Rita de Cássia Silva Sant’Ana Alvarenga

Comparison of Performance Between Granite Waste Pigments Based Paints and Soils Pigments Based Paints

This work aims to produce paints using granite waste, as a pigment, and compare their performance to soil pigments based paints, in terms of hiding power and abrasion resistance. Initially, the residue and soils were physically, mineralogically and morphologically characterized. For the production of the paint samples, an experimental model was defined, based on the variation of the proportions of pigment and resin. The proportion of water varied in each sample, in order to maintain the viscosity within a range considered ideal for application. Sequentially, tests were done to determine the hiding power and abrasion resistance of inks. It was found that, in comparison to soil paints, the granite residue paints presented greater hiding power. This result can be explained by the characteristics of the granite residue, which allowed a high nonvolatile content in the mixtures. With respect to abrasion resistance, granite residue paints showed less resistance than soil paints, possibly due to the granulometry of the residue that resulted in a greater roughness of film. In addition, none ink sample satisfied the minimum specifications prescribed in the Brazilian standards for hiding power and abrasion resistance, at the same time. This means that these inks, when used, will require more repair and repainting over time than conventional paints.

Addition of Dregs in Mixed Mortar: Evaluation of Physical and Mechanical Properties

The dregs is a waste from the cellulose production, and its reuse is an effective way to reduce environmental impacts. Researches have already been done to incorporate it into building materials. The present work aimed at incorporating dregs in the production of mortar to replace hydrated lime. The methodology adopted was the Simplex network with ten sampling points, varying the amount of cement, sand, and dregs. Each mix was submitted to flexural strength, compressive strength, apparent mass density and water absorption by capillarity tests. The results were analyzed by the software Minitab, obtaining the influence of each component in the mixture. The best results were observed in mixes with a higher proportion of cement and less of residue when it was analyzed the flexural and compressive strengths. Larger rates of apparent mass density and water absorption were noticed with a greater amount of dregs. The experimental design also allowed the obtainment of mixture ratios from predetermined values of the tested properties and indicated that the addition of dregs in mortar could be an alternative to civil construction.

Wood-to-Concrete Joints Using Steel Connectors: Experimental Evaluation

Over the last decades, modern technology to build wood structures have been substantially developed. Building solutions for floor systems of wood-concrete mixed T-beams with wood web and concrete flange stand out among these technologies. This work describes an experimental investigation of the performance of bond connectors made of round steel bars for wood-concrete mixed elements. Symmetric three-member specimens were built. The middle member was made of concrete and the other two were made of wood. The first kind of connector consisted of steel bar designed as straight pins with head, normally driven through the wood. The second kind consisted of arc-shaped connectors directly embedded into the wood or bonded using epoxy adhesive. The specimens were then tested in compression. The compressive strength and the force-displacement curve were obtained, in order to evaluate the failure mode and obtain the stiffness in the ultimate (Ku) and serviceability (Ks) limit states. The stiffness values were calculated in the interval corresponding to the secant straight line between, respectively, 10–40 and 10–70% of the ultimate strength. The obtained results indicate high strength and ductile failure mode for all of the cases. Bond stiffness gains were verified when using the arch-shaped connectors.

Evaluation of Incorporation of Dregs in Mortar Production in Replacement of Hydrated Lime

The dregs is a residue from the cellulose production, and finding new ways to use it would be interesting to reduce environmental impacts. This study aimed at incorporating it into mortar mixture ratios to replace the hydrated lime. Different proportions of cement, sand and dregs were evaluated using the Simplex-Lattice method of experimental design, and it was analyzed water absorption coefficient, compressive strength and flexural strength. The model adjustment was made with seven points plus three axial points and in terms of pseudo-components. A linear model was adjusted for the first characteristic, and a quadratic model for the second and third characteristics. Larger rates of capillary suction and smaller resistance values were noticed with a larger amount of dregs. This experimental design proved feasible, allowing the obtainment of mixture ratios from pre-determined values of water absorption coefficient and resistance, and making more objective the addition of dregs to mortar mixtures.

Incorporation of Paint Waste from Furniture Painting Booth into Covering Mortar

Aligned with the world’s tendency of searching for sustainable technologies, the waste addition into materials of the civil construction is an interesting option for wastes that do not have proper destination. This work has the objective of studying the feasibility of incorporating paint waste from furniture painting booth, which currently does not have any correct ecological destination, into covering mortars and investigate if this addition brings any improvement in performance. For this purpose, it was prepared six compositions of covering mortars, with a cement-sand volume proportion of 1:6 and a Flow-table consistency of 260 mm +- 10mm, varying the waste percentage added among the proportions of 0%, 2%, 4%, 6%, 8% and 10% on the cement weight. It was determined, for each composition, the specific gravity and the air-entrained content in the fresh stage. For physical tests, it was moulded nine prismatic samples and one mortar substrate for the bond tensile strength test per mortar composition. It was determined the flexural and compressive strength in the hardened stage, the specific gravity, the water absorption coefficient due to capillary action and the bond tensile strength. Leaching tests were performed for environmental analysis of the mortars produced with waste addition. It was observed that all the mortars with waste received a similar classification to the mortar without waste, according to NBR 13281 [], and the leaching tests showed that mortars with waste were not ecologically dangerous, demonstrating the feasibility of the incorporation. In addition, mortars produced with waste presented an increase in the entrained air percentage, which might be a beneficial action of the paint waste.

