This time at the historic Lake Minnetonka summer home we help out as We Foss, along with Red Gennrich and Jake Buetow, get the kitchen floor ready for a new concrete slab.
Statewide Construction, Inc.
They jacked up the walls a little from the outside and pulled out the crumbling and sagging foundations that the walls had been sitting on. Then they reached under with shovels and scoops and dug out a couple of 42” holes in the corners.
We lugged about 60 80-pound bags of concrete mix down the hill into the house so the guys could mix them up…
The concrete mix for this job had ½-inch aggregate (easier to work with than ¾-inch gravel, but not quite as strong), short fibers to help it hold together better, and something called “air entrainment.” This was the first time we’d heard of it, but apparently it’s been around since the 1930s. Microscopic air cells help the concrete expand and contract with changes in temperature.
When you see older concrete walls and slabs that are “spalling” (pieces are flaking off the surface) they’re probably from the days before entrainment was common. (For more about air entrainment, check out this page on the Portland Cement Associate web site.)