pidgeon chit welder
sticking metal since 1962
- Messages
- 961
Here is my take on / about inserting the expansion joint/gaps and using inter slab connecting re bar to prevent slabs lifiting .
I can't recall the actual slab size rule , but I often used to use the rough rule of no cast slab less then 2 mtr long and not longer than 10 mtr cast the inter connecting rebars in the slab 50/50 , drill throughnthe MDF to set the bars in place , support the MDF with steel pins , if the slab is thicker than three inches , no slab less than three inches thick unless impossible to avoid .
Expansion joint of 15 mm wide use MDF leave it to rot out or pick out and fill gap with compound .
That joint in the work you have already done ... yes you could polish it out but you will make it slippery in wet or icy weather. It likely as not will weather out and leave you edge to edge or a slight lip that can he hit with an angle grinder wiped broadside along it to reduce the lip oince it is dry .
If you tamp the mix till the " fat and finings " rise then gently wipe a steel trowel over it , after the water dries use a premade wooden float and gently rub the surface you will get a sound sand rough slip resistant topping . You usually discover that it is dry enough when you can wipe a soft sweeping brush over the laid work and it just leaves marks where the bristles have been ..your very close to being able to use the wooden float.
Float it in 5 foot long gentle arcs in several directions to get the best results.
If needed use raised planks to get you over the work , don't over stretch yourself for it is a back and shoulder killer to most people. Then set hose to fine mist and for the next few hours mist the surface to get it to set at an even rate throughout ..avoid hot sun or make up some cloth covers on frames that you can dampen to slow the final evaporation .
Some of the guys on site may have other ways /ideas , choose what suits you.
I can't recall the actual slab size rule , but I often used to use the rough rule of no cast slab less then 2 mtr long and not longer than 10 mtr cast the inter connecting rebars in the slab 50/50 , drill throughnthe MDF to set the bars in place , support the MDF with steel pins , if the slab is thicker than three inches , no slab less than three inches thick unless impossible to avoid .
Expansion joint of 15 mm wide use MDF leave it to rot out or pick out and fill gap with compound .
That joint in the work you have already done ... yes you could polish it out but you will make it slippery in wet or icy weather. It likely as not will weather out and leave you edge to edge or a slight lip that can he hit with an angle grinder wiped broadside along it to reduce the lip oince it is dry .
If you tamp the mix till the " fat and finings " rise then gently wipe a steel trowel over it , after the water dries use a premade wooden float and gently rub the surface you will get a sound sand rough slip resistant topping . You usually discover that it is dry enough when you can wipe a soft sweeping brush over the laid work and it just leaves marks where the bristles have been ..your very close to being able to use the wooden float.
Float it in 5 foot long gentle arcs in several directions to get the best results.
If needed use raised planks to get you over the work , don't over stretch yourself for it is a back and shoulder killer to most people. Then set hose to fine mist and for the next few hours mist the surface to get it to set at an even rate throughout ..avoid hot sun or make up some cloth covers on frames that you can dampen to slow the final evaporation .
Some of the guys on site may have other ways /ideas , choose what suits you.