Browse Forums Paving & Concreting 1 Feb 10, 2011 4:23 pm So yesterday we finally had our front yard concreted and stencil new. Today we woke up to this. There is no sealer yet as per the instructions of the concreter and told us to water it for a few days before the sealer goes in. Im thinking its a natural process of stenciling and will go away eventually but Ive never seen this before. Whats happening here? http://img15.imageshack.us/img15/8529/stencil1h.jpg http://img201.imageshack.us/img201/4321/stencil2.jpg http://img217.imageshack.us/img217/9822/stencil3.jpg http://img211.imageshack.us/img211/8925/stencil4.jpg http://img97.imageshack.us/img97/6900/stencil5.jpg http://img268.imageshack.us/img268/9217/stencil6.jpg Re: Stencil job gone bad? 2Feb 10, 2011 4:31 pm Looks like efforvesence, which is natural salts coming out of the concrete. You can brush it off or power wash it. It may continue to come out for some time so don't seal until its all gone. The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Stencil job gone bad? 3Feb 11, 2011 4:00 pm An Explanation of the Formation of Efflorescence on Concrete Pavers Analysis of the white deposits on the surface of concrete indicates that in the majority of cases, it consists predominantly of calcium carbonate (CaCO3), which is insoluble in water. Only very rarely will the deposits be of other salts, as these are usually soluble in water, and are therefore washed off very rapidly by rain, etc. The presence of this calcium carbonate can be explained as follows: Whilst the concrete is hardening, (that is, during the reaction of the cement with the mixing water) not only are familiar calcium hydrosilicates formed but, at the same time, considerable amounts of calcium hydroxide (Ca (OH)2 ) are emitted. This unavoidable by-product of the hydration process of cement, being a relatively soluble substance, dissolves in the excess water that is always present in wet-cast concrete. During the drying or curing phase of concrete, this excess water mixture, which is actually a calcium hydroxide solution, migrates to the surface of the paving or concrete unit, where it evaporates. However, since only the water can evaporate, the entrained calcium hydroxide remains behind on the surface of the concrete unit. Here, there is a very rapid carbonation of the hydroxide in which the latter is converted through the absorption of carbon dioxide (CO2) from the atmosphere into water-insoluble calcium carbonate, which we find again in the chemical analysis of this efflorescence: Ca (OH)2 + CO2 = CaCO3 + H20 This kind of efflorescence, which is actually formed during the curing of concrete, is known as “primary efflorescence” and usually covers the concrete unit in a uniform and closed layer. In extreme cases it may appear to alter the colouring of the affected concrete unit. As we know, the curing of concrete occurs over a long period extending over several weeks and longer. As a result of this curing process, fresh calcium hydroxide is constantly being released inside the concrete unit during this period. Hence, even if primary efflorescence can be avoided in the initial concrete mix, renewed penetration of water, (ie a wet / dry cycle) into the concrete unit can and will dissolve this calcium hydroxide, and again transport it to the surface in the same way as described above. This type of efflorescence, which is frequently caused by rain or condensation on the concrete unit, is known as “secondary efflorescence”. It usually differs from primary efflorescence in that it occurs very locally, and does not manifest itself evenly over the concrete unit. Generally we use a phosphoric acid mix to clean the surface, then neutralised with a light dish washing / water mix, but only time will cure the problem Da Vinci Outdoor Living Architectural landscaping http://www.davincioutdoor.com Re: Stencil job gone bad? 4Feb 11, 2011 5:18 pm Nice post Davinci Where you are coming from is where you are going to... Re: Stencil job gone bad? 5Feb 11, 2011 6:15 pm ...I'd add to that: It is important to wait for the 'bleed water' to happen before progressing to the 'cover' stage. It would appear the 'bleed' water has transuded through the colour. Where you are coming from is where you are going to... Re: Stencil job gone bad? 6Feb 11, 2011 10:30 pm Wow, all this sounds heavy going. By the sounds of it, it will be a long time before the whole stencil goes to its proper colour which is charcoal and im assuming not to put the sealer in before then? Where does one get this Phosphoric Acid. Bunnings? Re: Stencil job gone bad? 7Feb 12, 2011 2:32 pm hi there its a job gone wrong looking at all the imperfections chiped edging,oxide under stencil etc this is a comon problem we have with black coloured oxide only but waiting nomally does more harm than good as concrete is a pouris product and it is the sealer that not only protects the colour from fading but puts a protective seal over the pourus product and yes the sealer will take away the white 100% my advice since you are being bombarded with all this mind numbing info is to seal one brick only where the most affected area is make sure you use 3-1 ratio solvent to sealer do 2 coats. Re: Stencil job gone bad? 8Feb 13, 2011 9:03 am Maybe they used a 'scattered colour' approach? Apparently, when they scatter the colour on top of concrete, they can make it a uniform look, or randomly scattered, where you'll see shade variations in colour. My signature is distracting people from my wise posts ... Re: Stencil job gone bad? 9Feb 13, 2011 9:42 am Mind numbingly unobtrusive, but the legal disclaimer was, well,... l o n g. Do you offer a warranty of any kind? ..and so we know, what cost per sq mtr for the standard, mid range colour on flat ground in your local area? Where you are coming from is where you are going to... Re: Stencil job gone bad? 10Feb 13, 2011 5:35 pm thanks for uploading pictures from my web site champ. its called a hit and miss finish to give it a two tone natural and motel finish/effect the original post has calcium problems and to answer your question we stand by picture perfect driveways guaranteed or your money back + obviousley your industry standard 7 year warranty! and sorry we do not quote on square meter rate as it is an unfair system to use for the consumer.jax Re: Stencil job gone bad? 11Feb 13, 2011 7:19 pm Thanks for the reply jax ... pics now removed as you've explained the process of how that 'scattered' look is achieved. I suppose there would be clients who actually ask for that look My signature is distracting people from my wise posts ... Regardless of wall hung toilet or floor pan toilet your feet will be right on drain, seems to me the waste should not be in that location given the design. Also are you… 6 7048 Last year I had a gas leak at my house. 3 days later, I have about 1 sqm of my exposed aggregate paving broken up. I am not sure how to go about getting it repaired… 0 10415 Thanks for much mate. I see that you do cabinets before flooring. For timber flooring, for most parts it's fine because it's got base plates, and for door jabs you can… 7 11570 |