Asphalt durability

Another gap in our knowledge is the diflSculty of relating the properties of asphalts and specific test results to performance in each application (29). Penetration, viscosity, ductility, and elasticity properties are related to performance. However, the problem of correlating results from many of these empirical tests with the development of additives to increase asphalts durability has created diflBculties in interpreting the results (30, 31,32,33,34,35). 

Pa.ints, Paints (qv) prepared from poly(vinyl acetate) and its copolymers form flexible, durable films with good adhesion to clean surfaces, including wood, plaster, concrete, stone, brick, cinder blocks, asbestos board, asphalt, tar paper, wahboards, aluminum, and galvani2ed iron (147). Adherence is also good on painted surfaces if the surfaces are free from dirt, grease, and mst. Developments in emulsion polymeri2ation for paint latices have been reviewed (148). 

Durability. The term "durable" has several meanings, but in the present context it is used to describe an asphalt that possesses the necessary chemical and physical properties required for the specified pavement performance, being resistant to change during the in-service conditions that are prevalent during the life of the pavement. 

For the asphalt cements produced at that time the adoption of the volatilisation and penetration tests provided some degree of control of excessive changes during plant mixing that might be reflected in more durable asphalts. The adoption of the method for bitumen was intended to provide a means for identifying Trinidad asphalt by observing the amount and color of the insoluble ash. 

At the roofing plant, coating asphalts are blended with mineral stabilizer such as finely ground limestone, slate, flyash, or traprock. The stabilizer increases the coating asphalt s resistance to fire and foot-traffic and adds durability. 

Stability of the emulsion is of prime importance. If the emulsion breaks, the advantages of adding sulphur are completely lost, with the impact on strength and durability properties particularly detrimental. As sulphur in asphalt emulsions are unstable by nature, due attention has to be paid to this point. 

Dikes may be made of earth, steel, crushed stone, or concrete, and they may be lined with a layer of clay or asphalt, or plastic film. There are several constraints on dike material it must be chemically compatible with the process material, be durable under normal weathering conditions, have structural characteristics suitable to support loads from maintenance vehicles, and be cost effective. Ideally, to prevent ground contamination, the ground between a vessel and a dike wall should be nonporous. 

Vacuum saturating and freeze-thaw cycling has a much greater detrimental effect on the ordinary asphalt concrete than on the sulfur-asphalt concrete. Indeed after soaking, the sulfur-asphalt concrete shows a slight increase in stiffness, and the freeze-thaw cycling causes only a slight decrease in stiffness. The sulfur-asphalt concrete thus appears more durable than its ordinary asphalt counterpart. 

It is clear that sulfur-asphalt concretes have better potential durability than their non-sulfur counterparts. However, knowledge of the... 

The air-void content of asphalt concrete mixes affects mix permeability and is therefore very important from a pavement durability standpoint. The permeability of various sulfur-extended binder mixes, prepared at a variety of air-void contents, was measured with an air permeameter similar to that described in Ref. 16. The results, presented in Figure 7, indicate that the sulfur-extended binder mixes exhibit an air voids vs. 

Based on studies performed, some guidelines have been formulated for the design of sulfur-extended binder mixes. These include recommendations for limiting sulfur content to maintain existing mix flexibility and the replacement of asphalt with sulfur on an equivalent volume basis to maintain the existing standard of mix durability. 

A large apphcation of latex is in blends with asphalt to produce a waterproof membrane on cinder block and concrete walls. Here, as well as when incorpevated into concrete mortars, the rubber fraction produces better adhesion, durability, and temperature expansion tolerance than the asphalt or mortar base alone. 

In sulfuric acid production, acid brick lining of membrane coated mild steel tanks and reaction vessels is considered the most durable and versatile construction material for the sulfuric acid plant. Such linings wiil reduce the steel shell temperature and prevent erosion of the normally protective iron sulfate film that forms in stagnant, concentrated (oxidizing) sulfuric acid. Dilute (red uC ing) sulfuric acid solutions are very corrosive to carbon steel, which must be protected by impermeable (e.g., elastomeric) membranes and acid brick lining systems. Such acid brick linings often employ membranes comprising a thin film of Teflon or Kynar sandwiched between layers of asphalt mastic. 

The design asphalt content of mixtures with the plastic sample-1, which has the low softening temperature as shown in Fig. 1. decreased as the volume percent of plastic was higher. However, it is doubtful whether the low design asphalt content is the optimum value which must be adopted for construction, because the reduction of asphalt content may bring deterioration of durability of the asphalt mixture. That must be require further investigation. 

Keywords Asphalt concrete pavement, durability, pavement recycling, recycled hot-mixed asphalt concrete, re-recycling. 

This report contains the results of one study of long-term performance of recycled HMA pavement. The study in question is a 15 year follow-up survey of one of Japan s earlier (1978) full-scale applications of recycled pavement using recycled HMA to pave municipal roads in Nagoya City. In this pavement test, new HMA was applied at the same time so as to compare it with to the recycled pavement. Both the new and recycled pavements are in good condition even to date, and serve as a source of valuable information about pavement durability. We will also report on the results of our investigation of recycled and re-recycled HMA using asphalt concrete lumps collected at a study site. 

Kuriyama, M., Yoshikane, T., Kaneda, M. and Ookouchi, T. (1994) Durability and re-recyclability of hot-mixed asphalt pavement, Road Construction. 

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