15 Dec 98
at all times.
Mix the materials at a stationary mixing plant. The mixer shall be either a continuous or a
batch type plant, designed to accurately proportion either by volume or by weight, so that when
the materials are incorporated in the mix, a thorough and uniform mix will result. The mixer shall
be capable of providing accurate control, at all times, of the amount of material entering the mixer
per time interval. The mixer shall be equipped to mechanically interlock the material feeds, such
that the uniformity of the mixture is assured.
The mix may be transported in open haul units when the material is placed within 30 minutes of
the end of mixing. Material placed in excess of 30 minutes after the end of mixing shall be
transported in a rotating drum unit capable of 2 - 6 rpm.
The engineer will determine the flow consistency of the CLSM according to ASTM D 6103.
The method of placing CLSM shall be as approved by the engineer.
The CLSM shall be accepted on the basis of inspection by the engineer.
d. Method of measurement. Payment for CLSM material will be made for the number of
satisfactorily placed cubic yards computed between the payment lines shown on the plans or from
payment lines established in writing by the Engineer.
e. Basis of payment. The unit price bid per cubic yard shall include the cost of furnishing all
labor, materials and equipment necessary to complete the work.
5. Trial Mix Designs Using Example Performance Specification for 40-300 psi Flowable CLSM.
a. Description. To demonstrate the ability of a contractor to meet the flow consistency and 28-
day compressive strength requirements of the Example Performance Specification for 40-300 psi
Flowable CLSM, as well as the difficulty and constraints of doing so when using significant
amounts of coal-combustion ash and other-than-concrete-aggregate sand as aggregate materials, a
batch-plant concrete supplier was contracted to develop CLSM mix designs meeting these
requirements using bottom ash, sand, and fly ash as aggregate materials. Additionally, the
contractor was directed to follow ASTM Standard Methods 4832, 5971, 6023, and 6103 where
appropriate for developing the mix designs and for preparing cylinders for strength tests.
Following the spirit of the performance specification--i.e., allowing an experienced and
innovative contractor to develop CLSM mixes without specifying excessive detail--there were no
other mix design constraints included in the contract.
b. Mix Designs and Strength Results. Mix designs used by the contractor in attempting to meet
the 40-300 psi strength range of the Example Performance Specification are listed in the table
below. For aggregate the contractor used bottom ash in Mixes 1-8, washed concrete sand or
unwashed fill sand (as noted by (w) or (f), respectively) in Mixes 9-16, and sand and fly ash in
Mixes 17-24. All mix designs met the flow consistency specification. The contractor chose to
use two commercially-available air-entraining agents, DaraFillTM and Darex IITM (DX IITM) .