# Design and Construction of Oblique Prestressed Concrete Payement: A Case Study in China
## 1 Introduction  
The earliest application of prestressed concrete pavement was in as early as the 1940s. Prestressed concrete pavements have been constructed for highways and airfields in Europe and the United States since then [1]. Some basic geometrical and economical designs of prestressed concrete pavement have also been reported [2; 3; 4]. The benefits of prestressed concrete pavement include improved crackingresistance and reduced slab thickness; while the prestressing increases the cost of the materials and construction, the reduction in slab thickness and transverse joints can compensate some of this cost [1; 5; 6]. According to EI-Reedy, the prestressed concrete slab with 200 mm thickness can possess equivalent design life as the traditional concrete slab with 355 mm thickness [7]. In another airfield runway study, it was determined that the thickness of the concrete slab can be reduced by half when prestressing is applied [8]. Generally, there are two types of prestressed concrete pavement: cast-in-place and precast. In the cast-in-place method, concrete slabs are constructed on-site, and the prestressing is applied either before or after construction. The most widely used prestressing approach is post-tensioning in the longitudinal direction in the early stage [9]. This technique requires some space for the anchorage area at the two ends of the slabs. Additionally, this type of prestressing limits the length of concrete slab because the prestressing loss would be high if the concrete slab is long. Due to prestressing loss, another prestressing method, known as cross tensioned, concrete pavement was introduced [1]. In the cross tensioned method, the prestressed tendons are distributed obliquely with an angle in the road direction so that the prestressing can be applied in both transverse and longitudinal directions. By adjusting the angle, the proportion of prestressing in the transverse and longitudinal directions can be changed. The prestressing in the transverse direction provides lateral constraints to the slab so that the transverse joints can be eliminated [10]. The anchorage area is on the side of the concrete slabs so that long concrete slabs can be achieved without sacrificing the prestressing [10; 11; 12]. A sliding layer between the base layer and the prestressed concrete slab is necessary to reduce the friction during the tensioning. [PERSON] et al. reported that the sliding layer can reduce the stress and deformation resulting from longer concrete slabs [11]. They proposed a design for the sliding layer with sand, cement, and polyethylene-plastic sneeting. However, the prestressed concrete pavement may be still prone to cracks if the underneath base layer is not flat [11; 13]. Cement grout may be injected underneath the prestressed concrete slabs to compensate for the settlement of the ground. However, pulverization may occur due to repeated traffic loading in some cases [14]. Precast prestressed concrete pavement has been developed recently for the purpose of rapid pavement construction and rehabilitation. Compared to the cast-in-place method, the precast method can reduce construction time and improve durability [15]. The construction speed can be increased by two to three times if using the precast method instead of the case-in-place method [15]. The United States has been encouraging the application of precast prestressed concrete pavement in state highways and many demonstration sections have been constructed. While the long-term performance of prestressed concrete pavement has not been seen yet, the early-age performance indicates that it has a great potential to be used as a rapid construction or rehabilitation material [5]. In the precast prestressing concrete pavement, the prestressing is applied in the longitudinal direction, transverse direction, or both directions. Different tensioning methods have been reported in existing literatures. Transverse prestressing was applied on concrete slabs in the study by [PERSON] and [PERSON] [16].