ICRI Concrete Slab Moisture Testing Technician (CSMT)

When testing a concrete slab that is drying from only one side (e.g., slab on grade with vapor retarder beneath), ASTM F2170 requires that the relative humidity probe be inserted at what depth as a percentage of the slab thickness?

• A40% of the slab thickness
• B20% of the slab thickness
• C50% of the slab thickness
• D60% of the slab thickness

ASTM F2170 requires that relative humidity probes equilibrate in their installed holes for a minimum of how many hours before a reading is recorded?

• A72 hours
• B24 hours
• C48 hours
• D12 hours

Many flooring adhesive manufacturers and flooring industry standards cite 75% relative humidity as the maximum allowable in-situ RH level for installing resilient flooring over concrete. If a slab tests at 78% RH, the correct course of action is to:

• ADelay installation and allow additional drying time or apply a vapor mitigation system be…
• BProceed with installation since 78% is close enough to the 75% threshold
• CIncrease HVAC airflow over the slab surface for 24 hours, then immediately re-test and in…
• DApply flooring adhesive and install immediately because adhesive tolerances absorb minor…

ASTM F1869 is the standard test method for measuring moisture vapor emission rate (MVER) using anhydrous calcium chloride. What is the standard test duration for the ASTM F1869 calcium chloride test?

• A60 to 72 hours
• B24 hours
• C48 hours
• D7 days

According to ASTM F1869, what is the commonly cited maximum moisture vapor emission rate (MVER) threshold for most standard resilient flooring adhesive installations?

• A3 pounds per 1,000 square feet per 24 hours
• B5 pounds per 1,000 square feet per 24 hours
• C8 pounds per 1,000 square feet per 24 hours
• D1 pound per 1,000 square feet per 24 hours

Before placing the calcium chloride dish for an ASTM F1869 test, the slab surface must be prepared. Which of the following correctly describes the required surface preparation?

• ARemove all surface contaminants, coatings, and adhesive residue by mechanical means; the…
• BApply a concrete primer and allow it to cure for 24 hours before placing the dish
• CWet the slab lightly with water and allow it to surface-dry for 30 minutes before placing…
• DSweep the area clean and place the dish directly over any existing floor coating

ASTM F1869 specifies that the test area must be conditioned at a minimum temperature and relative humidity for a minimum time before testing. What are those requirements?

• AMinimum 65°F and 40% to 60% RH for at least 48 hours before testing
• BMinimum 60°F with no humidity specification for 24 hours before testing
• CMinimum 70°F and 50% RH for at least 72 hours before testing
• DAny temperature above freezing for 12 hours before testing

ASTM F2659 describes a method for measuring concrete moisture using an electrical impedance meter. Compared to ASTM F1869 and ASTM F2170, how is ASTM F2659 best characterized?

• AAs an indicative (screening) test only — results cannot be used as the sole basis for flo…
• BAs a primary test method with results that supersede ASTM F1869 calcium chloride test res…
• CAs equivalent to ASTM F2170 for measuring in-situ relative humidity throughout the slab d…
• DAs a destructive test method requiring core sampling

A concrete slab is 6 inches thick and is suspended above grade, exposed to air both above and below (drying from two sides). At what depth should the ASTM F2170 RH probe be installed?

• A1.2 inches (20% of 6-inch slab thickness)
• B2.4 inches (40% of 6-inch slab thickness)
• C3 inches (50% of 6-inch slab thickness)
• D4.8 inches (80% of 6-inch slab thickness)

ASTM F710 — the standard practice for preparing concrete floors to receive resilient flooring — requires that the concrete surface pH not exceed which value?

• ApH 9
• BpH 7
• CpH 11
• DpH 12

Subfloor flatness is often specified using F-numbers per ASTM E1155. In F-number notation, what do the terms FF and FL represent?

• AFF measures local flatness (short-wave waviness); FL measures overall levelness (long-wav…
• BFF measures the floor's fire resistance rating; FL measures floor load capacity
• CFF is the finished floor rating; FL is the floor levelness measured with a laser
• DFF and FL both measure flatness but at different frequency intervals with no distinction…

A common rule of thumb for estimating the drying time of normal-weight concrete before it can receive moisture-sensitive flooring is approximately:

• A28 days per inch of slab thickness under standard conditions
• B7 days per inch of slab thickness under standard conditions
• C90 days per inch regardless of conditions
• D14 days total regardless of slab thickness

What is the primary purpose of a vapor retarder installed beneath a concrete slab on grade?

• ATo reduce the transmission of ground moisture vapor upward through the slab by providing…
• BTo improve the compressive strength of the slab by preventing moisture loss during curing
• CTo provide thermal insulation between the ground and the slab
• DTo prevent the slab from cracking due to differential settlement

ASTM E1745 classifies polyethylene vapor retarders into three classes based on performance. Which class has the lowest permeance and is most appropriate for moisture-critical flooring applications?

