Had a real bad time with a grout bag on a bridge job in Savannah last month

We were doing a concrete patch on the pilings, about 20 feet down. The grout mix was too thick and the bag nozzle kept clogging. My dive partner topside kept adding water, but then it got too runny and just washed away in the current. We wasted three full bags before we got the mix right. How do you guys deal with mixing grout for underwater work when the specs from the engineer just don't seem to work in the real water?

3 comments

3 Comments

terry_mitchell2mo ago

My buddy swears by adding a bit of extra plasticizer to the mix for tricky currents.

amy_lopez802mo agoMost Upvoted

Your buddy's extra plasticizer trick is a fast way to ruin the whole batch.

blair_butler471mo ago

Honestly, that plasticizer thing is a gamble. Adding a little bit can help with flow, but if the water's moving fast, that extra plasticizer just makes the grout more prone to washout before it sets. Better to focus on the water-to-cement ratio from the start and use a non-sag admixture if the engineer allows for it. Mix it just thick enough that it holds shape in your hand, but not so stiff it clogs the bag. Tbh, I've had way better luck with a slow, steady mixing process than trying to fix it with additives mid-job.