Design of AC-WC Mixture. .1 AC-WC Mixture Gradation Marshall Properties

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a. Sieve Analysis

Procedures for checking the sieve analysis for the filler refers to the SNI 03-4142-1996.

b. Specific Gravity and Absorption

Inspection of procedures for filler refers to AASHTO T84-88 or SNI 03-1970-1990.

4. Examination of Crumb Rubber

Because there is no standard available to examine the properties of crumb rubber, the following tests were adopted: specific gravity and absorption of coarse and fine aggregates, specific gravity of asphalt with water and kerosene as the medium of the test. 3.3.4 Design of AC-WC Mixture. 3.3.4.1 AC-WC Mixture Gradation The gradation used in this study is fuller gradation for AC-WC mixture, as shown in Table 2.2 and Figure 2.6. .

3.3.4.2 Initial Estimates of Asphalt Content

Initial asphalt content was calculated based on the proportion of coarse and fine aggregates, and filler in aggregate gradation. The initial estimates of asphalt content can be determined by using equation 2.1.

3.3.4.3 Preparation of Specimens

Two types of specimens were prepared in this study. They are: 1. AC mixture without crumb rubber. 2. AC mixture with crumb rubber. The procedure of sample preparation is as follows: i calculate the initial estimate of asphalt content; ii made briquettes with variations in asphalt content, i.e. two points at above and two points at below the initial estimate of asphalt content with 0.5 interval. These briquettes were prepared for asphalt without crumb rubber and for asphalt with crumb rubber. 34

3.3.4.4 Number of Samples

The number of samples required to find the Optimum Asphalt Content can be seen in Table 3.4. Table 3.4: Number of samples Test in This Study Test Objects Variations of asphalt content Variations of Crumb Rubber Requirement of Each specimens Variations Total The specimens without crumb rubber 5 - 3 15 Specimens with crumb rubber 5 3 3 45 TOTAL 60 Remarks: variations of crumb rubber: 3, 5 and 15 35

3.3.5 Marshall Properties

. The Marshall properties of the briquette were evaluated by checking if the properties fulfill the specification presented in Bina Marga 2004, as seen in Table 3.5. Table 3.5: Specification of AC Mixture Properties Sieve Course WC BC Base Asphalt Absorption max. 1,2 The number of collisions per field 75 112 Voids in mixture VIM Min. 4,9 Max. 5,9 Voids in the aggregate VMA Min. 15 14 13 Voids filled with asphalt VFA Min. 65 63 60 Stability kg Min. 800 1500 Max. - - Flow mm Min. 3 5 Marshall Quotient kg mm Min. 250 300 Remained Stability Marshall After 24 Hours Immersion, 60Oc Min. 75 Voids in mixture on Refusal Density Min. 2,5 Source: Bina Marga 2004

3.3.6 Selection of Optimum Asphalt Content