ICC Reinforced Concrete SI cheat sheet

Inspection of concrete is observation and judgment of materials, placement, and workmanship to determine conformity with plans and specifications; it is not a substitute for the contractor's quality control.

Cover and bar spacing are verified before placement: measure clear cover to the outermost bar, not to the stirrup, and check that clear spacing between parallel bars is at least the larger of 1 bar diameter, 1.33 times the maximum aggregate size, or 25 mm.

Formwork inspection: check line, grade, dimensions, tightness of joints, release agent, and that all ties and shores are in place; forms must be clean and free of debris and standing water before concrete is placed.

Reinforcement inspection before the pour: bar size, number, spacing, splice locations and lengths, lap and development lengths, bar supports, tie wire, and that bars are tied and secured against displacement.

Embedded items - anchor bolts, sleeves, conduit, waterstops, and blockouts - are checked for location and grade and must not displace reinforcement or reduce required cover.

Cold-weather placement: concrete temperature at placement per specification (commonly at least 10 °C, with protection until it reaches a specified strength); do not place on frozen subgrade.

Hot-weather placement: limit concrete temperature (commonly 35 °C maximum as placed), cool ingredients, use set retarders, and begin curing immediately to prevent plastic shrinkage cracking.

Documentation: inspector records include pour cards, placement time and location, batch tickets, slump and air tests, cylinder identification, and any deviations reported to the engineer of record.

Concrete is proportioned by absolute volume; compressive strength depends primarily on water-cementitious materials ratio (w/cm), not on cement content alone. Lower w/cm raises strength and lowers permeability.

Slump test (ASTM C143) measures consistency; a collapsed or sheared slump is not a valid result and the sample should be retested. Slump is not a measure of strength or durability.

Air content (ASTM C231 pressure method) is required for freeze-thaw exposure; typical specified ranges are about 5–7 percent for 20 mm aggregate and 6–8 percent for 10 mm aggregate, adjusted for exposure class.

Strength specimens: cylinders are cast and cured per ASTM C31 (standard 150 × 300 mm cylinders, initial moist cure, then 28-day standard curing) and tested per ASTM C192/C39; field-cured cylinders represent the structure, standard-cured cylinders represent the mix.

Sampling frequency: a strength test set is taken at least once per day of placement, once per 110 m³ (or fraction), and once per 460 m² of slab or wall surface; each set is two cylinders.

Consolidation: internal vibrators are inserted vertically at regular spacing (about 1.5 times the radius of action), held until air bubbles cease, and withdrawn slowly; never use vibration to move concrete laterally.

Placement: concrete should be placed as near its final position as possible; free fall should be limited (commonly about 1.5 m or less) to avoid segregation, and each lift should be consolidated into the previous lift while still plastic.

Curing: maintain moisture and temperature for the specified period (commonly 7 days for Type I cement, 3 days for high-early-strength); curing compounds, wet burlap, or plastic sheeting are acceptable methods when permitted.

Construction joints are planned locations; they must be cleaned, roughened, and often have shear keys or dowels. Cold joints from unplanned interruptions are a defect and should be reported.

Reinforcing bar sizes: No. 10 (10 mm), No. 15, No. 20, No. 25, No. 30, No. 35, No. 45, No. 55 - the bar number times 3 gives the nominal diameter in mm; the number times 100 gives the nominal area in mm².

Grade designations: 420 MPa (Grade 60) and 550 MPa (Grade 80) for deformed bars; 420 MPa is the common grade. Yield strength is the specified minimum yield, f_y.

Deformed bar geometry and marking: bars carry a mill mark, a size mark, and a grade mark (line pattern). Inspectors verify grade by mark and by mill certificates when required.

Lap splices: Class A splice is 1.0 l_d and Class B is 1.3 l_d, where l_d is the tension development length. Splice class depends on the amount of steel spliced and the bar stress level.

Development length depends on bar size, spacing, cover, transverse reinforcement, and concrete strength; it is never less than 300 mm. Hooks (90° or 180°) and headed bars may be used where straight length is insufficient.

Mechanical splices and welded splices must be qualified; welded splices require a welding procedure and qualification of the welder.

Prestressing: post-tensioning uses ducts and anchorages with strands stressed after concrete hardens; pretensioning stresses strands before concrete is placed and transfers force by bond.

Prestressing steel: seven-wire strand is the common tendon; stress is measured by elongation and by gauge pressure, and the two must agree within a specified tolerance (often about 5 percent).

Grouting of post-tensioning ducts must be done promptly after stressing using an approved grout, with vents at high points to ensure complete filling; ungrouted or incompletely grouted ducts are a corrosion risk.

Plan reading: general notes, plan views, sections, details, bar schedules, and structural general notes together define the work; the bar schedule lists bar marks, sizes, shapes, lengths, and quantities.

Bar shape designations use standard bend types (e.g., 90° and 180° hooks, stirrup and tie shapes), and hook dimensions are specified by bar size; a standard 90° hook has a minimum extension of 12 bar diameters.

Cover requirements depend on exposure: cast-in-place beams and columns exposed to earth or weather commonly require at least 40 mm cover; interior protected members may use less. Verify against the project specification.

Nominal dimensions: a No. 20 bar has a nominal diameter of 20 mm and area of 300 mm²; a No. 25 bar has 25 mm diameter and 500 mm² area. Use nominal, not actual, dimensions for design checks.

Minimum clear spacing between parallel bars in a layer is the larger of 1 bar diameter, 1.33 times the maximum aggregate size, or 25 mm; for two or more layers, bars in upper layers are placed directly above those in the lower layer.

Inspection and testing: concrete strength is verified by 28-day cylinder tests; the acceptance criteria compare the average of three consecutive tests to the specified strength and require no single test below a specified threshold.

When test results fail, the engineer may require core tests (ASTM C42); cores are taken from representative locations and the results are evaluated against specified criteria.

Shop drawings and submittals: reinforcing steel placing drawings are reviewed for conformity with the design drawings; the inspector verifies field work against the approved placing drawings.

Code references: ACI 318 covers structural concrete design and detailing; ACI 301 covers specifications for construction; ACI 302 covers slabs on grade; the project specifications govern over general references where they conflict.