Max. Size Aggregate in Grout Mix

[M40A]

We have a requirement that the max. size aggregate in a grout mix be 3/8" and be batched from a ready-mix plant.

What may be some benefits of have a 3/8" aggregate in a mix?

 

[cvg]

lets start by defining the problem

what are you planning using the grout for?

 

[M40A]

The grout will be used behind angle iron in a dam.

 

[cvg]

so I am guessing (because you still haven't provided much) this is a structural piece and grout is used to set level, plumb or to proper elevation? If so, than 3/8 gravel is probably too large.

 

[Ron]

I sort of agree with cvg, except that the angle and the space behind it might be large enough to accept a 3/8" aggregate. If that's the case, there are several advantages to having larger aggregate in the grout. The first is that the relative shrinkage will be lower. The second is that the mix will be slightly less expensive because the volume taken up by coarse aggregate will displace some of the volume otherwise required to be filled with cement-rich paste. If you have a lot of grout to place, that can be a substantial cost difference.

 

[M40A]

I think that's along the lines I've been researching... The alleviation of shrinkage seems to be the key component. Thks.

 

[cvg]

at some point you are no longer providing a leveling pad, you are filling a void. for filling voids, any sort of grout or concrete that you can get into the void will work. If it is a large void than use even larger aggregate. However, for leveling structural elements, gravel is not generally used. Up to about an inch or two thick leveling pad, I would stick with sand. Note that for leveling structural elements, I always specify non-shrink grout.

 

[Ron]

cvg...I agree with you for leveling applications; however, the OP states that the grout will be used "behind" the angle, not "under" the angle.

Non-shrink, pre-mixed grout is great for small applications. I just get the impression this is for quite a bit of grout.

M40A could you fill us in on the application a bit?

 

[cvg]

agree, we are speculating - M40A needs to provide a lot more info in order to get a focused response

for instance

pumped?
size of opening
function of grout
vertical or horizontal space?
apply before or after installation of the angle
how big of an angle/structure are we talking about

 

[M40A]

I'm tracking down more information on the dimensions and volume of the pour. I was looking for generalities regarding the pros of 3/8" aggregate in a batched mix as opposed to sack grout.

I will post more information as it becomes available.