• AClass A
• BClass B
• CClass C
• DClass D

How do curing compounds applied to the surface of fresh concrete affect subsequent moisture testing for flooring installation?

• AThey trap moisture inside the slab by reducing evaporation, potentially increasing intern…
• BThey accelerate slab drying by pulling moisture to the surface through capillary action
• CThey have no effect on moisture testing because they are fully removed by normal slab tra…
• DThey lower the pH of the concrete surface, which improves adhesive bond strength

Moisture Vapor Emission Rate (MVER) and in-situ Relative Humidity (RH) measure different aspects of concrete moisture. Which statement best distinguishes these two measurements?

• AMVER measures the rate of moisture vapor leaving the slab surface; in-situ RH measures th…
• BMVER is measured by drilling a hole and inserting a sensor; in-situ RH is measured by a d…
• CMVER provides a more accurate prediction of long-term flooring performance than in-situ RH
• DBoth measurements are equivalent; either can be used interchangeably for flooring install…

When drilling holes for ASTM F2170 relative humidity probes, which of the following practices is correct?

• AUse a rotary hammer drill with a carbide-tipped bit sized to the probe sleeve diameter; c…
• BUse a water-cooled diamond core drill to prevent heat generation, and fill the hole with…
• CDrill into a cracked area of the slab to ensure a representative sample of the weakest zo…
• DThe hole diameter should be twice the diameter of the probe to allow free air circulation…

How many calcium chloride test kits does ASTM F1869 require per 1,000 square feet of slab for a standard installation of resilient flooring?

• A3 kits (minimum) for the first 1,000 sq ft, with 1 additional kit per additional 1,000 sq…
• B1 kit per 1,000 sq ft
• C5 kits per 1,000 sq ft
• D1 kit total regardless of slab area

When performing relative humidity testing per ASTM F2170, what is the minimum number of probe locations required for areas up to 1,000 square feet?

• A3 probe locations
• B1 probe location
• C5 probe locations
• D10 probe locations

An ASTM F2170 test report must include which of the following chain-of-custody and reporting elements?

• ADate of drilling, date and time of each reading, probe identification number, probe depth…
• BOnly the final RH percentage reading and the technician's signature
• CThe concrete compressive strength and original mix design
• DThe flooring manufacturer's name and the adhesive product selected for installation

A concrete slab has been in place for 4 months. However, a new HVAC system was installed and started operating two weeks before flooring testing. Why might this affect ASTM F2170 results?

• AThe HVAC system changes the ambient temperature and humidity conditions, which directly i…
• BThe HVAC system vibrations can dislodge probe sleeves and invalidate readings
• CHVAC introduction has no effect on concrete slab moisture; only the concrete age matters
• DHVAC systems accelerate carbonation of the concrete surface, which lowers pH and invalida…

Radiant heat tubing embedded in a concrete slab is activated prior to flooring installation. How does this affect moisture testing?

• ARadiant heat accelerates moisture migration toward the slab surface, potentially producin…
• BRadiant heat has no effect on moisture distribution within the slab
• CRadiant heat drives moisture downward away from the surface, increasing probe-depth RH re…
• DRadiant heat causes the concrete to fully cure, permanently eliminating all residual mois…

Which of the following slab conditions would most likely lead to the HIGHEST moisture vapor emission rate when tested with ASTM F1869?

• AA slab on grade without a vapor retarder, over moist soil, in a warm humid environment
• BA suspended slab in a conditioned space with RH maintained at 50%
• CA slab on grade with a Class A vapor retarder, tested in winter with HVAC dehumidification
• DA slab tested 6 months after placement in a well-ventilated, climate-controlled building

Before performing any ASTM F2170 or F1869 moisture test, the technician must document the HVAC operating conditions at the time of testing. Why is this required?

• ABecause ambient temperature and relative humidity directly affect the rate of moisture va…
• BBecause the HVAC system must be shut down during testing to avoid air movement over the t…
• CBecause the HVAC contractor must review and approve all moisture test reports before floo…
• DBecause documenting HVAC conditions is required by the general contractor's insurance pol…

In the context of concrete slab moisture testing, what does 'equilibrium relative humidity' mean?

• AThe stable RH level reached within the drilled hole after the probe has been sealed for t…
• BThe outdoor ambient RH that must be matched before any testing can begin
• CThe RH of the slab when it was originally placed and before any drying occurred
• DA theoretical 100% RH value used as a baseline to calculate moisture content

When calculating moisture vapor emission rate (MVER) from an ASTM F1869 test, the technician weighs the calcium chloride dish before and after exposure. The formula for MVER in lbs/1,000 sq ft/24 hr is:

• A(Weight gain in grams × 1,000) / (slab area in sq ft × test duration in hours) × 24 — adj…
• BWeight gain in grams divided directly by test hours
• CWeight gain in ounces multiplied by the number of days of testing
• DWeight gain in grams divided by total test area in square meters

A project specification requires that all moisture testing comply with ASTM F2170. The slab is 5 inches thick and is on grade with a vapor retarder beneath it. Where should probes be placed, and at what depth?

