4112Intermediate Aggregate for Portland Cement Concrete

4112.01

DESCRIPTION.

A.

Crushed carbonate stone chips or pea gravel from approved sources as described in Materials I.M. 409.

B.

For crushed limestone or dolomite chips, meet the durability class required for the coarse aggregate. Acquire uncrushed pea gravel from any PCC approved durability class gravel. When the gravel durability is lower than the coarse aggregate durability requirements, the pea gravel is not to exceed 15% of total aggregate in the mix.

4112.02GRADATION

Intermediate aggregate shall meet the requirements for gradation No. 2 of the Aggregate Gradation Table, Article 4109.02. 4112.03 A.

QUALITY. Intermediate Crushed Stone. Meet the requirements of Table 4112.03-1: Table 4112.03-1: Aggregate Quality

Aggregate Quality

Maximum Percent Allowed

Test Method

Alumina(a, b)

0.5

Office of Materials Test Method No. Iowa 222

A Freeze

Office of Materials Test Method No. Iowa 211, Method A

Clay Lumps and 0.5 Materials I.M. 368 Friable Particles If the Alumina value passes, the A-Freeze is not needed for specification compliance. If the Alumina value fails, determine the A Freeze for specification compliance. Alumina does not apply to gravel.

B.

Pea Gravel. Meet the requirements of Table 4112.03-2:

4115.02

Coarse Aggregate for Portland Cement Concrete

Table 4112.03-2: Maximum Permissible Amounts of Objectionable Materials Maximum Percent Objectionable Materials. Test Method Allowed Coal and carbonaceous shale 0.5 AASHTO T 113 Total of all shale, similar objectionable materials, coal and iron combined

1.0

AASHTO T 113

Organic Materials, except coal

0.01

Iowa DOT Materials Laboratory Test Method No. 215

Unsound chert particles retained on 3/8 inch sieve (Nonstructural concrete)

3.0

Materials I.M. 372

Unsound chert particles retained on 3/8 inch sieve (Structural concrete)

2.0

Materials I.M. 372

Note: Chert particle which break into three or more pieces when subjected to the freezing and thawing test will be considered unsound. Chert in aggregate produced from limestone sources is defined as unsound when any of the fractions of the crushed or uncrushed chert do not meet the soundness requirements.