High Tech materials are available such as super-low-viscosity (SLV) epoxy for "micro crack healer-sealer" including expandable chemical urethane to stop multiple leak branching sources. These materials have been used exactly for modern dam spillway repairs by reputable & experienced concrete specialization companies.
Oroville's spillway design poses many challenges*. They don't even know why the waterflow continues to discharge for a while after the gates are closed. It's clear that the original construction placed a layer of washable material -such as compacted aggregate & now revealed "clay" in spots - between the bedrock (or less than bedrock) and the slabs. Voiding formed and now there is discussion of "channel flows" (or "piping" in the engineering term) nearly everywhere (to some degree). Look at the "void seam" before they shotcreted the damaged upper spillway.
There is evidence that the "voiding" combined with the "thinning" of the slabs by the drain piping design is causing a flexure of the slabs** when the spillway is used (at a decent flow). This could cause all of the patching at the cracked drain profiles to re-crack.
So the question becomes: (IF the MS needs a superior sealing state to reduce problematic developments) - What are the "flexing" dynamics of the spillway? This will drive the answer to the effectiveness of a technological materials application choice.
btw- there are some amazing epoxies available today. One type that I favor is an aerospace grade epoxy that is used to bond joints in high stress flexing and aircraft grade reliability performance requirements in copter blades. It is expensive & is made by 3M.
*Drains emplaced "upward into the slabs" severely "thinned" the concrete slabs. The slabs severely cracked above nearly every single drain line run on the entire spillway. The 50 yr old spillway design does not have seam "water stops". The spillway concrete pour was emplaced upon a washable compacted gravel bed. Thus large crack volume + seams area per slab drives a pressurized waterflow from spillway operation.
**More flexure means continued failure of concrete surface patching, leading to re-cracking of the patch in addition to surface stresses exposing the seams to spontaneous spalling ("chipping").
Thanks gents for the thoughtful replies.
I can’t believe I forgot about the expansion issue, will have to give my self a dope smack for that one:-)
Off to work I must go:-(
Regards
alfa6 ;>}