Polyurethane injection is a safe, fast, and reliable alternative to rebuilding modular crossings that are affected by deflection, voids, settlement and deterioration of adjacent pavements.
Modular Grade Crossing Repair Process
CJGeo’s modular grade crossing repair service works by injecting high density polyurethane under the modular crossing panels to fill voids below the panels and in the adjacent soil, and displace water from the voids to correct deflection and instability. For panels that have settled, additional material is carefully injected below the panels to gently and precisely lift them back to the correct profile. Lifting is generally done to within 1/32 inch.
The polyurethane is injected through dime-size holes drilled through the panels. The grout cures within seconds, allowing for immediate resumption of rail and automobile traffic.
In addition to maintaining current RWP certification for our respective customers, CJGeo’s modular grade crossing repair crews use a repair process that’s specifically designed around safety.
Polyurethane injection is inherently safer than alternative repairs. It does not require heavy equipment or high pressure pumping of cement-based grouts. Additionally, because polyurethane injection is so much faster than alternative repairs, it requires significantly less fouling of rail and disruption of automobile traffic.
Speed Of Modular Grade Crossing Repair
A single polyurethane grouting crew can repair dozens of feet of modular grade crossing panels per hour. Because the polyurethane cures within a few seconds, the repair can be load tested immediately afterwards to ensure the repair has thoroughly addressed the problem. A fast process doesn’t mean we cut corners. Polyurethane grouting is faster than cement-based grout injection because:
- smaller holes (5/8″) are faster to drill than the 2″ to 4″ holes required for cement grout injection
- on demand production generates lifting polyurethane grout quickly, without batching, mixing or agitating
- efficient equipment–a single polyurethane grouting box truck carries the equivalent of 10 trucks of cement-based grout
- fast curing polyurethane grouts cure within a few seconds of injection. Mudjacking grout can take days to cure to the point of taking traffic
Polyurethane is a very resilient material which excels in dynamic loading environments. There are few dynamic loading environments more brutal than modular grade crossings. We use foams with bearing capacities starting around 7500PSF. This far exceeds the loads which crossings see, but is not prone to cracking and deterioration like cement-based grouts are in the same environment. The design life of polyurethanes (100+ years) used in modular grade crossing repair outlives the crossings themselves. Yet the material is easily excavatable, which eases future work in the area.
Other Rail Applications For Polyurethane Injection
High density polyurethane injection can also be used to raise precast rail structures other than modular grade crossings, such as inspection pits. Additional, CJGeo uses polyurethane for culvert joint repair, and void filling applications.
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