Papers by Keyword: Brick

Abstract: Retracted paper: Evaporation of a saline solution from a porous medium often leads to the formation of salt efflorescence at the surface of the medium. We look at the special case where the medium is formed by the assembly of fine and coarse medium vertical columns perpendicular to the evaporation surface and where there is a continuous wicking of the solution into the medium in combination with evaporation. Experiments lead to distinguish two main cases depending on the development or not of the efflorescence at the surface of the coarse medium. On the contrary, the presented analysis suggests that the coarse medium surface colonization occurs when the evaporation flux is sufficiently high no matter what the type of efflorescence is on the fine medium surface. In addition, the analysis suggests that the colonization will always occur when the supersaturation is close to the solubility.

Abstract: The mechanical behavior of brick elements depends on the properties of its components. The same ones that can be obtained through experimental tests or with numerical methods, both methodologies provide excellent results. Consequently, the aims of this work to analyze the behavior of bricks by applying the finite element method. For this, a methodology based on the physical, mechanical, chemical properties of fired bricks and ecological was established, with which the mechanical behavior of different geometric sections of the bricks was calibrated and analyzed. As results, the numerical model was calibrated, obtaining maximum stresses and deformations at simple compression of 6.91 MPa, in the G5 form, defined by the Ecuadorian standard INEN 293 as solid brick in a mixture of soil-cement with gypsum; and the maximum flexural resistance is obtained at 1.65 MPa, in the same geometric section in the mix of Catamayo fired brick; concluding that exists a reliability in the results of the computational simulation analysis applied to different mixtures and geometries whose correlation is 0.99.

Abstract: The circular economy is currently a highly discussed topic in many areas of production, due to the potential scarcity of natural resources. In the construction sector, it is often associated in the first place with the high shortages of natural aggregates for the production of concrete. To produce concretes up to strength classes C 30/37, the partial or complete replacement of natural aggregates by concrete or brick crushed recyclates in the 4/22 mm fraction can be used very efficiently and safely. This paper will show the current legislative limitations for the use of recyclates as aggregates for concrete production, the possibilities of their use when limiting the degrees of environmental influence or physico-mechanical parameters. In both cases of strength classes C 16/10 and C 30/37, a decrease in compressive strength of 16% was observed with replacement of coarse natural aggregate. The results of physico-mechanical properties of different formulations experimentally and practically verified will be shown and the areas of their safe use will be discussed.

Abstract: The normal and tangential adhesive strength between bricks and mortar in bed joints is the main parameter that determines the performance of masonry under biaxial stress conditions. This research aims to determine the possibility of increasing the tangential adhesive strength (shear) of masonry by using mortars reinforced with PET fibres obtained from recycled plastic bottles. Shear tests are proposed on simplified brick masonry specimens made with mortars containing PET fibres in percentages of 0.5%, 1% and 1.5% of the mass of cement and sand. It has been determined that the addition of PET fibres in percentages no greater than 1% increases the tangential bond strength. The addition of 0.5% PET fibres increases the tangential adhesive strength by 37% and 1% PET by 60%, while the addition of 1.5% PET fibres decreases the studied strength by 22.86%.

Abstract: This study presents a set of "particular" strength criteria of the constituent elements of masonry as a composite material constituted by homogeneous fragments of heterogeneous materials (brick and mortar) and contact interface (shear and normal adhesive strength). This paper proposes the expressions for calculate the values of each particular strength criterion used for the discrete modelling of masonry. The results were obtained based on the experimental study of stresses and failure modes in masonry specimens, mortar samples and brick units. There are determined a set of 8 particular strength criteria, which correspond to the actual work of the masonry constituent elements. Their use in the structural micromodelling of masonry allows to determine the body contact interactions, track the gradual accumulation of local stresses, exclude from the calculation model the elements in which a particular strength criterion has been exceeded, and modelling the degradation process.

Abstract: Increasing the durability of brick structures is a current requirement for reducing damage in particular natural disasters, over-pressure wind effects and extraordinary loads.The structures are designed today according to valid standards and on the basis of empirical experience. They are designed for extraordinary effects only in cases where this is required by regulations, especially fire regulations. For brick structures, it is often followed by established procedures and catalogue recommendations, and the solution of these structures is often considered banal. However, what if the damage exceeds the effects set by the standards. Therefore, this contribution is devoted to simple instructions for increasing the durability of low-floor masonry buildings above the normal limit given by the current construction and the applicable regulations.

Abstract: This paper investigates the effect of partial replacement of fly ash with sago pith waste ash and silica fume in fabricating the geopolymer mortar concrete. The mixtures of geopolymer mortar concrete were prepared by replacing sago pith waste ash and silica fume at 5% of total weight of fly ash. There were six specimens of geopolymer mortar cubes and bricks fabricated in this study. The specimens are tested with compressive strength test, rebound hammer test and ultrasonic pulse velocity test. The results from the tests are compared with some existing published works as to clarify the effect of replacing the fly ash with sago waste and silica fume on the strength of concrete. Comparisons had been made and concluded that the molarity of alkaline solution, Al₃O₂ and CaO influenced the development of compressive strength along the curing time of fly ash based geopolymer concrete.

Abstract: A lot of researchers have studied the rice husk brick and it is the most widely used material in earth construction. Although study has been carried out on rice husk brick previously, more in-depth study on the aspect of the optimal replacement levels of local black rice husk ash to the Ordinary Portland Cement (OPC) that will meet stated standard requirements for non load-bearing bricks need has not been carried out. Despite all the natural materials have been used in construction materials, black rice husk ash is important to be reviewed based on the rationale of availability and growing rice husk production year by year due to high demand of rice supply.

Abstract: Concrete of three different target strength, i.e. 17.23, 20.68 and 24.13 MPa was prepared using recycled brick concrete (RBC) and electric arc furnace slag (EAFS) blended as coarse aggregate. EAFS ratio was kept at 0%, 25% and 75% with respect to RBC. Concrete cylinder (200mmX100mm) specimens were prepared following standard procedure. Compressive and tensile strength on those concrete samples were conducted as per ASTM standard procedures. It was found that target compressive strength could not be achieved using 100% RBC as coarse aggregate. Through mixing EAFS with RBC both compressive and tensile strength of concrete was found to increase. 50% EAFS ratio was found to give maximum compressive and tensile strength for this type of blended aggregate concrete.

Abstract: The article analyzes the change in the stress-strain state of ceramic brick samples when tested in compression, depending on the variable parameters - the type of sample and the method of surface preparation. The experiment showed that the friction forces arising in the “sample-plate test press” zone of contact have a significant effect on the deformation conditions of the samples and lead to an uneven distribution of the breaking load over the surface. This in turn leads to an overestimation of the strength characteristics of the lot, and, consequently, to errors in the calculations of the bearing capacity of the structures. A numerical analysis of the stress distribution also showed that for the samples aligned by grinding and with the help of a mortar; the effect of compression caused by friction forces can be traced. Thus, the results of the numerical experiment are in good agreement with the results of the full-scale experiment. To increase the reliability of the test results, it is necessary to reduce the influence of friction forces and provide conditions for the realization of uniaxial compression. In this regard, it is necessary to adjust the standard test method, namely to use the technical felt gaskets as a method of preparing the surface.