How to Place Reinforcing Bars in Concrete Structures and Pavement
Reinforcing bars, or rebar, are steel rods that are used to strengthen concrete structures and pavement. Rebar provides tensile strength and helps prevent cracking and failure of concrete. Placing rebar correctly is essential for the performance and durability of concrete structures and pavement.
In this article, we will explain the best practices for placing rebar in concrete structures and pavement, based on the Placing Reinforcing Bars publication by the Concrete Reinforcing Steel Institute (CRSI). This publication is a definitive resource for preparing provisions in project specifications and for instructing apprentices, journeymen ironworkers, and inspectors on how to place rebar.
Placing Drawings and Bar Lists
Placing drawings and bar lists are the instructions from the engineers to the contractors on how to build the structure to resist the anticipated loads. They provide the details and placing instructions so that the ironworkers can set the rebar into place at the jobsite.
Placing drawings show where the rebar is placed, how it is bent, spliced, tied, supported, and anchored. They also show the dimensions of the structure, the location of joints, openings, embedments, and other details. Placing drawings should be clear, accurate, consistent, and complete.
Bar lists are tables that list all the rebar required for a project. They include information such as bar size, shape, length, quantity, weight, mark number, and bending details. Bar lists should be organized by structure type, location, elevation, or other criteria that facilitate material handling and placement.
Bar supports are used to hold the rebar in place to attain the proper depth of cover. The depth of cover is the distance between the surface of the concrete and the surface of the rebar. It is important to maintain adequate cover to protect the rebar from corrosion and fire damage, as well as to ensure proper bond between concrete and rebar.
Bar supports can be made of various materials, such as concrete blocks, metal chairs, plastic chairs, or wire supports. They should be strong enough to support the weight of the rebar and concrete without deformation or displacement. They should also be compatible with the concrete mix and curing conditions, and not cause staining or deterioration of the concrete surface.
General Principles for Placing, Splicing, and Tying Rebar
The following are some general principles for placing, splicing, and tying rebar:
Rebar should be placed according to the placing drawings and bar lists.
Rebar should be clean and free of rust, oil, grease, dirt, or other contaminants that may impair bond or cause corrosion.
Rebar should be bent accurately and carefully to avoid cracks or fractures.
Rebar should be spliced at locations and with methods specified by the engineer. Splices should provide adequate strength and continuity of reinforcement.
Rebar should be tied securely with wire or other approved devices to prevent movement during concrete placement. Ties should be tight enough to hold rebar in position but not so tight as to damage or deform rebar.
Rebar should be placed with sufficient clearance from formwork and other embedments to allow proper concrete consolidation.
Rebar should be placed with adequate spacing to allow proper concrete flow and compaction around bars.
Rebar should be placed with uniform spacing along each member and between layers of bars.
Rebar should be placed with staggered splices and laps to avoid congestion and stress concentrations.
Rebar should be placed with proper orientation and alignment to resist design loads.
Placing Rebar in Different Types of Structures
The CRSI publication Placing Reinforcing Bars provides detailed guidance on how to place rebar in different types ec8f644aee