Commonwealth of Pennsylvania PA Test Method No. 529 Department of Transportation July Pages LABORATORY TESTING SECTION. Method of Test for

Transcription

1 Commonwealth of Pennsylvania PA Test Method No. 529 Department of Transportation 6 Pages LABORATORY TESTING SECTION Method of Test for DETERMINING THE OPTIMIZED AGGREGATE GRADATION FOR HYDRAULIC CONCRETE PAVEMENT MIX DESIGNS 1. SCOPE 1.1 This method describes a procedure for analyzing combined aggregate gradations for use in optimized concrete pavement mix designs. 2. OUTLINE OF METHOD 2.1 The development of an optimized concrete mix gradation entails calculation of the combined gradation of aggregates to be included in a concrete pavement mix and identification of the percent of cumulative material retained on all required sieves on the percent retained chart to determine the desired characteristics of the combined aggregate structure. The basis of trial mix design components is one cubic yard. 3. APPARATUS 3.1 The apparatus used for sampling aggregates and performing sieve analysis will be as provided in PTM 607 and PTM PROCEDURE 4.1 Sieve Analysis Submit a sieve analysis report for the proposed aggregate showing the cumulative combined percent, the cumulative combined percent retained, and the combined percent retained as shown in Table 1, Example Sieve Analysis. Include all standard sieve sizes in the sieve analysis report beginning with the maximum nominal aggregate size of the proposed aggregate and proceeding in decreasing particle size to include the No. 200 sieve Perform sieve analysis in accordance with PTM 616 for each aggregate to be used in the mix. Complete the Sieve Analysis Report for the blended aggregates by calculating the cumulative combined percent, the cumulative combined percent retained, and the combined percent retained. Use the sieve analysis percent results of each aggregate gradation, the percentage of each aggregate for the concrete mix, and the following equations for the calculations Determine the percent of each aggregate used in the mix design combined aggregate gradation.

2 Page Calculate the cumulative combined percent each sieve using the following equation: Where: CCCC = {(PPPP)(BBBB)} Cp = Cumulative Combined Passing Px = the Passing of each Aggregate Bx = the of the Total Aggregate Gradation Calculate the cumulative combined percent retained on each sieve using the following equation: Cr = Cp Where: Cr = Cumulative Combined Retained Cp = Cumulative Combined Passing equation: Calculate the combined percent retained for each sieve using the following Where: C = Cr Crx 4.2 Gradation Analysis C = Combined Retained for each sieve Cr = Cumulative Combined Retained Crx = Cumulative Combined Retained of the next larger sieve size Submit a combined gradation percent retained chart for the proposed aggregates as shown in Figure 1, Combined Gradation Percent Retained Chart Calculate the total volume of the coarse portion of the fine aggregate by adding the Combined Retained (C) on each sieve from the No. 8 sieve to the No. 30 sieve inclusive. Total Volume of Coarse Portion = C No. 8 + C No C No. 30

3 Page 3 The total volume of coarse portion of the fine aggregate must be a minimum of 15 percent; therefore, if the Total Volume of Course 15, then the aggregate combination is acceptable Calculate the total volume of the fine portion of the fine aggregate using the Combined Retained (C) on all the sieves from the No. 30 sieve to the No. 200 sieve inclusive. Total Volume of Fine Portion= C No C No C No C No. 200 The total volume of fine portion of the fine aggregate must be from 24 percent to 34 percent; therefore, if 24 Total Volume of Fine Portion 34, then the aggregate combination is acceptable. 5. EXAMPLE 5.1 An example table with sample calculations for this test method. Table 1 Sieve Analysis Example Report Coarse Aggregate Fine Aggregate Cumulative Combined Combined (per sieve) #1 #2 #3 #1 #2 retained retained Sieve sizes P1 P2 P3 P4 P5 Cp Cr C 2 1/ / / / / No No No No No No No * of Total Blended Aggregate (Bx) *The No. 200 sieve includes what remains on the Pan

4 Page To provide assistance in complete the sieve analysis report, example calculations for the No. 8 sieve are shown for the cumulative combined percent, the cumulative combined percent retained, and the combined percent retained. Cumulative Combined Passing Cp = (P1 x B1) + (P2 x B2) + (P3 x B3) Cp = (1 x 44) + (3 x 16) + (80 x 40) Cp = Cp = 32.9 Cumulative Combined Retained Cr = Cp Cr = Cr = 67.1 Combined Retained C = Cr - Crx C = C = Example calculations to determine the total volume of the course portion and total volume of the fine portion using the calculated combined percent retained in Table 1, Sieve Analysis Example. Total Volume of Coarse Portion = C No. 8 + C No C No. 30 Total Volume of Coarse Portion = Total Volume of Course Portion = > 15, the aggregate combination is acceptable Total Volume of Fine Portion= C No C No C No C No. 200 Total Volume of Fine Portion = Total Volume of Fine Portion = < 27.5 < 34 the aggregate combination is acceptable

5 Page 5 6. EVALUATE COMBINED AGGREGATE GRADATIONS 6.1 Combined Gradation Percent Retained Chart Create the combined gradation percent retained chart for the combined aggregate mix by plotting the combined (per sieve) percent retained on the vertical axis vs. the sieve sizes on the horizontal axis, as shown in Figure 1. The combined percent retained aggregate must be within the limits outlined in Table 2 below. Table 2 Combined Percent Retained Limits Sieve Size Lower Limit Upper Limit 1 ½" 0 0 1" 0 16 ¾" 0 20 ½" /8" 4 20 No No No No No No No Selection of Optimized Aggregate Gradation Develop trial mix designs based on the aggregate gradations and percentages of the combined percent retained plot previously discussed. Select materials that plot within the limits of the chart. Develop trial batches from gradations meeting the limits of the chart, required fine aggregate volumes, and flat and elongated limits to determine which proportions meet the strength requirements of the project.

6 Page 6 Combined Gradation Percent Retained Chart 25 Lower Upper Retained 20 Percent Retained " 1 1/2" 1" 3/4" 1/2" 3/8" # 4 # 8 # 16 # 30 # 50 # 100 # 200 Sieve Size Figure 1 Combined Percent Retained Chart