Article 1 — Description
Furnish and place flowable backfill for trench, hole, or other void.
Article 2 — Materials
Use materials from prequalified sources listed on the Department website. Use materials from non- listed sources only when tested and approved before use. Allow 30 ca lendar days for the Engineer to sample, test, and report results for non- listed sources. Do not combine approved material with unapproved material .
2.1 Cement . Furnish cement in accordance with DMS -4600 , “Hydraulic Cement.”
2.2 Fly Ash . Furnish fly ash in accordance with DMS -4610, “Coal Ash.”
2.3 Chemical Admixtures. Furnish chemical admixtures in accordance with DMS -4640 , “Chemical Admixtures
for Concrete.” Use specialty type admixtures to enhance the flowability, reduce shrinkage, and reduce segregation by maintaining solids in suspension when necessary. Use and proportion all admixtures in conformance with the manufacturer’s recommendations .
2.4 Fine Aggregate . Provide fine aggregate that will stay in suspension in the mortar to the extent required for
proper flow and that meets the gradation requirements shown in Table 1. Table 1 Aggregate Gradation Chart Sieve Size Percent Passing 3/4″ 100 #200 0–30 Test fine aggregate gradation in accordance with Tex-401-A . Plasticity i ndex must not exceed six when tested in accordanc e with Tex -106-E .
2.5 Mixing Water . Use mixing water in accordance with Item 421, “Hydraulic Cement Concrete. ”
Article 3 — Construction
Submit a construction method and plan, including mix design, for approval. Provide a means of filling the entire void area and be able to demonstrate this has been accomplished. Prevent the movement of any inserted structure from its designated location. Remove and replace or correct the problem if voids are found in the fill or any of the requirements are not met as shown on the plans , without additional cost to the Department. Furnish a mix meeting the requirements shown in Table 2, unless otherwise shown on the plans. Table 2 Flowable Fill Mix Design Requirements Property Excavatable Non-Excavatable Test Method 28-day compressive strength1, psi 80–200 > 200 ASTM D4832 Consistency2, Min diameter, in. 8 ASTM D6103 Unit weight, pcf 90–125 100 to 145 ASTM D6023 Air content, % 10–30 5 to 15 ASTM D6023 1. Average of two specimens. 2. Mixture must not segregate. Mix the flowable fill using a central -mixed concrete plant, ready -mix concrete truck, pug mill, or other approved method. Furnish all labor, equipment, tools, containers, and molds required for sampling, making, transporting, curing, remov ing, and dispos ing of test specimens. Furnish test molds meeting the requirements of Tex -447-A . Transport, strip, and cure the test specimens as scheduled at the designated location. Cure test specimens in accordance with Tex-447-A . The Engineer will sample, make, and test all specimens. Dispose of used, broken specimens in an approved location and manner. The frequency of job- control testing will be at the direction of the Engineer.
Article 4 — Measurement
This Item will be measured by the cubic yard of material placed. Measurement will not include additional volume caused by slips, slides, or cave- ins resulting from the Contractor’s operations .
Article 5 — Payment
The work performed and materials furnished in accordance with this Item and measured as provided under “Measurement” will be paid for at the unit price bid for “Flowable Backfill.” This price is full compensation for furnishing, hauling, and placing materials and for equipment, tools, labor, and incidentals .