Natural Asphalt for High Modulus Asphalt Concrete HMB®
Natural Asphalt for High Modulus Asphalt Concrete HMB®
HMB®, as a binder for high modulus asphalt concrete, is divided into three types: HMB-C, HMB-W, and HMB-H, which are respectively applicable to different climatic environments. The technical performance of products is shown in the following table.
Storage Requirements of HMB®
· HMB® is stored in single tanks with agitator. For storage at high temperature, the storage temperature shall not exceed 190°C, and the product shall be stirred evenly before use.
· If to be used within 48 hours, the product shall be stored at 160-180°C and stirred for 2-3 hours before use.
· If to be used over 48 hours and below 7 days, the product shall be stored at 120°C or lower temperature, and before use, heated to the specified temperature and stirred for 2-3 hours.
· If the product is stored for over 7 days, it is recommended to naturally cool the product or reduce its storage temperature to less than 100°C, and later heat the product to the specified temperature and stir it for 2–3 hours.
High Modulus Asphalt Concrete
HMB-based high modulus asphalt Concrete (hereinafter referred to as HMAC) has the following advantages:
① The modulus and fatigue life of the mixture meet the technical requirements of European standard EN13108-1-2007 on HMAC.
② This HMAC has been used in construction on Qinghai-Tibet Plateau for its excellent low temperature anti-cracking performance that can prevent pavement cracking at low temperature.
③ High temperature stability and rutting resistance, effectively preventing heavy traffic and rutting problems at high temperature.
④ Low void ratio (1.5–4%) can effectively prevent surface water from seeping into subgrade and causing moisture damage.
⑤ HMB can be stored and transported for long time, and HMAC can be prepared without using high modulus agents or other additives.
⑥ HMB is a natural asphalt binder and can be recycled in the overhaul and medium repair stage, thus saving energy and protecting environment.
⑦ Compared with petroleum asphalt, natural asphalt has lower volatile components and is more environmentally friendly when used as the binder.
Table 2 Comparison of Technical Requirements between HMAC and Modified Asphalt Mixture
Note:Modified asphalt mixture follows the technical requirements of national standard "Standard Specification for Construction and Acceptance of Highway Asphalt Pavements" (JTG F 40-2004) on dense grade polymer modified asphalt mixture for heavy traffic of expressways and first-class highways.
· BBME is an HMAC used for surface layer.
· EME is an HMAC used for middle surface course or lower surface course.
When BBME is used for surface layer, its technical requirements meet Table 3.
Table 3 Skid Resistance and Water Tightness Requirements of BBME
