Question:

We want to improve our concrete curing standards. I have heard that there is now a new standard, ASTM 1315, which addresses our concerns. Can you tell me more about it?

Answer:

Congratulations on your interest in improving your concrete quality by paying extra attention to the curing phase.

As you mention in your question, in the past, the design professional had to either refer to outdated standards like the TT-C 800A or modify some of the language of existing standards (ASTM C 309) to ensure a high solids curing and sealing membrane of sufficient moisture retention and ultraviolet stability. This modifying language did not lend to the pursuit of clarity or uniformity that design professionals aspire to reach. The products' performance being specified needed to become standardized, which would simplify the bidding and product selection.

These mounting needs are now being met by the ASTM Standard Specification for Liquid Membrane-Forming Compounds, having Special Properties for Curing and Sealing Concrete. The numerical designation is ASTM C 1315 as published in volume 04.02. Materials meeting this standard will assist in the prevention of concrete dusting and provide excellent curing conditions for the concrete, as well as produce a surface hospitable to bonding adhesives.

The ASTM C 1315 standard provides precise requirements for membrane forming liquids. These membrane-forming liquids are intended to be applied to the surface of either fresh concrete or hardened concrete. The resulting membranes must demonstrate alkali resistance, mild acid resistance, and promote adhesion properties. Additionally, these membranes are able to have some predictable level of resistance to ultraviolet degradation which can be called out by selecting a particular class, namely, Class A essentially non-yellowing; Class B moderate yellowing allowed; or Class C not restricted as to yellowing.

The general requirements of an ASTM C 1315 membrane forming liquid are: 1) a minimum of 25% polymer solids, 2) a moisture loss maximum of 0.4 kg of water per square meter in 72 hours, 3) standard coverage of 300/sq.ft./gallon (7.5 sq.meter/liter) and 4) a promotion of adhesion of tile mastics, listed at 145 p.s.i. pull-off strength.

L&M Construction Chemicals, Inc. offers a number of ASTM C-1315 conforming products. The most popular ones are our solvent-based DRESS & SEAL and low odor, waterbased DRESS & SEAL #30. For completely non-yellowing, Class A performance we recommend solvent-based LUMISEAL PLUS and its water-based equivalent, LUMISEAL PLUS WB. All products comply with national EPA/VOC regulations, but the use of solvent-based formulas is prohibited in some states.

Sharpen up the concrete curing standards in your specifications and lend an air of professionalism to the concrete placement and finish work by using polymer based curing and sealing, membrane-forming liquids which comply with ASTM C 1315. For more information about this specification or L&M products that deliver extra curing protection, please contact L&M Construction Chemicals, Technical Department, or visit our product catalog. Thanks for asking.