BOND CONNECTIONS OF HIGH PERFORMANCE CONCRETE (HPC) AND STEEL: "EXPERIMENTAL VERIFICATION OF SELECTION GLUED FOR TWO DIFFERENT SURFACES OF STEEL"

This article deals with the test of selected adhesives for glued connection of high performance concrete and steel plates with various surface treatments. Results of this experiment can be used as a basis for the possible anchoring of concrete facade elements to the steel grate, the possible bonding of steel anchors on the surface of concrete facade elements. High performance concrete is a concrete that exceeds the compressive strength 100 MPa after 28 days. The second adherent is the uncoated steel and the steel with zinc coating as a second variant. Samples were tested in two different ways. The first experiment verified the single tensile strength of bond connection. The second test verified the shear strength, which is very important for connection designing

BOND CONNECTIONS OF HIGH PERFORMANCE CONCRETE (HPC) AND STEEL: "EXPERIMENTAL VERIFICATION OF SELECTION GLUED FOR TWO DIFFERENT SURFACES OF STEEL"

This article deals with the test of selected adhesives for glued connection of high performance concrete and steel plates with various surface treatments. Results of this experiment can be used as a basis for the possible anchoring of concrete facade elements to the steel grate, the possible bonding of steel anchors on the surface of concrete facade elements. High performance concrete is a concrete that exceeds the compressive strength 100 MPa after 28 days. The second adherent is the uncoated steel and the steel with zinc coating as a second variant. Samples were tested in two different ways. The first experiment verified the single tensile strength of bond connection. The second test verified the shear strength, which is very important for connection designing

EXPERIMENTAL VERIFICATION OF IMPREGNATED TEXTILE REINFORCEMENT SPLICING BY OVERLAPPING

This paper presents an experimental verification of impregnated textile reinforcement splicing by overlapping using tensile test of small textile reinforced concrete slabs before its using in the product. The specimen dimensions were designed 80×360mm and thickness approximately 18 mm. This specimen was reinforced using two pieces of impregnated flat technical fabric from carbon roving and epoxy resin. Two overlap lengths were designed using data from previous cohesion tensile tests and necessary anchoring length. The purpose of this experiment was experimental verification before flat reinforcement splicing by overlapping on the final product – furniture with textile reinforcement. This paper shows possible problems and complications in the anchoring of the textile reinforcements and in splicing by overlapping, the importance of the accuracy reinforcement position in the thin concrete cross-sectional area

Family House

katedra architektur

Reinforced L-Shaped Frame Made of Textile-Reinforced Concrete

Textile-reinforced concrete is becoming more and more popular. The material enables the realization of very thin structures and shells, often with organic shapes. However, a problem with this reinforcement occurs when the structure is bent (contains a corner), and the flexural stiffness around this bent area is required. This article presents the design, solution, and load-bearing capacity of an L-shaped rigid frame made of textile-reinforced concrete. Basic material parameters of concrete matrix and carbon textile reinforcement were supplemented by a four-point bending test to calibrate fracture energy Gf, critical compressive displacement Wd, solver type, and other parameters of a numerical model created by Atena Engineering in specialized non-linear structural analysis software for reinforced concrete structures. The calibrated numerical model was used to evaluate different variants of carbon textile reinforcement of the L-shaped frame. The carbon textile reinforcement was homogenized using epoxy resin to ensure the interaction of all fibers, and its surface was modified with fine-grained silica sand to increase the cohesion with the concrete matrix. Specimens were produced based on the most effective variant of the L-shaped frame reinforcement to be experimentally tested. Thanks to the original shaping and anchoring of the reinforcement in the corner area, the frame with composite textile reinforcement is rigid and can transmit the bending stresses in both positive and negative directions. The results of the mechanical loading test on small experimental specimens correspond well to the results of numerical modeling using Atena Engineering software

COHESION TEST OF A SINGLE IMPREGNATED AR-GLASS ROVING IN HIGH-PERFORMANCE CONCRETE

The development of light and very thin concrete building structures and demand for extremely thin elements in design are inter alia reasons for the development of composite materials as non-traditional reinforcement. Composite materials are currently used as reinforcement mostly in the form of fiber reinforced polymer bars similar to traditional steel reinforcement bars, but the last decade sees also rise in the use of technical textiles. This article is focused on the interaction between impregnated textile reinforcement and high-performance concrete matrix and its easy determination using originally modified pullout test. The second aim of this article is improvement of interaction conditions between reinforcement and cementitious matrix using fine-grained silica sand applied on the surface of the composite reinforcement similarly to the traditional fiber reinforced polymer reinforcement with commonly used diameters. To investigate an effect of this modification a bending test was performed on small thin concrete slabs with different amounts of reinforcement

Experimental Evaluation of Carbon Reinforced TRC with Cement Suspension Matrix at Elevated Temperature

Textile-reinforced concrete (TRC) is a new composite material comprising high-performance concrete and textile reinforcement from textile yarns with a matrix, usually consisting of epoxy resins (ER). The most significant advantage of ER is the homogenization of all filaments in the yarn and full utilization of its tensile potential. Nevertheless, ER matrix is a critical part of TRC design from the perspective of the fire resistance due to its relatively low resistance at temperatures of approximately 120 ∘C. This work expands the previously performed mechanical tests at normal temperatures with cement suspension (CS) as a non-combustible material for the yarn matrix. Here, the mechanical properties of CS matrix at elevated temperatures were verified. It was found that the addition of polypropylene fibers into HPC negatively affected the mechanical results of CS matrix specimens. Simultaneously, thermal insulation effect of the covering layers with different thicknesses did not significantly influence the residual bending strength of specimens with CS matrix and achieved similar results as reference specimens. Furthermore, all specimens with ER matrix progressively collapsed. Finally, CS as a textile reinforcement of yarn matrix appears to be a suitable solution for increasing the temperature resistance of TRC structures and for substituting synthetic resins

The Structural Use of Recycled Aggregate Concrete for Renovation of Massive External Walls of Czech Fortification

The use of recycled aggregate concrete is mainly negatively affected by its poorer mechanical and long-term properties. However, there are few structural applications for which recycled aggregates can be used. In this case study, the possibility of use as massive external reinforcement wall is verified. For this structural application, the most important characteristics are freeze–thaw resistance, and carbonation resistance and then the mechanical properties such as compressive strength. Durability characteristics of the materials have been tested and improved in the study. The mechanical properties and durability of recycled aggregated concrete have been verified and crystalline mixture has been used to improve durability. The specific structural application of the massive external reinforcement wall is for the renovation of the Czech WW2 concrete fortification, which is one of the most important cultural heritages of the Czech Republic of the 20th century. However, these buildings have not yet been professionally rebuilt, but this research project aims to change this trend. The thickness of the bunker wall is between 0.5 and 3.5 m (depending on the type of bunker) which leads to a huge amount of concrete and primary resources consumption; however, the security function is not necessary today, so the reconstruction could be provided by recycled aggregate concrete. The results showed a positive effect of the crystalline mixture on the essential properties of recycled aggregate concrete. Recycled aggregate concrete with a complete replacement of aggregate by recycled concrete or masonry aggregate is possible to use for the reconstruction of the Czech WW2 concrete fortification and save natural aggregate as a primary resource