Astm D 4355 Pdf

[Judd Eisenhauer]

ASTMD4355 is a standard test method for deterioration of geotextiles by exposure to light, moisture and heat in xenon arc type apparatus. This test describes the determination of the deterioration in tensile strength of any permeable textile material employed with earth, foundation, soil, rock and so on. It is based on practice ASTM G155. Micom offers ASTM D4355 testing as part of its polymer test services.

By exposing the samples to xenon arc radiation, moisture and heat (end use conditions), it is intended to induce property changes. Indeed, polymers can have their mechanical, electrical and optical properties significantly altered when exposed to these types of factors. The simulation of the deterioration provoked by localized weather, such as, atmospheric pollution, biological attack and salt water exposure is not intended by the exposure used in this practice. Following each exposure period, the specimens are subjected to a cut or ravel strip tensile test in order to produce a degradation curve. The latter allows the user to determine the tendency of a geotextile material to deteriorate when exposed to various factors such as solar radiation, water and heat. For a combination of UV exposure and salt water, you should consider ASTM D5894.

Table I : Specifications of the characteristics of the samples

ParametersSpecificationsNumber of specimens required20 for each orientation testedSpecimen size50 x 150 mm (2 x 6 in)ThicknessWithin 10% of the nominal dimensions

Sunlight exposure can have harmful impacts on carbon-based

materials such as coatings, polymers, textiles, and many others.

Learn more about our in-laboratory UV testing process in this guide.

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Ultraviolet (UV) radiation is critical to geosynthetic resins. It causes polymer bond breakage leading to loss of all properties including discoloration, tensile strength and tensile elongation. This paper presents the test results of outdoor weathering of a high strength woven polyester reinforcement geotextile at site locations in Auckland and Christchurch, New Zealand. The onsite exposed samples are tested for loss in tensile strength and elongation over time and compared with results of accelerated UV lab tests. The standard accelerated UV lab tests for geotextiles include the Xenon Arc Test according to ASTM D4355 and the QUV Test according to EN 12224. These results help establish some form of correlation between standard accelerated UV lab tests and onsite UV degradation of high strength woven polyester reinforcement geotextiles in New Zealand.

The exposure of a geosynthetic material to UV radiation generally has a negative impact on its intended engineering performance. It causes polymer bond to break or scission of main polymer chain, resulting in property changes over the exposure period (CUR 243, 2012). This is especially important when it concerns reinforcement applications because the material loses tensile strength and becomes more brittle. The general practice is to cover the reinforcement material, typically with a layer of soil cover, within a short period of time to minimise the loss of tensile strength and embrittlement. Very often questions are raised concerning how long is a reasonable and practical time limit to allow for before it should or can be covered up and how much of tensile strength loss and embrittlement happens during that period of exposure.

Accelerated UV lab test standards are available to benchmark the performance of geosynthetics against UV degradation. These accelerated tests that are set on standard artificially generated UV spectrum and intensity, are important in determining comparative UV degradation performance of geosynthetics but they have limitations for a variety of reasons. The UV radiation levels incident onsite is dependent on its geographical latitude and altitude; climatic and weather conditions; ground shading and reflectivity conditions; just to name a few. As such correlation between actual onsite exposure and standard lab test is a difficult subject. However, when such standard tests are calibrated with onsite UV degradation tests, they can then be used in a reliable way to predict UV degradation resistance under similar prevailing conditions.

It was with this in mind that a testing program was undertaken in New Zealand. A woven polyester geotextile of nominated ultimate tensile strength of 1000 kN/m in the machine direction (MD) and 100 kN/m in the cross direction (CD), commonly used for embankment basal reinforcement, was chosen as the test specimen. Controlled sites free from external disturbances were chosen for the exposure sites. Auckland was chosen as the representative location for North Island conditions while Christchurch was chosen as the representative location for South Island.

The protocol for the outdoor weathering exposure considered sampling of the high strength woven polyester reinforcement geotextile (Mirafi PET1000/100) for outdoor weathering exposure for 5, 14, 28 and 42 days. The selected exposure locations are within secured compounds to rule out disturbance or damage due to external factors. Samples are laid basically flat to reflect the geotextile laid out condition at construction site.

