Category:1005 Aggregate for Concrete

MGS Information

Current General Services Specifications (MGS) By Subject

This guidance establishes procedures for the inspection, testing and acceptance of coarse and fine aggregate for use in concrete.

1005.1 Procedure

Aggregate, Gradation Optimization

Report 2005

Durability Factor, Paving Concrete

Report 2009

See also: Research Publications

Inspection, testing, and sampling will be governed by the instructions contained in EPG 1001 General Requirements for Material.

Samples required for Laboratory tests are as follows:

(a) Initial Evaluation for coarse aggregate.

(b) Source Approval.

(c) Source Approval for lightweight aggregate.

(d) QC/QA samples for concrete Masonry.

1005.2 Acceptance

Source Approval is based on the results of Laboratory tests. Acceptance is based on routine tests in the field to ensure compliance with Sec 1005.

1005.3 Records and Reports

All plant records shown in EPG 1001.6 General Requirements for Material - Records and Reports shall be maintained. The aggregates shall be reported through AASHTOWARE Project (AWP) in accordance with AWP MA Sample Record, General.

1005.4 Laboratory Procedures for Sec 1005

1005.4.1 Types of Samples Tested

1005.4.1.1 Initial Approval Sample

Tests consist of specific gravity, absorption, Los Angeles abrasion, micro deval, and soundness (water-alcohol and sodium sulfate).

The minimum time required for completion of initial approval sample tests is 24 working days from the date received.

Test results and calculations shall be recorded through AWP.

1005.4.1.2 Source Approval Sample

Coarse aggregate tests consist of sieve analysis, specific gravity, absorption, rodded unit weight, Los Angeles abrasion, deleterious content, micro deval, and soundness (water-alcohol and sodium sulfate). The minimum time required for completion of tests is 16 working days from the date received unless T161 testing is required, then a minimum of 4 months should be allowed.

Conditional approval for use of PCCP and PCCM may be granted based off the results of the above listed tests, however, care must be taken when allowing conditional approval under these conditions as the results of durability factor and reactivity may result in the conditional approval being revoked and the material not being accepted for PCCP or PCCM use.

Both PCCP and PCCM will be evaluated for reactivity under MoDOT Test Method TM-93. If AASHTO T161 Resistance of Concrete to Rapid Freezing and Thawing is required, testing may take up to 4 months to complete from date received. If ASTM C 1105 Standard Test Method for Length Change of Concrete Due to Alkali-Carbonate Rock Reaction is required, testing may take up to 15 months to complete from the date received.

Test results and calculations shall be recorded through AWP.

Fine aggregate tests consist of sieve analysis; specific gravity; absorption, rodded unit weight; other deleterious substances, clay lumps and shale, and lightweight particle content when specified; and mortar strength test. The minimum time required for completion of tests is 16 working days from the date received. Test results and calculations shall be recorded through AWP.

1005.4.1.3 Source Approval Sample for Lightweight Aggregate

Source approval samples are obtained for lightweight aggregate. Tests consist of sieve analysis, specific gravity, absorption, loose unit weight, and soundness by sodium sulfate. Tests for soundness need not be run providing recent satisfactory results were obtained on a previous sample of similar characteristics and from the same source. Test results and calculations shall be recorded through AWP.

1005.4.2 Procedure

1005.4.2.1 Sieve Analysis

Fine and coarse aggregates shall be tested in accordance with AASHTO T 27.

Lightweight aggregate shall be tested according to AASHTO T 27 except the minimum weight (mass) of the test sample should be approximately one-half the amount shown.

1005.4.2.2 Specific Gravity and Absorption

Coarse aggregate shall be tested in accordance with AASHTO T 85 for Bulk Specific Gravity.

Fine aggregate shall be tested in accordance with AASHTO T 84.

1005.4.2.3 Specific Gravity of Lightweight Aggregate

Apparatus

(a) Vacuum System. A system capable of maintaining a vacuum of 16 mm or more of mercury in a chamber of sufficient size to accommodate the aggregate sample. The system must have airtight valves so there is no loss of vacuum when the system is closed and to allow inundation of the aggregate with water.

(b) Balance. A balance or scale having a capacity of 1 kg or more and sensitive to 0.1 g or less.

(c) Oven. The oven shall be capable of maintaining a uniform temperature of 110 ± 5 °C (230 ± 9 °F).

(d) Heater. An electric heater equipped with fan for drying aggregate to surface dry condition.

