Here's a response to some emailed questions we got this morning from a prospective customer in Europe. The questions are not included, but you can figure them out. Go to the "contact us" section of the main website www.CreteFoamer.com if you want any further information.
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Your mix can include Portland cement and sand and aggregate as well, depending on dry density desired. We will be glad to provide a suggested mix design based on your desired density and strength. You will have to adjust this based on the materials you have available. Your production rate is one that we can meet with at least one model of our CreteFoamers.
We have two different foaming agents. Both of them will cost about $10 per cubic meter of foam produced. If you wish to make panels of 1/2 normal density, you will use about one cubic meter of foam per cu meter of concrete slurry in the mixer. Cellular concrete tends to set up more slowly than standard density concrete. You can add accelerator admixture to speed up the set-up time. Silica fume also speeds set-up, if you have it available.
You will mix a batch of material and then add the foam to it directly from the CreteFoamer as it is produced. The amount of foam you will need depends on the batch size of your mixer and the desired density. I am not sure what type of "normal concrete mixer" that you think will cause foam to be lost, but I do not think this will be a major problem. We have used a number of small lab mixers, as well as drum truck mixers and volumetric truck mixers. Ribbon and paddle mixers are also used. None of them seem to have a big effect on the foam.
Concrete density is determined by the amount of foam you put in each batch. You control this by the amount of time you run the foamer for a batch. The density of the foam itself is determined by the machine design, the foaming agent used, and the amount of foaming agent used. Our production sized machines have the ability to change the ratio of foam concentrate used, as well as the foam output rate. The density usually falls in the 3 to 4 lb/cubic foot range. (4 lbs/cu ft = 64 gms/liter) In our experience, it is important to have constant flow rate of foam and constant density, but if the density is in the 2.5 to 4 lb/cu ft range, the exact density is not critical. Using too little foaming agent may produce a foam which has the desired density, but not enough bubble strength and life to produce a good finished product. As the density of the concrete is reduced, it tends to shrink when too little foaming agent is used.
I know of no problems with steel reinforcement and cellular concrete. It is possible that the foaming agent could cause corrosion of the steel, but the amount of foaming agent per cubic meter of concrete is very low. I have not read or heard of any problems. The foaming agent is very similar to air entrainment admixtures. Air entrained concrete is commonly used with steel reinforcement.
We recently shipped a machine to Viet Nam which I think is going to be used in a plant similar to yours, but I do not believe the plant is completely set up yet.
I hope this has answered all your questions. Please email me with any more that you have or if I was not clear in my answers.
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