Wet type / Dry type manufacturing method The current [asphalt pavement guildline (Korea Road Traffic Association 1998)] introduces wet manufacturing method for drain asphalt pavement. However, the new technology has adopted European dry manufacturing method, so as to make it easy and convenient for manufacturing and supplying . In addition, it meets every quality standard of mixed material. It is called drain asphalt, silent asphalt, porous asphalt, High Friction Open Grade Asphalt or Open Grade Friction Course, Flster asphalt : Whispering Asphalt in Germany, and Popcorn Mix in USA, because this asphalt contains 20% porosity of the volume of the mixture. The technology is expected to make further progress and solve problems still remaining. The original purpose of the asphalt was to prevent airplane accidents by quickly removing rainwater from the pavement of the runaway and thereby prevent slipping. Afterwards, it began to be applied to highways and its use has aggressively been spreading. The merit of porosity, which reduces plastic deformation compared to dense asphalt, has been confirmed from lots of experiences. [Asphalt Surfacings], written by J. C. Nicholls of United Kingdoms (98), says the asphalt construction method has become indispensable for the construction of highways. The book describes the reasons as follows. - Reduce risk of aquaplaning - Reduce traffic noise - Reduce spray in wet weather - Divers safety and reduce fatigue - Reduce glare in night, wet weather - Decrease fuel consumption. However, the asphalt mixture, which commands such merits, is required to have strong adhesiveness with the aggregate. Description of open grade additive for porous asphalt of many countries ¡á USA The use of CRM Asphalt (Open Grade Friction Course) - FHWA standard Test method classification Weather Condition High temp(a) Normal temp(b) Low temp(c) nvasion degree 25¡É (0.1 §®) Minimum 25 50 75 Maximum 75 100 150 Softening Point(¡É) Minimum 54 49 43 a. Use in Hot area: Average temperature in June 43°C(Maximum) Average temperature in January above -1°C b. Normal temperature area: Average temperature in June 38°C(Maximum) Average temperature in January -9°C ~ -1°C c. Cold area: Average temperature in June 27°C(Maximum) Average temperature in January under -9°C ¡á ENGLAND Binder modifiers, including natural or man made fibres, natural lake Asphalt, natural in latex or powder form synthetic rubber, EVA or other similar materials, modifiers include any material added to or blended with the Base Bitumen Modified additives? Binder modifiers, including natural or man made fibres, natural lake asphalt, natural in latex or powder form synthetic rubber. EVA or other similar materials. modifiers include any material added to or blended with the base Bitumen In Europe, fibre has been used to produce porous asphalt for a long time. I. E., SMA method. The additive is not open-graded. However, it remains in the form of minute fiber particles and it is its advantage. There are many solid test results in Europe and lots of construction experiences have testified to it since 1996. Also, rubber material (natural and synthetic rubber), LDPE,and EVA are put in for increase of strength, resistance to flowage and durability in porous asphalt. [Standard of Modified asphalt for Drain asphalt] from above complementary items 4 have been quoted from the Standard of Open Grade Asphalt Association and Road Corporation in Japan and applied to Pre-Mix Type open grade asphalt mixture. Also, Korea Road Traffic Association took the standards from the Japanese one and has been applying the standards Since the new technology is a dry method just like the SMA method, it cannot be applied by the standards set in [Korea Road Traffic Association (KRTA)]. The main point is that the additive used is AP-3 or AP-5, and the construction method is dry-type, putting it in dry state into the mixer of the hot-mixed asphalt factory. So, the main point should move to whether or not it satisfies the physical property. With the new technology, result of the preliminary test and test construction of porous asphalt mixture was as follows. Aggregate particle ratio of drain asphalt mixture (Percentage of passing through weight) Size of the body Standard of KRTA (Maximum particle diameter 13mm) Standard of new technology test result of Kyoungki hot mixed asphalt 19 §® 100 100 100 13.2 92 ¡­ 100 92 ¡­ 100 98.2 9.5 62 ¡­ 81 62¡­ 81 - 4.75 (NO.4) 10 ¡­ 31 10¡­ 31 28.6 2.36(NO.8) 10 ¡­ 21 10¡­ 21 18.2 300§­¥ì 3 ¡­ 12 3¡­ 12 - 75¥ì 2 ¡­ 7 2¡­ 7 6.3 amount of asphalt 4.5 over 4.5¡­ 5.5 4.82 Quality Standard of Drain asphalt mixture Item Quality standard of KRTA New technology test result of Kyoungki hot mixed asphalt number of Compaction ( both sides) 50 50 50 Gap(%) 20 over 15¡­ 25 17.4 Marshall stability(§¸) 500 over 500 over 785 flowage (1/100cm) 20¡­ 40 20¡­ 40 32 Remaining stability 75 over - - Water permeation modulus(§¯/sec) - 1x 10-2(§¯/sec) 8x 10-2 dynamic stability(frequency /HM) 3000 over 3000 over 6650 Noise reduction - 3¡­ 5 dB(A) 5 Slip resistance ratio - increase over 3~10 SN 10 Modified additive of the new technology, [DAMA] has been put into dense asphalt mixture (#78 and #67), Also Fiber(VIATOP) has been put into the normal density SMA instead of [DAMA]. The change of physical property ratio was tested and results were as below. (Refer to included test results) #78 The change of physical property ratio in dense asphalt mixture and DAMA added asphalt mixture Items normal (78) density Normal (78) + DAMA 67 density+DAMA stability(§¸) 1199 1231 1329 Flowage ratio(1/100§¯) 33 30 30 density(gr/§¨) 2.389 2.384 2.351 Yongin Everland(Used Speedway) Seoul West Office Danginli area KangbyunBuklo The change of physical property ratio in normal density SMA with added DAMA Item SMA density+VIATOP SMA density+DAMA stability(§¸) 629 709 flowage(1/100§¯) 30 44 density(gr/§¨) 2.220 2.228 Therefore, according to the test result of the new technology modified additive, [DAMA] is sufficiently adequate for the Standard of KRTA. Also, even when it was used on another kind of asphalt mixture, the test result showed satisfiable effect on quality improvement