Editor’s Note: This post was originally published in June 2018 and has been updated for accuracy and comprehensiveness. A concrete moisture meter is a type of moisture meter used by installers of flooring to measure the moisture levels of concrete.These meters have been used for decades to measure the moisture content in different materials and substances. Relative Humidity Testing (ASTM F2170) of the slab is done via special moisture probes embedded in the concrete substrate. In everyday use, Relative Humidity refers to how much water vapor is in the air at a given place and temperature. Moisture represents the presence of a liquid containing trace amounts of water. Measures moisture inside the concrete as % relative humidity. Nowadays, this process includes making cylinders or beams on site…, Monitoring the temperature of your pour after placement is one of the most important steps in the construction of a concrete structure. During the construction of a concrete building, an essential step in the application of flooring is the importance of monitoring the relative humidity (RH), moisture levels, and the moisture evaporation rate of your slab. The moisture content of grains is an essential property in food storage. Thank you for any advice you can provide on making sure the substrate is ready before the installer begins his work. With the increase and demand for more housing, in a shorter period of time, coupled with the use of laminated flooring systems, the failure rate of these flooring systems, being MDF or Ply based, or vinyl, has increased dramatically. Therefore, measuring RH levels at 40% depth of the slab (20% depth if drying on two sides), is more representative of the overall humidity conditions of the concrete. Additionally, other components (metal reinforcing bar, aggregate size, and amount, etc.) What is the conversion scale between RH and MC? Both categories are related by moisture isotherms. At first glance, relative humidity (RH) is a quite confusing topic. It is vitally important to test your concrete slab's moisture before installing flooring over it. In addition, drilling a hole in the concrete floor would change the flow of moisture, affecting the accuracy of RH measurements. Typical concrete failures due to relative humidity include: To avoid these failures from occurring, a variety of test methods are used to determine the amount of moisture in concrete before installing flooring. Relative Humidity Test (In-Situ Probe Test) Use a prepackaged relative humidity testing kit (must be compliant with the most recent ASTM F2170) and follow the manufacturer's instructions. The relative humidity is measured after allowing 72 hours to achieve moisture equilibrium within the hole. Relative Humidity Testing. Thanks for the comment and very good observations. Concrete, Gypsum, Wood . I can state though that I have never heard of moisture in concrete causing chipping or breaking of vinyl plank. Hi Jason, Required fields are marked *. You can call 1-800-634-9961 and ask for me specifically. Moisture content represents the amount of water in liquid form, while humidity levels represent the amount of water in vapor form. If we bring the air into our home and heat it to 72°F, the relative humidity drops to 7.59%. The shape and magnitude of such an isotherm depend on the pore size distribution of the material. Relative humidity (RH) is often mistaken for moisture; however, these terms measure two different characteristics of concrete. Concrete moisture meters should never be used to make the final determination as to whether or not a concrete slab is dry enough for a flooring installation. A further complication in such isotherms occurs from the associated hysteresis observed (presumably due to an ink-bottle effect) which can be predicted through, for instance, Mualem’s or Rubin’s model. When talking about wood MC and RH, there is a definite … We may share your information with our social media, advertising, and analytics partners. Thank you for the questions. There are three standard methods for measuring concrete moisture. Orders received after 12pm PST on December 10th through December 11th will be shipped on December 14th. As Sales Manager for Wagner Meters, Ron has more than 35 years of experience with instrumentation and measurement systems in different industries. Your email address will not be published. Relative humidity (RH) is often mistaken for moisture; however, these terms measure two different characteristics of concrete. We moved into a new build home on Feb 28, 2020 and have noticed the vinyl plank flooring starting to chip and break. That being said, in the wood flooring installation world, there are some adhesive companies that do recognize this type of testing, but you would have to consult them for acceptable numbers. Keep in mind that an uncovered concrete slab will indeed have an RH gradient (typically drier at the surface; much wetter at depth) throughout its thickness until a floor covering is put on top. Lars-Olof Nilsson, Moisture engineering institute. Sources of moisture in concrete: When flooring is installed and sealed too early, and not given enough time to dry, an excess of moisture is trapped inside the concrete. Missing or inadequate moisture barriers in a slab on grade, causing outside moisture to penetrate the slab. (The other, of course, is direct water that may come from a leaking appliance, flooding, standing water, or another source.) This means that a slab that may have been “dry” (low RH) at the surface (without a floor covering) will see a higher RH (migrated from down in the concrete) at the surface when the floor covering has been installed. There may still be sources of water within your concrete in the form of relative humidity. It is, indeed, understood that the relationship between moisture content and RH (adsorption/desorption isotherms) is not a unique one and does depend on concrete pore size distribution. Also what do you call