What are control joints in construction?
A control joint is a continuous vertical joint filled with mortar, but with a bond breaker on one side so that tensile stress cannot develop across the joint. If control joints are not provided, a concrete masonry wall may crack as it shrinks over time.
What is the difference between a control joint and expansion joint?
In building materials, a control joint is used to control cracking while an expansion joint is designed to handle structural movement.
What is a controlled joint?
WHAT ARE CONTROL JOINTS? Control joints are planned cracks which allow for movements caused by temperature changes and drying shrinkage. In other words, if the concrete does crack-you want to have an active role in deciding where it will crack and that it will crack in a straight line instead of randomly.
What is another name for a control joint?
Contraction joints (also sometimes called control joints)
Where are control joints in concrete?
Control joints are generally placed into the concrete during the finishing process or within 24 hours of being poured….Control joints are commonly found in concrete:
- Garage floors.
- Driveways.
- Sidewalks.
- Patios.
- Basement floors.
- House slabs.
Where do control joints go in a concrete slab?
Concrete control joints should be no less than ¼ of the total thickness of the slab (1” deep for a 4” thick pour) and placed no less than 2-3 times (in feet) the thickness (in inches) of the slab (8-12 feet apart for a 4” thick pour).
Do you need control joints in stamped concrete?
Fiber mesh should always be used for stamped concrete applications. It gives concrete more tensile strength and reduces the chances of cracking. This is especially important when the slab will have no expansion joints until they are saw cut the following day, leaving the slab vulnerable to cracks overnight.
Where is construction joint in slab?
Construction joints parallel to the slab span can be placed anywhere, except those locations in T-beam construction that rely on a portion of the slab to act with the beam in resisting flexure. For slabs and beams it is, therefore, usual to have construction joints at mid span of the middle third of the span.
Where do control joints go in concrete?
What is construction joint in civil engineering?
A construction joint is a type of concrete joint that is used when a new section of concrete is poured adjacent to another concrete section that has already set. The purpose of a construction joint is to allow for some horizontal movement, while being rigid against rotational and vertical movement.
Does a concrete patio need control joints?
Concrete expands and contracts with changes in temperature and moisture. If not properly controlled, cracks can begin to appear. Placement of concrete control joints and expansion joints are crucial when designing and pouring concrete slabs and sidewalks.
What is contraction joints in concrete?
Contraction/Control Joints. Contraction/control joints are placed in concrete slabs to control random cracking. A fresh concrete mixture is a fluid, plastic mass that can be molded into virtually any shape, but as the material hardens there is a reduction in volume or shrinkage.