(e) Pycnometer. A calibrated 500 ml volumetric flask.

(f) Water Bath. A water tank capable of maintaining a temperature of 23 ± 1.7 °C [73.4 ± 3 °F].

(g) Trowel. A small masonry trowel for stirring aggregate.

(h) Containers. A metal pail approximately 150 mm (6 in.) in diameter and 200 mm (8 in.) high and pans of suitable size to allow uniform drying of aggregate.

Sample Preparation

(a) Obtain approximately 2200 g of aggregate from the sample by use of a sample splitter.

(b) Dry the sample to constant weight in an oven at a temperature of 110 ± 5 °C [230 ± 9 °F].

(c) Remove the sample from the oven and allow to cool in air at room temperature.

Test Method

(a) Introduce the sample in the pail and place in the vacuum chamber. A piece of fine wire mesh fitted inside the pail will prevent particles from floating. Evacuate at 16 mm of mercury or more for 20 minutes.

(b) Inundate the aggregate with water.

(c) Remove the pail containing aggregate and water from the vacuum chamber and let soak for four hours.

(d) Drain the water from the sample and place in a pan of sufficient size to permit the sample to be spread in a thin layer. Expose the sample to a gentle moving current of warm air, with the use of an electric heater, and stir frequently with a trowel to ensure uniform drying.

When the sample approaches the surface dry condition, transfer the sample to a smaller pan to slow down the drying process. This aids in the detection of the surface dry condition. At this point, it is necessary to stir continuously to ensure uniform drying of the sample. The trowel is used to check the surface dry condition of the aggregate by running it horizontally through the aggregate several times and checking immediately for moisture. The surface dry condition is reached when moisture is visible on the tip of the trowel covering approximately 40 mm (1 1/2 in.) from the tip end.

(e) Immediately introduce approximately 300 g of the saturated surface-dry material into a pycnometer of known weight (mass) and record the weight of the pycnometer and sample. Record this and all other weights (masses) to the nearest 0.1 g.

(f) Fill the pycnometer with water to approximately 90 percent of its calibrated capacity. Roll and agitate the pycnometer eliminate all air bubbles.

(g) Immerse the pycnometer in a water bath. Adjust the water level in the pycnometer to the calibrated line with water at the same temperature as the bath. Record the total weight of pycnometer, sample and water.

(h) Remove the aggregate from the pycnometer, dry to constant weight at a temperature of 110 ± 5 °C [230 ± 9 °F]. Cool in air at room temperature and weigh.

(i) Determine the weight of the water required to fill the pycnometer of its calibration capacity at 23 ± 1.7 °C [73.4 ± 3 °F].

Calculate the bulk specific gravity as follows:

${\displaystyle Bulk\,Specific\,Gravity={\frac {A}{B-W-C}}}$

Where:

A = weight of oven-dry sample in air, g

B = weight of pycnometer and saturated surface dry material, g

W = weight of water required to fill pycnometer to calibration mark at 23 ± 1.7 °C (73.4 ± °3 F)

C = weight of pycnometer with sample and water to calibration mark, g.

1005.4.2.4 Absorption of Lightweight Aggregate

Apparatus

(a) Balance. A balance or scale having a capacity of 5 kg or more and sensitive to 0.5 g or less.

(b) Oven. The oven shall be capable of maintaining a uniform temperature of 110 ± 5 °C (230 ± 9 °F).

(c) Heater. An electric heater equipped with fan for drying aggregate to surface dry condition.

(d) Trowel. A small masonry trowel for stirring aggregate.

(e) Containers. Pans of suitable size to allow uniform drying of aggregate.

Sample Preparation

(a) Obtain approximately 2200 g of aggregate from the sample by use of a sample splitter.

(b) Dry the sample to constant weight (mass) in an oven at a temperature of 110 ± 5 °C (230 ± 9 °F).

(c) Remove the sample from the oven and allow to cool in air at room temperature.

Test Method

(a) Immerse the sample in water at room temperature for approximately 24 hours.

(b) Drain the water from the sample and place in a pan of sufficient size to permit the sample to be spread in a thin layer. Expose the sample to a gentle moving current of warm air, with the use of an electric heater, and stir frequently with a trowel to ensure drying. When the sample approaches the surface dry condition, transfer the sample to a smaller pan to slow down the drying process. This aids in the detection of the surface dry condition. At this point, it is necessary to stir continuously to ensure uniform drying of the sample. The trowel is used to check the surface dry condition of the aggregate by running it horizontally through the aggregate several times and checking immediately for moisture. The surface dry condition is reached when moisture is visible on the tip of the trowel covering approximately 40 mm (1 1/2 in.) from the tip end.

