219Controlled Low-Strength Material

219.1-DESCRIPTION: A Controlled Low Strength Material (CLSM) is a non-compacted, cementitious material used primarily as a backfill in lieu of a compacted material. This work shall consist of furnishing and placing CLSM as a backfill material in accordance with these Specifications and in reasonably close conformity with the lines, grades, thicknesses and cross sections shown on the Plans or established by the Engineer. 219.2-MATERIALS: Materials shall meet the requirements specified in the following Subsections of Section 700. MATERIAL SUBSECTION Admixtures 707 Aggregate Bottom Ash Fine Aggregate 703.3.3 (except with the following gradation and a maximum loss on ignition of 12%): Sieve Size Percent Passing by Weight: 3/4 inch (19 mm) 95% 3/8 inch (9.5 mm) 85-100% #100 (150 μm) 0-25% 702.1.1–702.1.5 with the following gradation: Sieve Size Percent Passing by Weight: 3/8 inch (9.5 mm) 100% #200 (150 μm) 0-10% Flyash 707.4.1 (except with a maximum loss on ignition of 12%) Portland Cement 701.1 or 701.3 Water 715.7 219.3-PROPERTIES: Type A B C 28 Day Compressive Strength 50 psi min./150 psi max. 50 psi min. 1,000 psi min. pH: 5.0-13.0 Flow: Minimum spread of six (6) inches 219.4-CONSTRUCTION METHODS: 219.4.1-Proportioning: Prior to the start of construction, the Contractor shall design and submit to the Engineer for approval the proportions of materials, including admixtures, to b e used which will result in a workable, CLSM mixture having the desired properties. 144 A mix design shall be required for each type of CLSM to be used in the work. The mix design shall be accompanied by a statement giving the source of materials and certif ied test data demonstrating the adequacy of the mix design. The results of the mix design testing shall include a listing of the components used in the mix, the results of unconfined compressive strength tests, pH, and flow. The unconfined compressive strength test specimens for mix design approval shall consist of two sets (3 cylinders per set) of standard six (6) inch by twelve (12) inch cylinders. Both sets of cylinders shall be molded, cured, and tested at an age of 28 days in accordance with ASTM D4832. Both sets of cylinders shall meet the strength requirements specified in section 219.3. A pH test, in accordance with ASTM G51, shall be performed on at least one sample during the mix design testing, and the results shall meet the requirements of Section 219.3. The mix shall have a consistency that will allow the material to fill all voids during placement without vibration or other consolidation methods. 219.4.2-Testing: Material shall be sampled in accordance with ASTM D5971. Flow tests shall be conducted in accordance with ASTM D6103. Compressive strength tests shall be conducted in accordance with ASTM D4832. The Contractor shall determine the flow, and shall mold one set (3 cylinders) of standard six (6) inch by twelve (12) inch compressive strength specimens for every 100 cubic yards, or fraction thereof, of material that is placed. These cylinders shall be cured and tested in accordance with ASTM D4832 except that they shall be stored at the construction site in the storage container until the fourteenth day after preparation. After the fourteenth day, they shall be transported to the site of the curing environment, specified in ASTM D4832, where they will be cured for the remainder of the 28 day period. The average compressive st rength at 28 days shall meet the strength requirements listed in section 219.3. Material not meeting the minimum compressive strength at 28 days shall be removed at the Contractor’s expense. The Division shall evaluate Type A material that exceeds the maximum compressive strength. Report all test results, in written form, to the Engineer within 24 hours after completion of each test. Contractor’s Quality Control: Quality control of the CLSM is the responsibility of the Contractor. The Contractor shall maintain equipment and certified Portland cement concrete inspector(s) who shall maintain equipment and direct all field inspection, sampling and testing necessary to determine the magnitude of the various properties of the CLSM governed b y the Specifications and shall maintain these properties within the limits of this Specification. A Quality Control Plan prepared according to MP 601.03.50 shall be submitted to the Engineer at the pre-construction conference. Acceptance Testing: Acceptance sampling and testing of CLSM is the responsibility of the Division. Quality control sampling and testing performed by the Contractor may be used by the Division for acceptance. 219.4.3-Equipment and Tools: Equipment shall be according to 601.5. 219.4.4-Site Preparation: The Contractor shall provide the necessary barriers to confine the CLSM. Pipe culverts and any other items to be backfilled that could move or float during backfilling, shall be secured by the Contractor to prevent movement. 145 219.4.5-Mixing: The mixing shall be in accordance with 601.7 except that CLSM shall be delivered in a truck mixer. Mixing and delivery is also permitted using volumetric batching and mixing equipment in accordance with AASHTO M 241. Volumetric mixers shall be properly calibrated and shall sufficiently mix the materials to produce a uniform product. The limitation on the total number of drum revolutions is waived. Sufficient drum revolutions shall be used just prior to discharge to insure a homogeneous slurry. 219.4.6-Placement: The drop height for the CLSM shall be limited to the minimum necessary by using chutes or other devices. CLSM shall be brought up evenly by moving the discharge points or by spreading the backfill manually. For b ackfilling around pipes, the backfill shall be placed evenly on both sides of the trench to avoid overstressing the pipe. The lift thickness shall be limited to that shown on the plans or as directed by the Engineer to avoid overstressing the pipe, forms , structures or to avoid floating the pipe. Prior to placement of successive lifts, the CLSM shall be allowed to cure until it is self-supporting. CLSM shall not be finished between lifts. The top of a lift shall be cleaned, if necessary, to insure bonding with the next lift. 219.5-METHOD OF MEASUREMENT: The quantity of CLSM will be determined by the volume noted on printed batch tickets with subtraction of rejected and wasted material. In situations where a foaming agent is used in the CLSM, the volume of CLSM will be determined after the foaming agent has been added. The volume of a batch of CLSM will be determined after a Unit Weight Test (conducted in accordance with AASHTO T 121) has been performed on a representative sample of that batch of CLSM after the addition of the foaming agent. The total volume of that batch of CLSM will be calculated by dividing the sum of the batch weights noted on printed batch tickets by the Unit Weight determined by the Unit Weight Test conducted on that batch. The net volume used for payment will be determined by su btracting the rejected and wasted material from the total volume. The Contractor and the Engineer shall agree in advance on a method to determine the volume of waste. 219.6-PAY ITEM: ITEM DESCRIPTION UNIT 219001-* Controlled Low Strength Material, Type “type” Cubic Yard * Sequence number 146