Expansion Joints

Concrete will expand and contract on site during thermal cycles and between static and dynamic movements so each concrete element does not crack.

A design engineer normally specifies where to place expansion joints to enable sections to move independently and to reduce cracking in structures (i.e. paving, tilt-wall panel construction, warehouse slabs, concrete basins, retaining walls, water retaining structures, parking garages, docks, piers, etc.

Slab Joint Installation

All expansion joints in concrete structures, existing or new construction, must be sealed to control moisture migration, corrosion at exposed reinforcing steel, and protect integrity of the concrete joint. Three of the most common materials used to seal concrete expansion joints is polyurethane sealant, silicone, and pre-molded extruded neoprene rubber. Product selection is determined by the anticipated total movement of the joint, the width to depth ratio, location, exposure, abrasion, chemical exposure and impact. The selected product must keep the expansion joint sealed at all times with long term flexibility. Sealing joints will prevent dirt and other foreign debris from filling up a designed joint location, become hardened and prevent the desired expansion of the concrete section.

To ensure all joint material stays bonded, the inside concrete surface of a joint (nosing) must be clean and dry, without voids, cracks or spalls. These conditions must be repaired before installing any sealant material. Compatible primers are applied to concrete joint interface before installing polyurethane sealant and pre-molded extruded neoprene rubber materials. Cellular backer rod must be installed to control proper depth of polyurethane and silicone sealant. This also prevents a three sided bond. Non-sag sealants must be “tooled” to bond sealant to joint edges and control the depth of sealant at the center of the joint

Some additional considerations for every application:

• Concrete surface temperature, saturated moisture in the joint, dew points and varied joint widths.
• Calculation of expansion contraction movement rate
• Joint design spacing, material cure time, and compatibility with any aggressive chemicals / elements
• Depth to width ratio of sealant
• When resealing an existing joint, determine what material was originally used.
• What kind of traffic will travel over the joint
• Is a UV inhibitor coating needed?

Expansion Joint CSI Codes

• 07 00 00 Thermal and Moisture Protection
• 07 01 10.81 Waterproofing Replacement
• 07 01 90 Maintenance of Joint Protection
• 07 01 90.71 Joint Sealant rehabilitation
• 07 01 90.81 Joint Sealant Replacement

Epoxy Design Systems takes pride in providing concrete expansion joint services and slab joint installation with excellent customer service. We provide domestic and international services to help as many people as possible with their concrete repair and restoration needs. Give us a call today at 713-461-8733 or contact us online for a consultation.