Conrado de Souza Rodrigues

Potencial da cinza do bagaço da cana-de-açúcar como material de substituição parcial de cimento Portland

This study is focused on the evaluation of the effects of the partial replacement of Portland cement by sugarcane bagasse ash (CBC) in mortars. The main objective was to find a suitable destination for an agricultural residue generated in an increasing amount in Brazil, as a result of the boom of the use of ethanol as an alternative fuel to gasoline. Also, the use of CBC as a mineral admixture in mortars and concretes contributes to a decrease in the environmental impact of these materials related to cement production. Experimental techniques were applied both for the CBC characterization and for the evaluation of its use as a mineral admixture in mortars, based on mechanical and physical tests. The yield of CBC from sugarcane bagasse burning was 10% (weight basis). The CBC presented a SiO2 content of 84% and a carbon content of 5%. Silica presented both amorphous and crystalline (cristobalite and quartz) structure. The pozzolanicity index applied indicates the reactivity of the CBC. Concerning the compression strength, the results from tests with mortars with up to 30% of CBC content indicated the viability of the partial substitution of cement by up to 20% of the CBC considered.

Evaluation of bony quality through biochemical, morphometrics and biomechanical aspects of broilers.

The objective of the experiment was to determine the biochemical, morphometrics and biomechanical aspects of femur bones of broilers. It was used six hundred male and female broilers at one day of age from three different lines (Hb1 and Hb2 – UFV and Hb3 – commercial). They were fed ad libitum on starter (1 to 21 days), grower (22 to 35 days) and finisher (36 to 42 days) rations. The experimental design was completely randomized, in a factorial arrangement 3 × 2 (three lines and two sexes) with 5 replicates and 10 birds per experimental unit (box). The weight, length, cross-sectional area, moment of inertia, maximum load, modulus of elasticity, bending strength, collagenous and non collagenous proteins and body weight of the broilers were evaluated in the femur. At 21, 28, 35 and 42 days of age, one male and one female of each line were randomly selected per box, in a total of five boxes per line. Among lines, Hb3 presented higher superior body weight in all ages, and among sexes, the males were heavier. The strength of maximum load was higher for the males and lines HB3 was higher than HB1and equal to HB2 at 42 days of age. The worst results of elasticity and bending strength at 42 days of age were observed in males from line HB2, which did not differ from HB3 regarded to bending at 42 days of age and to elasticity measured in all ages, which characterizes low bone quality of the males and line HB3. Biomechanical aspects of femurs bones, as modulus of elasticity and bending strength, to correct and avoid bone damages of broilers due to their heavier weight.The objective of the experiment was to determine the biochemical, morphometrics and biomechanical aspects of femur bones of broilers. It was used six hundred male and female broilers at one day of age from three different lines (Hb1 and Hb2 - UFV and Hb3 - commercial). They were fed ad libitum on starter (1 to 21 days), grower (22 to 35 days) and finisher (36 to 42 days) rations. The experimental design was completely randomized, in a factorial arrangement 3 × 2 (three lines and two sexes) with 5 replicates and 10 birds per experimental unit (box). The weight, length, cross-sectional area, moment of inertia, maximum load, modulus of elasticity, bending strength, collagenous and non collagenous proteins and body weight of the broilers were evaluated in the femur. At 21, 28, 35 and 42 days of age, one male and one female of each line were randomly selected per box, in a total of five boxes per line. Among lines, Hb3 presented higher superior body weight in all ages, and among sexes, the males were heavier. The strength of maximum load was higher for the males and lines HB3 was higher than HB1and equal to HB2 at 42 days of age. The worst results of elasticity and bending strength at 42 days of age were observed in males from line HB2, which did not differ from HB3 regarded to bending at 42 days of age and to elasticity measured in all ages, which characterizes low bone quality of the males and line HB3. Biomechanical aspects of femurs bones, as modulus of elasticity and bending strength, to correct and avoid bone damages of broilers due to their heavier weight.

Experimental Investigation of Steel-Concrete Bond for Thin Reinforcing Bars

THE STEEL-CONCRETE BOND IS A FUNDAMENTAL PROPERTY IN REINFORCED CONCRETE STRUCTURES. ALTHOUGH THERE ARE SEVERAL STUDIES ON THE STEEL-CONCRETE BOND, FEW OF THEM HAVE EVALUATED THE PERFORMANCE OF REINFORCING BARS WITH DIAMETERS LESS THAN 10.0 MM, WHICH INCLUDES 5.0, 6.3, AND 8.0 MM DIAMETERS, WHICH ARE NORMALLY USED IN REINFORCED-CONCRETE ELEMENTS. THIS STUDY EXPERIMENTALLY EVALUATES THE BOND BETWEEN THIN STEEL BARS AND CONCRETE OF 25MPA COMPRESSION STRENGTH. THREE TYPES OF METHODS OF TESTING THE BOND-STRENGTH WERE ADOPTED: SURFACE CONFORMATION TEST, PULL-OUT TEST AND BEAM TEST. THE PULL-OUT TEST RESULTED IN BETTER RESULTS IN TERMS OF EVALUATING THE BOND BEHAVIOR. THEREFORE, THE MAIN CONTRIBUTION OF THIS STUDY, BASED ON THE RESULTS OBTAINED AND THE METHODOLOGY USED, IS TO PRESENT A PROPOSAL FOR THE EVALUATION OF STEEL-CONCRETE BOND FOR THIN REBARS.