CMU ASTM C90 how often? 1

[boffintech]

I'm looking at an "approved" submittal and the test verifying compliance to C90 for the 12" block is more than 2 YEARS old. The 8" block test results are more than 1.5 YEARS old.

The manufacturer is getting every last mile out of that testing lab's reports!

Not sure why the EOR approved this submittal but at any rate C90 and C140 don't appear to give a requirement for how often the requirements of the standard must be met.

How old is too old for test data?

 

[concretemasonry]

The acceptance of test reports is up to the EOR/Architect to determine if the report is representative of the materials proposed to be supplied to the project. There is always the option of sampling on site during construction.

I have seen reports rejected because they were too recent since block to be supplied were coming out of old inventory in the opinion of the EOR. Also, I have seen reports rejected because they were too old.

ASTM stanards are written to control the product properties and the testing procedures and not the administrative items that are unique to a specific project. There is a big difference between a 30 day job and a 3 year project. A product submittal is intended to be proof that a product can be supplied, but the on-site controls may be similar to concrete cylinders (if necessary) or they may be non-existant depending on the specifications.

In my opinion, a product submittal test report for a basic 8" or 12" normal weight CMU should be less than one year old. Many producers just have a report that they routinely submit for administrative product acceptance and this does not get replaced with more current reports. Producers are reluctant to provide recent job site sampled reports from other projects because the specific project is noted and there could be liability/legal repercussions.

Unfortunately, much of this happens because the ASTM C90 specifications are far too loose and have not kept up with the manufacturing improvements and controls that make lab testing unimportant, slow and cumbersome. Most plants do daily testing using fast turn around methods using gysum board caps on 8 to 12 hour old block going into inventory, but obviously these results would never be accepatable since they are not representative of the probuct when it will be supplied and the fast procedure is not according to ASTM C140 requirements.

Strength is one thing that engineers worry about without really understanding masonry. A typicical block producer cannot afford to make a weak block because it would be too difficult and expensive to handle in the manufacturing process. That is the reason you never see non-loadbearing units available unless you are in the very low unit weights (<85 pcf) using unique weak aggregates. Cement is a minor factor in the total cost of a block and adding water to a zero slump mix is much more effective in increasing strength, but it also causes other problems and increases cost.

The dimension properties (except height) are controlled by the molds, but wear is not a factor since the units would only grow a very small amount. Molds are replaced/rebuilt for visual or manufacturing concerns long before they would grow out of the ASTM requirements. Height errors would be caught very early by a mason/contractor because it makes the block laying process more costly and difficult even if the block meet the ASTM requirements.

Just don't fall into the trap of requiring a test for something such as a bond beam/lintel block or a half length unit.