We were discussing polyurethane foam injections for slab foundation repair. In the previous post we have already learned that it have some additional advantages over conventional grout technology. We have discussed about setting time of this foam material. Now we will learn more information about it.
Now we will have idea about density of usual cement paste and polyurethane foam. The conventional cement grouts have weight around 150 lbs/cft whereas the polyurethane foam have density merely (2-10)lb/cft. As self weight of repair material is less, it produces overburden pressure, to soil beneath, of minimum value. This is also a very important factor to choose this material as repair and raising material.
Narrow Injection Holes:
In case of slabjacking the holes drilled to inject grout is around 1.5 inches whereas this foam requires mere 5/8 inch holes. Not only in hole diameter but also the foam have advantage over hole spacing. The injection holes required to penetrate foam is much further than of a slabjacking process.
Handling and Cleaning:
This work is much neater than grout injection. Being finished the injection of foam, the worker can pack up there instruments and materials very quickly i.e. demobilization time is less. Here in this process the cleaning operation for equipment is not required. Thus he work site can be left open for service without interrupting service area.
Polyurethane foam provides good thermal insulation too which produce a repaired area of not susceptible to extreme heat or extreme cold condition.
Closed-cell polyurethane results a repaired surface, that restricts or act as barrier to moisture to penetrate through the concrete slabs. This property is particularly important where expansive soil lies beneath pavement or slab.