Master pdf editor 5.7.20 crack cracked#

All concrete specimens were made of one concrete mixture: normal concrete based on Portland cement with a w/c ratio of 0.45 and a maximum aggregate size of 16 mm. Because of the short time between the main shock and the aftershock (hours, days), a PT-type polymer can be used as a temporary repair injection and confinement, replacing crushed concrete ( Figure 1c,d) and making visco-elastic hinge (with remained steel reinforcement), withstanding dynamic loads and introducing in the structure ductile and damping properties.ĬONCRETE.

Moreover, damages to columns after earthquakes (forming plastic hinges) requires a quick emergency repair before an aftershock.

Master pdf editor 5.7.20 crack cracked#

It can be used for the repair of cracked concrete surfaces ( Figure 2). It can be applied in cracks of concrete and RC elements making elastic (or nonlinear elastic) hinge, which is able to transfer bending loads and high deformation simultaneously, also under cyclic loads. This article presents experimental and numerical investigations of the most effective PT-type polymer for concrete repair.

The PM-type has the lowest and the PT-type the highest values of stiffness and strength, while the properties of the PS-type are between the other two types. Currently, PFJ research is focused on the application of PM-type, PS-type, and PT-type polyurethanes, which can be used as injection or prefabricated elements, named also as PUFJ (PolyUrethane Flexible Joints). Several types of PFJ are available, with tensile strength ranging from 1.7 to 20 MPa, and elongation at rupture between 10% and 120%. PFJ is based on polyurethane, which is a material with highly effective bonding and hyper-elastic properties. Therefore, it can be suitable for repairing damaged structures (mostly fragile building materials) as well as for joining new concrete elements. Polymer flexible joint is a method that allows effectively bearing the loads and absorbing large deformations at the same time. Recovering of strength and stiffness in damaged cross-sections leads also to the use of composite materials with various adhesives. Filling of cracks by external injection with bonding material such as epoxy resin or self-healing methods use mainly stiff and high strength, but hardly deformable materials, which generate stress concentrations in concrete weakened by micro-cracks. Cracked concrete is unable to transfer tensile forces thus various repair and strengthening methods of it are used. Earthquakes are the most serious excitations, resulting in concrete cracking and plastic, e.g., in infill structures ( Figure 1)-visible for a specimen tested on shake table. In addition, mechanical actions cause damage to concrete used in structural elements by overloading them. This results in damage of concrete components such as floors or roadways. Deformations caused by concrete shrinkage or temperature changes leads to local stress concentrations in the concrete. PFJ can therefore be considered an efficient repair method for connecting concrete elements.Įarly-age shrinkage as well as mechanical cracks in concrete are common problems in constructions. Furthermore, because of stress redistribution, connected elements can bear larger deformations than original ones. The application of flexible joint positively influences load capacity of the connected concrete elements. Particular attention was paid to the stress redistribution in concrete. The influence of flexible joint on concrete elements is described and behavior of elements repaired with PFJ is compared to original elements. The model is used to numerically analyze deformations and stresses under increasing load. A nonlinear numerical model is developed, which describes the behavior of concrete elements and polymer in the experiments. Based on the experimental results, the numerical characteristics of analyzed polymer and concrete were calibrated. The research program included flexural tests of plain concrete elements with a notch, as well as tests of elements which were repaired with PFJ after failure. An experimental investigation was conducted to determine the behavior of concrete in a four-point bending test. This article presents the possibility of applying PFJ on beams subjected to bending and describes the influence of such joints on concrete elements. Polymer Flexible Joint (PFJ) is a method for repairs of concrete elements, which enables carrying loads and large deformations effectively.