【正文】 Bevel Irons Bevel irons shape and pact the edges of the pavement. They are available with a bevel edge of 45176。 and 60176。C before starting work. It is remended to protect the screed against excessive loss of heat to the surroundings so that the heating power can be utilized effectively, for instance by putting down the screed, preferably on hot mix. Asphalt may stick to the tamper bar, screed plates or pressure bar(s) if the screed temperature is too low. This can lead to the formation of strips and an irregular surface texture. The floating behaviour of the screed may vary before it reaches its operating temperature, with the result that layer thickness may also vary and deviate from the desired one. For the “dash 2“ machines, a monitoring unit for screed heating is available as an optional extra. This feature monitors each single heating rod for proper function and indicates any fault without delay. Should one of the green indicator lights extinguish over a prolonged period of time, then the reason may be: n Poor insulation n Asymmetrical power consumption n Generator temperature too high Tip! Directly after switching on screed heating, correct operation of the heating rods can be checked by cautiously touching the tamper bar, screed plates and pressure bar(s). Advantage： A failure of heating rods is detected immediately. New parts can be procured without delay to promptly restore the screed‘s full functionality. Parameters Influencing the Paving Process Paving Material Mix Temperature The mix temperature should be constant and high enough to prevent the mix from cooling before it is laid. Paving material that has cooled is harder to pact. The load bearing capacity of the mix, too, depends on its temperature. Feed of the paver with mix shall be planned with a view to an optimal temperature for paving. Grain Size The maximum grain size should not exceed 1/3 of the layer thickness. Mix Composition The position of the mix should remain constant throughout the paving job. Properties of the Mix Properties of the mix have an influence upon the screed’s floating behaviour. Paving materials with a high bearing capacity confront the screed with a higher resistance than materials of poor bearing capacity. Conveying and pacting systems can be set up in an optimal manner to match the type of mix. Paving Parameters Layer Thickness The larger the layer thickness, the larger the screed planing angle. Pave Width The floating behaviour of the screed changes in accordance with the pave width. Paver Stop The longer the paver stop, the greater the irregularity to be expected in a longitudinal direction. Ambient Conditions Ambient conditions, such as temperature, can influence the mix and change the floating behaviour of the screed. Between Tamper Speed and Pave Speed While paving, when screed tow point rams are not changed in position, an equilibrium of forces prising pave speed, screed weight and tamper speed is established. If any one of these parameters changes, this immediately affects the screed‘s floating behaviour. Tamper speed and pave speed are very strongly dependent on one another. Any change in pave speed without changing the tamper speed and position of the screed tow point rams will affect prepaction of the mix. If the pave speed is increased without simultaneously increasing the tamper speed, the load bearing capacity of the mix will be reduced and the screed lay a thinner layer at a steeper planing angle. Paving with Automated Grade and Slope Control If Automated Grade and Slope Control is used for paving, the desired elevation of the screed can be maintaine