Hi, I'm new to this forum. We are mid-way through our pool/backyard renovations and I would like to ask for some advice, as we have received some conflicting information. A slab for the pool surrounds and entertaining area has just been laid, using exposed aggregate. We asked for minimal/low exposure so that the surface was not going to be too rough for little feet. The slab was poured by a concreter, gently washed on the day and his advice was to leave it for one week (wetting each day) and then he was going to come back and use an acid wash to expose the aggregate. Less than 48 hours later, the landscaper heading the project and a labourer showed up with a high pressure gerni and blasted the surface. He insisted that this had to be done, despite my objections. There are now several areas where the aggregate has been exposed very deeply. The landscaper is adament that this was caused on Day one when the slab was laid. I don't know who or what to believe?? Does anyone have any advice on the way an exposed aggregate slab should be laid and finished? Thanks in advance
Post subject: Re: Exposed aggregate, advice needed
Posted: Sep 08, 2012 10:49 am
Joined: 14 Oct 2007 Posts: 630 Location: sth est Melb
To get minimal expossure the concrete should not be washed down. It should be troweld to a steel trowel finish with either a fresno trowel or a stick trowel, left to cure for app. 2 weeks then ground down and then acid etched and finaly sealed with a 70/30 ration of xylene based sealer to thinners. One coat only
The correct way to expossed agg. for standard exposure is: pour conc. let bleed off then spray with MBT, let it soak in, cover with black poly plastic and then expose next day. Next day exposure gives an even finish, same day exposure can cause blow outs and "over exposure"
ps; MBT is the concrete retardent, it is designed for next day exposure
It seems to me that landscaper came too early and interfered with concreter's work. Landscaper ignored your instructions not to do it (you are builder in charge) I would be asking landscaper to pay for repairs or demolition and replacement
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