How to Distinguish and Choose the High-Quality GCL?
Hello everyone, this is the laboratory department of Zhonglong Environmental Protection.
Gcl is a common material in waterproofing projects, such as municipal engineering projects like artificial lakes or hazardous waste treatment like landfill, where GCL is widely used as a secondary anti-seepage layer. Its main working principle is that it gels and expands upon contact with water, thereby forming a barrier to block leaks.
The market offers a wide variety of GCL materials of varying quality. What should high-quality raw materials look like, and what are the differences?
Today, we’re going to discuss how to quickly distinguish between high-quality and low-quality raw materials for GCL.
As an anti-seepage material, the main working principle of GCL is that the bentonite within it gels and expands upon contact with water, forming a barrier to block leaks.
Well, you may have noticed that the water-absorbing expansion volume of bentonite in GCL has an limit. We conducted a comparative experiment in the laboratory as follows:
1. We took four samples of ground bentonite powder, each with a unit mass of 2g (including two non-standard samples and two samples we adopted), and simultaneously added them to containers filled with the same volume of distilled water.
2. After allowing 24 hours for full water absorption and expansion, the results are shown in the figure below.
(Figure 1 | The first and second sample from the left are non-standard; The first and second from the right are Zhonglong's raw material)
As illustrated, the two samples on the left expanded to less than 10ml in volume, while the two samples on the right expanded significantly more than those on the left.
(Figure 2 | Zhonglong's raw material sample swelling index reading)
The natural sodium bentonite adopted by Zhonglong can achieve an expansion volume of nearly 30ml. According to the GB/T 35470-2017 standard for natural sodium bentonite GCL, an expansion index of ≥24 ml/2g is required for long-term or permanent projects such as rail transit.
Thus, it is evident that GCL made from high-quality bentonite raw materials can expand to a greater volume upon contact with water, forming a denser three-dimensional waterproof layer to ensure project safety.
Reference blogs:
1. Geosynthetic Clay Liner Tips: Types and Swelling Index
2. What is GCL? How Does GCL Work? Hydration & Gelation
3. Geosynthetic Clay Liner Tips: Needle-Punching Process
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