Utility Cuts and Trench Patches That Fail
I still have the density sheet from a gas service cut across a two-year-old commercial drive: one test, near the top, 96.4 percent of standard Proctor. One test, on a trench 46 feet long and 5 feet deep. Nine months…
Moisture Vapor From Below: The Coating Killer
Three relative humidity probes went into a 620 square foot shop floor on a Thursday and read 94, 96 and 91 percent. The coating crew was booked for Monday. That slab was eleven months old and its 28-day cylinders had…
Control Joints: Where Concrete Is Supposed to Crack
A 5,400 square foot equipment yard apron was placed on a July morning and sawed the next day starting at 9:40. By then three panels had cracked full depth, right across where the saw lines were about to go. That…
Curbs, Wheel Stops and Bollards
The last two yards off a truck at a fuel canopy job went into eight bollard footings. Nobody sampled that concrete; the specification only called out testing for the slab. What I did write down was the six gallons the…
Patching Compounds That Actually Bond
The will-call window at our plant sells bagged product to whoever walks up, and I work that counter phone between dispatching loads. A guy bought two pails of resurfacer in the spring for a spalled patch by his garage door…
Frost Depth and Why It Changes the Design
Every November a question gets added to my order script, and I ask it on every ticket going up the canyon toward Manitou Springs: is the subgrade thawed and covered? If the answer is a confident yes from somebody who…
Driveways That Survive South Florida Sun, Salt and Storms
In July my first ticket prints at 4:40 in the morning and the truck is loaded and gone by 5:15. By ten o’clock I have stopped putting flatwork on the board, and anyone calling in a driveway pour for one…
Getting Comparable Quotes From Concrete Contractors
A few times a year I take two orders for the same address inside the same week. Two contractors bidding the same driveway, both calling to reserve concrete before they know if they won it. One books 9 yards of…
Protecting a Driveway During a Roof or Concrete Delivery
The site-notes box on my order screen is usually one line: “driveway pour, call on arrival.” The line I actually need is whether the truck is allowed on the existing concrete, because that answer decides which truck leaves the yard,…
Slab Flatness and Why Floors Puddle
The email from my flex-bay tenant had a photo and one line: “This is nine hours after we washed a truck.” The water stood 22 feet inside the overhead door, a puddle the size of a dining table, a half…