Do It Yourself

Frequently Asked Questions

• What is Concrete?

  Concrete is a material made primarily from cement, aggregates (rock and sand), and water.  Concrete dates back more than 5,000 years and is the most widely used man-made product in the world

  Many people believe cement and concrete are interchangeable terms, but cement is actually an ingredient used in making concrete.  You can learn more about concrete from this video from the Concrete Network.

• What is Redi-Mix concrete?

  Redi-mix is an unhardened, fluid form of concrete that is delivered in a concrete truck that agitates and mixes the concrete on the way to the job.

  
  

• How do you measure for concrete?

  Concrete is measured in cubic yards (areas 3’x 3’ x 3’). You can use our concrete calculator on this page to measure how much concrete you will need. It’s incredibly important that you measure accurately and order enough concrete. It’s a good idea to order a little more than you think you’ll need.

  
  

• What is slump?

  Slump measures the consistency of a batch of fresh concrete. It refers to the ease with which the concrete flows, thus indicating the workability of the concrete. Different types of jobs require different slump ratings. Slump testing is used on-site to ensure uniform consistency between individual batches of concrete. 

  
  

• How is pricing determined for concrete?

  The aggregates available for concrete mix design vary by location. Because of this, price also varies by location. Contact your nearest Croell Redi-Mix facility for an estimate.

  
  

• What are the temperature requirements for placing concrete?

  Concrete will not set on its own at temperatures under 35 degrees. While heated water and aggregates or the use of accelerants do allow concrete to be poured at temperatures below freezing, it is more costly.

  High temperatures above 90 degrees can make concrete set faster than recommended, reducing the strength of the concrete.  Additives can be used to slow down this process.

• How do I care for my concrete?

  One of the best ways to ensure your concrete stands the test of time is to work with a reputable ready mixed concrete producer. The Concrete Network offers tips on controlling and repairing cracks in your concrete, as well as how to clean and remove stains on concrete. In addition, it is highly recommended to always seal your concrete.

• What are the Benefits of Sealing Concrete?

  New information on www.ConcreteNetwork.com outlining the benefits of applying concrete sealer helps consumers protect newly finished concrete surfaces and provide examples of how to protect your investment

  According to the site, sealing newly placed concrete can offer a host of benefits, and is the most efficient way to improve the performance and longevity of interior and exterior concrete surfaces. With different sealer options to choose from, there's no reason why any concrete surface should be without the added protection.

  The six benefits of using a concrete sealer include:

  
  1. Enriching the color intensity.
  2. Adding sheen to the surface.
  3. Blocking the penetration of dirt and chemicals.
  4. Inhibiting dusting of the surface.
  5. Preventing the intrusion of water.
  6. Protecting against abrasion and wear.

  With the benefits outlined above, it's no wonder why protecting heavily used and trafficked areas like concrete driveways can benefit tremendously from these products. Concrete sealers ultimately protect the hard work and artistic effort that goes into creating beautiful decorative finishes.

  For more information on the benefits of concrete sealers, and sealer application and selection tips, visit The Concrete Network channel on YouTube at http://www.youtube.com/concretenetwork for detailed product videos.

• What are some methods to increase the strength of my sidewalk or driveway concrete?

  Concrete Driveway Reinforcement

  Use rebar for structural support and synthetic fibers to control shrinkage cracks
  Using steel reinforcement will provide additional structural capacity for your driveway and is especially important if the slab will be exposed to heavy traffic. Reinforcement won't prevent cracks, but it will help hold them together if they do occur. Reinforcement can be either wire mesh or ½-inch (#4) steel rebar placed in a grid pattern with a spacing between bars of approximately 12 inches. In either case, blocks should be used under the reinforcement to keep the grids centered within the concrete.

  Use Fibers for Secondary Reinforcement

  Fibers can be added to the concrete mix in lieu of welded wire mesh.

  If you could look into a section of concrete poured with fibers you would see millions of fibers distributed in all directions throughout the concrete mix. As micro cracks begin to appear due to shrinkage as water evaporates form the concrete (plastic shrinkage), the cracks intersect with the fibers which block their growth and provide higher tensile strength capacity at this crucial time. The problem with welded wire mesh is that it often ends up on the ground from being stepped on as the concrete is being placed (particularly if no support blocks are used). Another problem is that mesh does not prevent or minimize cracking-it simply holds cracks that have already occurred together.

• How Can I Protect Against Freeze and Thaw Cycles?

  Air entrainment is particularly effective in providing resistance to freeze-thaw cycles. When the moisture in concrete freezes, these air cells relieve internal pressure by providing microscopic chambers for the expansion of water as it freezes. Some air entraining mixtures contain a catalyst for more rapid and complete hydration of  Portland cement.

  To protect concrete from damage during freezing, bubbles must have the proper size, distribution and volume. ASTM C 260 specifies requirements for air entraining admixtures and you should be sure to mention how the concrete will be used when ordering your mix design.

  Benefits of air-entrainment include:

  • Improved resistance of concrete to severe frost action or freeze/thaw cycles
  • High resistance to cycles of wetting and drying
  • High degree of workability
  • High degree of durability

  Dosage: Typical air entrainment ranges from 5% to 8% of the volume of concrete.

• What are Admixtures? (i.e. fly ash, air entraining, water reducers, etc.)

  Admixtures are additions to the concrete mix used to achieve certain goals.  Here are the main admixtures and what they aim to achieve:

  Accelerating admixture--accelerators are added to concrete to reduce setting time of the concrete and to accelerate early strength. The amount of reduction in setting time varies depending on the amount of accelerator used (see your ready mix supplier and describe your application). Calcium chloride is a low cost accelerator, but specifications often call for a non-chloride accelerator to prevent corrosion of reinforcing steel.

  Retarding admixtures--often used in hot weather conditions to delay setting time. They are also used to delay set of more difficult jobs or for special finishing operations like exposing aggregate. Many retarders also act as a water reducer.

  Fly Ash--is a by-product of coal burning plants. Fly ash can replace 15%-30% of the cement in the mix. Cement and fly ash together in the same mix make up the total cementious material.

  -Fly ash improves workability
  

  -Fly ash is easier to finish
  

  -Fly ash reduces the heat generated by the concrete
  

  -Fly ash costs to the amount of the cement it replaces
  

  
  Air Entraining Admixtures--must be used whenever concrete is exposed to freezing and thawing, and to deicing salts. Air entraining agents entrains microscopic air bubbles in the concrete: when the hardened concrete freezes, the frozen water inside the concrete expands into these air bubbles instead of damaging the concrete.

  -Air entrainment improves concrete workability
  -Air entrainment improves durability
  -Air entrainment produces a more workable mix
  

  
  Water reducing admixtures--reduce the amount of water needed in the concrete mix. The water cement ratio will be lower and the strength will be greater. Most low-range water reducers reduce the water needed in the mix by 5%-10%. High-range water reducers reduce the mix water needed by 12% to 30% but are very expensive and rarely used in residential work.