SCP Tech Brief: Moisture Testing of SCP-Treated Concrete
Spray-Lock Concrete Protection (SCP) frequently gets asked about performing moisture testing of treated concrete. SCP technology is different than many moisture mitigation treatments because it penetrates into the concrete matrix, blocking the concrete capillaries and pores instead of sealing the surface. Some flooring and coating companies have had questions about testing SCP-treated substrates. SCP products should be regarded like all other moisture mitigation solutions. Other systems for vapor control that are applied after concrete placement do not require testing because there are not relevant or there are not applicable tests available. All treatments of coatings, reactive penetrants or patching and leveling systems preclude all standard tests for moisture vapor emissions. Flooring and coating companies, owners and contractors alike rely on the warranties of the manufacturers to proceed with application and look to them for solutions if problems arise.
Moisture Vapor Emission Rate (MVER) testing is one of the most commonly requested tests. The following is statements of why the MVER Test (ASTM F1869-16a Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride) should not be used for evaluating moisture evaporation rate of treated concrete subfloors.
ASTM F1869-16a states the following in the scope for the test standard:
1.2 This test shall not be used to evaluate the rate of moisture vapor emitted by gypsum concrete or floors containing lightweight aggregate.
1.3 This test shall not be used to evaluate moisture vapor emissions over coatings on concrete or through reactive penetrants or over patching or leveling compounds.
SCP products work by penetrating into the bleed water channels, capillaries, and voids left in the concrete as bleed water exits. Once in the concrete, SCP products react with available alkalis to primarily form Calcium Silicate Hydrate (C-S-H), the same reaction product provided by cement hydration that provides most of concrete’s desirable properties.
Based on the most current publication of the ASTM F1869 testing scope and how SCP products work within the concrete reacting with available alkalis, the test method should not be used to determine MVER for SCP treated concrete.
Another common test method requested is the Relative Humidity (RH) Test (ASTM F2710 Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using In-Situ Probes). This test method determines that relative humidity in the concrete matrix by placement of a probe embedded into the concrete and readings taken once the probe has become acclimated to the surrounding concrete. SCP products trap moisture in the concrete to by blocking off the capillaries and void spaces. The reaction products formed fill the capillaries and voids and shutdown liquid water transmission. This process allows for longer hydration of the concrete. By trapping the moisture in the concrete, the relative humidity will typically remain high for an extended period of time.
Other test methods of obtaining moisture readings can give misleading results as the previous test methods. SCP products are trapping the remaining moisture in the slab to enhance the curing of the concrete structure.
SCP does not feel that these test methods provide useful information for determining the effects of SCP-treatment. As with any remediation system for moisture, flooring or coating applications should proceed by the manufacturer’s directions without further testing.