our specifications. Periodically during each product run, samples are taken and subjected to Drop
Dart impact testing as defined by ASTM D 4226A in addition to Izod Impact Testing as defined
by ASTM D 256. These impact tests provide a good indication that our finished product is of the
proper cell classification and demonstrates the proper physical properties associated with a
weatherable, external grade vinyl.
Northstar is the only vinyl sheet-piling manufacturer that has orchestrated such an in-depth
testing program by third party industry experts Northstar devotes a significant amount of time and
resources into product testing, because we recognize that seawalls/bulkheads (retaining wall
structures in the marine environment) are demanding structural applications. It is worth noting
that Northstar Vinyl Products conducts testing of its finished product and does not rely solely on
compound data supplied by our vendors.
Confidence in the testing lab is almost as important as the data collected. Tensile, Flexural,
and Creep Testing was carried out by SGI Testing Services (formerly GeoSyntec), which has
certification from the Geosynthetic Research Institute. While impact and UV testing was carried
out by Applied Technical Services, Incorporated which is an ISO 9002 certified laboratory.
Flexural stress (ASTM D 790)
A beam (in this case sheet pile) is supported at each end and a lateral load to induce bending
is applied. One side of the beam (sheet) is in compression while the other is in tensile. This
depicts actual loading in the field due to lateral loading from the soil.
Maximum Flexural Stress expressed as an average and minimum was 8,396 psi and 7,968 psi,
respectively (Span/Thickness ratio = 56.6). Be careful, other manufacturers may overstate their
values by using too small of a span/thickness ratio. If one tests the material with too short a span,
overstated values due to shear will be realized.
Tensile stress (ASTM D 638)
A tensile test can most easily be described as a "pulling mechanism" that pulls on the
material like a rope. Here, samples of finished sheet pile material are secured at each end and
pulled apart(similar to a chain or rope). Maximum Tensile Stress expressed as an average and
Tensile test.
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