This study makes use of an accelerated durability test called the Immersion Ageing Test (IAT) to ... more This study makes use of an accelerated durability test called the Immersion Ageing Test (IAT) to simulate and obtain the combined effects of ageing and moisture on typical Thin Surface Course Systems (TSCS). The samples used for the assessment in this project incorporated a 40/60 paving grade bitumen, polymer modified bitumen (PMB) with some samples treated using asphalt preservatives.The IAT modified the EN 12697-45 procedure. This allows for the assessment of denser and/or less stiff asphalt mixtures. This test method involves conditioning 3 immersed asphalt specimens under a pressure of 0.5 MPa at a temperature of 85°C for 24 hours. The stiffness modulus is determined for each specimen before and after IAT. The rheological properties of tested samples are evaluated to ascertain the level of ageing. This study helps establish the influence of asphalt preservative treatment following accelerated durability tests
Compared to Hot Mix Asphalts (HMA), the behaviour of Cold Recycled Bituminous Mixes (CRBM) is mor... more Compared to Hot Mix Asphalts (HMA), the behaviour of Cold Recycled Bituminous Mixes (CRBM) is more complex due to the presence of water in the mix. CRBMs develop strength and stiffness with time and this relates to the rate at which curing occurs in the mix. Various accelerated laboratory curing and conditioning regimes exist for CRBM and are used in a variety of ways by researchers although the underlying question remains: how realistic are these curing and conditioning regimes in simulating pavement conditions as experienced in the field? The ideal curing regime for these mixture types would be to simulate conditions similar to those experienced in the field. Most accelerated curing regimes fail to reproduce the actual condition of the mix that is expected in the pavement and tests are therefore conducted at superior conditions. This results in overestimating the mix performance in the field. This is especially true when the fundamental properties of the CRBM are compared with other mixes such as HMA and Warm Mix Asphalt (WMA). Hence, there is a need to develop a curing regime that simulates as realistically as possible actual pavement conditions. This paper investigates the need for accelerated curing and the degree of acceleration that is realistic by studying different curing regimes and their effect on mechanical and performance behaviour of CRBMs. The experimental design is carefully selected in such a way that the curing conditions include regimes that are followed by different highway agencies and also conditions that are expected to simulate different climatic zones. The investigation includes both bitumen emulsion and foamed bitumen treated mixes with and without cement.
This study makes use of an accelerated durability test called the Immersion Ageing Test (IAT) to ... more This study makes use of an accelerated durability test called the Immersion Ageing Test (IAT) to simulate and obtain the combined effects of ageing and moisture on typical Thin Surface Course Systems (TSCS). The samples used for the assessment in this project incorporated a 40/60 paving grade bitumen, polymer modified bitumen (PMB) with some samples treated using asphalt preservatives.The IAT modified the EN 12697-45 procedure. This allows for the assessment of denser and/or less stiff asphalt mixtures. This test method involves conditioning 3 immersed asphalt specimens under a pressure of 0.5 MPa at a temperature of 85°C for 24 hours. The stiffness modulus is determined for each specimen before and after IAT. The rheological properties of tested samples are evaluated to ascertain the level of ageing. This study helps establish the influence of asphalt preservative treatment following accelerated durability tests
Compared to Hot Mix Asphalts (HMA), the behaviour of Cold Recycled Bituminous Mixes (CRBM) is mor... more Compared to Hot Mix Asphalts (HMA), the behaviour of Cold Recycled Bituminous Mixes (CRBM) is more complex due to the presence of water in the mix. CRBMs develop strength and stiffness with time and this relates to the rate at which curing occurs in the mix. Various accelerated laboratory curing and conditioning regimes exist for CRBM and are used in a variety of ways by researchers although the underlying question remains: how realistic are these curing and conditioning regimes in simulating pavement conditions as experienced in the field? The ideal curing regime for these mixture types would be to simulate conditions similar to those experienced in the field. Most accelerated curing regimes fail to reproduce the actual condition of the mix that is expected in the pavement and tests are therefore conducted at superior conditions. This results in overestimating the mix performance in the field. This is especially true when the fundamental properties of the CRBM are compared with other mixes such as HMA and Warm Mix Asphalt (WMA). Hence, there is a need to develop a curing regime that simulates as realistically as possible actual pavement conditions. This paper investigates the need for accelerated curing and the degree of acceleration that is realistic by studying different curing regimes and their effect on mechanical and performance behaviour of CRBMs. The experimental design is carefully selected in such a way that the curing conditions include regimes that are followed by different highway agencies and also conditions that are expected to simulate different climatic zones. The investigation includes both bitumen emulsion and foamed bitumen treated mixes with and without cement.
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