ASTM C 90 CMU testing procedures 1

[mckeejrob]

I am the QA on a hospital addition in Afghanistan and I have a contractor who is trying to make his own concrete block on site. I was curious if anyone knew a website that I could view the ASTM specs. I'm only finding sites that I have to pay for the info. I'm just needing to know the number of blocks that are allowed in a "batch" for testing. Any help in this matter would be greatly appreciated.

 

[concretemasonry]

The appropriate products specification is ASTM C90. The testing proceedure is ASTM C140.

You can essentially get the main portions of the specification/procedures free by going to ncma.org (National Concrete Masonry Association) site. Go to the TEK notes portion and select a state (any state) and a producer (any producer). Then, you can search by topic or use the index.

ASTM C140 requires SIX samples, THREE for weight, density, dimensions, area, % solids, absorption, etc. and THREE for compressive strengths. Units for compression testing CANNOT have been used for the weight, density, dimesnsions, etc.

The compressive samples should have a sampling date and testing as soon as possible to eliminate false curing that may change the compressive strength because there is no required time for curing as there is forconcrete lab testing.

The specification applies to the properties "when delivered" to the site. Because of this you will have to determine a method to control the timing between "casting" and use.

In factory production, units usually meet the C90 requirements when they come out of the plant, but a construction site produced CMU will not have the same aggregate controls, batching, material handling and curing.

Despite the low standards set by ASTM C90, it will be a real challege for site produced units to meet the C90 specs unless the materials are very good and there is some relaxation on the dimension requirements.

Is this inspection in association with "Global"?

 

[mckeejrob]

Thank you concretemasonry for the help. I'll check out that NCMA web site.

 

[rolkamatic]

I have a couple of freinds practicing architecture in Rangoon, they are working as local architects for a number of embassy projects that are designed by firms in the UK and Australia. They have first world specifications and a third world construction site. Local contractors are doing the work and the locally supplied material is not documented or tested at all per the job specification.

I'm wondering how you've negotiated some of these issues if you've had similar expiernce.

Thanks
JR

 

[concretemasonry]

rollcamatic -

The problem could easily be avoided if the out-of-country designers and the local architects discovered what materials are readily available locally since they should know they are designing a structure in london or sydney. - I guess that take more professional ability than using boilerplate from thousands of miles away.

It is always embarassing to a professional and the owner has to pay for excessive shipping and project delays.

Dick