Material Testing - Aggregates Impact Value.pptx

Aggregates impact value

1. AGGREGATES IMPACT AND CRUSHING VALUE

2. Aggregates undergo significant wear and tear throughout their life. Aggregates must be hard and tough enough to resist crushing, degradation and disintegration and be able to transmit loads from the pavement surface to the underlying layers and eventually the subgrade. Testing the strength of parent rock alone does not exactly indicate the strength of aggregates in concrete. INTRODUCTION

3. MECHANICAL PROPERTY OF AGGREGATE 01 02 Satisfactory resistance to crushing under the roller during construction Adequate resistance to surface abrasion under traffic Aggregates used in road construction should be strong enough to resist abrasion and crushing and also the impact load.

4. AGGREGATES IMPACT VALUE The stability of pavement structure will be adversely affected. The toughness of aggregate is its ability to resist sudden load acting on it The aggregates should have sufficient toughness to resist their disintegration due to impact.

5. CLASSIFICATION OF AGGREGATES BASED ON AGGREGATE IMPACT VALUE Aggregates Impact Value gives relative measure of resistance of aggregates to sudden shock or impact, which in some aggregates differs from its resistance to slow compression load. Impact Value should not be less than 45% for aggregates used for concrete other than wearing surface and 30% for concrete used in wearing surface. Table shows the classification of aggregate with respect to aggregate impact value and limits of aggregate impact value for different types of road construction.

6. APPARATUS KUPAL KA BA BOSS

7. KUPAL KA BA BOSS Prepare the test sample by selecting aggregates sized between 10.0 mm and 12.5 mm. Dry the aggregates by heating at 100-110° C for 4 hours or until constant mass is achieved, and then cool them. Sieve the aggregates through 12.5 mm or 14mm and 10.0 mm sieves. The material passing through the 12.5 mm sieve and retained on the 10.0 mm sieve will be used as the test material. Pour the test material into a measuring cylinder, filling it to approximately 1/3 of its depth. Compact the material by giving it 25 gentle blows with the rounded end of a tamping rod. Add two more layers of material to the cylinder, compacting each layer in the same manner until the cylinder is full. Strike off any excess material from the top of the cylinder. Determine the net weight of the test sample to the nearest gram. PROCEDURE

8. KUPAL KA BA BOSS Set up the impact machine on a rigid, level surface with the hammer guide columns vertical. Fix the cup firmly to the base of the machine and place the entire test sample in it. Compact the sample by giving it 25 gentle blows with the tamping rod. Raise the hammer to a height of 380 mm above the surface of the sample and allow it to fall freely on the sample. Repeat this process 15 times, waiting at least one second between each fall. Remove the crushed aggregate from the cup and sieve it through a 2.36 mm sieve until no further significant amount passes in one minute. Weigh the fraction of the sample passing through the sieve to an accuracy of 1 gram, as well as the fraction retained in the sieve. Calculate the Aggregate Impact Value by dividing the weight of the fraction passing through the sieve by the total weight of the sample, and multiplying by 100. Round the result to the nearest whole number, and report the mean of two observations as the Aggregate Impact Value.

9. KUPAL KA BA BOSS CALCULATIONS

10. AGGREGATES CRUSHING VALUE In construction, ensuring the quality and durability of materials is critical to the longevity and performance of infrastructure. One key method for assessing the strength of aggregates is the Aggregate Crushing Value test (ACV). Provides a practical and reliable measure of how well aggregates withstand crushing under gradually applied compressive loads, offering essential insights into their suitability for real-world applications.

11. CLASSIFICATION OF AGGREGATES BASED ON AGGREGATE CRUSHING VALUE In the Aggregate Crushing Value test , a sample of aggregates is subjected to a gradually increasing compressive load until failure occurs. Lower ACV values signify stronger aggregates that are better suited for high-load applications such as road bases and heavy-duty pavements, while higher ACV values suggest materials that may crush more easily under pressure.

12. APPARATUS KUPAL KA BA BOSS

13. KUPAL KA BA BOSS Place the cylinder onto the base plate and record its weight (W). Take the sample and divide it into three equal layers. Use the tamping rod to subject each layer to 25 strokes, making sure to handle weak materials with care to avoid particle breakage. Weigh the sample after tamping (W1). Carefully level the aggregate surface and place the plunger horizontally onto it. Ensure that the plunger does not get stuck in the cylinder. Put the cylinder with the plunger onto the loading platform of the compression testing machine. Apply a uniform load at a consistent rate to reach a total load of 40T over a 10-minute period. Remove the load and extract the material from the cylinder. Use a 2.36mm sieve to sieve the material, taking care not to lose any fines. Weigh the fraction of material that passed through the sieve (W2). PROCEDURE

14. KUPAL KA BA BOSS Aggregate Crushing Value = (W2 / (W1 - W)) * 100 W2 = Weight of fraction passing through appropriate Sieve (W1-W) = Weight of Surface Dry Sample CALCULATIONS

