South Carolina Concrete

Quality control is the action/documentation taken to control the product so applicable standards and contract documents are followed, while quality assurance is the action/documentation verifying that those controls are in place and working in accordance with applicable standards.

For applying ACI 347R lateral pressure formulas, a column is a vertical element with no plan dimension larger than 6.5 ft (2 m), whereas a wall has at least one plan dimension exceeding 6.5 ft (2 m); the classification determines which pressure equation applies.

Per SP-4 Section 4.3.5, tabulated effective section modulus KS must be used for all bending stress calculations, while moment of inertia I is used only for deflection calculations (effective I ÷ distance to extreme fiber does not equal effective KS for plywood).

In the SP-4 Chapter 3 bridge planning example, pier shaft forms are assumed strippable 1 day after placing while supported cap beam forms must stay in place 14 days, and that longer required curing/stripping period is the primary factor driving the need for two complete cap beam form sets.

The usual safety factor for form tie working loads is 2:1 (working load limited to half of ultimate tensile strength), while form anchors securing forms to previously placed concrete require a minimum safety factor of 3 including live load and impact because the concrete may still be 'green.'

Bank yards are the in-place excavated volume (length × width × depth ÷ 27), while loose yards are the swelled hauled volume (bank × (1 + swell %)); haul-off truck loads must be figured from loose yards, since using bank volume undercounts loads.

Wood joists or the bottom of a wood structural floor in a crawl space/unexcavated area within the foundation periphery need naturally durable or preservative-treated wood when closer than 18 in. to exposed ground, while wood framing members including columns resting directly on concrete or masonry exterior foundation walls need it when less than 8 in. from exposed ground.

Per Table 2.5, F3 permits a maximum w/cm of 0.40 with 5000 psi minimum, S2 permits 0.45 with 4500 psi minimum, and W1 (concrete in contact with water requiring low permeability) permits 0.50 with 4000 psi minimum.

Jobsite storage of strength test cylinders must be at 60 to 80°F (16 to 27°C) for specified strengths less than 6000 psi, while the tighter 68 to 78°F range applies only to specified strengths of 6000 psi or greater.

Criteria A requires the average of any three successive tests to equal or exceed the specified fc′, while Criteria B requires that no single test fall below fc′ by more than 500 psi (3.5 MPa) for fc′ of 5000 psi or less (or more than 10 percent of fc′ when fc′ exceeds 5000 psi).

Per IRC R408.2 the minimum net ventilation opening area is 1 sq ft per 150 sq ft of under-floor area, but may be reduced to 1/1,500 of the under-floor area where an approved Class I vapor retarder covers the ground surface.

Retarders delay setting, raise lateral form pressure (chemistry coefficient CC of 1.2 versus 1.0) and require lengthened stripping times, while replacing part of the portland cement with fly ash or slag cement can require about twice the cure time before forms are stripped due to slower early strength gain.

Per Table 4.1 (adapted from 2015 IBC Table 1809.7), one floor requires 12 in. width × 6 in. thickness and two floors 15 in. width × 6 in. thickness, while three floors require 18 in. width × 8 in. thickness.