**3.5 Use of lateritic concretions in road pavements in the Amazon**

As reported in Item 2.8 of the Chapter "Challenges in the Construction of Highways in the Brazilian Amazonia Environment: Part I: Identification of Engineering Problems", laterites are widely used in road pavings in the Brazilian Amazonia, but their occurrence is limited in some highland regions (*terra firme*), where the conditions are favorable for their formation. In addition, the deposits are not very thick, so the available volumes are not high. Thus, it is a "noble" material, and its use in highways is limited to the base course and in primary coatings (protection of the lower layers until the execution of asphalt course) of pavements with high traffic volume (**Figure 15a** and **b**) or only as a primary coating on rural roads with low traffic volume (**Figure 15c** and **d**). **Figure 15b** and **d** refers to Points 8 (state highway AM-363, "Estrada da Várzea") and 9 (Ramal Sargento Picanço, 123 km of federal highway BR-174) of **Figure 1**, respectively. Note the different shades of the lateritic materials.

**Figure 16a** shows some detail of a typical coarse lateritic concretion (*piçarra*) of the Amazonia, with a matrix in iron and aluminum oxides. There are records of roads with decades of construction which were used primary coatings of lateritic concretion, as shown in **Figure 16b** (Point 10 of **Figure 1**), on state highway AM-174, and even without the existence of a rainwater drainage system, it still shows satisfactory trafficability almost the entire length of the road.

#### **Figure 15.**

*Use of piçarra on highways. (a) Typical profile of the pavement courses for high traffic volume; (b) execution of the primary coating layer; (c) typical profile of the pavement layers for low traffic volume; (d) condition of the primary coating layer performed over decades (photos: NS Campelo).*

*Challenges in the Construction of Highways in the Brazilian Amazonia Environment: Part II… DOI: http://dx.doi.org/10.5772/intechopen.105017*

#### **Figure 16.**

*Use of laterites in Amazonian highways. a) Detail of lateritic concretion, with a predominance of iron and aluminum oxides; b) primary coating layer aiming at the durability of the pavement until the execution of the asphalt course (photos: NS Campelo).*