the gauge used to measure these? … One can obtain such adsorption/desorption isotherms empirically (Xi et al., 1994) or using a knowledge of the pore size distribution, through a simple Kelvin’s law and Brunauer-Skalny-Bodor (BSB) model. This means that a slab that may have been “dry” (low RH) at the surface (without a floor covering) will see a higher RH (migrated from down in the concrete) at the surface when the floor covering has been installed. Thanks. Under normal conditions, the RH at roughly 50% slab depth will be significantly higher than the surface unless the slab has been down for a long time, and a vapor retarder is directly underneath the slab. Some of the more cutting-edge companies may have a higher number because they have done testing to confirm they can go higher. This is one reason that surface meters are intended for scanning of a concrete floor surface and not intended, per ASTM F2659, to be used to make an installation decision. October 31, 2000. But pin-type ‘moisture’ meters are also not practical for moisture measurement because variable chemical and physical characteristics in concrete can cause false readings due to changes in electrical resistance that have nothing to do with moisture. If half of the water is removed, the amount of moisture is now at 50% but RH is still at 100% because the air is still fully saturated with water. Does this same info apply if the subfloor is 1 1/4″ gypcrete that is being asked to seal when moisture meter reading says 26% And can I convert them together? AH right? Keep it up. Here’s why: No ‘moisture meter’ of any type can give consistently accurate ‘moisture’ readings across the different mixes and densities of concrete. That is why ensuring optimal curing conditions for your element is critical, especially during…, When it comes to any construction project that requires the use of concrete, whether it’s a hospital, residential building, road, bridge, or dam, concrete strength testing is an essential step in ensuring the integrity and durability…, How Curing Methods Affect High-Strength Concrete ASTM C31 is the standard that defines two different concrete curing conditions, standard curing and field curing. The flooring company came out and did a pin meter moisture test is a couple of areas beneath the vinyl and carpeting in different parts of the home. Equilibrium moisture content of grains. can cause false indications of ‘moisture’, especially with non-pin meters. In the technical data sheet of two suppliers differ in concrete moisture content : You can prevent flooring failures also with Vapor Barrier, special epoxy or polyurethane primer. – RH above a curved water meniscus slower than 100 %; lower the more curved the meniscus is, The sensor is fully embedded in your concrete (secured on the rebar) to measure internal RH and temperature variations overtime. Concrete slabs and floors can be excellent subfloor surfaces for tile and other floor coverings, but too much moisture in the concrete can cause problems with flooring installations. A reading, taken using a moisture meter, which shows 14% Moisture Content correlates to approximately 75% Relative Humidity in the concrete at the area being tested at that particular time. The development of an alternative moisture test method, the in situ relative humidity (RH) test, has not made the calcium chloride test method … In water damage situations depending on the amount and head of water the depth to which the moisure has been absorbed will vary greatly. We are al aware of the need for more housing, but left unchecked/regulated, without describing a minimum time lapse and testing for moisture content, prior to being allowed to laying a floor on concrete, will only result in product and possible concrete base failure claims against builders to rise in a very short period of time. We have been involved with concrete moisture testing for many years and agree there were shortcomings with the calcium chloride test. The most advanced and comprehensive of the three methods, this test measures the presence and quantity of moisture throughout the depth of the slab. Learn More Here! To better understand the concept of relative humidity, imagine a glass of water that is sealed. Measure moisture in concrete as a moisture vapor emission rate, or MVER, and as in situ relative humidity, or RH. What Is Concrete Curing? But drying can be a slow process and contractors often find themselves in conflict with construction schedules. Relative humidity is the main source of moisture for cut lumber or finished wood products. I recently observed an application where the horizontal ceiling slab delaminated, while the vertical walls were well bonded. Relative humidity is defined as “the ratio of the amount of water vapour actually in the air compared to the amount of water vapour required for saturation at that particular temperature and pressure expressed as a percentage.” Asking about humidity in the concrete should help us find a knowledgeable contractor for the job, so thanks for giving me the idea! It involves drilling a hole into the concrete and inserting a probe that measures moisture deep within the concrete matrix. Results show that pore water saturation, considered as the characterisation of moisture content, changes non-linearly with relative humidity in concrete; the evolution is significantly influenced by the water–cement ratio and temperature. Hydration is the chemical reaction between cement…, On any job site, the strength of a concrete pour is a critical piece of information. This equates to a moisture content of about 2%. 