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Engineers' Independent Tests

The following engineering tests have been performed by an international independent testing company. This company is Stork Southwestern Laboratories in Houston, TX. Their phone number is 713-696-6226. Their web page address is: http://www.storksmt.com/      Stork SWL is fully accredited with a rating of A2LA, by the Texas Engineering Societies. in Louisiana, by the LPELSB, etc.

I. For high wind (Florida), seismic/earthquakes (California), retaining walls and basement walls, a VOBB wall with two vertical rebars in each cavity and solid fill grout in all cavities had the following results:

A. Compression tests

12,500 lbf., 6,250 psf - (tested up to this weight without failure)

B. Lateral tests

234 lbs. per square foot (tested up to the failure point)
Based on an "industry standard" of 60 lbs. per square foot is equivalent to 150 mph wind, then the VOBB wall tested up to 585 mph for wind load.

II. Lintels (headers)one horizontal rebar on the bottom row, all cavities filled with grout and one vertical rebar in each cavity

A. Seven foot lintel

compression tested to 60,000 lbf or 40,000 psf (tested up to the limit of the test equipment)

III. Summary & Comparison of CMU
Average gross strength

A. Common  12" * 8" * 16"  (Regular Normal Weight) - 1,352 psi

B. Common  8" * 8" * 16"   (2 hour UL block) - 1,055 psi

C. VOBB  6" * 6" * 6" - 3,047 psi

D. VOBB  6" * 6" * 12" - 1,977 psi

E. VOBB  6" * 6" * 18" - 1,441 psi

F. VOBB  6" * 6" * 18" one cell filled with grout - 1,732 psi

G. VOBB  6" * 6" * 18" all three cells filled with grout - 1,770 psi

It should be noted that VOBB blocks are produced with the exterior wall of 1 1/2" thickness compared to the ASTM requirement of only one-inch thickness. Likewise, VOBB is based on dry-stack (with no "weak" mortar joint) and at least one cavity filled with grout on a vertical basis. As such, the VOBB in item F is the most "normal" block in actual construction compared to the industry standard 8" * 16" of item B. Item G is for high wind and earthquake requirements and is used for the corners, around the door and window openings and for lintels (headers) above the door and windows. While there is no rebar used in these tests of the individual CMU blocks (for the sake of comparing apples to apples), VOBB dry-stack construction also uses rebar wherever there is grout to add tremendous lateral strength to the completed wall construction.

IV. Test of standard VOBB dry-stacked wall section, grout filled with one vertical rebar

A. Lateral test - Flexural Load

1,396 psf maximum load - tested to failure

         
V. Pictures of the engineering tests being completed

Lateral test - solid filled with grout and two rebars (picture # A)
witnessing the detail and methodical set-up and procedures to be sure of the integrity of the engineering tests.

Lateral test - solid filled with grout and two rebars (picture # B)

Lateral test - solid filled with grout and two rebars (picture # C)

Walls tested Walls and VOBB block tested (all rebar 1/2 inch):
1. 4' * 4' with all cavities filled with grout and two vertical rebars in each cavity - for high wind load and seismic requirements
2. 4' * 4' with alternating cavities filled with grout and one vertical rebar - for standard construction
3. Four foot lintel (header) for a three-foot door or window (all cavities filled with grout & one vertical rebar) - one horizontal rebar on the bottom row
4. Seven foot lintel (header) for a six-foot door or window (all cavities filled with grout & one vertical rebar) - one horizontal rebar on the bottom
5. One-foot high retaining wall (alternating cavities filled with grout except at corner where all three cavities are solid)6. 18" VOBB with all three cavities filled with grout (no rebar)
7. 18" VOBB with one cavity filled with grout (no rebar)8. 18" VOBB
9. 12" VOBB
10. 6" VOBB

Walls tested - partial construction (picture # A)

Walls tested - partial construction (picture # B)

Walls tested - partial construction - back side

Walls tested - seven foot lintel for a six-foot door or window

One foot retaining wall with a corner; a 18" VOBB with all cavities filled with grout (no rebar) and a 18" VOBB filled with grout in one cavity (no rebar)

Mixing the grout to fill the cavities (This is simple with two buckets, but no trowel was used as VOBB is dry-stack.)
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If you have any questions, comments, etc., please let us know. If you would like a full copy of the engineers' report on their tests, please send an email to : jg@vobb.com or call to 337-781-0705. Additional testing is available from this company by an independent Professional Engineer at $145 per hour, minimum of one (1) hour.