Use of Leather Residue in the Manufacturing of Soil-Cement Bricks

This work is an analysis of incorporation of leather powder residue to soil in order to apply it in soil-cement bricks. The leather powder is a byproduct of the finishing step of leather manufacturing that contains chromium in its composition. This element, when in its hexavalent form, is carcinogenic. Experiments were performed regarding brick pressing, water absorption, simple pressing, leaching and solubilization so that the mixtures have the minimum requisites for using the brick. The doses were 0%, 10%, 15%, 20%, and 30% in volume of leather powder in soil. Only the 10% dose met the requisites of ABNT: NBR 8491:1984 that prescribes a minimum resistance of 2 MPa and absorption content lower than 20%. For this dosage, according to the limits stated in ABNT regulation NBR 10004:2004 , the leaching extract was classified as a Class II non-inert, which makes it possible to use it for civil construction purposes.

Evaluation of Incorporation of a Leather Waste Powder in Mortars for Construction Industry

This paper has the objective to evaluate the technical feasibility of incorporation of leather powder in mortars. First a physical characterization of aggregate was carried and then preceded to the dissolution of the leather powder in alkaline solution, in the proportion of 1:1:1 of waste, alkaline solution and water respectively, obtaining the processed waste. In the next step, it has been molded specimen using two reference recipes in terms of mass, 1:3 of cement and sand, and 1:1:6 of cement, hydrated lime and sand respectively, keeping constant the flow table consistency of 130 ±10 mm and 220±10 mm, for each respectively recipe. Two groups of mortars were produced: one without processed waste, one with 5% and one with 10% in ratio to the cement mass. Tests had been carried such as compressive strength to axial compression, tensile strength to diametrical compression, and adherence strength on surfaces. The resistance tests performed; also the analyses of the leachate and solubilized extracts confirmed the feasibility of incorporation of leather powder in mortars.

Evaluation of the Potential of Waste from Pulp Production (Grits) in its Use in Mortar: Physical and Chemical Characterization

The grits is an inorganic solid residue generated during the Kraft process by the pulp and paper industry, which presents in its composition the main ingredients of Portland cement. According to some authors, the grits can be classified as a non inert, non hazardous, granular solid industrial waste. With this in mind, a study was proposed with the objective of evaluating, initially, the applicability of grits in mortar, by means of physical and chemical testing. The physical evaluations were realized through the following tests: determination of bulk gravity saturated - surface - dry (SSD) and water absorption; determination of the pulverulent material content; and the determination of particle size distribution. To chemically test the grits, a reading of the metal concentrations present in the grits was realized as well as an analysis of the leaching and solubilization extracts. It was concluded that the addition of grits to mortar is a potential alternative.

Avaliação experimental de vigas com emendas de topo coladas com cobrejuntas de madeira de eucalipto

The objective of the present work was to construction, to test and to evaluate the behavior of wooden beams made of eucalyptus boards with mid-span end-grain joints. A resorcinol-formaldehyde glue was used as adhesive and the joints were covered by side members of the same species of wood. Strength and stiffness of these beams were compared with the results obtained for solid beams. Eucalyptus lumber was purchased for this purpose. Wood properties were determined for these two sub-samples, according to the recommendations of the Brazilian Association of Testing Standards, NBR 7190/97. Prototype beams were built to find the best size of the side members that symmetrically covered the joints. These beams had a length of 170 cm, 3 cm of width and 10 cm of deepness with cobrejuntas consist of boards 35 and, or 43 cm long and 1.5 cm thickness and were tested to failure using a center load on a 160-cm span. It was found that a 1.5 cm thick side member should cover at least 25% of the two sides of the beam to give the same results of strength and stiffness of solid 170 cm long beams. Larger beams were then built and tested. They had a length of 420 cm, 20 cm of deepness and 6 cm of width the controls were built of a single piece of lumber; the others were made of 210 cm long boards, joined at mid-section by 100 cm long, 3 cm thick side members. After the test, these glued beams presented strength similar to the control witness, but the displacements of beams with cobrejuntas were on average 20% lower than the control, submitted showing a better structural performance.