Performance Testing & R&D
AVA 3000 (Air Void Analyzer)
Meets AASHTO TP 75-08
The AVA measures entrained air/cell parameters – specifically the spacing factor and specific surface. It is uniquely capable of accurately completing this type of measurement by taking a sample of fresh/plastic air-entrained concrete. Samples are simply taken after concrete has been cast in place and consolidated. Importantly, the AVA provides timely information to reveal the true quality level of the placed air-void system based upon predetermined and/or estimated mix parameters (such as mixing time, water addition, etc.). Miracon® has invested considerably in this system to insure reliable information, and as such we have developed new/easy to follow procedures which improve the reliability and value of the data it generates.
That said, it is our strong belief that this tool is most easily and preferably used in a controlled environment – which can, in turn, have great value in predicting field performance. And while it can be used in the field environment, it is only (again in our strong opinion) if certain environmental conditions are met as far as where/how this device is used.
In the lab, when trying initially to evaluate or later to re-confirm the quality of mix design air entrainment, we strongly believe in the use of two specific devices; those two being the AVA testing device alongside the SAM device (note: more detail about the SAM device is in the next section). This combined device/technology approach will provide a better, more systematic and data supported approach to evaluating quantity and quality of air entrainment in the field or plant. Of course, for better predictability/repeatability from lab to field, certain mixing/batching test parameters have to be followed as well – such as type of mixer, mixing/sheer speed, time of mixing, etc. – all of which are methods we have been able to adopt in our lab so that we can have a high success rate in going directly from the lab to the plant.
The AVA is one of our most unique pieces of testing equipment & one we use on a routine basis. Despite some of the reports on the AVA, we have been able to pin-point and control the issues that have caused so many to abandon the use of the AVA. For more information about how we are able to get repeatable & reliable data.
Properly used, the AVA, in our opinion provides very cost effective and comparable results in terms of the air void structure, to hardened air void analysis (per ASTM C457).
Super Air Meter (SAM)
Meets AASHTO TP 118
The Super Air Meter (SAM) is amazingly efficient and easy for any technician qualified to use the Type B Air Meter. And while the SAM can also be used as a standard Type B meter, in a matter of no more than 10 minutes total, the SAM provides not only air volume (%), but also results related to air void size and volume. This makes it an all-in-one, easy to carry, device. At Miracon®, we routinely run both a SAM and AVA test at the same time to ensure we have the best data prior to going from the lab to commercial production.
The SAM is definitely the fastest device – both in the lab and in the field - to analyze the air void size and to see if your concrete can endure freeze/thaw. And with enough data in the lab, correlating the AVA to the SAM, it is with considerable confidence that real plant or field mixes can be tested with just one device – which would then be the SAM.
Type B Meter
Meets ASTM C231, AASHTO T152
Relatively easy to keep calibrated, this device, which the industry has used for several decades now,
does exactly what it promises – that is, it indicates total amount of air entrained volume. Because this device is so widely used, we still use it routinely, but for the most part, it simply serves to prove that the SAM device does this measurement as accurately. Not to minimize the importance and value of this information, but unlike the SAM device, the Type B meter cannot provide qualitative information to predict freeze-thaw value as relates to air entrainment properties. When testing a mix in the lab and then in the plant or field, exactly how much air volume is needed to provide freeze thaw performance is done with much greater assurance if validated with the SAM device.
Compression Testing Machine
Meets ASTM C-39, E-4, AASHTO T-22
Basic strength testing of cubes, 3”x6”,4”x8” and 6”x12” cylinders. Once the specimen is properly loaded in the machine, the device is set to test the specimen size which has been selected. The rest is quite straightforward and results are displayed on the screen.
Meets ASTM C 1749
A very portable instrument, equally suitable for use in the field as in the lab. Its primary purpose is to measure fundamental flow (rheological) properties of fresh concrete – i.e. in a quantitative manner that allows comparative or confirmation testing over time. This flow method is a much better way of measuring flow than if using only the slump cone as the standard. Optimizing mixes for flow properties is done efficiently and with objective certainty using this device.
Meets ASTM C-157/157M
This lab-based digital read device measures length changes of hardened cement paste,mortar,and concrete specimens. Very easy to use, shrinkage values for a mix can be objectively determined. Samples for testing can be taken in the field or the lab.
pH Of Fresh Concrete
We can now measure and record pH during the curing phase of concrete (or any other binder system). At this point, this is a one of a kind device, as there is not a device like this on the market. When we were developing the CO2 technology around CapCell®, we knew it was critical to understand how/when the CO2 affects the pH of the concrete, as pH is a key determinant in not only the concrete strength initially, but most importantly will have a major impact on the long term performance properties of the concrete. As such, we developed this device to measure the pH of fresh concrete with a high degree of accuracy and then, of course, with the frequency of reading predetermined, to automatically record the pH readings from the fresh or plastic state, to the hardened state.
Relative Humidity (RH) of Fresh Concrete
Relative humidity of fresh concrete is an important factor in the set properties of concrete. Of great significance is the RH of fresh concrete when CO2 is part if the mix. There is a very definite range that the RH must stay in if the concrete is going to cure and harden properly- again, especially if CO2 is introduced before the concrete hardens. While there is no such monitoring device available on the market, we have developed such a device to accurately monitor and record how the RH is maintained throughout the curing stage of fresh concrete.
Volume Flow Meter
It is one thing to know how much volume of CO2 is injected into a mixing vessel and estimate the volume as to how much might actually go into a mix. With Miracon’s® system , because we can measure the volume of gas that is pressurized and then goes into our closed cell entrainment system, we know exactly how much CO2 is going into the mix.
Standard Lab Drum Mixer
In the lab we use different size drum mixers, depending on the test to be run. Regardless of the mixer used though, our lab mixers are all designed so that the mixer drum speed is controlled by a rheostat – so that rpm’s of the mixer can simulate the mixing rpm’s of a ready mix/transit mix truck in the field. And since most tests in our drum mixer(s) are run for time, we can simulate what happens with typical shear (rpm’s) and time in the field. This is the best way, in the lab, to approach developing and/or confirming field or plant suitability of a mix in terms flow (slump) and entrainment properties. Less R&D or guesswork (or failures)at the plant. This approach explains in part why we have a very high success rate going from the lab to the plant.
Mixers For Ultra-Lightweight Precast
We have some precast customers whose business primarily oriented to making lightweight densities that are 105pcf or below. It is our opinion that the best mixers for precast products in this density range are what are classified as colloidal mixers. These type mixers are very cost effective and best suited to provide the mixing efficiency and speed for products that contain very little sand or rock. We do not sell these lightweight mixer systems but we do have experience with one vendor who offers turnkey systems for these types of clients. We also prepare and refine mixes in our lab with these type mixers so that performance/performance comparison can be made. A picture is provided above of this type of mixer, which we use in our lab. There is also a link below to this machine system vendor.
Miracon® Machine System
The features and benefits of our system has already been outlined in the section titled: Miracon's® Operating System. This system, as described, is the same for ToughAir® or CellTech® or ThixoPro® - all three product technologies. One system that is designed to provide same quality entrainment from batch to batch, regardless of most variables such temperature, etc. . This machine system is pictured below.