ASTM Standard for Concrete Unit pavers 1

[sudhirvasan]

Dear All,
Kindly help me with your expertise knowledge in the below questions.
1. As I know the ASTM C936 is the standard specification for solid concrete interlocking paving units. Is this ASTM C 936 covers both wet cast concrete pavers and semi dry/dry cast concrete pavers? In BS 1338 the standard mention about face mix layer where as in ASTM C 936 no mention about the face mix layer.
2. Is it ASTM C936 is the only standard for concrete pavers in ASTM?
3. Is this ASTM C936 covers both wet cast concrete pavers and semi dry/dry cast two layer(Facemix and base mix) concrete unit pavers?
4. BS 1338 mention specifically about face mix concrete pavers. Why ASTM C 936 has no mention about this?
5. How important is the split tensile strength test for concrete pavers?
6. Can we compare the abrasion resistance test result for the pavers tested by ASTM C 418 and BS 1338 Wide wheel abrasion method?
7. Which abrasion resistance test is more recommended for concrete unit pavers?
8. Is there in US semi dry/drycast concrete pavers are manufacturing? If yes which standard is referred for this type of pavers?

 

[concretemasonry]

sudhirvasan -

ASTM C936 for Solid Concrete Interlocking Paving Units is written without regard to the manufacturing process.

The use of pavers made using a wet cast method is not common because the wet cast units are probably not cost effective. There are also very few (if any) manufacturers that meet the standards for the installation requirements. ASTM usually does not get involved in manufacturing processes, but only specifies the minimum standards of the units.

The face layer does present some problems regarding determining durability testing, but does not preclude the use of a face layer, since it is a standard for type of construction material.

In my opinion, the standard is very minimal and the demands of the specifiers and contractors over-ride the of the ASTM standard. There are some features incorporated in the design of the paving units are not even addressed in C936. The 8000 psi compressive strength requirement is very low and a manufacturer could not afford to make the minimal units because this would require compromising other factors including handling and installation. A typical concrete brick could be 12,000 psi.

The tensile splitting test is of no value since the pavers never see a similar loading because of the restraint and effects of the surrounding units. The compressive strength is far below the level of the usual manufacturing equipment. - Most of the manufacturing equipment used for manufacturing pavers is from European equipment manufacturers.

Dick



Engineer and international traveler interested in construction techniques, problems and proper design.

 

[sudhirvasan]

Thank you Mr Dick.I agree with you that the standard is very minimal, but when we deal the subject in construction contracts,though we specify the product with manufacturer name,the reference to International standards becomes mandatory. I am talking about case in middle east. I am working in Kuwait.
As you said,Tensile split strength has little effect if the pavers are of interlocking type. But some pavers are not interlocking type example Narrow modular paver(wet cast paver) manufactured by M/s Stepstone USA, which we have specified in one of our projects. This paver is a long one, size 610mm x 72mm x 100mm,which has great potential for tensile splitting.
Is there any ASTM standard which has mention about face mix type (2 layer) semi dry cast concrete pavers?
What is common practice in US?
Kindly share your experience and knowledge.

 

[concretemasonry]

sudhirvasan -

If you refer to a standard (ASTM or others)in your specifications, make sure you understand the specification and note the requirements that are excluded or waived for your specific use.

In your case, the ASTM 936 contains a requirement that the the length to thickness of the unit be less than 4.0. Based on the size of your paver, the l/t is 6.1 (610/100). This can effect the applicability of this factor based on the testing of the sample you referred to.

The ASTM C396 standard may be "loose in comparison to the "Step Stone" in some minimal areas, but ASTM does require a 8000 psi concrete compressive strength in comparison to "Step Stone" compression strength of 5000 psi. I am sure they have had units tested in a lab somewhere that may have an acceptable machine to test such a long unit if the ASTM standards were used.

To my knowledge, the the units you have visualized are not the typical "interlocking concrete pavers" that the specification written for, which is for heavy loads wheel loads than can be carried if installed properly. Perhaps the supplier you mentioned can address the variation if they are active in writing the ASTM standard.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[sudhirvasan]

Thank you Mr Dick. Thanks for your valuable comments.