Rinaldo José Barbosa Pinheiro

Construção de estruturas de contenção utilizando pneus inservíveis: análise numérica e caso de obra

The use of scrap tires in civil engineering involves creative solutions and diversified applications. The present paper presents parametric analyses based on laboratory data with different tires, wall heights, filling materials, water levels and soil friction angles. A design draft for 376 different earth retaining structures (combining all variables) was made and a statistical analysis performed to study the effect that each variable had on the base value. Finally, a case study is presented of a tire wall construction near Ijui City - RS. The cost of this solution is given in comparison with the traditional concrete ones.

Rational Approach to the Evaluation of Soils for Low-Volume Roads

Given the paramount importance of soils in unsurfaced or thinly surfaced roads, it seems worthwhile to evaluate soils on the basis of both pavement and soil mechanics. Such a rational approach is used to discuss the mechanical behavior of a residual soil found in southern Brazil. The experimental program included tests traditionally used in pavement engineering, such as grain size distribution, Atterberg limits, compaction, California bearing ratio, resilient modulus, and permanent deformation under repeated loading. The influence of water content and compaction degree on soil strength and stiffness was quantified. In addition, direct shear tests were performed to define shear strength parameters that were used to verify layer safety against failure. Water retention curves, which relate soil suction to saturation degree, were used to analyze permanent deformation evolution under repeated loads. The interpretation of test results confirmed the suitability of the suggested approach for evaluating soils for low-volume road construction.

Comportamento mecânico de material fresado após processo de estabilização granulométrica e química por meio da incorporação de cimento e cinza de casca de arroz moída

This research aims to evaluate, through laboratory testing, the feasibility of using pure and stabilized reclaimed asphalt pavement (mechanical, chemical and grading) in layers of flexible pavements. The milled materials are from BR-290 and ERS-509 roadways. Grading stabilization was performed and determined the level of 70% of milled material and 30% of virgin aggregate. For testing of compressive strength were molded into test specimens of 10x20 cm with different levels of Portland cement (CP IV-32), and determine the content of 4,86% (BR-290) and 5,37% (ERS-569) from the compressive strength of 2.1 MPa at 28 days. From these results, specimens were molded for testing the axial compressive strength, indirect tensile strength and resilient modulus; in these specimens, the cement was replaced by rice husk ash (mesh #325 and #500) in ratios of 15, 30 and 50% by weight of cement content, and put into moist chamber for 7, 28 and 160 curing days. The results showed that for compressive and tensile strength, the replacement of 15% of cement by CCA was efficient, with no drop resistance compared to the reference samples. Also evident the effectiveness of CCA, showing positive results when compared to those mixes only with the real content of Portland cement used and with the environmental appeal becomes an interesting alternative for use in pavement layers.