Lia Lorena Pimentel

Viabilidade do aproveitamento de resíduos de fibras vegetais para fins de obtenção de material de construção

Twenty vegetable fiber by-products from agro-industrial production of eight different commercial fibers were analyzed in this study. Based on previously established selection criteria, six main types of residue were identified. Results showed that the selected by-products may be used as reinforcement of fragile cementitious matrices, for ductility improvement. Tiles produced with composites reinforced by residual fibers of sisal baler twine, coir, eucalyptus pulp, malva, banana, or a mixture of coir fibers and eucalyptus pulp, supported flexural loads in excess of 680N in keeping with international specifications.

Durabilidade de compósito biomassa vegetal-cimento modificado por polímero

The durability of the cellulose-cement composites is a decisive factor to introduce such material in the market. Polymers have been used in concrete and mortar production to increase its durability. The goal of this work was the physical and mechanical characterization of cellulose-cement composites modified by a polymer and the subsequent durability evaluation. The work also evaluated the dispersion of acrylic polymer in composites made of Pinus caribaea residues. The physical properties observed were water absorption by immersion and bulk density. Rupture modulus and toughness were determined by flexural test. The specimens were obtained from pads, produced by pressing and wet curing. Samples were subjected to accelerated aging tests by repeated wetting and drying cycles and hot-water bath and natural aging. The scanning electron microscopy (SEM) allowed verifying the fiber and composite characteristics along the time. For the composite range analyzed, it was observed the polymer improved the mechanical properties of composites besides a significant decreasing in water absorption. The use of polymer improved the performance of vegetable fiber-cement composites when compared to the conventional mortar, due to water absorption decreasing.

Assessment of the Material Loss in Walls Renderings with β-Hemihydrate Paste

In civil construction, β-hemihydrate pastes have been used as decorative ornaments, plasterboards, dry-wall and renderings. The application procedure of β-hemihydrate pastes for rendering generates large amounts of waste due to its hydration kinetics. Waste production also occurs due to the technique of preparation and application of this material. It is essential to minimize gypsum waste. The aim of this work was to quantify the amount of gypsum waste produced by the process of using it as renderings. It was observed the influence of workers applying pastes rendering on gypsum waste production. The application process of plaster renderings was followed measuring the waste generated and the time for finishing the process was also observed. Results pointed out waste production values in the range between 16% and 47%. The application technique influences the amount of waste production.

Estudo do reaproveitamento de resíduos de construção em concretos empregados na fabricação de blocos

The use of construction and demolition waste (CDR) comes as an alternative for recycling, for costs reduction and for raw material. The CONAMA Resolution 307 (National Council for the Environment) establishes that all cities should find an environmentally correct destination to CDR. In this research the mechanical properties of the concrete containing CDR were analyzed aiming its use in the production of concrete blocks. Here, increasing percentages of aggregates of CDR with the same granulometry an substitute the natural aggregate, and then concrete blocks were molded. Tests were then performed in order to determine the compression strength according to NBR 12118:2007, at ages of 14 days and 28 days. It was noticed that the values resulting from the compression strength test were also influenced by the increasing substitution of CDR percentages to the mixture. This research discusses the great potential of using this material in substitution to the natural aggregates used in the production of concrete based materials such as blocks.

Steel and concrete bond stress: a contribution to the study of APULOT tests using concrete with rubber addition

Resumo The bond stress between steel and concrete is the essential condition to the good behaviour of reinforced concrete structures. To preview the use of concrete with waste incorporation for structural aims, the verification of its quality control is necessary, whether of compression strength and bond. This paper presents the study results about the viability use of APULOT tests, that is a bond tests, to prevent the compression strength of concrete with rubber addition. The purpose of APULOT tests become study in many laboratories in France and Brazil, where is to estimate the compression strength using the bond stress obtained in tests execute inside of building construction. Also the use of concrete with rubber addition to structural use has been made with safe because this kind of addition makes the concrete compression strength decrease. To study its compression strength behavior is also make part of this research. This work aims to contribute with standardization of APULOT tests, and also give conditions to use the concrete with rubber addition in structural elements with more safe.

