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Specifications for asphalt
Published in J. Cliff Nicholls, Asphalt Mixture Specification and Testing, 2017
Macadam is a densely packed aggregate skeleton developed by Scottish engineer John Loudon McAdam around 1820 that, with a crowned profile, produced a relatively impermeable road prior to the development of bound pavement materials. The dense finish was produced by using a continuous grading such that each size of particles filled the gaps left in the skeleton of the larger sizes. Later, macadam was bound by tar, subsequently identified as a carcinogen, to produce tarmacadam or tarmac (the terms that the general public applies to all ‘black’ pavement materials, irrespective of grading or binder type) and later by bitumen to produce bitmac (later shortened to just macadam as the use of tar declined), these being bound layers.
McAdam invents a major new pavement using broken stones
Published in Maxwell Lay, John Metcalf, Kieran Sharp, Paving Our Ways, 2020
Maxwell Lay, Metcalf John, Sharp Kieran
As traffic increased, the cost of maintenance also increased, and in urban areas, the daily cost of removing dust in dry weather and unsanitary mud in wet weather made macadam pavements increasingly unattractive. By the mid-1930s, many existing macadam pavements had been surface dressed with bitumen or tar (Chapter 14) and, due to their well-tested subgrades, they often gave many years of further service.367 Furthermore, the more coherent pavements discussed in the following chapters were beginning to provide realistic alternatives to macadam. By the mid-20th century, water-bound macadam was only being used for very lightly trafficked pavements.
Laboratory investigations of DBM (Grade 1) mix using different types of additives
Published in Sandra Erkens, Xueyan Liu, Kumar Anupam, Yiqiu Tan, Functional Pavement Design, 2016
Karan Gupta, Tanuj Chopra, Maneek Kumar
Dense bituminous macadam is mainly used as binder course for roads having much higher number of heavy commercial vehicles. In DBM mix there is a wide scope of varying the gradation to obtain the good mix without affecting the durability of pavement. Generally, Marshall Mix design method is adopted for mix design of Dense Graded Bituminous Macadam, (DBM). DBM is also intended for use as road base material. The construction work of DBM consists of construction in a single layer of DBM on a previously prepared base or sub-base layer.
Forest roads: regional perspectives from around the world
Published in International Journal of Forest Engineering, 2023
C Kevin Lyons, Stelian Alexandru Borz, Campbell Harvey, Muedanyi Ramantswana, Hideo Sakai, Rien Visser
Forest road construction practices vary across Europe. The guidelines or standards available for some countries indicate the required geometry of forest roads, and classify the forest roads depending on factors such as the intended traffic intensity, and the regulated traffic characteristics. The road classification reflects the geometry of forest roads as well as in the prescribed construction materials. In Austria, the forest roads are classified into two groups: main and secondary. Roads from the main category are typically built with a lane width of 3.5–4.5 m, a minimum longitudinal grade of 3%, a maximum longitudinal grade of 10–12%, and a minimum radius of 8 m. Secondary forest roads have similar geometric features, with a lane width of 3.5 m and a maximum longitudinal grade of 12–15%. Macadam (crushed rock with additives) and gravel are the typical materials used in road construction, with a surfacing layer of 10–12 cm and a base layer of 20–40 cm, respectively.
Strong interlocking skeleton gradation design and performance evaluation of cement-stabilised crushed gravel via vertical vibration test method
Published in International Journal of Pavement Engineering, 2021
Tian Tian, Yingjun Jiang, Yu Zhang, Changqing Deng, Yong Yi, Jiangtao Fan
In major cities across the globe, cement-stabilised macadam is a popular choice for fabricating pavement bases/sub-bases on metropolitan pavements (Disfani et al. 2014). Macadam shows irregular shapes, sharp edges and corners, uniform strength distribution, and basically controllable quality and good adhesion to cement and other cement-based materials, and is extensively used in highway construction (Wei and Zhang 2011, Ji et al. 2016, Wang et al. 2017). However, the increase in demand for pavements globally has resulted in the consumption of large amounts of natural resources in the form of road-building materials. Gradually, this overexploitation has resulted in stone shortage and increase in resource prices. The recognition of causes of this limitation has led to a shift toward the development of alternative road-building materials. Therefore, researchers have begun considering waste rock (Arulrajah, et al. 2012a, Zhang and Fang 2014), crushed brick (Arulrajah, et al. 2012b, Disfani et al. 2014), recycled concrete aggregate (Poon and Chan 2006, Azam and Cameron 2013), reclaimed asphalt pavement (Puppala Anand et al. 2011, Taha et al. 2002), and waste glass (Disfani et al. 2011) as cement stabilisation materials.
Resilient modulus and influencing factors of vertical vibration compacted cement-stabilized macadam
Published in International Journal of Pavement Engineering, 2021
Changqing Deng, Yingjun Jiang, Tian Tian, Zhejiang Chen
Cement-stabilized macadam (CSM) is a common semi-rigid base material used in road engineering, exhibiting advantages of high strength and good durability (Xuan et al. 2012, Ismail et al. 2014, Wang et al. 2017). Therefore, it is widely used as a subgrade material in current high-grade highway bases (Ji et al. 2013, 2016). CSM is primarily composed of low-dosage cement, aggregate, water, and other materials (Davis et al. 2007). CSM exhibits high mechanical strength after curing because of physicochemical reactions between cement, water, and aggregate. Therefore, CSM is often used to improve the drawbacks of flexible asphalt pavements, such as their low strength and poor bearing capacity, without increasing the total thickness of the pavement layers (Barišić et al. 2015, Du 2016). Moreover, when applied to concrete pavements, CSM can prevent the emergence of material ‘pumping’ (Barišić et al. 2014). Due to these advantages, CSM is used as a base course material worldwide, particularly in China.