Section 21.409 — Rejection
If the samples tested from a shipment fail to conform to the specified requirements, the manufacturer may sort it, and new specimens shall be selected by the purchaser from the retained lot and tested at the expense of the manufacturer. If the second set of specimens fails to conform to the specified requirements, the entire lot shall be rejected.
MOISTURE CONTENT REQUIREMENTS FOR TYPE I UNITS
|LINEAR SHRINKAGE, PERCENT||MOISTURE CONTENT, MAX. PERCENT OF TOTAL ABSORPTION (Average of 3 Units)|
|Humidity Conditions at Job site or Point of Use|
|0.03 or less||45||40||35|
|From 0.03 to 0.045||40||35||30|
|0.045 to 0.065, max.||35||30||25|
- 1Average annual relative humidity above 75 percent.
- 2Average annual relative humidity 50 to 75 percent.
- 3Average annual relative humidity less than 50 percent.
STRENGTH AND ABSORPTION REQUIREMENTS
|COMPRESSIVE STRENGTH, MIN, psi (MPa)||WATER ABSORPTION, MAX, lb./ft. (kg/m) (Average of 3 Units)|
|Average Net Area||Weight Classification—Oven-dry Weight of Concrete, lb./ft. (kg/m)|
|Average of 3 Units||Individual Unit||Lightweight, Less than 105 (1680)||Medium Weight, 105 to less than 125 (1680-2000)||Normal Weight, 125 (2000) or more|
|1900 (13.1)||1700 (11.7)||18 (288)||15 (240)||13 (208)|
MINIMUM THICKNESS OF FACE-SHELLS AND WEBS
|NOMINAL WIDTH (W) OF UNIT (inches)||FACE-SHELL THICKNESS (FST) MIN., (inches)1,4||WEB THICKNESS (WT)|
|Webs1 Min., (inches)||Equivalent Web Thickness, Min., In./Lin. Ft.2|
|× 25.4 for mm||× 83 for mm/lin. m|
|3 and 4||3/4||3/4||15/8|
- 1 Average of measurements on three units taken at the thinnest point.
- 2 Sum of the measured thickness of all webs in the unit, multiplied by 12 (305 when using metric), and divided by the length of the unit. In the case of open-ended units where the open-ended portion is solid grouted, the length of that open-ended portion shall be deducted from the overall length of the unit.
- 3 This face-shell thickness (FST) is applicable where allowable design load is reduced in proportion to the reduction in thicknesses shown, except that allowable design load on solid-grouted units shall not be reduced.
- 4 For split-faced units, a maximum of 10 percent of a shipment may have face-shell thicknesses less than those shown, but in no case less than 3/4 inch (19 mm).