Easier to get right - diamond grinding or shot blast?

[terryp]

My question is this - which is easier to use and get a sufficient end result (floor ready for an epoxy coat)? I understand they can both do the job, but I am looking for opinions on which is least likely, in the hands of a newbie that has used neither, to damage the floor and cause problems. Shot blaster is an 8 inch wide impact area, I think the grinder takes 12" discs / heads.

I also have a 10 foot long (about 1/8" wide at widest) crack in one subsection of floor and am considering using a crack chaser to widen / profile and then fill. What should I budget for time on the grinding? Also, should this be done before or after the grinding / shot-blasting?

 

[thegarageguy]

Sir, in life we usually get what we pay for. In my industry this saying is reality. These are manufactured on site flooring systems. If you are just comparing the two bids by final amount you are doing yourself a disservice.

What is being specified for $3200? Give me the specs on the $2000 job as well. I can then tell you why one is cheaper than the other.

At 700 sqft, I can do a cheap water based epoxy primer(400 sqft per gallon or 1.5 gallons), roll on a cheap high solids epoxy base (250 sqft per gallon or 3 gallons), full broadcast of chips(100 lbs) and topcoat it with a decent epoxy(200 sqft per gallon or 2.5 gallons) and come in cheap. Total 7 gallons of cheap epoxy and 100lbs of chips

on the other hand...

I can specify a poured 100% solids system, consisting of a quality primer (300 sqft/gl or 2.5 gallons), pour an aliphatic 100% solids epoxy (100sqft per gallon or 7 gallons), full broadcast of chips (125 lbs of chips), then topcoat with a quality high solids(above 90) polyaspartic (100 sqft/gl or 7 gallons) 9.5 gallons of quality epoxy and 7 gallons of top of the line topcoat. Basically twice as much material and 3 times the cost on our end.

Both, if made a samples side by side would be very difficult to tell the difference, even to a seasoned pro. Only time will show the difference, when its ambering and wearing, by then it'll be too late.

Again, in the end you'll get what you pay for.

 

[AlphaGarage]

How large is the floor overall, what shape is it in other than the crack? What's the crack from, how deep is it? Are the two sides of the crack on the same grade?

How many discs does the grinder have?

 

[terryp]

The floor is 700 sqft, divided into 6 subsections (created by stress relief V cuts... the big wide "V"s that I see in some of the pictures rather than a vertical slot that I have seen on floors as well). The crack is contained to one of the 6 subsections and runs thru the middle of that subsection. Both sides of the crack are at the same level... it is a stress relief crack that is basically hairline, but widens in a few spots. My guess is that it cracked shortly after pouring (3 years ago... I've only owned the house for a month and a half). All of the stress relief V's have cracks in the bottom of them (that I was trying to figure out how to seal / deal with as well.

It is a dual disk diamond floor grinder rental (+ vac.). Looks kind of like a floor buffer.

Overall the floor is in pretty good shape and fairly clean. 3 years old, no real oil stains. There was one or two "weird" small sections of some kind of dark thick gooey round drops (that seem to come up a little with a finger nail) (and this is post application of muratic acid). There are also about 10-12 small (dime size) drops of paint that are well bonded with the concrete.

I had considered acid stain and AcryliSeal 3501 after seeing some of the other posts liking the results and the apparent reduced effort and lower cost, but someone (long story, not me) has already applied muratic acid in spots and I can't come up with any ideas for putting something attractive under the sealer that can be applied after the acid application (as that seems to remove the minerals needed by the acid staining to have the chemical reaction). Consequently, I am looking at shotblasting or diamond grinding and then epoxy. Just want to choose the floor prep method that is more likely to be done well by someone with experience with neither.

Any feedback you could provide would be hugely appreciated.

 

[thegarageguy]

I can't come up with any ideas for putting something attractive under the sealer that can be applied after the acid application (as that seems to remove the minerals needed by the acid staining to have the chemical reaction).

You have 2 choices;

1. Use a concrete dye. An experienced installer can give it a mottled look. Believe it or not, most "acid stain" jobs are really dye jobs. Since the "GREEN" push, its the only option. Even most acid stain jobs are accented and or touched up with dyes.

2. If you need crack repair and don't want them to show, you can have your floor overlayed with a polymerized cement system. These systems get either poured out and self leveled at a 1/4 inch to 3/8 inch thick or done in 3 tight skim coats. They can be integrally colored or stained if you wish. These systems will up the price but the only way to hide unsightly crack repairs.