ICC Reinforced Concrete SI key terms

The distance from the outer concrete surface to the nearest surface of embedded reinforcement, measured to the bar itself, not the center. It protects steel from corrosion and fire and ensures bond.

The distance from the extreme compression fiber of a flexural member to the centroid of the tension reinforcement. It governs moment capacity and shear strength calculations in design and field checks.

The specified cover value used in design and drawings, before construction tolerances are applied. Field inspectors compare measured cover against the specified nominal value plus or minus permitted tolerance.

The center-to-center distance between parallel reinforcing bars. Minimum spacing rules ensure concrete can flow around bars, achieve bond, and limit crack widths in the member.

Two or more parallel reinforcing bars placed in contact or tied together to act as a group. Bundled bars have limits on number per bundle and require adjusted development and spacing checks.

The minimum length of embedded bar required to develop the bar's design yield force in the surrounding concrete through bond. It depends on bar size, cover, spacing, concrete strength, and coating.

A splice where two bars overlap parallel to each other so force transfers through bond in the surrounding concrete. Lap length is typically a multiple of development length and must be staggered and tied.

A splice that transfers bar force through a manufactured device such as a coupler or threaded sleeve rather than through bond. It must be qualified by test and accepted by the designer.

The adhesion and mechanical interlock between reinforcing steel and surrounding concrete that allows force transfer between the two materials. Bond depends on cover, bar deformation, concrete strength, and embedment length.

Steel placed in the region of a member that is expected to carry tensile stress, such as the bottom of a simple beam. It is sized from the factored moment and checked against minimum and maximum limits.

Steel placed in the compression zone of a member to carry compressive force, reduce long-term deflection, or provide ductility. It is common in columns and doubly reinforced beams.

The area of tension steel divided by the effective area of concrete (b times d) in a flexural member. It must fall between minimum and maximum limits to ensure ductile, adequate behavior.

A closed or U-shaped transverse bar placed around longitudinal reinforcement to resist shear and confine concrete. Spacing and anchorage of stirrups are common field inspection checkpoints.

A transverse bar, often closed, that confines longitudinal bars in a column and restrains them against buckling. Tie spacing, hooks, and arrangement are governed by code and detailed on plans.

Transverse steel, usually stirrups or welded wire, provided to resist shear forces and improve ductility. It must be anchored at both ends and spaced within code limits.

A code-defined bend at the end of a bar, such as a 90-degree or 180-degree hook, used to anchor the bar when straight length is insufficient. Bend diameter and tail length are specified.

A curved portion of reinforcing bar formed to a specified inside diameter and angle. Minimum bend diameters depend on bar size to prevent cracking or fracture of the steel.

Cutting, bending, and marking reinforcing bars to the shapes and lengths shown on placing drawings. Fabrication tolerances and bend dimensions are checked before bars reach the site.

A shop drawing that shows bar sizes, shapes, quantities, and locations for a specific concrete element. Inspectors use it to verify that installed reinforcement matches the design intent.

A design drawing showing member sizes, reinforcement, and general notes for a concrete structure. It is the primary reference for checking that field work conforms to design.

The written specifications on a drawing set covering materials, cover, concrete strength, and workmanship requirements. They govern items not dimensioned on individual plans.

The written project document defining material standards, testing, workmanship, and acceptance criteria for concrete and reinforcement. It supplements drawings and takes precedence where conflicts are stated.

The process of selecting proportions of cement, water, aggregate, and admixtures to achieve specified strength, durability, and workability. It is usually submitted for approval before placement.

The mass of water divided by the mass of cementitious material in a concrete mix. Lower ratios increase strength and durability; higher ratios improve workability but reduce both.

Any material that reacts with water to bind concrete, including portland cement and supplementary materials such as fly ash or slag. Total cementitious content affects strength and heat of hydration.

A material added to a concrete mix in small quantities to change properties such as set time, workability, or air content. Dosage and compatibility must follow manufacturer and specification limits.

Intentional introduction of tiny air bubbles into concrete, usually with an admixture, to improve resistance to freezing and thawing. Air content is tested and must meet the specified range.

A field test measuring the consistency and workability of fresh concrete by the settlement of a standardized cone. Results must fall within the specified slump range for the mix.

Maintaining adequate moisture and temperature in concrete after placement so cement hydration can continue. Proper curing develops strength, reduces cracking, and improves durability.

Temporary molds and supports that hold fresh concrete in shape until it hardens. Formwork must be strong, tight, properly braced, and removed only when concrete has sufficient strength.

Compacting fresh concrete, usually by vibration, to remove entrapped air and ensure it fills around reinforcement and forms. Poor consolidation causes voids and honeycomb.

Voids or cavities left in concrete where mortar did not fill spaces among coarse aggregate, often from inadequate consolidation or congested reinforcement. It is a visible defect subject to repair evaluation.

A plane of weakness formed when fresh concrete is placed against concrete that has already begun to set. It can reduce shear and watertightness and must be evaluated and often repaired.

A planned stopping place in a concrete pour where fresh concrete meets previously placed concrete. It requires a prepared, clean surface and careful placement to ensure continuity.

Introducing internal compressive stress into concrete, usually with high-strength steel, to offset tensile stresses from loads. It allows longer spans and thinner sections than ordinary reinforced concrete.

A prestressing method where steel strands are stressed in a casting bed before concrete is placed, then released after the concrete hardens. Force transfers to concrete through bond.

A prestressing method where steel tendons are stressed after concrete has hardened, usually through ducts, and locked off by anchorage. It requires grouting or corrosion protection of the tendon.

A complete assembly of prestressing steel, such as strands or wire, used to apply prestress to concrete. Tendons are stressed to a specified force and elongation recorded for acceptance.

A tube or sleeve embedded in concrete to form a void for a post-tensioning tendon. It must be aligned, sealed against grout leakage, and later grouted or protected as specified.

Filling a post-tensioning duct with cementitious grout after stressing to protect the tendon from corrosion and bond it to concrete. Grout mix and injection procedure are specified.

The measured stretch of a prestressing tendon during stressing, compared with a calculated value to verify applied force. Significant deviation signals friction, seating, or tendon problems.

The specified limits and test results that determine whether materials or work conform and can be accepted. They appear in specifications and codes and guide inspection decisions.

The permitted variation from a specified dimension, position, or property. Reinforcement placement, cover, and member dimensions all have code tolerances the inspector checks.