Análise da viabilidade da fabricação de blocos intertravados de pavimentos de concreto com o uso de resíduos de termelétrica e de agregados reciclados da construção civil

Abstract

In the state of Ceará, there is a considerable production of waste, such as bottom ash, from the Pecém Thermoelectric Plant (PTP), as well as Construction and Demolition Waste (CDW), from the civil construction sector, which, in general, do not receive an adequate destination. With the advancement of the use of Interlocking Pavements (IPs) in Ceará, the use of waste in the manufacture of Interlocking Pavement Blocks (IPBs) is a possibility of applying these materials. Thus, the objective of this dissertation was to analyze the properties of IPBs, using thermoelectric waste and recycled aggregates from civil construction, to verify the technical, financial and environmental feasibility of the manufacture of concrete blocks. First, environmental tests were performed on the alternative materials, and physical characterization tests on the other aggregates. In this phase, ten concrete mixtures were created, two of which are reference and eight alternatives (six mixtures with ash and two with recycled CDW aggregates). It was observed that the ash had a significant concentration of the fluoride (F-) anion in the leached extract test. Regarding the CDW sand used, it had chloride and sulfate contents below the limit of 1 %. In the second part of the experiment, the fresh concrete consistency was determined by the VeBe method, and specific density, yield and air content tests were performed. In hardened concrete, IPBs type I (rectangular shape) were molded. All concrete mixtures showed IPBs with average water absorption below the limit of 6 % at 28 days of curing. In the Simple Compressive Strength (SCS) test, the values were below the minimum of 35 MPa. At 28 days, among alternative mixtures with a water/cement ratio of 0.63, IPBs with 50 % replacement of conventional materials by recycled CDW aggregates showed the most satisfactory results. In the alternative concrete mixtures with a water/cement ratio of 0.73, the highest values were for blocks with a 20 % replacement of 19 mm gravel by coarse ash. Thus, it was observed that it would be possible to allocate some of the IPBs in areas with lower traffic, such as pedestrian sidewalks. In the third part of the research, the design was made, using empirical and mechanistic-empirical methods, of an idealized IP with the investigated mixtures. It was found, in general, that the resulting sections from the mechanistic-empirical method required a smaller amount of materials. In this way, it was possible to optimize the thickness of the granular layers of the IP and, thus, make the investment in this type of structure more economically attractive.