106.3.2.71 TM-71, Deleterious Content of Aggregate

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This test method determines the deleterious content of fine and coarse aggregates.

Contents

106.3.2.71.1 Apparatus

The "rock cap", in place for a new highway, is the top 2 ft. of material laid before asphalt or concrete is placed on the new road. The rock cap is graded to the final elevation of the road, provides a stable base for the surface and allows water to drain from under the road without compromising the pavement or ground around the highway.
The "rock cap", in place for a new highway, is the top 2 ft. of material laid before asphalt or concrete is placed on the new road. The rock cap is graded to the final elevation of the road, provides a stable base for the surface and allows water to drain from under the road without compromising the pavement or ground around the highway.

1) Containers of such a size and shape to contain the sample.

2) Sieves - No. 4 (4.75 mm) and No. 16 (1.18 mm).

3) Water to wet particles for observation.

4) Balance sensitive to within 0.5 percent of the weight (mass) of sample to be weighed.

106.3.2.71.2 Procedure for Coarse Aggregate Deleterious

106.3.2.71.2.1 Preparation

The sample shall be tested in an "as obtained" condition. The obtained sample shall be sieved over a No. 4 (4.75 mm) sieve, discarding the material passing the sieve. The material retained shall be the test sample used to determine the deleterious content.

106.3.2.71.2.2 Sample Size

Recommended minimum test sample sizes of plus No. 4 (4.75 mm) material are as follows:

Maximum Size1, in. (mm) Sample Size, g
2 (50) 10,000
1 ½ (37.5) 9,000
1 (25.0) 5,000
3/4 (19.0) 3,000
1/2 (12.5) 2,000
3/8 (9.5) 1,000
1 Maximum size is defined as the smallest sieve through which 100 percent of the material will pass.

106.3.2.71.2.3 Test

Each individual particle comprising the sample shall be examined piece-by-piece and separated into the various constituents as required by the specifications and in accordance with the descriptions shown in EPG 106.3.2.71.6, Deleterious Definitions. The sample may be rinsed at the time of examination but shall not be soaked in water. Material not considered deleterious may be discarded except as needed for review. Each deleterious constituent shall be weighed, and the weight recorded. In some instances when required by the specification, the constituents are to be combined prior to weighing.

106.3.2.71.3 Procedure for Fine Aggregate Deleterious

106.3.2.71.3.1 Lightweight (Low Mass Density) Particle Content including Coal and Lignite

The test shall be in accordance with AASHTO T 113, however lightweight (low mass density) sand particles are not considered deleterious lightweight (low mass density) particles.

106.3.2.71.3.2 Percent Other Deleterious Substances, Clay Lumps and Shale in Fine Aggregate

106.3.2.71.3.2.1 Preparation

Recommended test sample size is approximately 200 grams, before sample is sieved over the No. 16 sieve.

106.3.2.71.3.2.2 Sample Size

The sample shall be tested in a dry condition (dried to a constant weight). Sample shall be sieved over a No. 16 sieve, discarding material passing the sieve. The material retained shall be the test sample used to determine the clay lumps and shale.

106.3.2.71.3.2.3 Procedure

The test sample shall be visually examined for shale, clay lumps and other deleterious substances. Particles may be lightly rinsed at the time of examination, but shall not be soaked in water. The deleterious substances shall be separated out into the constituents required by specification.

Shale is determined by using a non-glazed ceramic bowl (Plastic Index bowl). If particles leave a black mark on the bowl when pressure is applied to the material while moving it across the bottom of the bowl, this material is considered shale.

106.3.2.71.4 Calculations for Deleterious Content

Quick Test for Per Cent of Deleterious Material
Report, 2009
See also: Innovation Library

The percentage of a deleterious substance shall be calculated as follows:

P = 100 x C / W

Where:

P = Percentage of each deleterious substance component.
C = Actual weight (mass) of deleterious substance for that component.
W = Weight (mass) of test sample for the portion retained on the No. 4 sieve

106.3.2.71.5 Reports

Report the percent deleterious obtained for each constituent required by specification, to the nearest tenth (0.1).

106.3.2.71.6 Definitions of Deleterious Materials

The definition of deleterious material varies with the intended use and the anticipated affect on the final product.

106.3.2.71.6.1 Coarse Aggregate for Portland Cement Concrete

For coarse aggregate for portland cement concrete (Sec 1005), the following definitions apply:

106.3.2.71.6.1.1 Deleterious Rock

Deleterious rock includes the following material:

(1) Shaly rock. A rock that is generally contaminated with shale to a high degree. Color may vary but the rock usually has a dull gray appearance and is reasonably uniform in appearance. Also may occur in the form of numerous shale lines or seams closely spaced throughout the particle, thus giving a laminated or streaked appearance.

(2) Cap plus 20 percent. A rock particle with a line of demarcation of a layer or “cap” of shale or shaly rock which usually occurs on one face, but may be found on two faces; in either case, the summation of the percent of “caps” exceeds 20 percent of the volume of the rock particle.

(3) Extremely soft and/or porous rock. A rock which can be readily broken with the fingers. In some cases, due to the size or shape of the rock it cannot be broken, however, small areas can be spalled or chipped off with the fingers. Porosity or high absorption may be detected by rapid disappearance of surface water or by breaking rock in half and observing the depth of penetration of moisture.

106.3.2.71.6.1.2 Shale

A fine-grained rock formed by the consolidation of clay, mud, or silt; generally having a finely stratified or laminated structure.

106.3.2.71.6.1.3 Chert in Limestone

A fine-grained rock consisting of silica minerals, sharp-edged and may be highly absorptive. May occur in the form of nodules, lenses, or layers in limestone formations; and may vary in color from white to black. Quartz-type material is excluded. Any particle that contains more than 50% chert will be entirely classified as chert.

106.3.2.71.6.1.4 Other Foreign Material

Clay lumps, mud balls, lignite, coal, roots, sticks and other foreign material not related to the inherent material being inspected.

106.3.2.71.6.1.5 Material Passing No. 200 [75 μm] Sieve

The portion of material passing a No. 200 (75 μm) sieve as determined by a washed analysis.

106.3.2.71.6.1.6 Thin or Elongated Pieces

Rock particles that have a length greater than five times the maximum thickness. In case two sizes of coarse material are required to be combined into coarse aggregate, the limitation on “thin or elongated pieces” shall apply only to the coarser size so combined and shall only apply to particles retained on the 3/4 in. (19.0 mm) sieve. In the case of coarse aggregate produced without combining two sizes, the limitation on “thin or elongated pieces” shall apply only to particles retained on a 3/4 in. (19.0 mm) sieve.

106.3.2.71.6.2 Coarse Aggregate for Asphaltic Concrete, Plant Mix Bituminous Pavement, Plant Mix Bituminous and Seal Coats

For coarse aggregate for asphaltic concrete, plant mix bituminous pavement, plant mix bituminous leveling and seal coats (Sec 1002 and Sec 1003), the following definitions apply.

106.3.2.71.6.2.1 Deleterious Rock

Deleterious rock includes the following materials:

(1) Shaly rock. A rock that is generally contaminated with shale to a high degree. Color may vary but the rock usually has a dull gray appearance and is reasonably uniform in appearance. Also may occur in the form of numerous shale lines or seams closely spaced throughout the particle, thus giving a laminated or streaked appearance.

(2) Cap plus 20 percent. A rock particle with a line of demarcation of a layer or "cap" of shale or shaly rock which usually occurs on one face, but may be found on two faces; in either case the summation of percent of "caps" exceeds 20 percent of the volume of the rock particle.

(3) Extremely soft rock. A rock that can be readily broken with the fingers. In some cases, due to size or shape of the rock it cannot be broken, however, small areas can be spalled or chipped off with the fingers.

(4) Chert. Chert which is soft and highly absorptive is considered deleterious.

106.3.2.71.6.2.2 Shale

A fine-grained rock formed by the consolidation of clay, mud, or silt; generally having a finely stratified or laminated structure.

106.3.2.71.6.2.3 Other Foreign Material

Clay lumps, mud balls, lignite, coal, roots, sticks, and other foreign material not related to the inherent material being inspected.

106.3.2.71.6.3 Coarse Aggregate for Bituminous Surface and Plant Mix Bituminous Base

For coarse aggregate for bituminous surface and plant mix bituminous base (Sec 1004), the following definitions apply:

106.3.2.71.6.3.1 Deleterious Rock

Deleterious rock includes the following materials:

(1) Shaly rock. A rock that is generally contaminated with shale to a high degree. Color may vary, but the rock usually has a dull gray appearance and is reasonably uniform in appearance. Pieces of rock having shaly seams, skin shale, and pieces of rock, which are not predominantly shaly, are not to be considered as deleterious.

(2) Extremely soft rock. A rock that can be readily broken with fingers, or from which small areas can be spalled or chipped off readily with the fingers.

106.3.2.71.6.3.2 Shale

A fine-grained rock formed by the consolidation of clay, mud or silt; generally having a finely stratified or laminated structure.

106.3.2.71.6.3.3 Mud balls

Balls of mud.

106.3.2.71.6.3.4 Clay

A clay material that is more or less uniformly dispersed throughout the produced product.

106.3.2.71.6.3.5 Other Foreign Material

Any material not related to the inherent material being inspected.

106.3.2.71.6.4 Coarse Aggregate for Surfacing

For coarse aggregate for surfacing (Sec 1006), the following definitions apply:

106.3.2.71.6.4.1 Deleterious Rock

Deleterious rock includes extremely soft rock; a rock that can be readily broken or spalled with the fingers.

106.3.2.71.6.4.2 Shale

A fine-grained rock formed by the consolidation of clay, mud, or silt; generally having a finely stratified or laminated structure.

106.3.2.71.6.4.3 Mud Balls

Balls of mud.

106.3.2.71.6.4.4 Other Foreign Material

Any material not related to the inherent material being inspected.

106.3.2.71.6.5 Coarse Aggregate for Base

For coarse aggregate for base (Sec 1007), the following definitions apply:

106.3.2.71.6.5.1 Deleterious Rock

Deleterious rock includes extremely soft rock; a rock that can be readily broken or spalled with the fingers.

106.3.2.71.6.5.2 Shale

A fine-grained rock formed by the consolidated of clay, mud or silt; generally having a finely stratified or laminated structure.

106.3.2.71.6.5.3 Mud Balls

Balls of mud.

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