DSpace Collection:https://repositorio.ufu.br/handle/123456789/190222026-04-17T19:06:28Z2026-04-17T19:06:28ZAnálise experimental de blocos sobre duas estacas metálicas com armadura metálica e não-metálica de barras de polímeros reforçada com fibra de vidro (GFRP)https://repositorio.ufu.br/handle/123456789/484492026-03-04T06:26:06Z2026-02-06T00:00:00ZTitle: Análise experimental de blocos sobre duas estacas metálicas com armadura metálica e não-metálica de barras de polímeros reforçada com fibra de vidro (GFRP)
Abstract: Pile caps are fundamental structural elements in deep foundation systems, responsible for transferring loads from the superstructure to the piles. Due to their typical exposure to aggressive environments, such as high moisture conditions, these elements are prone to deterioration associated with steel reinforcement corrosion, which motivates the investigation of more durable reinforcement alternatives. In this context, this study experimentally evaluated the structural behavior of rigid pile caps supported by two steel piles, designed according to the strut-and-tie method, comparing models reinforced with CA-50 steel bars and glass fiber-reinforced polymer (GFRP) bars. All models were designed with identical geometry, loading conditions, and concrete strength, varying only the type and distribution of the main tensile reinforcement. The experimental program included material characterization tests, load tests up to failure, and detailed instrumentation to monitor strains, displacements, crack development, and load distribution at the supports. The results showed that steel-reinforced pile caps exhibited behavior consistent with rigid block assumptions, presenting lower deformations and better crack control. Conversely, GFRP-reinforced pile caps showed larger deformations and crack widths, indicating a more flexible structural response, even when designed using the same criteria. It was also observed that distributing the GFRP reinforcement along the entire length of the tie resulted in improved structural performance compared to concentrating the reinforcement only in the anchorage region. The study concludes that the use of GFRP bars in pile caps is structurally feasible in terms of ultimate strength; however, additional design criteria related to deformation and crack control are required.2026-02-06T00:00:00ZEstudo do coagulante tanfloc e do coagulante sulfato de alumínio no tratamento de efluente de laticíniohttps://repositorio.ufu.br/handle/123456789/480192026-01-15T06:32:27Z2025-12-12T00:00:00ZTitle: Estudo do coagulante tanfloc e do coagulante sulfato de alumínio no tratamento de efluente de laticínio
Abstract: The increase in demand for water and the need for adequate treatment of industrial effluents
have encouraged the search for more efficient and sustainable processes. In the dairy industry,
which generates effluents with high organic load, color, and turbidity, coagulation and
flocculation are essential steps for the removal of particles and organic matter, and the choice
of coagulant is decisive for the performance of the treatment. In this context, this study
compared the chemical coagulant aluminum sulfate to the natural coagulant Tanfloc in the
removal of color and turbidity from dairy effluent, through tests in Jartest equipment and the
preparation of coagulation diagrams to define the ideal pH and dosages, complemented by
digital image analysis to evaluate the characteristics of the flocs formed and sedimentation
behavior. The results indicated that aluminum sulfate showed good removal, but required strict
pH correction and higher dosages, implying an increase in input consumption and the
production of sludge with a higher metal content. Tanfloc, on the other hand, showed efficiency
in wider pH ranges and at lower dosages, in addition to generating less sludge, with
biodegradable characteristics. Although Tanfloc has a higher unit cost, its application can
reduce indirect operating costs and environmental impacts. It can be concluded that Tanfloc is
a promising and sustainable alternative to aluminum sulfate, especially in systems that seek
efficiency combined with waste reduction and operational simplification.2025-12-12T00:00:00ZEfeito de aditivos superplastificantes em argamassas de revestimento com fíler calcário e incorporadores de arhttps://repositorio.ufu.br/handle/123456789/479092025-12-20T06:26:25Z2025-11-18T00:00:00ZTitle: Efeito de aditivos superplastificantes em argamassas de revestimento com fíler calcário e incorporadores de ar
Abstract: The use of superplasticizers can influence the properties of mortars in both the fresh and
hardened states, as well as the tensile bond strength when applied to a substrate. This study
aims to evaluate the effect of different superplasticizing admixtures on the applicability of
rendering mortars. Four base compositions were evaluated: (i) cement (C10), (ii) 30% cement
replacement by limestone filler (C40), (iii) an air-entraining admixture (IA), and (iv) a
plasticizing and stabilizing admixture (PE); each was tested both without and with the addition
of one of three superplasticizers: a lignosulfonate-based (A) and two polycarboxylate ether
based types (B and C). The investigation was conducted in three stages: (1) on pastes to evaluate
the influence of superplasticizers on hydration kinetics via isothermal calorimetry; (2) on
mortars to determine their impact on fresh and hardened properties; and (3) on mortar
applicability to evaluate how the admixtures affect rendering application procedures and the
properties of the mortar–substrate system. In the first phase, sixteen pastes mixtures with a
water–binder ratio of 0.50 were tested. For the mortar phase, a 1:4 (cement: sand) volumetric
mix proportion was used as the reference. Fresh mortar properties evaluated included bulk
density, entrained air content, and water retention capacity. At 28 days, hardened properties
was assessed, including flexural tensile strength, compressive strength, dynamic modulus of
elasticity, and capillary water absorption. In the third phase, selected mortars were applied by
a professional workmanship onto ceramic brick panels and subsequently tested for fresh and
hardened state properties, as well as tensile bond strength tests. The results indicated that the
superplasticizer admixtures influenced the hydration kinetics of the pastes, increasing the
dormant period and thereby retarding hydration; this retarding effect was most pronounced for
the lignosulfonate-based admixture (A). In the mortar study, admixture A yielded lower
mechanical strength compared to the polycarboxylate-based admixtures (B and C). Conversely,
superplasticizers B and C increased flexural tensile strength. The use of superplasticizers
delayed the the setting time in all pastes mixtures.In mortars, the use of superplasticizers
improved performance in both fresh and hardened states and increased the tensile bond strength.2025-11-18T00:00:00ZEstudo da aderência entre concreto e aço de alta resistênciahttps://repositorio.ufu.br/handle/123456789/479072025-12-20T06:26:09Z2025-09-08T00:00:00ZTitle: Estudo da aderência entre concreto e aço de alta resistência
Abstract: Reinforced concrete is the most widely used structural material worldwide, and the search for greater efficiency and sustainability has driven the development of high-performance materials, such as new high-strength steels bars. This paper presents an experimental study on the bond behavior between CA-70 high-strength steel (fyk = 700 MPa) and self-compacting concrete of different strength (C1, C2, and C3), using conventional CA-50 steel as a reference. The main objective was to analyze the bond stresses and failure modes, aiming to provide support for the safe application of this new material, which is not yet covered by the Brazilian standard NBR 6118 (ABNT, 2023-a). To this end, an experimental program was developed with direct pull-out tests on 36 cubic concrete specimens, using straight steel bars of the two categories with diameters of 10 mm, 12.5 mm, and 16 mm. The results indicated that CA-70 steel, in most scenarios, resisted pull-out forces greater than those of CA-50, especially in high-strength concrete (C2 and C3). However, this research observed a change in the mode of failure in conventional strength concrete (C1) for 16 mm bars, while CA-50 steel tended to yield and exhibit ductile failure by tearing, CA-70 steel suffered brittle failure by cracking the concrete with lower applied loads. It is concluded that, although the use of CA-70 steel is promising for optimizing structural designs, its application requires careful analysis of the failure mode, as simply replacing CA-50 can reduce ductility under certain conditions.
Keywords:2025-09-08T00:00:00Z