But drying can be a slow process and contractors often find themselves in conflict with construction schedules. From the 1940s to today, many contractors have relied on surface-based methods for monitoring or evaluating relative humidity levels and moisture content. moisture in the air is about .2%, even though the relative humidity is near 100%. If your concrete contains excess moisture and high RH levels this can lead to disastrous flooring failures, resulting in costly repairs and liabilities. 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. According to ASTM F2170, when drying, concrete slabs have lower moisture levels near the surface and higher levels towards the bottom of the slab. 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. Relative Humidity Testing. This is done with a (de)sorption isotherm. Learn More Here! Save my name, email, and website in this browser for the next time I comment. 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. You have to explain that Thanks for the comment and very good observations. The moisture can be regarded in the following two main categories in concrete: As a concentration (mass per volume) and as pore relative humidity. I never knew there was a difference between moisture and humidity until I begin to familiarize myself with the two. Equilibrium and Transfer in Porous Media 1: Equilibrium States. Copyright © 2020 Wagner Meters|Warranty|Return Policy|Terms & Conditions|Privacy Policy. By using methods that analyze the moisture level within the slab, more accurate and reliable RH readings are available. Help please!!! Purchase a Tramex RH moisture test kit (easiest way to test for RH in a Concrete slab) 2. Concrete, Gypsum, Wood . This information can be used for quality control and quality assurance purposes, allowing you to optimize the time in which you place your floor covering material. However the down side is that its time consuming and could be expensive, although the expense should be minor consideration compared to the cost for replacement of a failed floor covering. Additionally, even IF the so-called ‘concrete moisture meters’ were sufficiently accurate (again, they are not), they only measure ‘moisture’ (not relative humidity) in a very small area near the surface of the concrete slab. + The other is Substrate moisture content within 75% RH Thanks. 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. Pammy. This will allow you to determine the ideal time for placing your flooring. Features: • Measures to 6,9% Moisture Content in Concrete. Understanding RH in concrete Can you show me the relationship of these two quantities? Three Methods for Testing Concrete Moisture Levels . Additionally, other components (metal reinforcing bar, aggregate size, and amount, etc.) Moisture represents the presence of a liquid containing trace amounts of water. AH right? The relative humidity is measured after allowing 72 hours to achieve moisture equilibrium within the hole. 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. Global Headquarters:245 Menten Place, Suite 300Ottawa, OntarioCanada K2H 9E8, Toll-Free: +1 (877) 497-6278sales@giatecscientific.comsupport@giatecscientific.com. 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% can cause false indications of ‘moisture’, especially with non-pin meters. In previous positions, he has served as Regional Sales Manager, Product and Projects Manager, and Sales Manager for manufacturers involved in measurement instrumentation. Hi Jason Mike, Asking about humidity in the concrete should help us find a knowledgeable contractor for the job, so thanks for giving me the idea! 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. 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. This type of surface ‘moisture’ testing tells us nothing about the conditions down in the slab. You can call 1-800-634-9961 and ask for me specifically. As Sales Manager for Wagner Meters, Ron has more than 35 years of experience with instrumentation and measurement systems in different industries. But we feel those shortcomings have largely been overcome through the years as more research has been done. If you would like to contribute to our daily blog posts or suggest some ideas for future articles with a more technical content, yet relatable subjects to non-academic readers, feel free to contact us at knowledge@giatecscientific.com, we would certainly be glad to publish your article on our blogpost page. Thanks for the question. 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. 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. 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. A pin meter isn’t the industry standard for testing moisture in concrete for the purposes of installing flooring, so I can’t really judge the numbers you have provided. It was interesting when you talked about how moisture levels in concrete can change up to six months after it’s poured. Relative Humidity Testing. – RH above a curved water meniscus slower than 100 %; lower the more curved the meniscus is, • Plug in Probe for Relative Humidity, Temperature, Dew-Point and Mixing Ratio readings ( optional ) 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. Secondly, based on any information you have provided here, I see no reason to think there is an issue with your foundation. 