Bituminous emulsion

To prevent this deterioration of the insulation, a vapour harrier is required across the warm face. This must he continuous and offer the hest possible harrier to the transmission of water vapour. The traditional vapour harrier was bituminous emulsion or hot bitumen, applied in two or more layers. More recent materials are heavy-gauge polythene sheet, metal foil and metal sheet. It is sometimes... 

Higher workabilities produce a frothing action with soaps, waxes and bituminous emulsions, particularly if large admixture doses are used. The use of higher than recommended dosages results in reduced density, strength and watertightness [82,83]. 

BExM. [Exxon/Tomah] Cationic modifier for use in colloidal bituminous emulsions, esp. coal tar and asphalt emulsions. 

Bitumen can be subject to further processing apart from blowing, such as emulsification or dissolution with solvents. In these cases, bituminous emulsions and cut-back and flashed bitumens are produced, respectively. 

In an unmodified bituminous emulsion, the proportion by mass of bitumen, water, emulsifier and other additives typically range within the values 40%-70% bitumen, 58%-28% water, 0.5%-1.5% emulsifier and less than 1% other additives. 

According to CEN EN 13808 (2013), the required properties of a cationic emulsion suitable for use in the construction and maintenance of roads, airfields and other paved areas are selected from the classes shown in Table 3.13. Additionally, the technical requirements and performance of the residual, recovered, stabilised and aged binder from the cationic bituminous emulsion is selected from the classes shown in Table 3.14. 

It is noted that the CEN EN 13808 (2013) standard applies to emulsions of paving bitumen, fluxed bitumen or cut-back bitumen and to emulsions of polymer-modified bitumen, polymer-modified fluxed bitumen or polymer-modified cut-back bitumen, which also includes latex-modified bituminous emulsions. 

Table 3.13 Specification framework for cationic bituminous emulsions - properties of the emulsion... 

Performance classes for the technical requirements of cationic bituminous emulsions... 

Source Reproduced from CEN EN 13808, Brtumen and bituminous binders - Framework for specif ng cationic bituminous emulsions, Brussels CEN,20l3. With permission ( CEN). 

The residual binder content determined is the binder residue from a bituminous emulsion after distillation of water and oil distillate. 

Table 3.14 Specification framework for the technical requirements and performance classes for residual, recovered, stabilised and aged binders from cationic bituminous emulsions... 

The test is suitable for all bituminous binders for surface dressings, such as conventional or polymer-modified bitumen, cut-back bitumens, fluxed bitumen or bituminous emulsions with conventional or modified bitumen. 

The addition of fibres takes place at the stage of mix production or directly after spraying the bitumen or the bituminous emulsion on the pavement s surface. The latter creates a stress-absorbing membrane to inhibit reflective cracking (Yeates 1994). 

The hazards associated with skin contact of bitumens other than burns are negligible. Flowever, cut-back bitumens and bituminous emulsions, because they are handled at lower temperatures, increase the chance of skin contact. Studies carried out by Shell demonstrated that the bitumen is unlikely to penetrate the skin and the bitumens diluted with solvents are unlikely to present a carcinogenic risk. Nevertheless, bituminous emulsions can cause irritation to the skin and eyes and can produce allergic responses in some individuals (Shell Bitumen 2003). 

CEN EN 1429. 2013. Bitumen and bituminous binders - Determination of residue on sieving of bituminous emulsions, and determination of storage stability by sieving. Brussels CEN. 

CEN EN 13074-1.2011. Bitumen and bituminous binders - Recovery of binder from bituminous emulsion or cut-back or fluxed bituminous binders - Part 1 Recovery by evaporation. Brussels CEN. 

CEN EN 13075-2. 2009. Bitumen and bituminous binders — Determination of breaking behaviour -Part 2 Determination of fines mixing time of cationic bituminous emulsions. Brussels CEN. 

Nikolaides A.F. 1983. Design of dense graded cold bituminous emulsion mixtures and evaluation of their engineering properties. Ph.D. Thesis, University of Ijeeds, Department of Civil Engineering. 

Redilius P. 1993. A novel system for delayed breaking control of bituminous emulsions. Proceedings of the 1st World Congress on Emulsions, Vol. 1, Workshop 22, Order No. 147. Paris. 

This rotating spindle viscometer is used for the determination of dynamic viscosity of a variety of bituminous binders modified and unmodified bituminous binders, bituminous emulsions, cut-back and fluxed bituminous binders by means of rotating spindle (coaxial viscometer) viscometer, at typical test conditions (temperatures and rate of shear). 

The typical test temperature for bituminous emulsions is 40°C, and for cut-back and fluxed bituminous binders, it is 60°C. However, other temperatures may also be used, such as 90°C for cut-back and fluxed bituminous binders. 

There are various types of efflux or cup viscometers, two of which are shown in Table 4.1. The standard tar viscometer type (STV), also called efflux viscometer, is recommended to be used for bituminous emulsions (CEN EN 12846-1 2011) or for cut-back and fluxed bituminous binders (CEN EN 12846-2 2011). An efflux viscometer (STV) is shown in Figure 4.6. 

The test method is applicable to bitumen, modified binders and bituminous mastics (homogenous mixture of filler and bituminous binder) and stabilised (recovered) bitumen from bituminous emulsions, cut-back or fluxed bitumen. 

Mixing stability with cement is the mass of coagulated material (bitumen and cement), which is produced when a bituminous emulsion is mixed with cement under the conditions of the test. 

This test determines the fines mixing time of diluted cationic bituminous emulsions, under standardised conditions. 

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