Q1. (a) With examples, briefly describe the difference between tack coat and prime coat in road...

  

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Q1. (a) With examples, briefly describe the difference between tack coat and prime coat in road construction in terms of location in the road layer, function and material used. (6 marks) (b) As an engineer, you are required to check on aggregate properties based on few aggregate tests. (i) Provide name of the aggregate test that need to be conducted in determining the aggregate moisture content. Briefly describe how this property affects the asphalt mixture performance. (3 marks) (ii) Given below are data from the aggregate tests that have been conducted. Los Angeles Abrasion Value test: Sample tested Mass retained on 1.70mm sieve 5000.7 g 3650.8 g Flakiness Index test: 3104.5 g Sample tested Aggregate retained slot 63mm to 6.3mm 2366.3 g Aggregate passed slot 63mm to 6.3mm 738.2 g Water absorption test: Mass of oven dry aggregate 501.5 g Mass of saturated aggregate in water 969.0 g Mass of the saturated surface dry aggregate in air 523.2 g (c) Assess the suitability of the coarse aggregates to be used in the road construction project. Table Q1(a) provides the aggregates requirements based on the specification stated in JKR (2008). TABLE Q1 (a): Aggregate Properties (9 marks) Aggregate Properties Los Angeles Abrasion Value Flakiness Index Water absorption Requirements (JKR, 2008) < 25% < 25% <2% California Bearing Ratio is a test to determine the bearing capacity of a material against standard crushed aggregate. CBR tests consist of two parts: compaction test and CBR test. Discuss briefly the parameters measured in compaction test and sketch the relationship between these parameters. Further, describe the possible factors that would affect the CBR value. (7 marks) (25 marks) Q1. (a) With examples, briefly describe the difference between tack coat and prime coat in road construction in terms of location in the road layer, function and material used. (6 marks) (b) As an engineer, you are required to check on aggregate properties based on few aggregate tests. (i) Provide name of the aggregate test that need to be conducted in determining the aggregate moisture content. Briefly describe how this property affects the asphalt mixture performance. (3 marks) (ii) Given below are data from the aggregate tests that have been conducted. Los Angeles Abrasion Value test: Sample tested Mass retained on 1.70mm sieve 5000.7 g 3650.8 g Flakiness Index test: 3104.5 g Sample tested Aggregate retained slot 63mm to 6.3mm 2366.3 g Aggregate passed slot 63mm to 6.3mm 738.2 g Water absorption test: Mass of oven dry aggregate 501.5 g Mass of saturated aggregate in water 969.0 g Mass of the saturated surface dry aggregate in air 523.2 g (c) Assess the suitability of the coarse aggregates to be used in the road construction project. Table Q1(a) provides the aggregates requirements based on the specification stated in JKR (2008). TABLE Q1 (a): Aggregate Properties (9 marks) Aggregate Properties Los Angeles Abrasion Value Flakiness Index Water absorption Requirements (JKR, 2008) < 25% < 25% <2% California Bearing Ratio is a test to determine the bearing capacity of a material against standard crushed aggregate. CBR tests consist of two parts: compaction test and CBR test. Discuss briefly the parameters measured in compaction test and sketch the relationship between these parameters. Further, describe the possible factors that would affect the CBR value. (7 marks) (25 marks)

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a sol In road construction a prime coat is typically applied to the prepared base before the asphalt layer is laid Its function is to protect the base from moisture and provide a bonding surface for t... View the full answer