Adhesive bonded anchor bolts

[Hydrostru]

I am working on a bridge where existing 1.5 inch anchor bolts are so corroded they need replacements. I checked hilti and sika adhesives and the maximum bolt size in their chart is 1.25 inches. Does anybody know why? And can I use epoxy bonded anchor of 1.5 inches?

I was also thinking drill 6 inches holes and put in headed anchor bolt and pour in grout? Is it doable? 6 inches hole around 2 ft long?

Thanks!

 

[SlideRuleEra]

I consider your proposal for a drilled, deep hole, with a (nonshrink) grouted in, headed anchor bolt to be reasonable. Two comments:

1. A 4" diameter hole should be large enough. The head of a 1.5" diameter bolt is less than 3" across the points of the bolt's head. The smaller the drilled hole (within reason) the less chance of cutting existing rebar.

2. Before grouting, fill the hole with water and keep it filled for 24 hours. Then remove all the standing water and immediately grout the bolt in place. Wet cure the top of the grout.

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[gwynn]

I believe Hilti recommendations limit the size of the anchor because some their values are test based. The values are limited to the largest size rod they have tested. However, they do provide enough information on bond strength etc. that you can do the schedule D calculations on some of the epoxies for larger rod diameters (mainly RE500 and HY200). Their Profis software will not handle the larger diameters though.

Something like Williams spinlock anchors may also be suitable (Dywidag has comparables, but I don`t recall the name).

I agree with Sliderule that for a headed anchor you can likely reduce the hole size, but the hole diameter may be governed by bond strength of the grout you are using.

Are the anchors cast into the cap or in grout cans? If they are in grout cans you have much larger clearance between bars.