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.” 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. This equates to a moisture content of about 2%. Moisture content represents the amount of water in liquid form, while humidity levels represent the amount of water in vapor form. Thanks for the question. 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. Thank you for any advice you can provide on making sure the substrate is ready before the installer begins his work. Relative humidity is the main source of moisture for cut lumber or finished wood products. Good luck. 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. 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. Measure moisture in concrete as a moisture vapor emission rate, or MVER, and as in situ relative humidity, or RH. For a more scientific and globally valid discussion of such phenomena, the reader can refer to the relevant textbooks or articles (e.g. Again, most major floor covering and adhesive manufacturers in North America and Europe already have concrete RH specifications in their installation guidelines. can you RH test a 1 14/” gypcrete level? M = moisture content (%) T = temperature (o F) H = relative humidity (%) / 100 W = 330 + 0.452T + 0.00415T 2 K = 0.791 + 0.000463T - 0.000000844T 2 K 1 = 6.34 + 0.000775T - 0.0000935T 2 K 2 = 1.09 + 0.0284T - 0.0000904T 2 We obtained the basic information to create the calculator and table from the U.S. Forest Products Laboratory. Daian, J. F. (2014). Your email address will not be published. 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. Required fields are marked *. Concrete temperature and strength monitoring, A value-added solution for ready-mix concrete producers, Concrete sensor for relative humidity and temperature monitoring, Sensor for concrete resistivity and temperature, NDT device for testing the rate of corrosion, NDT device for half-cell corrosion mapping, Laboratory device for testing chloride permeability, NDT device for measuring electrical bulk resistivity, Laboratory device for testing surface electrical resistivity. It is the standard that dictates the procedures for making and curing test…. There are three standard methods for measuring concrete moisture. This includes anhydrous calcium chloride (CaCl) testing, the hood method, the plastic sheet method, and the use of hand-held moisture meters. At first glance, relative humidity (RH) is a quite confusing topic. 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. 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. Q. All my queries about this equipment got solved after reading this. Clean area and drill 3/4 inch hole to 40 percent of … Generally the internal relative humidity needs to be above 80% to 85% relative humidity for hydration to take place. Even though your concrete may look dry on the surface, that doesn’t necessarily mean it is dry throughout. 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. In the technical data sheet of two suppliers differ in concrete moisture content : The meters you are referencing aren’t really intended to make absolute decisions on installations, they are intended to identify hot spots on a given floor where you should do accepted tests like calcium chloride and relative humidity tests. In everyday use, Relative Humidity refers to how much water vapor is in the air at a given place and temperature. Thanks for the question. The best way to answer this question is by contacting the gypcrete manufacturer and the flooring and adhesive manufacturer. Missing or inadequate moisture barriers in a slab on grade, causing outside moisture to penetrate the slab. ahwile back i did a laminate install over concrete where carpet and pad was removed……pin type moisture readings were about 3% average which is acceptable……two months later the floor failed due to moisture. In any event, ALWAYS check with the individual manufacturer for their specific information. Henri, I think it would be best if we could discuss this over the phone. + Substrate moisture content is between 4% to 6%. The relative humidity test determined by driling holes would be most appropriate. 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. On a range from 0-6 what is an acceptable reading to install? After doing a lot of research, I decided to share what I’ve learned below. The % water vapor is still .2% if all we do is heat the air. 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”. If you continue using our site you consent to our cookies. Ratios: Relative humidity to moisture content Common conversions and instruments used in measuring wood moisture content. The development of an alternative moisture test method, the in situ relative humidity (RH) test, has not made the calcium chloride test method … 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. The moisture content of grains is an essential property in food storage. The concrete pore structure influences its physical properties, … With lower moisture content, the RH value will decrease as the air is no longer saturated. This is where the problems occur. Concrete meters have evolved from the successful wood moisture meter as flooring contractors tried to use their wood meters to measure the moisture in concrete. We have been involved with concrete moisture testing for many years and agree there were shortcomings with the calcium chloride test. Hoboken: Wiley.). Read Sarah De Carufel, M.A.Sc. Thus, relative humidity testing was born and the industry has grown to embrace this method of testing that lets you know what the moisture WILL be, on the surface, prior to spending all of the time and money on a flooring installation (RH testing) vs. doing moisture testing that tells you what is going on at a specific point in time prior to installation (calcium chloride testing). The moisture content that is safe for long-term storage is 12% for corn, sorghum, rice and wheat and 11% for soybean. 