• AProbes placed in the slab body (avoiding edges, cracks, and drains), drilled to 2 inches…
• BProbes placed anywhere on the slab surface, drilled to 2.5 inches depth (50% of 5 inches)
• CProbes placed at the slab perimeter only, drilled to 1 inch depth (20% of 5 inches)
• DProbes placed at expansion joints, drilled to 4 inches depth (80% of 5 inches)

What is the primary difference between a vapor retarder and a vapor barrier in the context of sub-slab applications?

• AA vapor retarder has a measurable but low permeance (e.g., ≤0.1 perms per ASTM E1745 Clas…
• BA vapor retarder is installed above the slab; a vapor barrier is installed below the slab
• CA vapor retarder is made of fiberglass; a vapor barrier is made of polyethylene
• DA vapor retarder controls liquid water; a vapor barrier controls water vapor

A technician opens a sealed RH probe hole after 48 hours (instead of the required 72 hours) and records a reading. Compared to the true slab RH, this premature reading will most likely be:

• ALower than the true value, because the hole has not fully equilibrated with the surroundi…
• BHigher than the true value, because moisture continues to accumulate in the hole over time
• CIdentical to the 72-hour reading, because equilibration is essentially complete by 48 hou…
• DHigher than the true value, because drilling generates heat that temporarily inflates RH

ASTM F710 requires pH testing of concrete floors before installing resilient flooring. How is the pH test typically performed in the field?

• ADampen a small area of the concrete surface with distilled or deionized water, wait one m…
• BDrill a core sample and test the pH of the core in a laboratory
• CApply a few drops of phenolphthalein indicator solution to the dry concrete surface
• DTest the pH of the water used to clean the slab before flooring installation

What is the maximum allowable surface pH for concrete floors per ASTM F710 Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring?

• A9
• B7
• C11
• D8

A flooring contractor receives an ASTM F2170 test report showing that three probes in a 2,000 sq ft area read 68%, 71%, and 79% RH. The flooring manufacturer's threshold is 75% RH. What is the appropriate course of action?

• AThe installation cannot proceed as-is because one probe exceeds 75% RH; the high-reading…
• BAverage the three readings (72.7% average) — since the average is below 75%, installation…
• CProceed because only one probe exceeded the limit and two are below it; majority rule app…
• DDrill additional probes in the area that read 79% and average those new readings with the…

What type of topical treatment is commonly applied to concrete floors to reduce moisture vapor transmission when slab RH or MVER exceeds the flooring manufacturer's threshold?

• AEpoxy moisture vapor reduction coating or a topical sealer rated for the measured moistur…
• BLatex primer applied to the slab surface
• CConcrete curing compound applied after the slab has cured
• DPolyurethane floor finish applied over existing flooring adhesive

The water-cement ratio (w/c) of a concrete mix significantly affects slab drying time. Which statement correctly describes this relationship?

• AA higher w/c ratio results in more evaporable water and a longer drying time before the s…
• BA higher w/c ratio accelerates drying because more water evaporates quickly from the surf…
• Cw/c ratio has no effect on drying time; only slab thickness matters
• DA lower w/c ratio always produces higher in-situ RH readings because less water is presen…

After completing ASTM F2170 testing, the technician seals the probes in the holes but does not record the probe serial numbers or calibration dates. Why is this a problem?

• AASTM F2170 requires that probe identification and calibration information be documented t…
• BIt is not a problem; probe serial numbers are only required for ASTM F1869 calcium chlori…
• CProbe serial numbers are optional documentation that may be included at the technician's…
• DCalibration information is only required when the measured RH exceeds 80%

Light-weight concrete (LWC) slabs, which use porous expanded shale or clay aggregate, generally dry differently than normal-weight concrete slabs. Which statement correctly describes this difference?

• ALightweight concrete absorbs and retains more moisture than normal-weight concrete and ty…
• BLightweight concrete dries faster than normal-weight concrete because the porous aggregat…
• CLightweight concrete and normal-weight concrete have identical drying characteristics if…
• DLightweight concrete always tests below 75% RH within 28 days regardless of thickness

What is the significance of the 'anhydrous' specification for calcium chloride used in ASTM F1869 testing?

