ACI 423.9M-10 Test Method for Bleed Stability of Cementitious Post-Tensioning Tendon Grout.
SECTION 2—REFERENCED STANDARDS 2.1 ASTM standards C938-02 Standard Practice for Proportioning Grout Mixtures for Preplaced-Aggregate Concrete C125-09a Standard Terminology Relating to Concrete and Concrete Aggregates
SECTION 3—TERMINOLOGY 3.1 Definitions 3.1.1 For definitions of terms used in this test method, refer to ASTM C125. 3.2 Definitions of terms specific to this standard 3.2.1 bleeding—autogenous flow of mixing water within, or its emergence from, newly placed grout; caused by the settlement of the solid materials with the mass and filtering action of strands and wires. 3.2.2 grout—a mixture of cementitious material and water, with or without aggregate, proportioned to produce a pourable consistency without segregation of the constituents. 3.2.3 post-tensioning—method of prestressing in which prestressing steel is tensioned after concrete has hardened. 3.2.4 bleed stability (of cementitious grout)—resistance to bleeding.
SECTION 4—SIGNIFICANCE AND USE 4.1 The majority of durability problems found in grouted post-tensioned structures are related to voids in the grout due to incomplete filling of ducts or bleeding of the grout. Voids in the grout within the duct result in a loss of the protective environment and may end up as a collection point for moisture or outside contaminants such as saltwater. Voids can be formed from water separation from the grout before setting. Bleed water may remain trapped in the tendons or may be reabsorbed into the hardened grout, leaving voids. Bleeding increases with vertical pressure head. This test method is designed to evaluate the bleed stability of a freshly-mixed grout under static pressure. It can be used in both the laboratory to qualify grout materials and in the field as a quality-control test. When used to qualify grout materials, replicate tests may be specified. It is intended that the test pressure, acceptance criteria, and number of replicate tests be set forth in the Contract Documents.
SECTION 7—PROCEDURE 7.1 Fill the filtration funnel with 200 mL of freshly mixed grout within 5 minutes after completion of grout mixing. 7.2 Screw top stem cap on funnel hand tight, while keeping funnel in upright position. 7.3 Place funnel in stand. 7.4 Connect gas supply (gas pressure at 0 kPa). 7.5 Allow grout to rest in funnel for 10 minutes (+30 s, –0 s) after grout placement. 7.6 Increase pressure to specified pressure level (±20 kPa) within 30 s. 7.7 Hold at specified pressure for 5 minutes (+30 s, –0 s). 7.8 Release the pressure and tip the filter funnel slightly to break the surface tension and allow the bleed water remaining in the exit stem to be collected as part of the bleed volume to be measured. 7.9 Measure the volume of the collected bleed water to the nearest 0.2 mL at the end of hold time. 7.10 If a complete loss of pressure occurs before comple- tion of the 5 minute hold period, the test is considered invalid for the specified pressure level. Note 1—Loss of pressure in this test generally occurs as a “blow out” or complete loss of pressure with gas blowing out of the stem.ACI 423.9M pdf download.