(c) Weigh the saturated surface dry sample and record the weight. Record this and all subsequent weights to the nearest gram.

(d) Dry in the oven to constant weight at a temperature of 110 ± 5 °C [230 ± 9 °F], cool in air at room temperature and weigh.

Calculate the absorption as follows:

${\displaystyle Absorption,percent={\frac {100(B-A)}{A}}}$

Where:

A = weight (mass) of oven-dry sample in air, g, and

B = weight (mass) of saturated-surface-dry sample in air, g.

1005.4.2.5 Unit Weight

Aggregate shall be tested in accordance with AASHTO T 19.

1005.4.2.6 Los Angeles Abrasion

Coarse aggregate shall be tested in accordance with AASHTO T 96.

1005.4.2.7 Deleterious Content

The percentage of deleterious substances for coarse aggregate is to be determined according to TM-71, Deleterious Content of Aggregate. Where field determinations show a total deleterious content of 2.0 percent or less, including not more than 0.5 percent shale, the deleterious content shall be inspected visually. The sample is to be tested if visual inspection indicates more than 2.0 percent total deleterious material present in the sample. Source approval samples shall always be tested regardless of the content of deleterious material.

The percentage of lightweight particles in fine aggregate shall be determined according to AASHTO T 113, except the heavy liquid shall be a solution of zinc chloride and water of having a specific gravity of 2.00 ± 0.01.

The other deleterious substances, clay lumps, and shale in fine aggregate shall be visually determined and separated into the constituents required by the applicable Specification when an examination of the sample prepared for sieve analysis indicates a need for exact determination of deleterious content. Percentages shall be calculated as follows:

${\displaystyle P={\frac {C\times 100}{W}}}$

Where:

P = Percentage of deleterious material

W = Weight (mass) of test sample

C = Actual weight (mass) of deleterious material.

1005.4.2.8 Mortar Strength

Fine aggregate subjected to the mortar strength test shall produce a mortar having a tensile strength at the age of seven days of at least 90 percent of that developed at the same age by mortar of the same proportions, consistency, made of the same cement, and Standard Ottawa sand. Tests shall be AASHTO T 106. Cement used in the tests shall be Type I meeting the requirements of Specification Sec 1019.

1005.4.2.9 Soundness by Use of Alcohol Freeze

Coarse aggregate shall be tested in accordance with MoDOT Test Method T 14.

1005.4.2.10 Soundness by Use of Sodium or Magnesium Sulfate

Lightweight aggregate and coarse aggregate shall be tested in accordance with AASHTO T 104.

1005.4.2.11 Rapid Freeze-Thaw

Coarse aggregate for PCCP shall be tested in accordance with AASHTO T161 (Method B).

1005.4.2.12 Alkali-Silica Reaction in Concrete

Coarse aggregate for PCCP shall be tested in accordance with ASTM C 1260.

1005.4.2.13 Colormetric Test

Fine aggregate shall be tested in accordance with AASHTO T21.

1005.4.2.14 Alkali-Carbonate Reaction in Concrete

The State of Missouri has aggregate formations that are prone to alkali carbonate reactivity (ACR). This reaction is caused when the alkali contained in the Portland cement reacts with the aggregate, chemically changing the aggregate to an expansive material. Concrete that uses aggregate prone to ACR will experience significant map cracking caused by the aggregate expanding inside the concrete. Currently, there is no way to mitigate this reaction. The only way to prevent this reaction from occurring in concrete (masonry or pavement) is to avoid using aggregates prone to ACR. MoDOT has two ACR screening protocols for evaluating coarse aggregate. One protocol is for handling new quarries or new ledge combinations coming online. The second protocol is for handling existing quarries that have previously been sampled and tested for Source Approval. See EPG 106.3 for MoDOT Test Method TM-93 – Alkali Carbonate Reactivity Screening Protocol.

1005.4.3 Sample Record

The sample record shall be completed in AASHTOWARE Project (AWP) in accordance with AWP MA Sample Record, General and shall indicate acceptance, qualified acceptance, or rejection. Appropriate remarks, as described in EPG 106.20 Reporting, are to be included in the remarks to clarify conditions of acceptance or rejection. Test results shall be reported on the appropriate templates under the Tests tab.