Selected Structural Detail


Parameter (report numbers)Rating/ValueRemarks
Recycled Content± 85% by volumeMainly postconsumer expanded or extruded polystyrene.
Bulk density22 lbs/ft3  ± 10%Elements for specific applications may be produced with higher density.
Compressive strength of Rastra Inc Mixture56 psiDepending on density.
Tensile strength of Rastra Inc Mixture43 psiDepending on density.
Water vapor transmission



PI-4582/ws, 5/80

7.3This is a (dimensionless) factor to measure possibility of condensation in the wall, particularly in cooler periods or with high air conditioning; the low value of Thastyron is a guarantee that no condensation will occur.
Fire endurance








UL – R14366, 9/91, 2/99

4 hours rating (ASTM E119)A 10″  unplastered Rastra wall has been tested for 5 hours under a load of 10,000 lbs/lin.ft.; two tests have been performed with an additional positive and negative load perpendicular to the wall, simulating a 35  mph wind pressure; with a temperature in excess of 2000°F on the exposed side the surface temperature on the unexposed side of the wall did not increase for more than 7°F; a high pressure water stream directed towards the wall immediately after burning did not penetrate the wall.
Thermal barrier (Room fire test)

OPL – 15715-1808, 9/97

no flame spread,

no smoke development,

wall meets UBC 26-3

A wood crib is burned in a corner built with unplastered Rastra walls exposing it to appr. 1700°F; flame spread, smoke and any damage of the wall is monitored.
Surface burning characteristic





SGS – 113924. 9/98

Flame spread index  0

Smoke development. index 5

NFPA class A

UBC class   1

ASTM E 84 (NFPA 255, UBC 8-1)

4″ thick Thastyron panels were exposed to flame and spreading of the flame front and smoke density, compared to red oak was measured. The flame front was proceeding less than 0.5ft, which is within the flame spread of the burner. For smoke development light absorption is measured. The test showed some very low absorption, for the test result values are always rounded to the next figure divisible by 5.
Frost resistance


TIB – KR/SI, 10/84

Highly frost resistantThastyron specimen have been soaked in boiling water and frozen at -4°F; after 50 cycles no reduction of compressive strength could be found.



BI – 08-95-0338, 5/95

Low toxicTesting conducted using Leaching Procedure by EPA SW-846 method 1311, metals by method 6010 & 7470, volatiles by method 8240; metals are less than 1/20 of regulatory limit, only traces of 4 volatiles out of 40 tested found.
Formation of mildew



API – 17137, 4/83

Mildew , Black Mold & fungus growth is not anticipatedTest cubes were kept under moist conditions for 40 days after innoculation of test germs (aspergillus niger, rhizopus nigricans). No growth of cultures could be observed; formation of mycel or konidien culture did not take place.
Water transmission


ATI – 03-30070.01, 12/98

ATI – 03-30305.01, 12/98

Meets requirements  ASTM E331, ASTM E514, meets UBC 14-1 (grade “C” craft paper)10″ thick Rastra wall with skim coat has been exposed to a water spray with a  flow rate of 5.0 USgal/  at a differential pressure to  simulate a 125mph wind. (Extended time testing has been done by US Navy and met standards).
Average wall humidity

MA-39 – f711/83, 10/83

Average 2.5% by volumeSamples have been taken from a home more than 5 years in use from areas where most humidity is expected.


TUG – 52.620/83, 7/83

0.0018inch/ft (as standard concrete)Even as Rastra  elements without concrete grout show shrinking and swelling in changing humidity, shrinkage is neglectible once the concrete is poured.
Thermal performance




MPA – 970344-Hu, 1/98

Effective R-values

20 to 49 h.°F.sqft/Btu

European testing on a 1.5m by 1.5m, and US testing of 8’x8’ walls revealed heat conductivities of 0.084 to 0.053 Btu/h.°F.ft of dry, grouted 10”,12” and 14” walls. DBMS values between 1.79 and 2.17 have been established for 6 US climate zones. Energy usage shows even better efficiency.
Sound insulation






BVFS – U3/19A/87, 2/87

MA-39 – F956/85, 6/85

>50dB(a)Measurements have been taken in laboratories and in real buildings; dB is a value measured on a logarithmic scale, therefore, f.i. the difference between 27dB (an average value for a 2×4 framed wall) and a 50dB Rastra  wall result  in a  199 times lower sound intensity. The value indicated in test results is an average measure on a band width of 100 to 3150 Hz. Another aspect is sound absorption, which a Rastra wall provides.



Pillar strength


TUG – 53.725/84, 3/84

> 70 kips/lin.ft (failure load)Tested was a pillar consisting of 1 Rastra std. Element capped with 2 end elements; concrete strength 3000psi, no reinforcement
Cyclic shear





UCI – RAL 20177-IP, 9/96

10ft x 10ft: ±68 kips

5ft x 10ft high: ±20 kips

Walls have been constructed with reinforcement on 15” centers not centered in the cavity. In order to simulate high wind or earthquake loads cyclic loading in plane and a constant axial load of 10000 plf has been applied. The wall showed extreme good ductility and a deflection of 1.14” re. 1.24”. Failure occurred near the base connection to the foundation.
Narrow wall cyclic shear






UCI – RAL-25683-NSW, 11/98

30” x 10ft high

load at 60”: 11kips

load at 75”: 10kips

load at 90”: 9kips

To investigate shear resistance on very short elements of a wall specimens consisting of only 1 std. and 2 end elements have been tested. Boundary reinforcement has been increased to avoid premature failure due to flexural forces. A constant axial load of 10000plf has been used. Shear load has been applied in 3 heights to gain information about pillars with different aspect ratios.
Slender wall





UCI – RAL-23940-SW, 10/97

Axial load 1000plf, 7.5” out of center, width 45” (4 col.)

Flexural load at failure:

Wall 16ft high: 2800lbs

Wall 20ft high: 2200lbs

The specimens were loaded with a constant out of center load to simulate roof loads introduced by ledgers. The out- of-plane load was applied on 1/3rd points on the side to increase the eccentricity of all loads. The walls were able to sustain the applied axial and out-of-plane loads through the deflection limits given in the codes and beyond.
Out of plane load


UCI – RAL-20177-OP, 9/96

9ft span: 9kipsLoad was applied in 1/3rd points on a 10” Rastra element laying flat. No brittle failure occurred even as the test was continued beyond 80% peak load. Deflections at peak load were 2.44”.
Lintels & beams


UCI – RAL-20177-L, 9/96

Height:1 element (2 pillars) 10ft span: 21kips

5ft span: 26kips

One Rastra element was used capped on the lower side with an end element to simulate a lintel design as it may be used in the field. Support was free at 10ft distance, loaded at 1/3rd points.


The outline of test results above are for rough reference only. For any application of these tests in structural calculation request the full text of these reports or ask for engineering information based on such testing.