Apr 22, 2011 · For a new parking garage floor with specified 5% to 8% air entrained concrete, and a urethane waterproofing membrane 60 mils thick, a wood float finsh is too rough. The concrete requires a steel trowel finish according to the membrane manufacturers. CSA Standard S413 says that a "single pass" of the steel trowl is ok on the air entrained concrete.

May 21, 2013 · Excerpt from A23.1 "7.5.4.3.2 Exterior or air-entrained concrete One or more passes of a magnesium float or concrete broom shall be made at suitable time intervals to obtain a level finish free of ridges. A steel trowel finish shall not be applied to air-entrained concrete."

Feb 4, 2008 · We specified 3500 psi non-air entrained concrete at slab on grade for a commercial project, and the GC poured 3500 psi air entrained concrete. Does it make a difference? I would appreciate your input.

Jul 23, 2012 · Perhaps a way to minimize problems associated with finishing of air-entrained concrete slabs is to specify in (Div 3 of Specicification and Structural Notes)acceptable finishing methods, require the work be done by ACI certified concrete flat work finishers, and require post-concrete placement inspection of finishing.

Jun 23, 2016 · The engineer who wrote the specifications states that the air entrainment is required for workability of the concrete. This seems to be an issue of means and methods. Also, there are much more economical alternatives to improve workability where we are located. As this is not normally done, air-entraining concrete is vert costly.

Nov 2, 2011 · If you decide to specify air-entrained concrete, I would suggest conforming to codes based on the type of exposure. For example, ACI 318-02, Table 4.2.1 gives total air content of 5% for nominal aggregate size of 3/4" and moderate exposure.

Jul 29, 2005 · The summerized specs read: for normal weight concrete air content = •no entrained air for concrete placed in foundation •5% +- 1.5% entrained air UNO •3% +- 1.0% entrained air for mixes with compressive strength greater than or equal to 5000 psi •4% +- …

Aug 25, 2010 · So freeze/thaw is expected. The drawings specify 4,000 psi and 6% +/- 1.5% air content. I received documents of (2) samples which tested (3) cylinders each. One sample says that % air (T152 or T196) is 3.0% and has 28 day strengths of 6250, 6050, and 6150 psi. So the air is lower than specified but the strength is higher than required.

Dec 28, 2003 · It is somewhat similar with air entraining, the microscopic entrained air bubbles don't allow quite as dense of a surface finish. It is fine for exterior work where you trade-off some finishing charactoristics for freeze/thaw charactoristics. Interior concrete is expected to have a more dense finish, better looking finish.

Aug 5, 2009 · In my area, air entrained concrete is used more often than non-air entrained. Further, most slabs get hard troweled finishes. The article JAE provided is a good one and points out some of the pitfalls of the blistering issues that can occur. One key to controlling the blistering is controlling the bleed rate relative to the finishing process.