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Intro and request for info on HAC - Forno Bravo Forum: The Wood-Fired Oven Community


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Intro and request for info on HAC

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  • Intro and request for info on HAC

    GDay folks, I live on a 100 arce farm in the Adelaide Hills with many wooded areas. I always wanted to make several bar-b-qs around the property but have deceided that several wood ovens would be even better. As I have worked with concrete most of my life I have an interest to using concrete for my ovens. I would like to use High Alumina Cement HAC. From the research I have done I know I should acheive no less than 400 Kgs/M3 HAC. I also want to use in my mix, white sand, perlite, lime, as little water as possible and may be plasticisers in place of alot of the water. Is there anyone out there with experience with HAC who can advise me of ratios etc. I plan to construct a mould out of ply to make my components.
    Thanks everyone

  • #2
    Re: Intro and request for info on HAC

    Your post was a complete mystery to me. I decided to zoom in on one word, and work out from there: Plasticisers
    Plasticizers are commonly manufactured from lignosulfonates, a by-product from the paper industry. High Range Superplasticizers have generally been manufactured from sulfonated naphthalene condensate or sulfonated melamine formaldehyde, although new-generation products based on polycarboxylic ethers are now available. Traditional lignosulfonate-based plasticisers, naphthalene and melamine sulfonate-based superplasticisers disperse the flocculated cement particles through a mechanism of electrostatic repulsion (see colloid). In normal plasticisers, the active substances are adsorbed on to the cement particles, giving them a negative charge, which leads to repulsion between particles. Lignin, naphthalene and melamine sulfonate superplasticisers are organic polymers. The long molecules wrap themselves around the cement particles, giving them a highly negative charge so that they repel each other.

    Polycarboxylate ethers (PCE) or just polycarboxylate (PC), the new generation of superplasticisers, are not only chemically different from the older sulfonated melamine and naphthalene-based products, but their action mechanism is also different, giving cement dispersion by steric stabilisation, instead of electrostatic repulsion. This form of dispersion is more powerful in its effect and gives improved workability retention to the cementitious mix. Furthermore, the chemical structure of PCE allows for a greater degree of chemical modification than the older-generation products, offering a range of performance that can be tailored to meet specific needs.

    In ancient times, the Romans used animal fat, milk and blood as a superplasticizer for their concrete mixes[2].
    That's about where i stopped reading.

    Perhaps someone else can delve into your question.
    My geodesic oven project: part 1, part 2