Category:1018 Fly Ash for Concrete: Difference between revisions

This article establishes procedures for inspecting, sampling, and accepting fly ash at the source and destination and to establish a list of qualified fly ash sources. Refer to Sec 1018 for MoDOT’s specifications.

1018.1 Apparatus

Keep all sample containers and equipment used in sampling clean and free of moisture or any foreign material. It is important that the sample be kept in airtight, moisture-proof containers from the time it is obtained until tests are started. The apparatus consists of:

(a) Canvas bags with plastic liners.

(b) Rubber bands for securely fastening the top of plastic liners.

(c) Slotted tube, tube sampler, scoop or any other device suitable for obtaining the sample.

(d) Labeling materials.

1018.2 Procedure

1018.2.1 Source Acceptance and Qualification

All fly ash for use in MoDOT projects must be furnished from a qualified marketing entity or a qualified terminal and must comply with the requirements of Sec 1018. The procedures for qualification are listed in Sec 1018. Questions from potential suppliers concerning qualification are to be directed to the Central Office. The latest copy of each marketing entity's quality control plan is to be kept on file in the Central Office. Send any updates to the quality control plan directly to the Chemical Laboratory Director.

1018.2.2 Inspection and Sampling

The Senior Chemist may coordinate with the marketing entity to obtain a semi-annual split sample of fly ash from each qualified source. Complete a sample record in AASHTOWARE Project (AWP) showing manufacturer, marketing entity, silo number, class and other pertinent information. Designate sample type as a " Split Sample". The marketing entity shall furnish test results on the split sample direct to the Senior Chemist within two weeks of completion.

1018.2.3 Disqualified Facilities

Fly ash marketing entities or terminals that fail to comply with the qualified status as set forth in Specification Sec 1018 will be required to designate the silo(s), bin(s), or storage facility from which they propose to furnish fly ash for MoDOT projects. The producer must sample, test, and report satisfactory test results for each designated silo, bin, or storage facility. Prior to any shipment and following a satisfactory report furnished to the Chemical Laboratory Director, each silo, bin, or storage facility will be sampled and sealed by the Senior Chemist. If the results of testing by the Central Laboratory are satisfactory, the sealed silo, bin, or storage facility will be approved. This procedure will continue until adequate quality control has been re-established.

1018.2.4 Destination Inspection of Approved or Certified Fly Ash

The ready-mix, precast or paving plant operators shall furnish a copy of the bill of lading or delivery receipt for each shipment to MoDOT work.

Use the following procedure to sample fly ash on paving jobs and at ready-mix plants. Samples shall weigh a minimum of 5 lb. (2.25 kg). Obtain samples from the storage bin or weigh hopper in one operation representing a brief period in the fly ash stream.

Take a sample for each 600 tons (544 Mg) or portion thereof at destination for each paving job and submit to the Laboratory.

At ready-mix or precast plants, take a sample for each 600 tons (544 Mg) or portion thereof with a minimum of one sample every other month during the period that the ready-mix or precast plant is furnishing fly ash modified concrete for MoDOT work.

Place the samples taken at destination in a canvas bag containing a plastic liner and ship to the Central Laboratory. Complete a sample record in AWP and show the manufacturer, marketing entity, silo or bin number, type, and other pertinent information such as contractor, plant location, and county. Designate the sample type "Proj-Check Sample".

The district is to ensure that the qualified marketing entity is certifying each shipment in accordance with Sec 1018 including all requirements for signatures and shipments from other entities.

1018.3 Report

Reports of Central Laboratory test results on random samples of fly ash originating from a qualified marketing entity will not be distributed unless specifically requested and conditions warrant this information for a specific purpose.

The receiving District Construction and Materials Engineer shall continuously monitor shipments to the particular ready-mix or paving plants to assure the fly ash was shipped from an approved source.

Perform a review of each plant's inspector's daily report at regular intervals not to exceed one week. Verify that enough tickets are shown to account for the amount of fly ash used and that the fly ash came from a qualified marketing entity.

If the report does not contain the required information, notify the District Construction and Materials Engineer.

1018.4 Qualified Fly Ash Sources

Refer to Qualified Fly Ash Sources on MoDOT's website.

1018.5 Laboratory Procedures for Sec 1018

1018.5.1 Sample Preparation

Prior to testing, the sample should be thoroughly mixed, passed through a No.20 [850 mm] sieve, and brought to room temperature. All foreign matter and lumps that do not pulverize easily in the fingers must be discarded.

1018.5.2 Procedure

Chemical analysis is to be conducted according to ASTM C114 and MoDOT Test Methods T46 and T91. Original test data and calculations are to be recorded in Laboratory workbooks. Test results are to be recorded through AWP and retained on file in the Laboratory.

Physical tests on the following are to be conducted in accordance with ASTM C311.

(a) Fineness, 325 (45 mm) sieve analysis ASTM C430

(b) Pozzolanic Activity Index (7 day) ASTM C311

(c) Water requirement ASTM C311

(d) Soundness, autoclave ASTM C311

(e) Specific Gravity ASTM C311

Original test data and calculations are to be recorded in Laboratory workbooks. Test results are to be recorded through AWP and retained on file in the Laboratory.

1018.5.3 Source Acceptance

Samples are to be taken by the manufacturer in accordance with ASTM C311 from the conveyor, after exiting the precipitator collector and prior to entry into the designated storage silo, or where designated by the engineer.

Ash, that is manually sampled and tested every 400 tons, is to be held until the required tests have been run and the results are properly certified and are available for pick up by MoDOT personnel prior to shipment.

Ash, that is continually sampled and tested via auto samplers at a frequency and duration acceptable to the engineer, can be continuously shipped direct from a generating station silo, provided the following minimum criteria are met:

a. The storage silo has a minimum capacity of two days production or 1000 tons, whichever is the largest.

b. The storage silo is full, and certified test results on the entire contents are available prior to the first shipment.

c. The ash quantity in the silo is never less than 400 tons.

d. A continual inventory of the quantity of ash in silos is maintained within one shift of being correct.

e. The engineer has free access to station facilities and records necessary to conduct inspection and sampling.

f. All ash conveyance lines to the designated silo or silos will be sampled after precipitator collector and prior to entry into the designated silo(s), or by an auto sampler where designated by the engineer.

g. Each precipitator bank line shall have its own auto sampler placed per paragraph (f) above, if it does not join a common line with an auto sampler.

h. The allowance of one auto sampler in a common line serving multiple precipitator banks will depend on the placement of the auto sampler, tons of ash generated per day, the number of hoppers in each bank and the number of banks. This will be at the discretion of the engineer.

i. The generating station personnel handle and expedite all documents required to ship by MoDOT Certification.

1018.5.4 Plant Inspection

Qualified fly ash manufacturers and terminals shipping material by certification to Department projects shall be inspected on a regular basis by a representative of the Laboratory. This inspection shall include a review of plant facilities for producing a quality product; plant testing procedures; frequency of tests; plant records of daily test results and shipping information; company certification procedures of silos, bins, and/or shipments; and a discussion of items of mutual interest between the plant and the Department. The Laboratory representative shall coordinate test results and test procedures between the Laboratory and the respective plant laboratory, and investigate associated problems.

All silo or bin certifications and results of complete physical and chemical tests received in the Laboratory are to be checked for specification compliance and to determine if the required certifications have been furnished.

1018.5.5 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 rejections. Test results shall be reported on the appropriate templates under the Tests tab.