• #121 by Tscarborough on 24 Jun 2018
  • You add vermiculite/perlite to concrete to make it lighter, but it also reduces the strength by a significant amount.  The purpose of the grog is to prevent cracking, and to reduce the amount of paste needed to make the concrete.  It will increase the strength.
  • #122 by BANTAR1000 on 24 Jun 2018
  • Well crap... lol now I have to go take out some aggression!
  • #123 by BANTAR1000 on 27 Jun 2018
  • I think I'm gonna look for one of these!  lol 
  • #124 by BANTAR1000 on 22 Jun 2019
  • So I'm back to work again!  But I'm not using a hammer, I'm using a big hammer drill to make grog with my fire bricks.  My plan is a 2" wall all the way around the first sailor course up to the top of the first bricks.  Is the mix for this concrete the same as usual just with fire brick rocks instead of regular aggregate?  Also, how can I tell how much grog I'm gonna need?  Yes, the hammer drill is easier than the metal plate and hammer posted before but it still sucks!  LOL  Thanks guys!  -John
  • #125 by Jon in Albany on 22 Jun 2019
  • The mix I used was homebrew plus grog.

    1 part hydrated lime, 1 part fireclay, 1 part Portland cement, 3 parts sand plus grog.

    No idea how much you will need. I had a good sized box full of it it and thought I could have used some more. As the making of the grog continued, the size of the pieces got bigger out of laziness and possibly grog making fatigue.

  • #126 by BANTAR1000 on 22 Jun 2019
  • Wow, Jon I had this all wrong.  I thought it was the

    3 aggregate, 2 sand, 1 portland mix and I was just going to use firebrick grog instead!

     How big was your box?  I was planning on using 5, 5 gallon buckets full of grog!
  • #127 by Jon in Albany on 24 Jun 2019
  • I can't speak to that mix. I followed Tscarbough's lead from when he built and oven for Gene. You can see what he did in this area of the thread.

    My oven is 42 inch diameter. I poured a 2 inch thick ring around the walls. I also added a little more to add mass to the dome.
  • #128 by BANTAR1000 on 15 Feb 2020
  • Again, Iím back at it this time hopefully for good.  Iím still stuck at the refractory concrete for reinforcing the ďSailorĒ walls.  Iíve found an easier way to make the firebrick grog, but I donít know how much to make!

    For a 2Ē thick wall all the way around 42 diameter Iím gonna use:
    1 part Portland
    1 part fireclay
    1 part hydrated lime
    3 parts sand
    2 parts crushed fire brick
    How much crushed fire brick will I need to have?  I have one and a half 5 gallon buckets at the moment but plan to spend tomorrow making more.  Thanks for checking on me! 

  • #129 by BANTAR1000 on 08 May 2020
  • I need clarification.  This is taking me so long because of work and kids.  I took my tarp off the other day to start mortaring new bricks and several bricks fell over.  It's very possible it was a very hot day when I did it and the mortar dried too fast.  So,  Is this correct:

    homebrew refractory Concrete
    1 portland, 1 fireclay, 1 hydrated lime, 3 sand, 2 crushed fire brick

    Homebrew refractory Mortar
    6 sand, 1 portland, 1 lime, 1 fireclay

    Masonry is WAY too complicated for this banjo player!
  • #130 by Jon in Albany on 08 May 2020
  • In my build I used HeatStop 50 for mortar so I don't have hands on homebrew mortar experience. But the way I did it was the only difference between homebrew mortar and homebrew refractory concrete was the grog.

    Homebrew mortar

    1 Portland
    1 Fireclay
    1 Hydrated Lime
    3 sand

    Add grog to make it a concrete.

    The 6 parts sand seems high, I'm wondering if you are crossing a perlcrete formula which I have seen have 6 to 10 parts of perlite in it.
  • #131 by BANTAR1000 on 08 May 2020
  • Thank you again Jon! That may have been an issue before.  But now I feel better about it.  Iím hoping to mortar the last of the low bricks today or tomorrow, then set my form for the concrete early next week!
  • #132 by BANTAR1000 on 08 May 2020
  • How far did one 50lb bag get you? 
  • #133 by Jon in Albany on 08 May 2020
  • How far did one 50lb bag get you?
    I think I used 3 bags plus some of a 4th on the build. If I was a better mason, it would have taken less than 3 bags. I had a plastic cup that I kept in the bag of heatstop. I'd scoop some into a plastic bowl and then add some water from a liter sport water bottle. Made what felt like a million small batches. Only make you need right away.