Concrete Mixture Proportions

Two series of concretes, as shown in Table 2, were undertaken for testing of air-void stability. The fresh concrete mixtures were designed based on a weight-basis water-binder (W/B) ratio of 0.35, an air-dry and weight-basis sand-aggregate ratio of 0.50, and nominal air contents of 4 and 8%. For both air contents, the content of rice husk ash was varied with 0, 15 and 20% of binder by weight. The basic mixture proportions for the two series of concretes, as shown in Table 3, were determined based on the absolute volume of the constituent materials. The dosages of HRWR and AEA are not included in basic mixture proportions. HRWR and AEA were used in concrete as additives, and their dosages have been presented in Table 4. The amounts of HRWR shown in Table 4 are the saturation dosages for various concretes. These dosages were obtained by testing the flow of various binder pastes, which are not detailed here. Also, the proportions of coarse and fine aggregates given in Table 3 are based on their absolute volume in saturated surface-dry condition. But, the aggregates were batched in air-dry condition and hence they absorbed some mixing water. In addition, the liquid HRWR contributed some water during mixing. Therefore, the proportions of coarse and fine aggregates, and water presented in Table 3 were adjusted before concrete batching.

Table 2: Different Types of Self-consolidating Concrete for Testing of Air-void Stability

Concrete

Series

Concrete

Designation

W/B

Rice Husk Ash (% B)

Design Air Content (%)

Time of Testing (minute)

C3 5/0/4

0

S1

C3 5/15/4

0.35

15

4

15, 30, 45, 60

C35/20/4

20

C3 5/0/8

0

S2

C3 5/15/8

0.35

15

8

15, 30, 60, 90

C35/20/8

20

Table 3:

Basic Mixture Proportions of Different Self-consolidating Concretes (W/B

= 0.35)

Concrete

Mixture

Coarse Aggregate

kg/m3

Fine Aggregate

kg/m3

Cement

kg/m3

Rice Husk Ash

kg/m3

Water

kg/m3

C3 5/0/4

902.7

898.3

422.3

0

147.8

C35/15/4

888.6

884.2

359.0

63.3

147.8

C3 5/20/4

883.9

879.5

337.8

84.5

147.8

C3 5/0/8

849.4

845.2

422.3

0

147.8

C35/15/8

835.3

831.2

359.0

63.3

147.8

C3 5/20/8

830.6

826.5

337.8

84.5

147.8

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