Bagged Grout Fluidifier

No. 100

Design Mix for Pumped Concrete for Underwater Use [Quantities indicated are per cubic yard of concrete.]

Table 2-27

Design Mix for Pumped Concrete for Underwater Use [Quantities indicated are per cubic yard of concrete.]

Item

Quantity

Cement (Type II)

640 pounds (8 sacks)

Fly Ash

112 pounds

Sand

1,300 pounds

Gravel (3/8-inch maximum)

1,800 pounds

Water

40 gallons

Admixture - Water Reducer

In accordance with manufactuer's recommendations

Slump

6 inches

Strength

Steps for placing prepacked concrete into form.

Submarine Structure Design

Figure 2-55

Steps for placing prepacked concrete into form.

Step 2. Form completed and grout being placed.

Step 2. Form completed and grout being placed.

diameter ratios of the smallest particles of coarse aggregates to the largest particles of sand should not be less than 4 to 1.

The void content of the coarse aggregate is as low as possible, which can usually be attained by grading it uniformly from the smallest aggregate size to the largest aggregate size. The gradation shown in Table 2-28 is recommended to minimize the void content. Gap grading sometimes provides a lower void content than uniform grading. The void ratio of the cavity after the aggregate is placed is usually 35 to 40 percent.

The grout is proportioned in accordance with the requirements of ASTM C938, Standard Practice for Proportioning Grout Mixtures for Preplaced-Aggregate Concrete. Its consistency is determined in accordance with ASTM C939, Flow of Grout for Preplaced-Aggregate Concrete (Flow Cone Method). The consistency, which is measured as an efflux time, should be on the order of 22 ±2 seconds. The grout con sists of Portland cement, sand, and Class F fly ash of Class N pozzolan. Whether fly ash or pozzolan is used will largely depend on the Contractor's previous experience and/or the results of trial tests. Generally, the mix that provides the best workability, highest strength, and least shrinkage should be recommended for repairs.

Class F fly ash is normally produced from burning anthracite or bituminous coal, while Class N pozzolan is a raw or calcined natural material containing silica or aluminum in a finely divided reactive form. The fly ash and pozzolan are used to improve pumpability of the grout, extend its handling time, and provide increased impermeability and erosion resistance.

The fly ash and pozzolan must conform to the requirements of ASTM C618, Specification for Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete. The proportion of portland cement to pozzolan is in the range of 2.5:1 to 3.5:1, by weight, as discussed in ACI 304.2R-91. The ratio of cementitious material (i.e., portland cement plus pozzolan or fly ash) to sand is approximately 1:1, while the water to cementitious material ratio ranges from 0.42 to 0.50.

In addition, a grout fluidifier, meeting the requirements of ASTM C937, Standard Specification for Grout Fluidifier for Preplaced-Aggregate Concrete, is used to offset the effects of bleeding, reduce the water/cement ratio, and retard stiffening. The dosage of fluidifier is approximately 1 percent of cementitious material by weight. The amount of bleeding in the grout should be less than the amount of expansion, as determined in accordance with ASTM C940, Standard Test Method for Expansion and Bleeding of Freshly Mixed Grouts for Preplaced-Aggregate Concrete in the Laboratory.

Table 2-28

Gradation of Aggregates for Prepacked Concrete

Table 2-28

Gradation of Aggregates for Prepacked Concrete

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