Formulation of Non-Fired Bricks Made from Secondary Aluminum Ash

The secondary aluminum ash is the black slag left after the primary aluminum ash is extracted from the metal aluminum. To address the environmental pollution and resource waste caused by the accumulation and landfill of aluminum ash, this study fabricated non-fired bricks by using secondary aluminum ash as the principal raw material, which was supplemented by cement, slaked lime, gypsum and engineering sand. The effects of mix proportions of various admixtures on the mechanical properties of non-fired bricks were investigated, and on this basis, the hydration mechanism was analyzed. The results showed that the mix proportions were 68.3% aluminum ash, 11.4% cement, 6.4% slaked lime, 4.2% gypsum and 9.7% engineering sand. The compressive strength of the fabricated bricks reached 22.19 MPa, and their quality indicators were in line with the MU20 requirements for Non-fired Rubbish Gangue Bricks. Evident hydration reaction occurred inside the non-fired bricks, with main products being calcium silicate hydrate (CSH), calcium aluminate hydrate (CAH) and ettringite (AFt). Besides, a dense structure was formed, which enhanced the brick strength.

Impact of dampness to changes in the mechanical properties of solid fired bricks

This work deals with the monitoring of changes in the mechanical properties of solid fired bricks depending on their dampness using non-destructive methods. Decreases of first natural frequencies by the resonance method and increase of passage times of ultrasonic waves depending on increasing dampness are monitored. The elements were firstly fully saturated and then slowly dried so that it was possible to record the values of the first natural frequencies and the passage times of the ultrasonic waves at different dampness. It is not possible to record values in all dampness, so the measured values were interpolated by regression models. A polynomial of the 2nd degree seems to be the most suitable. Dampness corresponding to the minimum natural frequencies and the maximum passage times of the ultrasonic waves were performed on these regression models. This research is the first step in determining the durability criteria for ceramic products, especially solid fired bricks. In the future, durability criteria should help in the reconstruction of historic buildings to assess whether the element that will be exposed to the weather is durable or not. These tests are completely non-destructive, which means that the tested element can be subsequently used in construction.

Towards the Use of Yellow Clay in Fired Bricks

This chapter deals with the study of the possibility of using yellow clay - which was only used in pottery so far- in the civil engineering field as building materials, especially in the field of fired bricks. With the aim to improve the technological properties of yellow clay based bricks, two wastes were used as secondary raw materials. The first one is a mineral waste - pyrrhotite ash - this waste was neither characterized nor valued before by any other author. While the second waste is an organic waste - cedar sawdust - which is from the artisanal sector. Clay bricks containing yellow clay and different content of wastes were prepared and tested to evaluate their technological properties: water absorption, bulk density, porosity and mechanical strength… The test results indicate that the addition of wastes to clay bricks improves their technological properties and highlights the possibility of wastes reuse in a safe and sustainable way.

Potential use of alluvial clays from Monoun in ceramics by adding feldspar from Batie (West-Cameroon) as a fluxing agent

The present study focuses on the use of feldspars from Batie granites (West-Cameroon) as a fluxing agent in ceramic applications, in order to reduce the energy cost of brick manufacture. Three alluvial clays were collected in the field using an auger and the feldspar sample was collected by hammering. Mineralogical, physical and geochemical analysis of alluvial clays samples were carried out, as well as the microscopy analysis of feldspar. The specimen of fired bricks was formulated with different proportions of feldspar (0%, 10%, 15%, 20%, and 25%) and calcined respectively at 750 °C, 850 °C, 950 °C and 1050 °C in an electric furnace. The physical analysis of the clay material showed a well graded granulometry composed of 3% gravel, 10% coarse sand, 23% fine sand, 13% silt and 51% clay. Thin section microscopic analysis revealed essentially perthites. The mineralogical analysis obtained by XRD on total powder shows that the alluvial clays are composed essentially of: 55.8% of total clays; 19.2% quartz; 14.2% goethite; 8.5% K feldspar; 1.2% anatase; 0.7% hematite and 0.4% gibbsite. Geochemical analysis shows that clay material consists of: SiO2, Al2O3, Fe2O3, TiO2, P2O5, MgO, CaO and K2O. The ceramic tests carried out on these bricks showed that their colors were red for all the formulations and temperatures tested. The sound of the bricks is metallic for the formulations of 20 and 25% of feldspar as from 850 °C. The flexural strength (greater than 3 MPa) and compressive strength (10–20 MPa) obtained at 20 and 25% of feldspar meet the standard of traditional ceramics requirements. The bricks obtained at 20 and 25% of feldspar and at a sintering temperature below 850 °C have good technological properties. It was observed that brick formulations with 0% of feldspar fired between 950 and 1000 °C are similar to those of 20 and 25% of feldspar fired at 850 °C).Highlights The alluvial clays from Monoun characterized have highest proportion of kaolinite and good mechanical properties (950 and 1050 °C). Thin section microscopic analysis of Batie feldspar revealed essentially perthites. The brick formulations with 0% of feldspar fired between 950 and 1050 °C are similar to those of 20 and 25% of feldspar fired at 850 °C.

