Strengthening - Special technical works
EANDAS | LABORATOR OF ANTISEISMIC EVALUATION | CHANIA CRETE
The company undertakes a wide variety of special technical projects and specialized structural repairs. Having years of experience in such projects and using only the best materials and the most contemporary equipment, we achieve the best result for our clients.
More specifically we are concerned with:
Strengthening – Restorations F.O. of Existing Structures
Improvements of Subsoil Foundations
Important techniques of strengthening the existing structures
Gunite or Shotcrete or Sprayed concrete concerns concrete of high resistance, which is implemented on the structure with a high pressure ejection. It usually contains increased cement content (compared to the injective concretes) and aggregates of small gradation. After its ejection from a nozzle, concrete is firstly applied onto a surface in order to form a concrete layer. Then the sprayed concrete, after the ejection, is coated and becomes flattened, so as to provide a final flat surface where needed. The way concrete is ejected is the most important factor for the proper completion of the project. This method is mainly used to enhance especially the most serious damage of the structural elements of a building, such as columns, beams, sheets, foundations, walls, bearing walls, masonry, etc.
There are two methods for shotcrete’s production, the dry and the wet process. In both methods, the mixture is transferred by elastic hoses with the help of an air- compressor until the intervention point.
Dry method: the mixture is prepared in the construction site, where the dry ingredients of concrete (cement, aggregates) are mixed and put into the blasting machine and after water is added the mixture is ready to exit the nozzle.
Wet method: after the mixture gets prepared by a concrete production plant, comes ready in the construction site, containing all the necessary ingredients (cement, aggregates, water). After that, the mixture is plumbed into the liquid gunite machine and directly is ejected. This method presents more advantages over the dry one, as the product’s quality remains stable and high, while the losses are minimized.
// It may be ejected even on vertical surfaces or surfaces with of slopes
// The same satisfying result is achieved, only with smaller layers’ thickness compared to cast concrete
// Better adjustment and adherence to the already existing concrete is achieved due to the high pressure of the ejection
// Due to the low rate of water / cement, it has high amounts of resistance
// No formwork is needed
|Cement - Resin Injections
The technique of Cement Injections is used for the restoration and the reinforcement of masonry and stonework. It is a new repairing technique applied so as to achieve the welding of damaged concrete. After having sealed the joints of the masonry and having installed tubes on a grid, the content of the cement injection is prepared and ready to be used, in order to fill the gaps inside the walls.
// Quick and safe repair of cracks
// Reliable strengthening of construction
// Complete restoration of underground walls
// Easy stabilization of soils
The Resin Injections is a repairing technique, which is applied to restore cracks existing in the concrete. The type of epoxy materials - resins vary regarding their applications and characteristic properties. Firstly, the crack is sealed and there are nozzles placed at regular spots. Then the epoxy resin is injected and thus the cracked concrete has successfully been welded.
// Reliable structural repair
// Short time of completion (maximum: 48 hours)
// They present little shrinkage and low degree of creep
// Extremely high structural strength
// They do not affect the dimensions of the components that are to be implemented
|Carbon Fibers (FRP)
Carbon fibers composites concern materials, which are manufactured by of carbon whose levels of strength are very high. Main application is to strengthen columns, beams and sheets, as they increase the bending and shearing ability of the supporting elements.
Appear in two forms, carbon fabrics and carbon panel. Both types of materials are glued to epoxy resin in the external side of the supported element. Carbon fibers are applied to strengthen columns, sheets, beams etc and applied with the help of special epoxy resins on one, two or more layers.
Compared to the traditional support interventions, such as adhesion of thin steel plates or sprayed concrete, fiber reinforced polymers produce equivalent results in terms of strength, while showing significant advantages.
// Low weight
// Easy installation and swift implementation
// High tensile strength
// Durable, resistant to moisture, corrosion and fatigue
// Minimal alteration of architectural construction
// They do not affect the static stiffness of the structure
|Metallic Cages - Metallic Envelopes
The technique of the metal cage is the most common procedure for applying an enclosure. At the brace’s corners there are four metal corner plates and some horizontal metal strips applied which are welded angularly for their enclosure. The gaps between the corners and the concrete are covered by non-shrinking plaster or epoxy glue.
// Possibility of transport a section of the vertical loads of the column
// Quick implemented technique
// Appropriate temporary solution for the direct assumption of vertical loads on implements that were damaged and are no longer able to carry axial loads
The technique of the metallic envelope is the most practical way to impose the enclosure. This is the main reason why the application of this technique is spreading rapidly. This method comprises welding the metal plates (usually two plates whose cross section creates a Π on either side of the pole ), around the existing column, with epoxy resin. The plates are mounted in horizontal direction, thereby contributing to the element's enclosure and increasing its shearing strength.
// The prevention of peeling the coating of concrete
// The development of side support to the longitudinal reinforcement
// The increase in strength and plasticity of concrete
The 3D Panels concern panels of expanded polystyrene and form the new frame of masonry construction. They are placed in conjunction with structural grid in and out of the frame, while the rest of the shell's coating process remains the same (plasters, painting, tiling, etc.). The 3D panels are mainly used for masonry in composed manufactures with structures of metal components, in the existing bearing organizations of reinforced concrete, for masonry of buildings with spraying concrete, to stone structures, and many others.
Uses of 3D Panels
// For masonry in composited structures with load-bearing bodies (frames) metallic elements
// In existing bearing bodies (frames) of reinforced concrete
// For masonry of buildings with spraying concrete (wet or dry mixture of gunite)
// For masonry of buildings
// Buildings by injecting concrete into metallic or wooden formwork
// Stone construction with metal frame or reinforced concrete
// Transportable structures (rooms-homes-churches)
// Lower manufacturing costs by at least 30%
// Modern technology to industrialization of construction's worksite
// Speed of construction
// Architectural construction without any restrictions or any further charge to the cost of construction
// Multiple application fields
// Ability to build to the most inaccessible areas