Why ESCR and OIT is so important for Geocell Retaining Wall?
When HDPE Geocell is used on the retaining wall project, below two specifications are very important, one is ESCR=Environmental stress crack resistance, another one is OIT=Oxidation Induction Time. You can check below case study first, then I will let you know the specification requirement for ESCR and OIT.
In the year 2021, I receive an inquiry from Egypt, which want me to help them to fix their Geocell wall. More details are as follows:
First email from customer:
Dear sir,
Good day, we are a tourist development company. Our resort project is located in Egypt and we used the geogrid concept for the retaining walls.
We would like to quest if there are techniques for repairing and fixing the Geocell wall if the outer layer is cut.
Many thanks
My answer:
Dear Karim,
Thanks for your email.
What you mean is you have done your Geocell wall with Geocell and Geogrid, but the wall is broken now.
So you want to cut the outmost layer and repair it with Geocell? If my understanding is right?
__________________________________________________________________________________________________
Dear Karim,
I talked about your project with our engineer and have several questions want to confirm with you:
1, Your previous wall uses 100% Geogrird or use Geogrid + Geocell to build?
2, What’s the width & length of your retaining wall?
3, Could you please share some photos of your current wall?
After get your answers, then we can recommend you suitable technicals for repairing and fixing the wall.
Waiting for your reply.
Many thanks.
____________________________________________________________________________________________________
Second email from Customer:
Dear Claire,
Many thanks for your email,
Yes, we have finished the construction of the Geocell with Geogrid like the photo I attached below.
The problem is that after one year, the outer skin of the wall started to collapsed (cut of the outer layer of the cells). We want to repair these cells that had been cut.
Hence, we quest about which techniques are helpful to resolve this problem.
Dear Karim,
Thanks for your information and pictures.
I talked with our engineer and we both think the best way to repair your wall is to enclose the best quality Geocells in the outmost layer and use the screw washer to fix them, exactly as in the attached photo.
By the way, in order to better repair this project, we’d like to confirm below questions with you:
1, What is the Geocell height/ welding distance/ thickness you used for this project?
2, What are the requirements for OIT and ESCR of this project? and What are the testing results for the OIT and ESCR of all the Geocells that you used?
3, What color do your need? still Green or black also ok?
4, Do you also have other specifications of your used Geocells? like seam peel strength, tensile strength at yield, and carbon black content? If you know, please also tell us.
By the way, OIT=Oxidation Induction Time, and ESCR=Environmental stress crack resistance, which are the most important 2 factors for Geocell to be used on the retaining wall project. And from your information and photo, our engineer guesses the Geocells you used should be very very low quality, OIT may be less than 80min, and ESCR not reach 1000hrs.
For our Geocells be used on retaining wall projects, the OIT could reach 300mins and ESCR can reach 5000hrs, due to the retaining wall out layer will expose under the sun, so OIT and ESCR are very very important values.
Dear Karim,
We have supplied large quantity of Geocells to Japan for retaining wall projects.
Last order, our Japanese customer require OIT no less than 250min, you can check our test result in our factory lab, the result is 294.94min.
And for ESCR we can reach as high as 5000hrs, you can also check our testing report in attachment.
Any further questions, please let Claire know freely.
Thanks a lot.
Dear Claire,
I don’t know how to thank you for your help.
The image is helpful and the questions.
We will try the option you have sent, many thanks for your support.
Kind Regards
Karim
From the above case study and information, I believe you have already known the importance of the ESCR and OIT, so if you want to build a Geocell retaining wall and buy HPDE Geocell, you should pay more attention to these 2 values.
And for Geocell retaining wall, the requirement for OIT must no less than 150min, our Excell Geocell can reach 300min. And the requirement for ESCR must no less than 5000hrs, our Excell Geocell can reach 5000hrs.
If you want to improve the specifications of ESCR and OIT, not only need to use a special virgin HDPE resin, but also need to add additional additives(like light stabilizers and antioxidants) to produce. And the prices of these new special resin and additives are very high, so in order to save cost, many manufacturers always not add them on production, and it is not easy to test for ESCR, need much long time(5000 hours), consider this, you should pay more attention on this.
