Concrete additives or release agents that contain contaminants, can cause compliance problems for the municipal drinking water utility and present potential health risks to the consumer.
Drinking water contaminants can come from many sources, including the equipment used for water storage and transportation. Concrete used in large storage tanks, reservoirs and pipelines is usually a combination of cement, admixtures, curing compound, sand and gravel. It can also contain fly ash and other additives to strengthen the concrete and increase its durability. However, any of these additives can have contaminants that can cause compliance problems for the utility and present potential health risks to the consumer. If any of these additives can have contaminants that can cause compliance problems for the utility and present potential health risks to the consumer.
The following are excerpts pertaining to release agents.
5 Barrier materials
The requirements of this section apply to products and materials intended to form a barrier providing containment of drinking water or to prevent drinking water contact with another surface. The products and materials that are covered include, but are not limited to: coatings and paints applied to fittings, pipes, mechanical devices and non residential storage tanks, linings, liners, bladders and diaphragms, and constituents of concrete and cement-mortar (e.g., Portland and blended hydraulic cements, admixtures, sealers, and mold release agents. These products and materials can be field-applied, factory applied, precast, or cast in place.
5.2.10 form/mold release agent: A material applied to the inside of a form or mold used to cast concrete or cement-mortar, which prevents adhesion of the concrete or cement-mortar to its surface.
5.5 Extraction Procedures
220.127.116.11 Products requiring cement mortar cubes
Test sample mortar cubes shall be prepared in accordance to the applicable sections of ASTM C 109. Mix water shall meet reagent water requirements (see Annex B, section B.9.2.1 ). Sand shall be washed in accordance with the procedures in ASTM C 778. Mixing tools and other items coming into contact with the mortar shall be washed with soap and water, rinsed with tap water, rinsed with reagent water, and rinsed with isopropyl alcohol. The mortar shall be placed in polyethylene or polypropylene lined molds; no form release agents shall be used. Specimens shall be removed from the molds after 24 h and placed in glass or polyethylene beakers and covered with an inverted watch glass supported on glass Rebel hooks (or other devices to prevent air seal of the vessel) and placed for 28 d ± 12 h, or fewer as specified by the manufacturer, in a moist cabinet meeting the requirements of ASTM C 511. The specimens shall be removed from the moist cabinet and air dried at 23 ± 2 °C (73 ± 4 °F) and 50 ± 5% relative humidity for 7 d.
18.104.22.168.4 Form and mold release agents
These products shall be applied per manufacturer specifications to the mold used during the preparation of the test cubes (see 22.214.171.124 ).
5.5.4 Conditioning (optional)
Test samples shall be conditioned immediately after curing. This conditioning procedure simulates the disinfection of water mains and storage tanks prior to placing into service, and is based on AWWA Standards C651-05 and C652-02. Coatings intended for pipes and fittings can be conditioned as follows:
1) prepare 50 mg/L free available chlorine solution using sodium hypochlorite (NaOCI - reagent grade or equivalent);
2) using a spray bottle, spray the previously rinsed test samples, wetting all surfaces to be exposed;
3) let the test samples stand for at least 3 hours; and
4) place the test samples in racks, rinse with cold tap water, and rinse with reagent water, meeting the requirements of Annex B, section B.9.2.1.
5.5.5 Exposure protocols
For all test samples, exposure shall commence immediately following the conditioning step. If immediate exposure is not possible, the test samples shall be dried in a laminar flow hood and exposed within 4 h. Successful evaluation at an elevated exposure temperature shall preclude testing at a lower exposure temperature. A separate sample shall be exposed for each type of exposure water selected in 5.5.3.
The exact surface area-to-volume ratio achieved during the exposure shall be recorded.
126.96.36.199 Cold application
Cold application product samples, as designated by the manufacturer, shall be placed in an exposure vessel and completely covered with exposure water of the applicable pH (see 5.5.3). The exposure vessel shall be placed in a 23 ± 2 °C (73 ± 4 °F) environment for the duration of the exposure period.
Benefits of NSF Certification
To help minimize the risk of contaminants, NSF certifies individual concrete ingredients to the requirements of NSF/ANSI Standard 61: Drinking Water System Components – Health Effects. Our Concrete Site Mix Design Evaluation Program provides a one-time evaluation that certifies concrete consisting of non-certified cement or other ingredients against this same standard.
NSF/ANSI 61 testing covers all products with drinking water contact from source to tap, and determines what contaminants may migrate or leach from your product into drinking water. It also confirms if they are below the maximum levels allowed to be considered safe.
NSF Certification Process
We require information on each ingredient in the site mix and details of its end use structure. Since we have worked with the cement admixture industry for over 20 years, we are able to obtain any additional information on ingredient composition relatively quickly. We perform testing on concrete cylinders manufactured from the mix, including analysis for the potential release of regulated metals, radionuclides, volatile organics and other contaminants that may leach directly into drinking water. Results are typically available in 30 days or less.
For additional information, read these articles published in Precast Inc. by the Hill and Griffith Company:
- "Biodegradability Redefined and Volatile Organic Compounds Update" by Bob Waterloo, Precast Inc.,
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- Biodegradable, NSF Concrete Form Release Agents Offer a Range of Options for Concrete Applications
Read More »
Precast Concrete in Google News and NPCA, National Precast Concrete Association
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