RESUMO
The search for alternative materials to replace ordinary Portland cement has been the object of work that enhances the investigation of the use of pozzolanic materials and the reduction of the carbon footprint with supplementary cementitious materials. However, not all materials are available to meet the large-scale demand for cement replacement. A relevant exception is the calcined clay, a material found worldwide that, when subjected to appropriate heat treatment, presents pozzolanic reactivity and can be used as a supplementary material to cement. This review presents, through a systematic search, methods for measuring the pozzolanic reactivity of calcined clays, namely, direct, indirect, qualitative, quantitative, chemical and physical methods such as electrical conductivity (Lùxan), the force activity index, the modified Chapelle, R3, Frattini test, thermal analysis, X-ray diffraction and X-ray fluorescence spectrometry. The most usual methods to assess the pozzolanic reactivity of calcined clays were exposed and analyzed. It should be pointed out that there is greater use of the Frattini and modified Chapelle methods as well as the analysis of the mechanical strength behavior of the material in cementitious matrices. X-ray diffraction and thermal analysis were exposed as the most used correlation methods but it was also concluded that different tests are needed to generate accurate results.
RESUMO
In the search for better constructive efficiency and a reduction of the waste of construction materials, several researches have been performed in the last years around the world. Red ceramic blocks are artifacts widely used in civil construction around the world, and they result in a great consumption of raw materials and energy. The great innovation of this research was the development of ceramic blocks through an innovative method of pressing and dosing materials, replacing the traditional stage of extrusion in the manufacture of ceramics. In such a sense, a new manufacturing technology for ceramic blocks was proposed through the pressing process, adapting the soil-cement brick press machine, thus attaining more even pieces with greater compliance to the dimensions and preset geometry. In this work, the physical and mechanical features of the pressed and burned blocks (PBB) are produced in a partnership with Arte Cerâmica Sardinha, a traditional ceramic industry in the region of Campos dos Goytacazes, RJ, Brazil. It was sought to set the quality parameters for the blocks, to set their mechanical compressive strength, deformation modules and the Poisson coefficient. The blocks were tested in use by means of three layers of prism and small wall samples, and it was checked the fragile-type failure of the PBB. Results indicate that the blocks can be employed in small-sized construction works, as the characteristic compressive strength to block measured was 3.62 N/mm2 for average water absorption of 20.84%.