5.5% moisture content This is a trigger figure used by some product manufacturers to specify when concrete is dry enough to allow their product to be applied to it. The measurements of relative humidity in concrete assess the percentage of RH in the concrete as compared to the amount of RH that it can hold. Our office hours are 7:30am to 4:00pm PT, Monday through Friday. Moisture meters, similar to other non-quantitative test methods, are not final determination tools. We are still under warranty and do you think we may have serious foundation issues. Can you show me the relationship of these two quantities? If you continue using our site you consent to our cookies. This is done with a (de)sorption isotherm. Therefore, it's advisable to have a floor tested for moisture content prior to installing flooring or moisture barriers. Generally the internal relative humidity needs to be above 80% to 85% relative humidity for hydration to take place. A knowledge of the aforementioned illustrations is typically not available within the construction industry (and in fact a number of other practical fields dealing with porous materials). According to ASTM F2170, when drying, concrete slabs have lower moisture levels near the surface and higher levels towards the bottom of the slab. From the 1940s to today, many contractors have relied on surface-based methods for monitoring or evaluating relative humidity levels and moisture content. Your email address will not be published. This is where the problems occur. Concrete Cylinder Test: Which Method is More Effective? Wood is fairly straight forward, but I am not sure what the right method and device is for the surface of concrete. A Relative Humidity (RH) meter is a device that uses in-situ probes to get an accurate reading of moisture conditions deep within a material — typically a concrete slab. • Plug in Probe for Relative Humidity, Temperature, Dew-Point and Mixing Ratio readings ( optional ) But what exactly is the difference between relative humidity and moisture and why should you care? For example: 75% RH = what amount of MC? Nevertheless, it has to be noted that the primary objective behind the vast majority of these blog posts is to simplify some of the common concepts and not to provide an exhaustive summary of the state of knowledge. This water will try to evaporate, leading to pressure buildup in the concrete below the flooring which can cause damage and deterioration of your material. as lbs of moisture … This test method involves measuring relative humidity levels inside of the concrete … The 4-6% is usually measured with a surface moisture meter and the 75% RH is usually measured with a device such as http://www.rapidrh.com. moisture in the air is about .2%, even though the relative humidity is near 100%. The moisture can be regarded in the following two main categories in concrete: As a concentration (mass per volume) and as pore relative humidity. This, generally, provides a challenge in generating content that is both informative as well as simple for readers with little to no background on such topics. Daian, J. F. (2014). At best, moisture meters (pin-type or surface-type) may have some practicality as relative (qualitative, not quantitative) measurement devices for possibly indicating best placement for accurate, quantitative RH sensors within the concrete. • Instant Readings in Non-Destructive and Wood Probe modes. Save my name, email, and website in this browser for the next time I comment. Predictor of future moisture emission. They should be able to give you specific guidance on this that would cover their specific warranties. All my queries about this equipment got solved after reading this. Ratios: Relative humidity to moisture content Common conversions and instruments used in measuring wood moisture content. However, with these techniques, moisture is only measured at or near the surface of the concrete, and RH levels within the slab are not taken into consideration. Features: • Measures to 6,9% Moisture Content in Concrete. Under the vinyl the meter was maxed and under the carpet it was mid 80% reading, I purchased a meter at Lowes and checked it and got a 100% vinyl reading and 82-87% reading under the carpet. First for the meter readings you describe. environment is particularly low, the relative humidity in concrete will usually remain quite high after the majority of water has evaporated, typically about 75%. Purchase a Tramex RH moisture test kit (easiest way to test for RH in a Concrete slab) 2. In reality, the surface of the concrete will more closely reflect the RH in the room or building which gives no indication of the potential for a flooring failure due to the high RH deep in the slab that will migrate to the surface when the concrete can no longer emit water vapor due to the non-permeable floor covering. Simply put, relative humidity represents the amount of water vapor that is present in the air in comparison to the amount that the air can hold. Probes and wired sensors are examples of these in-situ methods. RELATIVE HUMIDITY In Situ TEST The Test Results Mapping Diagram provides a visual depiction of the numerical values represented over the concrete slab. What is a concrete moisture content on meters? Retaining moisture in concrete is a good thing if the ultimate goal is a good curing condition, but what if you must install finished flooring materials requiring low concrete relative humidity (RH)? Moisture content represents the amount of water in liquid form, while humidity levels represent the amount of water in vapour form. The relative humidity test Depth is one area where the relative humidity test excels. Moisture content represents the amount of water in liquid form, while humidity levels represent the amount of water in vapor form. The concrete pore structure influences its physical properties, … Being two different testing methodologies, there are no conversions. Concrete Maturity vs. You have to explain that If your concrete contains excess moisture and high RH levels this can lead to disastrous flooring failures, resulting in costly repairs and liabilities. Thanks for the question. Thank you! Im confused on that. content, 15 g/m2/24 hours and 75% relative humidity. When called upon to test the moisture readings it would be advisable to add a disclaimer and advise