<p><p><strong>Reference(s):</strong></p><p><em>Brown et al. (2007)</em></p><p><strong>Method Summary</strong></p><p>Representative samples of the grout or concrete mix must be obtained at the project site for QC/QA testing. The ideal location and time to obtain samples for testing is at the point of discharge into the soil and after the mix has been pumped through the lines and the auger, as the properties (especially workability) can be changed by pumping extended distances. Generally, sampling at the point of discharge is not possible and samples are typically obtained from the discharge location into the pump hopper.</p><p>The three parameters most commonly measured are temperature, workability, and strength. Each of these is discussed below.</p><p><u>Temperature</u></p><p>Temperature should be checked on every truck as a means of verifying the consistency of the mix. Grout or concrete should not be placed when its temperature falls below 4° C (40° F) or exceeds 38° C (100° F), unless approved procedures for cold or hot weather are followed.</p><p><u>Workability</u></p><p>Workability is measured using slump testing for concrete and flow cone testing for grout. Workability should be checked on every truck as a means of verifying the consistency of the mix.</p><p>Slump ranges for concrete in CFA piles should typically be 200 mm ±25 mm (8 inches ±1 inch). Slump measurements should be made according to ASTM C 143 (Standard Test Method for Slump of Hydraulic-Cement Concrete).</p><p>Workability of grout is tested using a flow cone as specified in ASTM C939 (Standard Test Method for Flow of Grout for Preplaced-Aggregate Concrete) and U.S. Army Corps of Engineers CRD-C 611-94. These specifications call for a 12 mm (0.5 inches) outlet for the flow cone. Grout mixes used for CFA piles are typically too thick to flow through a cone with this outlet diameter, so it is common practice to modify the above specifications to provide a 19 mm (0.75 inches) opening. Grouts suitable for CFA piles typically have a fluid consistency represented by an efflux time of 10 to 25 seconds when tested with the 19 mm (0.75 inches) opening.</p><p><u>Strength</u></p><p>Strength testing is performed in the laboratory after collecting and curing samples from the field. For concrete, 150-mm (6-inch) diameter by 300-mm (12-inch) high cylinders (ASTM C 31 “Standard Practice for Making and Curing Concrete Test Specimens in the Field”) should be made from samples of the mix from the field in the same manner as for most other cast-in-place concrete construction, including drilled shaft construction. Samples should be cured and tested according to ASTM C39 (Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens) or the agency’s normal procedures. Concrete compressive strength requirements for CFA piles are typically 24 to 31 MPa (3,000 to 4,500 psi) and will be specified according to the project requirements. For grout, 50-mm (2-inch) cubes are most often used for strength testing, (see Figure 7.10) per ASTM C109 (Standard Test Method for Compressive Strength of Hydraulic Cement Mortars). Typical strength requirements for grout are 27.6 to 34.5 MPa (4,000 to 5,000 psi).</p></p>