide range of applications it is used for, and weather conditions concrete is exposed to, we have a multitude of different mix designs created and ready to use. We also create new mix designs regularly to meet
customer and owner needs. What are the critical properties of ready mixed concrete commonly specified?
- Compressive Strength
our mixes range from very weak (as low as 30 psi) excavatable CLSM (Controlled Low Strength Material) to very strong (over 9,000 psi) structural concrete. The most commonly specified compressive strengths range from 3,000 to 4,500 psi for applications such as footings, walls, interior floors, exterior flatwork, paving etc.
- Air Content
exterior concrete exposed to freeze-thaw cycles requires air entrainment for durability. Millions of tiny air bubbles are incorporated into the concrete allowing freezing water in the concrete to expand safely without scaling/spalling the concrete.
- Water/Cementitious Materials Ratio
one of the most important factors in achieving strength is controlling how much water is in the concrete mix. The water to cementitious materials ratio is the amount of water in the mix (in lbs) divided by the amount of cementitious materials in the mix (in lbs). The w/cm ratio of lower strength concrete is generally 0.60 or higher. High strength concrete can have a w/cm ratio of less than 0.40. Exterior flatwork concrete is limited to a 0.45 w/cm ratio for durability.
- Cementitious Materials
all of our plants have Portland cement. They also have an SCM (Supplementary Cementitious Material) – fly
ash or slag. These products are used at various levels to replace Portland cement (5% up to 70%). The amount used depends on the application and also ambient conditions. SCM’s generally extend set times so replacement levels are less in cooler weather. Commonly used mixes range from 15 to 35% fly ash or slag.
at our plants, we have natural sand, gravel and limestone of various sizes and lightweight aggregate. We have mixes with no aggregates (neat cement grouts), sand only (CLSM, grouts), 3/8” pea stone, 3/4” gravel or limestone, and 1 ½” gravel or limestone. The commonly used mixes use 3/4” gravel or limestone and sand. Mixes with smaller aggregates or sand-only grouts need more cementitious material to achieve the same strength as mixes with larger aggregates.
almost all of the recent advancements in concrete technology have come from the use of chemical admixtures. We use 3 different types of water reducers (normal-range, mid-range and high-range) to help the concrete flow and consolidate without adding excess water. High-range water reducers are also call superplasticizers. We also use set-accelerators, set-retarder/hydration stabilizer, and air- entraining admixture. Less commonly used are corrosion inhibitor, shrinkage-reducing admixture, moisture-vapor reducing admixture and crystalline waterproofers.
If you have any questions regarding the above, or have other concrete-related questions, please feel free to contact our Quality Control Department: