Section 4130. Revetment Stone, Erosion Stone, and Gabion Stone

 

4130.01 REVETMENT DESCRIPTION.

 

A. Broken limestone, dolomite, quartzite, or granite from an approved source as described in Materials I.M. 409 and meeting the following requirements.

         A minimum of 50% of the stone is to be composed of beds or slabs more than 5 inches thick.

         A minimum of 10% of the beds or slabs are to be thick enough to produce the required weight of either the stone or concrete, with the greatest dimension not more than two times the smallest dimension.

 

B. When the source test plot or service history is not available, meet the requirements of Table 4130.01-1 for virgin stone crushed to 3/4 inch to 1 1/2 inch nominal sizes. Abrasion loss for all revetment stone is not to exceed 50% when tested according to AASHTO T 96.

 

Table 4130.01-1: Virgin Stone Requirements

Revetment Type

Revetment Quality

Test Limits

(max)

Iowa DOT Materials Laboratory Test Method No.

Class A, B, C, & E revetment

Alumina

0.7

222

A Freeze

10

211, Method A

Secondary Pore Index

25

219

Class D revetment

C Freeze

10

211, Method C

Note: Revetment may pass either Alumina or A Freeze for compliance.

 

C. Recycled PCC pavement or broken concrete meeting the requirements of Materials I.M. 210 may be used with the approval of the Engineer.

         All reinforcement material is to be cut flush with the flat surface of the concrete.

         A minimum of 50% of the broken concrete revetment is to be composed of slabs more than 5 inches thick.

         A minimum of 10% of the slabs are to be thick enough to produce the required weight of the concrete with the greatest dimension not more than two times the smallest dimension.

         No petroleum based or HMA material is to be included in revetment.

 

4130.02 REVETMENT GRADATION.

 

A. Engineer will determine gradation compliance by visual inspection. After visual inspection and prior to loading, the Engineer may designate material as too fine or too coarse.

 

1. Class A Revetment.

         Nominal top size of 400 pounds.

         At least 75% of the stones are to weigh more than 75 pounds.

         At least 95% of the stones are to weigh more than 50 pounds.

         Stones weighing more than 50 pounds are to have at least one relatively flat face with one dimension at least 15 inches.

 

2. Class B Revetment.

         Nominal top size of 650 pounds.

         At least 20% of the stones are to weigh more than 500 pounds.

         At least 50% of the stones are to weigh more than 275 pounds.

         At least 90% of the stones are to weigh more than 25 pounds.

 

3. Class C Revetment.

         Nominal top size of 450 pounds.

         At least 50% of the stones weighing more than 275 pounds.

         At least 90% of the stones weighing more than 75 pounds.

 

4. Class D and Class E Revetment.

         Nominal top size of 250 pounds.

         At least 50% of the stones are to weigh more than 90 pounds.

         At least 90% of the stones are to weigh more than 5 pounds.

         The Engineer may approve using revetment containing material larger than 250 pounds.

 

B. Mechanically process Class D and Class E material to remove material 3 inches and less.

 

4130.03 EROSION STONE DESCRIPTION.

Broken limestone, dolomite, quartzite, granite, or broken concrete with steel removed.

 

4130.04 EROSION STONE GRADATION.

Engineer will determine gradation compliance by visual inspection. After visual inspection and prior to loading, the Engineer may designate material as too fine or too coarse.

         Nominal 6 inch size.

         100% passing the 9 inch screen.

         100% retained on the 3 inch screen.

 

4130.05 EROSION STONE QUALITY.

Except for recycled concrete, meet the requirements of Table 4130.05-1. There are no quality requirements for recycled concrete.

 

Table 4130.05-1: Aggregate Quality (Erosion Stone)

Aggregate Quality

Maximum Percent Allowed

Test Method

C Freeze

15

Iowa DOT Materials Laboratory Test Method No. 211, Method C

Abrasion

50

AASHTO T 96

Clay Lumps and Friable Particles

5

Materials I.M. 368

Note: Perform tests on product crushed to 3/4 inch or 1 inch maximum size.

 

4130.06 GABION STONE DESCRIPTION.

Broken stone or gravel boulders meeting the requirements below. Use stone and boulders from sources similar in geological origin.

 

4130.07 GABION STONE AND MATTRESS GRADATION.

Process stone or boulders for gabions and mattresses to sizes ranging from 4 inches to 8 inches in nominal dimensions. Three inches to 5 inches is recommended for mattresses.

 

4130.08 GABION STONE QUALITY.

Meet requirements of Table 4130.08-1. Sources with Revetment A, B, or E approvals need not meet these requirements.

 

Table 4130.08-1: Aggregate Quality (Gabion Stone)

Aggregate Quality

Maximum Allowed Percent

Test Method

Alumina

A Freeze

0.7

10

Iowa DOT Materials Laboratory Test Method No. 211, Method A

Abrasion

50

AASHTO T 96

Note: Pass either Alumina or A Freeze for compliance (alumina does not apply to gravel).

Perform tests on product crushed to 3/4 inch or 1 inch maximum size.