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Concrete Scaling
April 26, 2008
Notice to all customers:
VanDerVaart has produced high quality concrete since 1888.
We have experienced professionals on staff to assist you with your ready-mixed concrete needs. Our staff are ACI/WRMCA certified in concrete testing, and our ready mix plants are certified each year. We are active participants in the Wisconsin Ready-mixed Concrete Association in an effort to keep informed on the latest information available in our industry.
During 2007 and 2008, the entire mid-west United States experienced a higher than normal amount of exterior concrete surface scaling. Reports from Iowa, Minnesota, Michigan and Ohio as well as Wisconsin have indicated a problem. Many independent Investigations are taking place to determine why the higher amount of problems occurred.
VanDerVaart Inc. has had relatively few calls on concrete we manufactured that has surface scaling, but we have had some. We are not avoiding the problem, and if we did provide a product that was at fault we will replace it.
There is no one single reason that concrete scaled at a higher rate in 2007-2008 than in the past. The winter weather seasons we experienced were unique and contributed to the problem, however properly placed concrete is freeze thaw durable. It is also clear that there is no single concrete producer, cement supplier or admixture company that experienced this problem. The problem occurred with all brands available and with almost every ready mix concrete producer.
Deicing and anti-icing materials have been used by municipalities and private snowplowing firms at an increased rate because of the above average snowfall and severe winters. Both the municipal and private firms found it difficult to acquire sufficient deicing materials because of the high demand, and as a result some are using materials that are extremely detrimental to concrete. If concrete is not properly cured and sealed, it is more likely to scale if these alternative deicers are used.
Ammonium nitrate, ammonium sulfate and magnesium chloride are types of deicers now being used that have not been used [or used very little] in the past. With the application of these materials to roads, streets and parking lots, the deicers cling to auto traffic and these deicers drip onto residential driveways.
Our industry is governed by the American Concrete Institute [ACI] and the American Society of Testing Materials [ASTM]. VanDerVaart recognizes these groups as the industry’s professionals and the documents they have drafted are the standards we follow.
ACI states that all exterior concrete in Wisconsin is to be 4500 psi. @ 28 days with a maximum .45 water/cementitious ratio. This specification is not always followed by concrete contractors because of relatively few problems in the past. We encourage all of our customers to follow the industry standards in effort to avoid potential problems.
There are six requirements for producing high quality exterior concrete flatwork.
- Proper sub-grade preparation
- Proper design
- Proper concrete mix
- Proper placement and finishing
- Proper curing
- Proper sealing and aftercare
There are three parties involved in the six steps as listed above and all need to do their part. The Ready-mixed concrete supplier, concrete contractor and the property owner all share in providing and maintaining durable concrete.
Richard Lohr
Chief Operating Officer
VanDerVaart, Inc.
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