The use of precast lattice-reinforced joist slabs in reinforced concrete structures has advanced since the 1990s. Such slabs are produced in two steps: one at the manufacturing plant where the joists are made, and the other on site, when concrete topping is applied. These slabs offer several advantages over other systems, such as reduced consumption of building materials, lower labor costs, simplicity and speed of erection, easy installation of service conduits, lower self-weight of the concrete structure, versatility in use, and economy. The procedures involved in manufacturing the joists and assembling the slabs in various types of buildings in the region of São Carlos, state of São Paulo, Brazil are described and analyzed, and the results of interviews with manufacturers, designers and builders are reported. The data collected show that in most cases this system has been executed inadequately, without taking simple precautions that would have prevented many of the problems of quality and durability that usually arise during use.
Lattice-reinforced joists; production; construction; quality; durability