Polyurethane Concrete Raising Vs. Traditional Mudjacking kwells Jun 4, 2009 0000 The equipment is costly and the material is 4 to 5 times more expensive than mudjacking. Why would polyurethane concrete raising be used instead of traditional mudjacking? Four major questions need to be answered. I’ve been hearing about polyurethane concrete raising for the past 20 years. Having been in the mudjacking business for the past 35 years, I thought that because the process was so expensive it would come and go. Polyurethane Concrete Raising Vs. Traditional Mudjacking The equipment is costly and the material is 4 to 5 times more expensive than mudjacking. Why would polyurethane concrete raising be used instead of traditional mud jacking? Four major questions need to be answered. I’ve been hearing about polyurethane concrete raising for the past 20 years. Having been in the mudjacking business for the past 35 years, I thought that because the process was so expensive it would come and go. Vs. Why would anyone spend 4 to 5 times the amount of money to have their concrete raised using polyurethane opposed to traditional mudjacking? Is polyurethane strong enough to raise and support concrete slabs? Does the finished job look better than traditional mudjacking? Who wants their concrete raised using polyurethane foam? Question #1: It does pay to use the more expensive polyurethane method when raising slabs that are poured over very unstable or unsuitable fill. Polyurethane weighs 3-4 pounds per cubic foot compared to 100-150 pounds per cubic foot of traditional mud, making polyurethane material much less likely to overburden unstable soil. In an article written by G. L. Bowen PE. LLC, Helical Piers & Polyurethane Foaming in the April addition of Helical Pier World, Mr. Bowen discussed the advantages of using closed cell polyurethane to fill voids and support floors over peat moss soils in Alaska. In situations like this, light weight polyurethane has a tremendous advantage over much heavier mudjacking materials. Question #2: Traditional mudjacking does have an advantage over polyurethane when it comes to compressive strengths. A contractor can make the compressive strength of mudjacking material be whatever is desired by adding cement or combining cement with lime or sand achieving compressive strengths of 2,400 PSI. Polyurethane’s compressive strength is consistently around 80 to 100 PSI. It is preferable to pump a higher compressive strength material than the existing sub-base. Question #3: A feature of polyurethane that will make the end results more attractive especially to the residential market is a smaller injection hole. Polyurethane utilizes a hole that is only 5/8” or smaller compared to mudjacking holes that run between 1” and 2”. Question #4: US Departments of Transportation seem to be preferring the use of polyurethane concrete lifting for sagging bridge approaches or removing dips in highways. The main reason being the light weight characteristic of the material which will not overburden the soil. My experience tells me that conventional mudjacking will be around for a long time. The average consumer will always look for the most inexpensive way to fix settled concrete. However, polyurethane concrete lifting has found a home and will be the solution to raising slabs when a light weight material is needed. I look forward to continuing to explore the multiple benefits and characteristic of polyurethane in future blog postings, until them I welcome any comments or questions you may have.