the flooring supplier should satisfy himself if the concrete moisure content is within acceptable range. This in it’s self is a concern for the health and well being of both the occupants and the installers. How to do a relative humidity test on a concrete floor. BlueRock™ is the most advanced wireless relative humidity and temperature sensor on the market. I never knew there was a difference between moisture and humidity until I begin to familiarize myself with the two. Understanding RH in concrete By using methods that analyze the moisture level within the slab, more accurate and reliable RH readings are available. Once a floor covering is placed on a concrete slab, the relative humidity (RH) within the slab will equilibrate throughout the thickness of the slab. It was interesting when you talked about how moisture levels in concrete can change up to six months after it’s poured. is 75% a typical RH level for a coatable concrete floor? Under constant temperature conditions, measurements of both relative humidity and moisture content in concrete are carried out synchronously. However, these techniques require you to drill multiple holes into your slab and continuously monitor the condition of the flooring, taking up time and costing money. Clean area and drill 3/4 inch hole to 40 percent of … Unlike current time-consuming methods that measure only one data point at the time of testing, this wireless sensor continually collects data. Relative Humidity Probe (ASTM F 2170) – This procedure involves measuring the relative humidity of concrete at a specific depth from the slab surface inside a drilled or cast hole in a concrete slab. Concrete Relative Humidity Test. A definitive test that measures the amount of moisture released from the concrete requires a calcium chloride kit or a relative humidity meter. Relative humidity (RH) testing goes back to at least the 1950s and 1960s, ... First and foremost, it would save 48 hours on the testing procedure and allow for quicker, documentable concrete moisture test results with which to make installation decisions. Since people use different terms such as moisture, vapour, water content, relative humidity, absolute humidity, actual humidity, specific humidity or just humidity to indicate how moist the air is, many of them feel confused when they come across the term “relative humidity”. Multiple factors can influence the amount of moisture in a concrete slab, thus contributing to high RH levels for up to six months or more after concrete is poured. As a Technical and R&D Support Specialist for Giatec Scientific, Sarah De Carufel utilizes her civil-engineering background to assist in the development of innovative products. I am trying to control the moisture in a room, and I would like to see which of my methods works the best. Hi Jason Upon removal of the carpet and under, moisture build up causing mould is clearly visible. Learn how your comment data is processed. The best way to answer this question is by contacting the gypcrete manufacturer and the flooring and adhesive manufacturer. I would like to assess the effect of surface moisture on spray foam adhesion. Good luck. This is where the problems occur. In any event, ALWAYS check with the individual manufacturer for their specific information. It is the standard that dictates the procedures for making and curing test…. The % water vapor is still .2% if all we do is heat the air. The initial amount of water in the concrete (from a high water/cement ratio); Ambient conditions such as high ambient relative humidity, cold temperatures, additional sources of water, and limited air movement; The use of pozzolans, such as silica fume, which tend to retain water and take longer to dry; and. Required fields are marked *. Consequently, it is different for different concretes. Wetting the surface of bare concrete creates a barrier of water that prevents the moisture from inside the concrete from being drawn out when the surface moisture evaporates. Moisture vapor emission from a concrete surface, and relative humidity within the slab, are strongly dependent on the relative humidity and temperature of the ambient air over the concrete surface. It would, certainly, be beneficial to present Kelvin’s effect or the influence of the water meniscus curvature on vapor pressure and, subsequently, the equilibrium between vapor and liquid phases. Proper documentation of test results for all tests includes: Start date and time of testing with ambient temperature and humidity. The moisture content that is safe for long-term storage is 12% for corn, sorghum, rice and wheat and 11% for soybean. Since we closed and moved in Feb the slab is less than a year old, we do you recommend? It also helps monitor: Interested in measuring relative humidity and temperature of concrete? In this case, you’ll need your slab to dry out as soon as possible. Three Methods for Testing Concrete Moisture Levels . Again, most major floor covering and adhesive manufacturers in North America and Europe already have concrete RH specifications in their installation guidelines. Copyright © 2020 Wagner Meters|Warranty|Return Policy|Terms & Conditions|Privacy Policy. The moisture readings obtained from the meters would effectively be meaningless. Good luck. + The other is Substrate moisture content within 75% RH © 2020 Giatec Scientific Inc. All Rights Reserved. Your email address will not be published. Read Sarah De Carufel, M.A.Sc. + Substrate moisture content is between 4% to 6%. That is why in-situ RH testing has become the new standard for flooring applications. This includes anhydrous calcium chloride (CaCl) testing, the hood method, the plastic sheet method, and the use of hand-held moisture meters. Humidity drops to 7.59 % room, and analytics partners build home on Feb 28, 2020 and have the! On making sure the substrate is ready before the installer begins his work have serious issues! 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