• AAnhydrous calcium chloride has had all water removed, so any weight gain during the test…
• BAnhydrous calcium chloride absorbs water more slowly, providing a more accurate average r…
• CAnhydrous calcium chloride is safer to handle than hydrated forms and reduces worker expo…
• DAnhydrous designation means the calcium chloride meets ASTM purity requirements for the s…

A concrete slab was placed with a vapor retarder directly below it (concrete placed directly on the vapor retarder). How does the vapor retarder placement affect slab drying compared to a slab placed over granular fill without a vapor retarder?

• AThe vapor retarder blocks downward moisture escape, forcing all drying to occur upward th…
• BThe vapor retarder accelerates drying by reflecting heat energy back into the slab and in…
• CThe vapor retarder eliminates all moisture issues in the slab by preventing ground moistu…
• DThe slab drying time is unaffected by the presence of a vapor retarder

During an ASTM F1869 calcium chloride test, which of the following actions would INVALIDATE the test results?

• ALifting or disturbing the sealed dome during the 60–72 hour test period
• BTesting with the HVAC system operating normally
• CTesting in an area that was mechanically abraded to remove a curing compound before placi…
• DWeighing the dish on a calibrated scale before and after the test

When a concrete slab surface exhibits efflorescence (white salt deposits on the surface), what does this indicate about the slab's moisture condition?

• AActive moisture vapor transmission through the slab, carrying dissolved salts to the surf…
• BThe slab has fully dried and the salts are a permanent cosmetic feature
• CThe slab has a low w/c ratio and is not a moisture concern for flooring
• DEfflorescence indicates contamination from construction chemicals and is unrelated to moi…

Which of the following accurately describes the relationship between concrete slab temperature and relative humidity measurement in ASTM F2170 testing?

• ARH is temperature-dependent; a change in slab temperature between installation and measur…
• BRH measurements are independent of temperature and do not require thermal equilibration
• CHigher slab temperatures always produce lower RH readings regardless of the actual moistu…
• DTemperature affects MVER readings (F1869) but has no effect on in-situ RH readings (F2170)

A project has a 4-inch thick normal-weight concrete slab on grade. Using the industry rule of thumb, approximately how many months of drying would be expected before the slab might be ready for moisture-sensitive flooring under standard conditions?

• AApproximately 3.7 months (4 inches × 28 days = 112 days ≈ 3.7 months)
• BApproximately 1 month (4 weeks total)
• CApproximately 6–12 months minimum regardless of slab thickness
• DApproximately 14 days per inch (56 days total ≈ 2 months)

What does the term 'indicative test' mean when applied to ASTM F2659 electrical impedance testing?

• AThe test provides comparative screening results that can identify areas of relative moist…
• BThe test results are fully indicative of the actual in-situ relative humidity at the 40%…
• CThe test indicates only whether moisture is above or below 50% RH with no measurement pre…
• DAn indicative test is one that requires 72 hours to complete before results are valid

What is the ICRI (International Concrete Repair Institute) CSMT credential designed to certify?

• ATechnicians who demonstrate verified knowledge and competence in performing concrete slab…
• BConcrete structural repair specialists who perform post-tensioning work on bridge decks
• CFlooring installation contractors who specialize in resilient flooring products
• DBuilding inspectors who evaluate concrete slabs for code compliance and structural adequa…

When ASTM F1869 test results and ASTM F2170 results for the same slab area disagree — for example, F1869 calcium chloride shows an acceptable MVER of 2.5 lbs but F2170 probes show 82% RH — which result governs the flooring installation decision?

• AThe flooring manufacturer's specification governs; if they specify F2170 as the required…
• BThe lower (more favorable) result always governs, so the F1869 acceptable result allows i…
• CF1869 always takes precedence because it is the older, more established standard
• DBoth tests must pass simultaneously; otherwise, the test with the more favorable result i…

A technician is testing a slab that was newly placed 45 days ago. The project specification states that 'all HVAC systems must be operational and maintaining service conditions for at least 14 days prior to moisture testing.' The HVAC was started only 5 days ago. What should the technician do?

• ANotify the project team that testing cannot begin until the HVAC has been operating at se…
• BProceed with testing immediately since the slab is already 45 days old and well past the…
• CAverage the 5-day HVAC runtime with the slab age (45 days) to determine readiness
• DTest one probe location first; if it is below 75% RH, proceed with full testing regardles…

A slab on grade was tested with ASTM F1869 calcium chloride three months ago and passed at 2.1 lbs/1,000 sq ft/24 hr. Flooring installation was delayed, and the building envelope was not closed during the rainy season. Before flooring installation, what must be done?

• ARe-test the slab — previous passing results are invalid because the moisture conditions h…
• BProceed with installation because the slab already passed testing three months ago
• CAverage the old result (2.1 lbs) with a spot check in one area to confirm acceptability
• DApply an epoxy coating over the slab as a precaution and install without re-testing