Concrete Slab Value Stream Mapping of Brazilian Residential Buildings - a Lean Construction Study Case

Sustainable research inconstruction environments has being weakening more interest for theconstruction sector, due to visible wastes during the constructive processes.In this scenario, high costs and consumptions of unnecessary materials in the work activities are inserted also, which generate waste and customer dissatisfaction.The real knowledge of this situation can be present with the Lean Thinking concepts application. The scientific initiation research identifies, from the Value Stream mapping application, the structural elements processes and all the waste detected in their observation. This study case shows how to apply the lean principles, and presents your informally application in the Brazilian Company specifically. This study has an investigative character, and considers that the company applies just a part of the Lean principles. Therefore, the paper has as objective to present the application of VSM and the preliminary sustainable analyses too.

Finite element analysis of composite concrete-timber beams

In the search for sustainable construction, timber construction is gaining in popularity around the world. Sustainably harvested wood stores carbon dioxide, while reforestation absorbs yet more CO2. One technique involves the combination of a concrete slab and a timber beam, where the two materials are assembled by the use of flexible connectors. Composite structures provide reduced costs, environmental benefits, a better acoustic performance, when compared to timber structures, and maintain structural safety. Composite structures combine materials with different mechanical properties. Their mechanical performance depends on the efficiency of the connection, which is designed to transmit shear longitudinal forces between the two materials and to prevent vertical detachment. This study contributes with the implementation of a finite element formulation for stress and displacement determination of composite concrete-timber beams. The deduced stiffness matrix and load vector are presented along to numerical examples. Numerical examples are compared to the analytical equations available in Eurocode 5 and to experimental data found in the literature.

An Alternative to Paver in Living Areas of Social Interest Housing (SIH)

The waste rubber from tire have been employed as aggregate in concrete due to their distinct characteristics, such as: less density, drainage properties improve thermal and acoustic isolation in construction, beyond final cost production reduced. This way, the substitution of part of natural aggregate by tire rubber, contributes to the natural aggregates preservation and offer an alternative for recycling this kind of waste. In view of these advantages, this study proposes the utilization of tire waste in projects of Social Interest Housing. The project has as mailing objective the construction of unfamiliar housing (vertical and horizontal) for low income families, searching a conciliation of sustainable development: social, environmental and economic. Social development means the worry with that low income family have a basic infrastructure; environmental development is to minimize the natural resources impact available; and economics is to offer new jobs and costs opportunities. The purpose of study the incorporation of this kind of waste in concretes used for interlocked pavers for floor to construct Social Interest Housing, aims to solve the problems of adequacy of this housings, offering a semi-rigid pavement that have a large use in landscaping for floor manufacturing, low maintenance and do not require specialist worker to their installation.

Short steel and concrete columns under high temperatures

The growing demand for knowledge about the effect of high temperatures on structures has stimulated increasing research worldwide. This article presents experimental results for short composite steel and concrete columns subjected to high temperatures in ovens with or without an axial compression load, numerically analyzes the temperature distribution in these columns after 30 and 60 minutes and compares them with experimental results. The models consist of concrete-filled tubes of three different thicknesses and two different diameters, and the concrete fill has conventional properties that remained constant for all of the models. The stress-strain behavior of the composite columns was altered after exposure to high temperatures relative to the same columns at room temperature, which was most evident in the 60-minute tests due to the higher temperatures reached. The computational analysis adopted temperature rise curves that were obtained experimentally.

Brazilian Geological Sandstone Characterization and its Utilization as Aggregate in Structural Concrete

The sandstone extraction is an essential activity to the production of specific products. It is employed in the civil construction sector. However, there is still a deficiency in physical and geological characterization. This research develops two experiments in the sandstone matrix located in São Carlos region (City of São Paulo State – Brazil). The first experiment is related to the geological aspect of the specific sandstone. It identified the geographic location and investigated the porosity and absorption rates of the Brazilian sandstone rock, besides verifying its compressive strength. The purpose was to identify and evaluate possibilities of sandstone use in the structural concrete composition. The second experiment tested the concrete strength with this aggregate. Some quantities of crushed sandstone were used as fine aggregate in the manufactured concrete. The experiments presented sandstone properties and sandstone aggregate possibilities in concrete composition. The present study is a result of an undergraduate project, aiming to contribute with new information on the Brazilian sandstone characterization and concrete strength application with the sedimentary aggregate. This work showed some possibilities to use this type of yellow and red sandstone as aggregate.