Except for maybe the one week a year that much of the concrete industry is in Vegas for the WOC, there should be no gambling related to concrete.
With pervious concrete, if you are not starting with a known moisture level in your rock, then you are doing just that and gambling on your resultant product's quality. With an incorrect or unknown moisture level in your aggregate, your aggregate batch weights could be off affecting your yield, and ability to meet a tighter tolerance to design density.
There are several means to check the moisture in your aggregate before batching, but the two simplest and most effective tools presently on the market today are; a speedy moisture meter, or a Micro Lance.
The speedy moisture meter is simply a pressure vessel where a known aggregate mass is added to the vessel with a quantity of reagent. The reagent and aggregate are added and sealed into the container where the moisture in and on the aggregate reacts to the reagent forming a quantity of gas which correlates to the percentage of moisture in the aggregate.
The Micro Lance is a probe that once calibrated (which is quite easy) can be used to measure the percentage of moisture in any aggregate. Each probe can be calibrated for 5 different aggregate types, which is ideal for any testing agency or QC personnel since there are often many different mix designs in the market place and each one has a different aggregate source. The advantage of the Micro Lance is that the readings are nearly instantaneous. The device can be accurately used in 5 gallon buckets of materials, or in large stockpiles. The Micro Lance can also have an extension put on it so it can penetrate deeper into a stockpile. Surprisingly, to me at least, this tool retails at $1,700, which is less expensive than the typical speedy moisture package.
With either of these tools at your disposals you can double down on your bet that your pervious concrete mix will be right on the money.
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