Concrete Column Jacketing
When, in specific cases, foundation columns need strengthening, Perfection has the expertise to handle any widening and strengthening of existing foundation. This is handled by constructing a concrete jacket around existing footings. The new jacket is anchored to the existing footings and column necks to guarantee proper load transfer. The exact proper size of the “jacket” is determined so that the average maximum weight of foundation pressure will not exceed the recommended engineered value. Attention shall be maintained to excavations for the new “jackets” so that they do not affect the existing nearby foundations.
Concrete Post Tensioning
Perfection, as many professional concrete designers, use post-tensioning to reinforce concrete by prestressing it. In prestressed members, compressive stresses are introduced into the concrete as it reduces tensile stresses which occur from applied loads, including the weight of the member (dead load). Pre-tensioning is a method of prestressing in which the steel or wire tendons are tensioned prior to the concrete being placed. The prestressing force is transferred to the concrete through bond. Post-tensioning is a method of prestressing in which the tendons are tensioned after the concrete has hardened and the prestressing force is transferred to the concrete through the tendons to the end anchor points.
Expansion joints allow for volume change or movement of a concrete structures or members. These are usually constructed by installing pre-formed, or pre-molded elastic/resilient material of about 1/4″ to 1/2″ thickness before the concrete is installed. Such materials must be highly resilient, and will not extrude in extremely warm weather, or become brittle in cold weather.
Expansion joints should always be used where concrete members join or abut existing structures of any type. This includes a junction for sidewalks, sidewalk with a driveway, building, curb, as well as where a floor slab joins a column or staircase, etc.
Expansion joints should be utilized in a building floor slab where the slab abuts a wall or footing. Sealing of any expansion joints is desirable in most outdoor and some industrial applications.