Now that a cold winter is upon many of us, some guidelines follow on deicer use for concrete pavers.
As a first step, always check the content of deicers sold. If the types of chemicals are not stated, the deicer company’s website should be visited as it typically includes material safety sheets with content descriptions.
Never the friend of any type of concrete, deicer damage can be minimized because the high density of pavers and slabs can limit absorption of deicers. In addition, a high cement content helps paving units resist damage from the stress of expanding ice on and inside them. Research and experience have highlighted factors affecting the winter durability of concrete pavers, including the utilization of:
- Aggregates with low absorption that will not degrade when subject to freezing and thawing with deicing materials
- Proper aggregate gradation that enables high density from compaction during manufacturing
- Sufficient cement paste to coat the aggregate and reduce capillary pores
- Sufficient compaction during manufacturing to ensure maximum density and uniformity
ASTM C936 Standard Specification for Solid Concrete Interlocking Paving Units includes freeze-thaw durability criteria for assessing the freeze-thaw durability and resistance to deicing salts. C936 references the test method ASTM C1645 Standard Test Method for Freeze-thaw and De-icing Salt Durability of Solid Concrete Interlocking Paving Units. C936 includes an optional lower freezing temperature to use in test method C1645 for regions of the U.S. that experience severe freezing conditions based on a climatic zone map. The optional testing in 3% saline for these regions is equivalent to the testing required in the Canadian concrete paver standard, CSA A231.2 Precast Concrete Pavers. To obtain a copy of ASTM C936 or ASTM C1645 visit www.astm.org. The CSA standard is available from www.csagroup.org.
A literature review prepared for the Utah Department of Transportation* in 2013 found that concrete exposed to sodium chloride experienced only minor, if any, adverse effects, while specimens exposed to calcium chloride, magnesium chloride, or calcium magnesium acetate (CMA) experienced significant deterioration, including scaling, cracking, mass loss and compressive strength loss. The report recommends that engineers responsible for winter maintenance of concrete pavements utilize sodium chloride whenever possible, instead of calcium chloride, magnesium chloride or CMA, and apply only the amount necessary to ensure safety of the traveling public. While the literature review did not specifically address segmental concrete paving, the findings support ICPI’s guidelines for deicing salt exposure. l
*Physical and Chemical effects of Deicers on Concrete Pavement: Literature Review, Report No. UT-13.09 Prepared for Utah Department of Transportation Research Division by Brigham Young University, July 2013.