## 1 Introduction  
Population growth and the direct impact that potable water supply and the sewage network have on the health and life quality of citizens indicate a very high rate of growth in demand for manhole covers over the coming years. Climatic changes result in the need for the upgrading of existing rainwater networks and for the construction of new ones, which also require manhole covers. Manhole covers have been commonly produced using steel or reinforced concrete (with conventional steel reinforcements). Steel manhole covers can suffer deterioration by corrosion and local ruptures (Figure 1), and have been stolen for resale as steel scrap [1; 2; 3] causing serious risks for the transients and residents, with numerous cases of disasters, and significant costs for particulars and to the municipalities [4; 5]. Manhole covers produced by RC are susceptible to corrosion of the steel reinforcement, which limits the long-term performance of this type of urban infrastructure. This weakness causes the loss of structural serviceability and safety due to the decrease in the concrete-steel bond strength and cross-section of the reinforcements. In recent years, some initiatives have aimed at developing manhole covers exclusively in fibre-reinforced polymers (FRPs). Besides the higher price, the structural performance of these manhole covers is dependent on the glass transition temperature (Tg) of the polymer component of the composite material, since, in road applications, the temperature can exceed the Tg. In fact, temperatures exceeding 70 Celsius degrees have been recorded in pavements [6]. The glass transition temperature of the polymeric matrix used in the major part of the GFRP applied in construction systems is between 65 and 150 Celsius degrees [7]; therefore, the mechanical properties of these GFRPs are detrimentally affected when subjected to the maximum temperatures possible to be attained in pavements. The long-term inelastic deformability of these composites is also significant, which results in their needing replacement in relatively small periods of time. Fibre-reinforced cementitious (FRC) materials have been combined with FRP in the development of new construction systems in an attempt at mobilizing the potential of these materials in a complementary perspective towards intended objectives like functionality, sustainability, economic viability and structural and functional performance [8; 9; 10; 11; 12; 13]. Concrete has a relatively high compressive strength and modulus of elasticity, high durability and resistance to high temperatures, and can be engineered to have rheology capable of filling relatively small spaces and moulds of complex shape, from self-compacting to ultra-fluid. However, when subjected to tension, concrete develops brittle behaviour; therefore, small fibres have been used as an extra constituent of concrete composition to increase its post-cracking tensile capacity and energy dissipation and absorption at a relatively low cost. Fibres have been used to eliminate partially or even completely conventional steel transverse reinforcement in beams [14; 15; 16] and slabs [17; 18; 19; 20], to increase the flexural capacity of members in combination with a certain percentage of conventional flexural reinforcement (hybrid reinforcement, HFRC) [21; 22] or to be the exclusive reinforcement [23]. In the case of HFRC structures, fibres can contribute significantly to increasing the load-carrying capacity during the crack propagation phase and decreasing the crack width and the maximum tensile stress in the flexural reinforcement for the load combinations corresponding to the serviceability limit state (SLS) design verifications [24; 25; 26]. When used as the unique reinforcement, FRC has been used in structures of high redundant support, like slabs on soil [27; 28; 29], slope stabilization [30; 31; 32; 33] and tunnel lining [34; 35], by taking advantage of the relatively high level of stress redistribution capacity of this type of structure during the crack propagation process.