What are they? Do I need them?Concrete admixtures are used to improve the behavior of concrete.
There will always be the next best thing with concrete. Every manufacturer has their own mix design, when trying new mix designs, practice makes perfect. Write down your mix design to start, to ensure your basic design. Test your mix design and make changes as necessary. While the basic mix design used by most is 1 part portland to two parts sand, below are some admixtures to achieve the final product you are looking for.
Air-Entrainment (beneficial for northern states)
Air entrained concrete can increase the freeze-thaw durability of concrete. This type of admixture produces a more workable concrete than non-entrained concrete while reducing bleeding and segregation of fresh concrete. Improved resistance of concrete to severe frost action or freeze/thaw cycles.
Reduce the required water content for a concrete mixture by about 5 to 10 percent. Consequently, concrete containing a water-reducing admixture needs less water to reach a required slump than untreated concrete. The treated concrete can have a lower water-cement ratio. This usually indicates that a higher strength concrete can be produced without increasing the amount of cement.
Plasticizers or high-range water reducers (HRWR), reduce water content by 12 to 30 percent and can be added to concrete with a low-to-normal slump and water-cement ratio to make high-slump flowing concrete. Flowing concrete is a highly fluid but workable concrete that can be placed with little or no vibration or compaction. The effect of superplasticizers lasts only 30 to 60 minutes, depending on the brand and dosage rate, and is followed by a rapid loss in workability.
Fiber reinforced concrete is one of the fastest growing segments in the concrete industry. Building professionals and concrete contractors are increasingly turning to the use of fibers in different shapes, sizes, and colors to reinforce concrete for many building applications. These fibers may be steel, synthetic, glass, cellulose, or natural materials such as sisal, jute, or sugar cane byproducts.
Micro Fibers – Generally used to increase the toughness and post-crack load carrying capacity, micro fibers may be used in any application to improve durability. An extremely high number of micro fibers uniformly disperse multi-dimensionally throughout the concrete mixture, helping to prevent cracking that might permanently weaken concrete. With the use of micro fiber admixtures, permeability is decreased, while surface characteristics, impact, and toughness properties are improved.
Macro Fibers – Unique for the level of strength it provides, macro fibers are specifically designed for ease of use, disperse ability, good finish ability, and improved pump ability. They add toughness, and increase concrete’s resistance to impact and fatigue. Unlike traditional micro fiber reinforcement, macros fibers are specifically engineered to provide high, post-crack control performance. They are best suited for use in flooring and other flat-work applications, as well as in form work applications.
While there are other additives for our industry, the above are the most commonly used by statue manufactures. Do you have to use additives, no, will they produce a better product, yes. Test different mix designs and you be the judge…
Would you like to try additives in your mix? Fritz-Pak Corporation does offer sample sizes of their products. Give their products a try, you will be impressed. Click HERE to visit their site. Request some samples and give us your opinion.