The onsite exposed samples were tested according to ISO10319 at a GAI-LAP accredited lab. Accelerated UV tests which included the Xenon Arc Test according to ASTM D4355 and the QUV Test according to EN 12224 were conducted to establish correlation between them and onsite UV degradation.

Table 1 shows the test results of MD peak tensile strength and strain at peak strength for the samples exposed in Auckland. Table 2 shows the test results of MD peak tensile strength and strain at peak strength for the samples exposed in Christchurch.

The peak tensile strength retention after 42 days of exposure was 91% for sample exposed in Auckland (see Table 1) while the peak tensile strength retention after 42 days of exposure was 96% for sample exposed in Christchurch (see Table 2). For reinforcement geotextiles it may be more relevant to understand the retained strength at working strain levels than at peak levels. For embankment basal reinforcement applications, working strain levels typically may vary between 2% to 5%.

Table 3 shows the test results of MD tensile strengths at 2% and 5% strains for the samples exposed in Auckland. Table 4 shows the test results of MD tensile strengths at 2% and 5% strains for the samples exposed in Christchurch. At strain levels of 2% and 5%, it appears that there has been no measured loss in tensile strengths for up to 42 days of samples exposure at both Auckland and Christchurch (see Tables 3 and 4), even though a drop in peak tensile strength over time is seen.

The graphs clearly show higher level of solar radiation at the Auckland site when compared with the Christchurch site where the testing occurred later into the autumn months. The 5 day and 14 day testing in Christchurch occurred towards the end of the 42 day test resulting in lower radiation values for this period late into autumn. Sunshine hours have also been taken measured and the results shown in Table 5.

The samples used for the accelerated UV tests were taken from the same geotextile roll as those used for onsite weathering tests. Both the accelerated UV tests were conducted at GAI-LAP accredited labs. Table 6 shows the test results of peak tensile load and strain at peak load for the Xenon Arc accelerated UV test conducted according to ASTM D 4355. Table 7 shows the test results of peak tensile load and strain at peak load for the QUV accelerated UV test conducted according to EN 12224.

The standard accelerated UV lab tests for geotextiles typically use the peak tensile strength for relating the loss in tensile strength with exposure time. As such for correlating these standard accelerated UV lab tests with real time onsite weathering characteristics, the peak tensile strength will be used as the benchmark. For the real time onsite weathering exposures, the late summer into autumn season, which coincides with the peak construction period in New Zealand, was chosen for the exposure to represent an average condition for the exposure intensity. Figure 5 shows the residual strength (as a % of the original peak tensile strength) versus exposure days for real time onsite weathering exposures in Christchurch and Auckland and the accelerated UV tests according to ASTM D4355 and EN 12224.

For reinforcement geotextile applications the recommendation for construction period weathering exposure limit is generally based on evidence showing little or no loss in tensile strength over the recommended exposure. If for unexpected circumstances the exposure limit is exceeded, then correlation factors established between accelerated UV tests and onsite UV degradation tests may be used to estimate residual strength.

The rate of tensile strength reduction with time for all tests appear to be linear over the duration of tests. The rate of strength reduction for samples subjected onsite weathering in Christchurch is 0.1% per day while the rate of strength reduction for samples subjected onsite weathering in Auckland is 0.25% per day (see Figure 5). The rate of strength reduction for samples subjected to the accelerated UV test according to ASTM D4355 is 2.7% per day while the rate of strength reduction for samples subjected to the accelerated UV test according to EN 12224 is 3% per day (see Figure 5). Therefore, the accelerated UV test according to ASTM D4355 corresponds to acceleration factors of 27 and 11, when correlated with the real time onsite weathering in Auckland and Christchurch respectively. And the accelerated UV test according to EN 12224 corresponds to acceleration factors of 30 and 12, when correlated with the real time onsite weathering in Auckland and Christchurch respectively.

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