CONSTRUCTION JOINT BASICS
Not all concrete jobs are one-day projects. When you have to stop a pour before finishing, you’ll need to place a construction joint or two. Planning ahead makes placing construction joints part of your overall jointing plan.
A construction joint gives you a clean stopping point that lets you resume work without compromising either the strength or esthetics of the job. On light-duty projects like sidewalks or patios, construction joints can serve as contraction joints with the aggregate and base serving to bind the two sections together. But in heavy load situations, you’ll want some extra reinforcement to prevent joint floating. In those cases, set the load transferring mechanism at the edge of the pour, leaving sufficient exposure for the subsequent pour to gain purchase. Keyed profiles have long been used as construction joints for load transfer, but studies have shown them to be ineffective since contraction of the concrete during drying causes them to separate and lose their ability to transfer loads.
Wood, metal, or plastic forms are used to act as bulkheads for construction joints. It may be as basic as boards and stakes, or you may use bulkhead forms made specifically for construction joints. These bulkheads often serve a dual function, acting as screed rails for pouring and finishing the slab.
It’s important to use internal vibration at the construction joint to assure proper consolidation along the joint’s edge and a good grip of any dowels or other joining devices. And be sure to let the vertical face of the joint cure once the bulkhead is removed. A liquid curing compound will speed the process.
Granted that work stoppages aren’t always part of the plan—weather, breakdowns, and material shortages can enter the picture, too—but whatever the reason, being ready to handle the need for construction joints will make the job easier and avoid expensive tear-outs.
For more information about the various types of concrete joints, visit ConcreteNetwork.com.
Using the right tools and techniques ensures a professional job and results you’ll be proud to show off. Whatever your concrete cutting, coring, and finishing requirements may be, equipment and tools from Ace Cutting Equipment are your choice for top-quality results.