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Concrete form pressure is determined based on the height of concrete being placed. The height of concrete times the density of concrete will determine the pressure exerted on the forms at a given depth. EFCO forms, such as PLATE GIRDER, are rated for a maximum allowable pressure to be exerted from the concrete. As concrete transitions from a flowable liquid mix to a solid, the concrete will no longer continue to build pressure with depth. Monitoring this transition point is important to ensure the allowable pressure on the forms isn’t exceeded. For more information, see “A Practical Guide to Concrete Pressure & Formwork”

Engineered formwork systems consist of prefabricated steel panels. The advantage of using these systems are to increase the speed of construction, increased durability and longevity, and the ability to span formwork across supports. EFCO provides a wide variety of products including HAND-E-FORM, EFCO LITE, PLATE GIRDER, and SUPER PLATE GIRDER. For more information on what system would best fit your applications, please contact us.

In concrete construction, shoring is referring to temporarily supporting overhead concrete, typically floor slabs or beams, while concrete is being poured or curing. These shoring systems typically consist of beams, posts, and bracing components. EFCO provides a wide variety of products including EFCO DECK, E-Z DECK, PRO-4, and ADJUST-A-DECK to shore a wide variety of overhead concrete. For more information on what system would best fit your applications, please contact us.

The duration of time between placing concrete and removing/stripping formwork and shoring depends on a variety of factors, but it is ultimately based on age criteria and the minimum concrete strength determined by the project engineer/architect (reference ACI 347-R14; 5.7.1). Example factors that affect concrete strength include methods of cure, construction sequence, and project schedule. Based on the various criteria established by the project engineer/architect, the removing/stripping time can range from 12 hours to 28 days. The removing/stripping time can often be increased when supplemental concrete supports are used. Examples would include EFCO’s Box Culvert Roof Support System that temporarily supports the top slab of a box culvert while the forms are cycled ahead to the next pour. Another example would be the EFCO DECK shoring system which includes a “drophead” feature that enables contractors to strip joists and stringers early while the posts continue to support the recently placed slab.

Pre-Tensioning: Steel tendons (wires, strands, or bars) are tensioned before the concrete is placed in the form. Once the concrete has cured to a sufficient compressive strength, the tendons are released and the prestressing force is transferred to the concrete by the bond along the length of tendon. Pre-tensioning methods are typically used by precasting companies creating precast concrete elements used in building construction.

Post-Tensioning: Steel tendons (wires, strands, or bars) are tensioned after the concrete has been cured to a sufficient compressive strength. The steel tendons are typically placed in the formwork before the concrete is case inside a hollow steel duct. Tendons are typically anchored at one end inside the concrete (anchor block) with long strands extending out the opposite free end. Hydraulic jacks are connected to the tendons extending from the free end, tensioned, then tied off creating permanent tension in the steel and compression in the concrete. Post-tensioning is typically used in long span bridge construction and commercial slabs.

Formwork can refer to an engineered system that is used to efficiently form and support poured concrete.

Shuttering generally refers to using plywood and timbers to create a mold for pouring concrete.

The removal of concrete formwork can be described as either stripping or striking.

A concrete slab is typically a flat, horizontal surface. Concrete slabs that are poured on the ground are described as being “on grade” versus an elevated slab, such as a floor of a building that can be formed with E-Z DECK.