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. October 31, 2000. content, 15 g/m2/24 hours and 75% relative humidity. Many of the coatings manufacturer’s I see have a 75% maximum listed. Unlike current time-consuming methods that measure only one data point at the time of testing, this wireless sensor continually collects data. To better understand the concept of relative humidity, imagine a glass of water that is sealed. Proper documentation of test results for all tests includes: Start date and time of testing with ambient temperature and humidity. I can state though that I have never heard of moisture in concrete causing chipping or breaking of vinyl plank. 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. Relative humidity (RH) is often mistaken for moisture; however, these terms measure two different characteristics of concrete. Measures moisture inside the concrete as % relative humidity. Why You Should Use Relative Humidity (RH) Testing, Become a Wagner Meters Authorized Distributor, Flooring, Millwork, Furniture and Cabinet Manufacturers, Musical Instrument Manufacturer and Luthiers, Building Restoration and Inspection Professionals, Concrete Moisture Meters vs. Both categories are related by moisture isotherms. How to do a relative humidity test on a concrete floor. RELATIVE HUMIDITY In Situ TEST The Test Results Mapping Diagram provides a visual depiction of the numerical values represented over the concrete slab. Moisture vs. Humidity – Understanding The Difference . Predictor of future moisture emission. Good luck. Required fields are marked *. Concrete Relative Humidity Test. The moisture readings obtained from the meters would effectively be meaningless. A definitive test that measures the amount of moisture released from the concrete requires a calcium chloride kit or a relative humidity meter. In water damage situations depending on the amount and head of water the depth to which the moisure has been absorbed will vary greatly. Basic steps to perform a Relative Humidity test in concrete floors & slabs 1. I loved this blog, and this blog provides all the information that is required to know about concrete moisture. When 20% Is the Right Depth for RH Testing, How to Prepare a Concrete Floor for Coatings, Leveling Compounds: Concrete Moisture Can Slant the Results. This test method involves measuring relative humidity levels inside of the concrete … The most advanced and comprehensive of the three methods, this test measures the presence and quantity of moisture throughout the depth of the slab. You can prevent flooring failures also with Vapor Barrier, special epoxy or polyurethane primer. Concrete Cylinder Test: Which Method is More Effective? Keep it up. My husband and I need to find a contractor to put in a large concrete patio in the backyard of our new home before this summer. Moisture meters, similar to other non-quantitative test methods, are not final determination tools. I recently observed an application where the horizontal ceiling slab delaminated, while the vertical walls were well bonded. 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. Your email address will not be published. It also helps monitor: Interested in measuring relative humidity and temperature of concrete? 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. Therefore, it's advisable to have a floor tested for moisture content prior to installing flooring or moisture barriers. Upon removal of the carpet and under, moisture build up causing mould is clearly visible. 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. 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. (The other, of course, is direct water that may come from a leaking appliance, flooding, standing water, or another source.) Thank you for the questions. First for the meter readings you describe. The calcium chloride test method (moisture vapor emission), and the UK-based ‘hood’ method (RH) both have the same problem, as they are also surface tests. If the glass is full of water, the moisture level and the relative humidity level will both be 100%. That is why more and more contractors and project managers have turned to wireless relative humidity and temperature sensors, like BlueRock™. Concrete curing is the process of maintaining adequate moisture in concrete within a proper temperature range in order to aid cement hydration at early ages. Now, remove almost all the water from the glass. Ron, 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. 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. 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. 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