Quantifying the safe limit of moisture in a concrete slab is very important prior to the installation of impermeable membranes or certain floor coverings, in particular timber flooring. Premature encapsulation of concrete slabs will lead to moisture becoming entrapped which in turn can result in a raft of building defects. One way of ensuring the moisture within the slab is at an acceptable level is by using Protimeters concrete flooring kits.
In this review I will be looking at the Protimeter MMS2 Flooring Kit, giving an overview of its use and looking how it has evolved in line with current standards. There is also a HygroMaster L version of the kit which is also capable of measuring relative humidity but lacks the additional functionality that the MMS2 brings.
The BLD8800-FL package comes with the following:
- Protimeter MMS2
- 5 mini hygrostick probes
- 20 adjustable humidity sleeves
- Carbide-tipped masonry drill bit and drill stop
- Salts calibration test bottle and adapter
- Hygrostick extraction tool
- Hygrostick extenstion cable
- Wire cleaning brush
- Data cable and software
- Rugged carrying case
The kit comes in a briefcase-sized hard plastic carry case. The components of the kit are well presented and neatly laid out within the case.
The kit is in strict adherence to the standard set out in ASTM F2170, this standard specifies the components to be used when conducting the in-situ humidity test. When researching this kit I noticed that the design of the humidity sleeves had changed over time and compliance with the ASTM F2170 standard is the reason behind this.
The sleeves actually go over and above the standard set out by containing extra fins to ensure a tight fit to the testing area. The sleeve is also extendable which means the same sleeve can be used to test different slab thicknesses (100-150mm). The sleeve has written measurements in inches and millimetres to assist with setting the correct depth.
The drill bit I received for review was slightly different than the one shown in the brochure. The drill bit I have in my kit is a DeWalt high impact carbide SDS plus drill bit which is not a bad thing as DeWalt are a highly recognised brand known for their quality tools. The carbide head drill bit with its sharp cutting edges is used to deliver clean round holes to accommodate the humidity sleeves.
The Hygrosticks, which utilise a resistive sensor, have two isolation gaskets to keep that airtight seal within the sleeve. They are designed in such a way to be foolproof when using them in conjunction with the extension cable and extraction tool. Each Hygrostick holds a sticker with some sort of QR code which I was not able to scan and a unique identification number in tiny writing. I was able to more easily read this number by using a magnifying lens attachment I have with my smartphone. The identification number will also show up on the MMS2 when you plug it in.
I will not be going into the MMS2 itself, I rate the MMS2 very highly and the full individual review for this device can be found here.
Carrying out a calibration check is a very easy process but fairly time-consuming. The salt calibration test bottle is used to test the probes at 75% relative humidity. It is recommended that the probes are tested 30 days before use. The probe needs to be left for several hours, if you are planning to use two or three probes then this process would find itself becoming hardly convenient.
If there some sort of multi-chambered digital calibration device that could test multiple hygrosticks simultaneously I think this would be an advantage. Yes, my imaginary super-duper calibration device does not currently exist but imagine how much easier this process could be.
I tested one of the probes overnight and it fell comfortably within the tolerable test point range. I found the extension cable that connects from the Hygrostick probe to the MMS2 to be rather tough going to come in and out, I was weary of potentially causing damage by forcefully removing the cable so it took a bit of coaxing to come out of the MMS2.
Using the Kit
Firstly it’s worth pointing out that there are some items that are not included in the kit that will be crucial to allow you to carry out this test in accordance with the current standards. These include:
- SDS hammer action drill (preferably with dust extraction)
- Rubber mallet
- Vacuum with mini accessory kit
- Rubber oval ball air blower (optional but good practice)
- Depth Micrometer (optional but helpful in confirming depth)
- PPE equipment associated with drilling
You may already have some or all of the above although some of these items are not the standard kit for most surveyors or contractors.
I tested out the kit on a concrete test sample and found the kit to be very simple to use. The drill bit made easy work of the concrete and the sleeve fit snuggly into the hole. You probably want an SDS drill with dust extraction as it can be a decent amount of debris that needs to be cleared away.
According to the ASTM standard, the floor slab should be at service temperature and relative humidity for 48hrs before taking measurements. 24 hours should also be given to allow moisture equilibrium within the sleeve to be achieved. So for accurate measurements to be taken a bit of forward planning is required.
I think it is best separating the process from the equipment as my view is slightly different on each. The in-situ test is quite a time consuming and methodical test procedure which in of itself can seem a bit off-putting, so I am not a fan of the process. I am a fan however of the equipment that Protimeter has produced to conduct this task.
The probes and sleeves have been designed to be easily deployed whilst giving the accurate results you would expect from conducting precise relative humidity measurements in concrete floor slabs.
Due to the extra items required to conduct this test and the time it takes for calibration and seeing the test through to completion I can understand why surveyors may look towards other methods of testing such as the speedy carbide meter or the hygrobox. This is in no way an indictment on the flooring kit itself as I feel like it couldn’t really be much better than it is apart from possibly a way of calibrating multiple probes at once.