Characteristics of unfired soil blocks stabilized with industrial waste and agricultural waste

The problem of pollution is on daily rise and environment protection is becoming challengeable task due to production of fired bricks and improper disposal of waste materials. This experimental investigation is conducted on unfired compacted soil block stabilized with waste materials. The waste materials utilized in this investigation were paddy straw fiber, sugarcane bagasse ash and marble dust because of their improper disposal and burning of paddy straw is one of them. Marble dust was put on at distinct percentages in the span of 25% to 35%, bagasse ash and paddy straw fibers (75mm length) were also added in varied %age. Experiments were conducted on the blocks to determine the compaction properties and compressive strength of the blocks. The outcome of this experimentation determined that the light weight unfired admixed soil block is achievable with optimum amount of waste materials. Also, inclusion of marble dust in soil block admixed with bagasse ash and paddy straw fiber increases the compressive strength.

Pressed non-fired bricks from phosphogypsum waste for non-load bearing wall

In several countries of the world, phosphogypsum represents a large quantity of waste that poses serious problems of environmental and groundwater pollution. This study aims at recovering phosphogypsum, in its raw state without treatment, in the manufacture of non-load-bearing non-fired bricks. The study starts with the analysis of the radionuclide activity of the materials constituting the bricks, in particular phosphogypsum, in order to avoid any human health problems after the manufacture and use of the bricks. Then, several compositions are tested with several preservation methods in order to optimize the composition. The physical, chemical and mechanical resistance is determined. The results show the possibility to produce non-load-bearing bricks based on untreated phosphogypsum which comply with the standards requirements, using low energy. Indeed, among the considered mixtures, two compositions (60% of PG and of 75% of PG) perfectly verify the physical and mechanical tests. Also, storage of the mixtures for two days in the laboratory and then three days in an oven at 70°C, allows to obtain the best resistance to compression. Thus, the obtained resistance is much higher than the minimum value required for non-load-bearing bricks.

Thermal behaviour of ceramics obtained from the kaolinitic clays of Terra Alta, Catalonia, Spain

The thermal properties and evolution of mineralogy and colour of kaolinitic clay from the Terra Alta region were studied. The mineralogy of these materials consists mainly of kaolinite (13–27 mass%) and quartz (48–86 mass%). Minor illite, hematite, K-feldspar and calcite also occur. The linear expansion and absorption curves were used to predict the optimal firing temperature of the raw clays. During firing, from 1100 °C the water absorption decreases steeply, due to an increase in liquid phase, which penetrates into the pores and close the porosity. At this temperature, the firing shrinkage increases progressively. The fired clays are mainly composed of quartz, cristobalite and mullite, with minor hematite and rutile. Mullite starts to appear at 1050–1100 °C. SEM observations show that porosity decreases with the firing temperature. The colour properties were measured in the raw clays and in the fired bricks at different temperatures. The lightness, L*, is lower in the fired test pieces respect to the natural clays. This colour varies according to the hematite content, being from white to reddish in the fired samples.