Bitumen penetrability

Some of the characteristic properties of thermoplastic polymers are modified when they are added to bitumen. Penetration decreases and softening point increases in particular. These changes indicate that the bitumen becomes harder and less susceptible to temperature variations. Additionally, bitumen s binding ability increases. However, the Fraass breaking point and bitumen elasticity did not significantly improve (Brule and Lebourlot 1993). 

The tank of the delivery vehicle should always be clean, before loading bituminous materials. Small proportions of foreign matter, usually petrol, diesel, oils and so on, directly influence bitumen s properties and, hence, the bituminous mixture and the quality of pavement. Furthermore, safety is affected since the presence of these substances may lower the flash point of the bitumen substantially. It has been found that 0.1% of diesel in bitumen can decrease the flash point up to 28°C and increase the bitumen penetration by 10 units (Asphalt Institute MS-4 2007). In case of transporting bitumen emulsions, the presence of foreign substances will certainly affect the breaking time of the emulsion. 

The standard NF T 65-001 gives a classification for bitumen as a function of their hardness. This is measured using a needle penetrability test, which measures the penetration depth of a weighted needle into the bitumen. Five grades have been defined. 

The standard NF T 65-004 classifies the types of composite bitumen it distinguishes three grades of bitumen-tars by their pseudo-viscosities and two grades of bitumen-coal tar pitch by their penetrabilities. 

The principal characteristics of bitumen are its softening point and its needle penetrability. In France the latter has always been the basis for bitumen classification and class designation. Yet, the former is more representative of a bitumen s capacity to deform when the service temperature increases. The other properties have more or less importance depending on the application. 

Penetrability is the depth, expressed in tenths of a millimeter, a standard steel needle penetrates into a bitumen sample at 25°C. The needle carries a weight of 100 g and the test is applied for five seconds. The corresponding test method is relatively difficult to carry out and is defined in France by the standard NF T 66-004, and in the USA by the method ASTM D 583. Penetration is related to the viscosity. 

Needle penetration (bitumen) NF EN 1426 ISO/DIS 3997 ASTM D5 Penetration of weighted needle... 

The bitumen in the Athabasca deposit, which has a gravity on the API scale of 8°, is heavier than water and very viscous. Tar sand is a dense, soHd material, but it can be readily dug in the summer months during the winter months when the temperatures plunge to —45° C, tar sand assumes the consistency of concrete. To maintain acceptable digging rates in winter, mining must proceed faster than the rate of frost penetration if not, supplemental measures such as blasting are required. 

Trinidad asphalt has a relatively uniform composition of 29% water and gas, 39% bitumen soluble in carbon disulfide, 27% mineral matter on ignition, and 5% bitumen that remains adsorbed on the mineral matter. Refining is essentially a process of dehydration by heating the cmde asphalt to ca 165°C. The refined product averages 36% mineral ash with a penetration at 25°C of about 2 (0.2 mm), a softening point (ring and ball method) of 99°C, a flash point (Cleveland open cup) of 254°C, a sulfur content of 3.3%, and a saponification value of 45 mg KOH/g. The mineral matter typically contains... 

In 1903 an American Society for Testing and Materials (ASTM) Committee on Road and Paving Materials was formed to develop test methods and specifications for highway materials. Test methods for volatilization, penetration, and bitumen were developed by the Office of PubHc Roads and were... 

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. 

Blends with styrenic block copolymers improve the flexibiUty of bitumens and asphalts. The block copolymer content of these blends is usually less than 20% even as Httie as 3% can make significant differences to the properties of asphalt (qv). The block copolymers make the products more flexible, especially at low temperatures, and increase their softening point. They generally decrease the penetration and reduce the tendency to flow at high service temperatures and they also increase the stiffness, tensile strength, ductility, and elastic recovery of the final products. Melt viscosities at processing temperatures remain relatively low so the materials are still easy to apply. As the polymer concentration is increased to about 5%, an interconnected polymer network is formed. At this point the nature of the mixture changes from an asphalt modified by a polymer to a polymer extended with an asphalt. 

During manufacture it is important that the fuse should not be allowed to stand in the molten bitumen, or the core may be penetrated. The time for such faults to develop depends on the construction of the fuse, and is shorter the lower the potassium nitrate content of the powder and the... 

Post-impact sediments were penetrated by research well Nordlingen-1973 near the center of the basin and described in detail by Jankowski (8). They consist of a "basal unit" overlying the suevite, a 140 m thick laminite series, 60 m of marl and a clay layer at the top. Bituminous sediments mainly occur in the laminite series (Figure 1). In the Nordlingen-1973 well, in which the laminite series was recovered between 256 and 111m depth, Jankowski (8) distinguished four subunits a basal clinoptilolite subunit very rich in organic matter (256-244 m), an analcime subunit with low bitumen concentration (244-195 m), a bituminous subunit (195-145 m) and a diatomaceous subunit with lower bitumen content (145-111 m). Deposition of these sediments was estimated to have extended over a period of 0.3 to 2 Ma (8). 

Floors call for special consideration. They need to be protected against moisture and chemical action. The best material is concrete with a chemical-resistant coating. The next best is good-quality linoleum, which should be kept clean and well waxed to help prevent the penetration of spilled solutions.This can be underlain with bitumen paper as an extra precaution against liquids getting through and damaging the sub-floor. A drain is useful but not entirely necessary if the floor is dried after spills. 

Themme, Gasschutz und Luftschutz, 1936, 189, also considers the penetration of dichloroethyl sulphide into bitumen, tar, linoleum, road-making materials, etc,... 

The sugarcane bagasse was provided by United States Sugar Corporation, CIcwiston, Florida. The feedstock was air-dried to 8 wt,% moisture content and then sieved in order to remove the particles smaller than 0.450 mm. The petroleum residue supplied by Shell Canada, Montreal, was a grade 150-200 penetrability petroleum bitumen. 

Looking at the shares occupied by different types of recycled HMA in Fig. 5, we find that these proportions have not changed much since the first survey. Table 1 shows the changes in the penetration of old bitumen included in RAP. The penetration of old bitumen is an important factor in the recycled HMA mix design. The average penetration has dropped, if only slightly, between the second and third surveys, and the rate of this change is on the increase. 

These results support the idea that re-recycling is possible if (1) a RAP mixing ratio of 50% is used, (2) the penetration of old bitumen is adjusted using only for new HMA, and (3) the bitumen content is set using a reiterative... 

This study of a test pavement using recycled HMA, in which the penetration of the old bitumen had been adjusted using new HMA, confirmed the durability of such a pavement and showed that it could maintain a comparatively good level of utility even after 15 years and 3 months of use. Also, with respect to the physical properties, we have found that the bitumen deterioration of layers of the HMA subject for public use was comparatively small and that the repeated reuse of pavement is indeed possible. Such a high evaluation of pavement recycling from the viewpoint of both utility and physical characteristics should broaden the possibilities for expansion into re-recycling. 

Type D crude oils. These are non-toxic and do not penetrate porous surfaces and are black, heavy, semi-solid, tarry bitumen. They also contain traces of residual oils, heavy crude oils and lighter paraffin oils. Analysis of this type of crude oil for metals content, particularly toxic metals, is important because it is used for road surfacing, roofing, children s playgrounds and other uses that could have environmental concerns. 

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