When Is Polyurethane Grouting An Effective Repair Solution?

Update:16 Mar 2021

  The application of polyurethane grouting agent in soil densification and structural restoration is completely changing the way public works managers and construction managers think about restoration and replacement. Due to cost-effectiveness and innovations in injection technology, the feasibility of this solution has been "expanding rapidly", and its applications span a variety of uses, such as roadway lifting, manhole and joint sealing, dam seepage barriers, breakwater reinforcement, and Make basic adjustments. The question is, when does polyurethane grouting make sense as a rehabilitation solution?


  As you can imagine, this question is full of many variables, but we will try to determine the typical recovery opportunities and the questions you should ask about overall viability.


  1.) Can the problem be fixed by polyurethane injection?


  The first question to consider is "Is it a soil problem?" First of all, polyurethane injection is used to fill voids, whether it is large voids without soil or voids between uncured soil. The polymer expands rapidly, so once the void is filled, the polymer compresses and densifies the soil and increases its load-bearing capacity. Therefore, if your problem is caused by weak soil, then polyurethane may be a good solution.


  2.) What are the conditions for repairing the structure? What is your goal?


  Although we obviously think that polyurethane injection is very good, this is not the case. If the intended use of the structure is continued use, the structure should be in a relatively operable state. Although we have been able to accomplish amazing things with manholes that have lost cement slurry, we are mainly focused on repairing the soil around or below the structure to ensure that the structure still meets current needs. However, if the structure breaks down, or the focus is on making the structure meet a considerable volume increase, repair may not be the solution.


  3.) When considering sewer infrastructure, when is polyurethane appropriate?


  When it comes to repairing pipes and manhole joints, polyurethane injections are highly adaptable. The reason is that the application can be executed from within the structure (access allowed) or from the surface. This polymer is ideal for sealing leaking joints or stabilizing structures. After being injected, the polymer will expand rapidly throughout the gap to seal the joint and prevent inflow and penetration. In addition to sealing joints and filling voids, polymers can also stabilize adjacent soil, thereby providing more support to the structure and preventing future erosion by stable soil.


  As mentioned in item 2, when determining whether polyurethane injection is a feasible repair plan, structural conditions and future requirements should be considered. That being said, groundwater leaks and IandI may be the main cause of sewer overflows, if alleviated, your actual wastewater flow can be better utilized, and you may find that the current design is more appropriate than you think.


  4.) Can polyurethane injection be used to increase the bearing capacity of the soil to cope with heavier loads?


  In short, the answer is yes, but it really depends on the weight, the quality of the soil, and the nature of the geology and underground structure. In many cases, we have helped to repurpose foundations to cope with sharply increased loads, such as silos, cranes, heavy equipment and machinery, and structural support columns. In each case, the injection method is uniquely designed to take advantage of the current soil and geological structure of the site.


  Not every site has the ability to increase the load. In places where the soil has high plasticity, the increase in the bearing capacity of polyurethane is limited by the bearing capacity of the polyurethane itself, because it cannot penetrate the soil, nor can it build structural integrity by mixing with the soil. In order to increase the ideal bearing capacity, it must have the ability to saturate the polymer and bond the soil into a continuous structural layer. Injection design can help develop a bridging technique to help distribute the load more evenly on the newly reinforced soil.