Bridge Spherical Bearing Grout Pad Shoulder Cracks

[KalTheBuilder]

Hello all,

I am currently working on a bridge project where some narrow cracks (0.05mm to 0.3mm) have appeared symmetrically in the shoulders at exactly 90 degrees to the face of the grout pad. These cracks appear consistently on every side of the shoulder and almost every bearing we've poured (which was designed to be quite wide). We are using a metallic aggregate ultra-high compressive strength grout (100 MPA +) and the depth of the grout pad is 200mm. The cracks are shallow (do not extend past reinforcement) and stop before the base plate.

According to BS EN 1992-1-1 table 7.1N (below), the maximum allowable crack width in this structure WOULD be 0.3mm which would be fine.

However, the client is arguing that BS EN 1992-1-1 does not apply as it only explicitly mentions concrete, and that grout should NEVER crack. They claim that since there is no mention anywhere in BS or BS EN of allowable crack widths in structural grout, cracks should not be acceptable.

Does anyone have any experience with this or know a standard I could cross-reference? From a durability perspective, the grout should not be any different than concrete in my opinion and these cracks are not in the load path of the bearing.

Thanks

 

[bridgebuster]

Sorry, I didn't mean to be flippant. Would your client accept sealing the cracks and calling it a day?

 

[BridgeSmith]

A 20mm grout pad might not crack, but a 200mm thick grout pad? I'd find it absolutely amazing if it didn't have cracks.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[KalTheBuilder]

Would your client accept sealing the cracks and calling it a day?

Ideally that would be the next step. I have wasted so much time and resource on this. The designer and client are very inexperienced, so they think the problem could potentially be structural and become worse once the structure is loaded. I suspect this is a political/commercial move TBH.

A 20mm grout pad might not crack, but a 200mm thick grout pad? I'd find it absolutely amazing if it didn't have cracks.

Agreed. That was my argument from the start. The design is in line with the Euro code as the grout is reinforced, but we have some areas of cover that are as high as 140mm (140mm of unreinforced grout) in the extremely wide shoulders. Reason is not working with the client, unfortunately, which is why I need something from a code or standard that will back up my position. They're also afraid that something would happen and they'd be liable to replace all the bearings if they approve the cracks--which is why they want us to monitor them until the structure is open to live traffic (3 years from now or something lol).