Almir Sales

Use of Brazilian sugarcane bagasse ash in concrete as sand replacement.

Sugarcane today plays a major role in the worldwide economy, and Brazil is the leading producer of sugar and alcohol, which are important international commodities. The production process generates bagasse as a waste, which is used as fuel to stoke boilers that produce steam for electricity cogeneration. The final product of this burning is residual sugarcane bagasse ash (SBA), which is normally used as fertilizer in sugarcane plantations. Ash stands out among agroindustrial wastes because it results from energy generating processes. Many types of ash do not have hydraulic or pozzolanic reactivity, but can be used in civil construction as inert materials. The present study used ash collected from four sugar mills in the region of São Carlos, SP, Brazil, which is one of the worlds largest producers of sugarcane. The ash samples were subjected to chemical characterization, sieve analysis, determination of specific gravity, X-ray diffraction, scanning electron microscopy, and solubilization and leaching tests. Mortars and concretes with SBA as sand replacement were produced and tests were carried out: compressive strength, tensile strength and elastic modulus. The results indicated that the SBA samples presented physical properties similar to those of natural sand. Several heavy metals were found in the SBA samples, indicating the need to restrict its use as a fertilizer. The mortars produced with SBA in place of sand showed better mechanical results than the reference samples. SBA can be used as a partial substitute of sand in concretes made with cement slag-modified Portland cement.

Moisture content effect on ultrasonic velocity in Goupia glabra

This paper discusses the application of ultrasound waves on a Brazilian hardwood, Goupia glabra, to evaluate the sensitivity of the ultrasonic technique to the moisture content in wood. The velocity of ultrasonic wave is sensitive to the materials quality-determining factors; hence, this technique is an important industrial tool to improve the quality control of processes. The nature of the response of velocity of sound to changes in moisture content led us to conclude that moisture gradients during drying exert a dominating effect. The ultrasonic velocity was measured both parallel and perpendicular to the fibers of Goupia glabra during drying from green to 6% moisture content. The results of this study showed that velocity of ultrasonic waves is sensitive to changes in moisture content of lumber during drying. The velocity under dry conditions was always higher than the velocity under more humid conditions, in both directions of propagation.

Wettability, Shrinkage and Color Changes of Araucaria angustifolia After Heating Treatment

The effects of thermal treatment on the wettability and shrink resistance of Araucaria angustifolia (Parana pine) were studied from 20 to 200 °C. The contact angles of water droplets on untreated and heat-treated samples were measured by the sessile drop method in the grain of heartwood and sapwood cut in the radial, longitudinal, and tangential directions. A significant increase of the contact angles was verified for the samples from room temperature to 120 °C, in particular in the radial and tangential directions; at higher temperatures, the contact angles assumed almost constant values. From 120 to 200 °C, the sapwood of Araucaria angustifolia showed better dimensional stability and lower thermal resistance when compared to the heartwood. Variations of color were also studied by using the CIELab system, which showed to be capable of accurately distinguishing samples treated at different temperatures.

NONDESTRUCTIVE EVALUATION OF WOOD USING ULTRASONIC TECHNIQUE

En este trabajo se presenta un estudio sobre la utilizacion de ultrasonido como una tecnica para la evaluacion de las propiedades mecanicas de la madera. En el mismo, se utilizo madera de la especie Pinus taeda , se determino la densidad (ρ ap,12% ) y el modulo de elasticidad en la flexion (MOE). Con el ensayo ultrasonico se determino el modulo de elasticidad dinamico (E d ). Los resultados y analisis de las correlaciones entre los valores dinamicos y estaticos permiten concluir que la aplicacion del ultrasonido puede ser utilizada con confiabilidad en coniferas Palabras clave : ultrasonido; evaluacion no destructiva; madera.

Efeito do comprimento do corpo-de-prova na velocidade ultra-sônica em madeiras

This paper reports on a study of the variation of ultrasonic velocity with the length of the specimen of pinus caribaea (Pinus caribaea var. caribaea) eucalipto citriodora (Eucalyptus citriodora), eucalipto grandis (Eucalyptus grandis) and jatoba (Hymenaea sp). Ultrasonic measurements were taken with an experimental apparatus having 22 kHz transducers. Tests were carried out with length from 300 cm to 10 cm and constant cross-section (12 cm x 5 cm). The results showed that velocity of ultrasonic waves is sensitive to changes in the distance between transducers and wavelength ( λ). The adjustment between the frequency of transducer and the length of the specimen is essential in order to obtain correct measurements of ultrasonic velocity in wood.

Concretos com cinza do bagaço da cana-de-açúcar: avaliação da durabilidade por meio de ensaios de carbonatação e abrasão

The bagasse is generated in the sugar and alcohol production process. This waste is used for cogeneration of electricity by burning it in boilers and at the end it produces sugarcane bagasse ash (SBA). Currently, those ashes are also used in cane plantations as organic fertilizer, despite the fact that it is poor in nutrients. The aim of this study was to evaluate the durability of concrete made with SBA as a replacement material for fine aggregate, through abrasion and carbonation tests. The results were compared to those obtained for a concrete without SBA. The concretes were designed to have the same workability and the same content of mortar. Mixes were made with 0%, 30% and 50% of SBA (in mass) replacing fine aggregate in three different groups. Mechanical tests were carried out with the concretes and the best concrete mixes made with SBA were submitted to the carbonation test at 60, 120 and 210 days, and the abrasion test at 28 days. The results indicated that the abrasion and carbonation of concrete produced with SBA as an aggregate replacement and slag-modified Portland cement are similar to concrete without ash addition.

Betão auto-compactável com resíduo agroindustrial

Os autores agradecem o programa EBW+ pela bolsa concedida, o CONSTRUCT/LABEST / FEUP, a engenheira Paula Silva e o tecnico Claudio Ferraz pelo suporte nos testes laboratoriais, o PPGECIV / UFSCar, o Instituto de Pesquisas Tecnologicas de Sao Paulo –IPT e a empresa Raizen pela doacao da ACBC. Este trabalho foi financiado por: Projeto POCI-01-0145-FEDER-007457- CONSTRUCT – Instituto de I&D em Estruturas e Construcoes – financiado pelo Fundo europeu de Desenvolvimento Regional (FEDER), atraves do COMPETE2020 – Programa Operacional Competitividade e Internacionalizacao (POCI) e por fundos nacionais atraves da Fundacao para a Ciencia e a Tecnologia I.P.

Avaliação da durabilidade de concretos produzidos com resíduos da construção civil

The civil construction is responsible for generating a lot of waste. In the city of São Carlos (SP) the generation of construction waste (CW) exceeds four times the generation of household waste. Generally the CW are disposed in inappropriate places resulting in serious environmental problems. This article is in the context of an alternative to the application of CW as aggregate in concrete. The main objective of this study was to verify the depth of carbonation and the physical properties of concrete produced with CW compared with a concrete reference ( without CW). The CW samples were collected in the municipality of São Carlos recycling plant and was performed physical and chemical characterization. After the grain size treatment, was proceeded the mixture and production of concrete with 0 % , 30 % , 50 % and 100 % of CW in replacement of natural coarse aggregate. The specimens were stored for 56 and 112 days in a carbonation chamber with CO2 content of 15 ± 5 %, constant humidity and temperature. After this period, the depth of carbonation was verified by colorimetric method. Assays for the determination of water absorption, void index and compressive strength of the concrete were also