15. DPWH STANDARD SPECIFICATIONS FOR PUBLIC WORKS AND HIGHWAYS, 2004 EDITION: VOLUME II, HIGHWAYS, BRIDGES AND AIRPORTS.

16. TABLE 703.1 RANGE OF GRADATION TARGET VALUES

17. 703.6 AGGREGATE FOR BITUMINOUS PLANT MIX SURFACING No intermediate sizes of aggregate shall be removed for other purposes without written consent of the Engineer. If crushed gravel is used, not less than 50 mass percent of the material retained on the 4.75 mm (No. 4) sieve shall be particles having at least one fractured face. That portion of the composite material passing a 4.75 mm (No. 4) sieve shall have a sand equivalent of not less than 35, as determined by AASHTO T 176, Alternate Method No. 2. The aggregate shall show a durability index not less than 35 (coarse and fine) as determined by AASHTO T 210. The material shall be free of clay balls and adherent films of clay or other matter that would prevent thorough coating with the bituminous material.

18. 703.7 AGGREGATE FOR HOT PLANT-MIX BITUMINOUS PAVEMENT The provisions of Subsections 703.5.1, 703.5.2 and 703.5.3 shall apply. The several aggregate fraction for the mixture shall be sized, graded and combined in such proportions that the resulting composite blend meets one of the grading requirements of Table 703.2 as specified in the Schedule. The gradings to be used will be shown in the Special Provisions, adjusted to reflect variations in aggregate densities. The ranges apply to aggregates with bulk specific gravity values that are relatively constant throughout a grading band. When such values vary from sieve to sieve, such as with lightweight aggregates, the ranges for each sieve size shall be adjusted to reflect the variations.

19. 703.8 AGGREGATE FOR COLD PLANT-MIX BITUMINOUS PAVEMENT The provisions of Subsections 703.5.1 and 703.5.2 shall apply. 703.8.1 AGGREGATE FOR PAVEMENT The several aggregate fractions for the mixture shall be sized, graded and combined in such proportions that the resulting composite blends meet the respective grading requirements of Table 703.3 adjusted to reflect variation in aggregate densities.

20. 703.8.2 AGGREGATE FOR TOP DRESSING The material for the top dressing shall consist of dry sand, stone screenings or slag screenings so graded that at least 95 mass percent shall pass the 4.75 mm (No. 4) sieve and not more than 40 percent shall pass the 0.300 mm (No. 50) sieve.

21. TABLE 703.2 GRADATION RANGES – HOT PLANT MIX BITUMINOUS PAVEMENTS (MASS PERCENT PASSING SQUARE SIEVES, AASHTO T 11 AND T 27)

22. 703.9 AGGREGATE FOR ROAD MIX BITUMINOUS PAVEMENT Aggregates for road mix bituminous pavement construction shall be crushed stone, crushed slag, or crushed or natural gravel which meet the quality requirements of AASHTO M 62-74 or M 63-74 for the specified gradation, except that the sodium sulfate soundness loss shall not exceed 12 mass percent. When crushed gravel is used, at least 50 mass percent of the particles retained on the 2.00 mm (No. 10) sieve shall have at least one fractured face. Gradation shall conform to Grading F of Table 703.2.

23. 703.10 AGGREGATE FOR COVER COATS, SURFACE TREATMENTS AND BITUMINOUS PRESERVATIVE TREATMENT Cover aggregate for type 2 seal coat (Item 303) shall consist of sand or fine screenings, reasonably free from dirt or organic matter. Aggregates for type 3 seal coat (Item 303) surface treatments or bituminous preservative treatment shall be crushed stone, crushed slag or crushed or natural 381 gravel. Only one type of aggregate shall be used on the project unless alternative types are approved. Aggregates shall meet the quality requirements of AASHTO M 78-74. When tested in accordance with AASHTO T 182, (ASTM D 1664) aggregate shall have a retained bituminous film above 95 mass percent.

24. 703.10 AGGREGATE FOR COVER COATS, SURFACE TREATMENTS AND BITUMINOUS PRESERVATIVE TREATMENT Aggregates which do not meet this requirement may be used for bituminous surface treatments and seal coats provided a water resistant film. Lightweight aggregate, if required or permitted by the Special Provisions, shall meet the pertinent requirements of Subsection 703.5.4. When crushed gravel is used, not less than 50 mass percent of the particles retained on the 4.75 mm (No. 4) sieve shall have at least one fractured face. Aggregates shall meet the gradation requirements called for in the Bid Schedule.

25. TABLE 703.3 GRADATION REQUIREMENTS – COLD PLANT MIX BITUMINOUS PAVEMENT (MASS PERCENT PASSING SQUARE MESH SIEVES, AASHTO T 27)

26. TABLE 703.4 GRADATION REQUIREMENTS FOR COVER COATS (MASS PERCENT PASSING SQUARE MESH SIEVES, AASHTO T 27)

27. THANK YOU MGA BOSS!!!