Ctislav Fiala

Cohesion of Composite Reinforcement Produced from Rovings with High Performance Concrete

The reinforcement of concrete with composite technical textile creates a tensile load-bearing capacity. It allows the elimination of steel reinforcement and minimisation of concrete cover. Based on this, the concrete cover is designed with respect to the cohesion of reinforcement with concrete. By using of textile reinforcement very thin structures could be created. The aim of this paper was to determine the interaction conditions of carbon and basalt composite reinforcement in a matrix of epoxy resin with high performance concrete (HPC). The tensile strength of used composite reinforcement and the other mechanical parameters of HPC were determined by experimental tests. Experiments copied the production method of technical textiles. These two combinations of materials present the influence on the design of the structures with textile reinforcements.

Evolution from High Strength Concrete to High Performance Concrete

High strength concrete for the production of concrete railway sleepers was designed more than 20 years ago. The compressive strength of the concrete was very high from the start, but flexure strengths showed some irregular development - a decrease in time. Later, also a significant decrease of fracture properties was recorded. Microcracking was found to be the reason for this; therefore some modifications were performed to avoid this happening (especially the reduction of the maximum size of aggregates from 22 mm to 16 mm or 11 mm). Some problems concerning frost resistance of the concrete with a slag addition were reduced by applying ternary binders. All of the results are discussed from the point of view of a long-term observation of the strengths and fracture properties ́ development during the time period of 5 years or even more.

Construction and Static Loading Tests of Experimental Subtle Frame from High Performance Concrete for Energy Efficient Buildings

Mechanical properties of high performance concrete (HPC) enable design of subtle structural elements. Subtle HPC frame concept comes from the effort to integrate load bearing elements into building envelope in order to reduce risks of thermal bridges. Substantial advantages of subtle structural elements are material and energy savings during production, transportation, manipulation and assembling. Paper presents implementation of construction of experimental frame at University Centre UCEEB in Buštěhrad. Individual structural elements were made in prefa plant ŽPSV a.s. in Litice nad Orlicí and Čerčany, the company also assembled the experimental frame. The frame was built from February to April 2016. Within June and July, the construction was tested by static loading test, which partial results are presented in the paper. Accomplished calculations, experimental verification and analysis show that subtle HPC frame is the effective solution from reliability aspects as well as from environmental and economical parameters.

Experimental Verification of Subtle Frame Components Prototypes from High Performance Concrete for Energy Efficient Buildings

Mechanical properties of high performance concrete (HPC) enable design of subtle structural elements. Subtle HPC frame concept comes from the effort to integrate load bearing elements into building envelope in order to reduce risks of thermal bridges. Substantial advantages of subtle structural elements are material and energy savings during production, transportation, manipulation and assembling. Paper presents preparation and implementation of construction of experimental frame at University Centre UCEEB in Buštěhrad. Individual structural elements were made in prefa plant ŽPSV a.s. in Litice nad Orlicí. Construction of frame prototype is the result of long term research when the vertical and horizontal structural elements and their connections were successively designed and experimentally verified. This article shows experimental results of horizontal load bearing structures - floor panels and beams - in detail. Samples were tested by four-point bending test and also creep of floor panels was measured. Accomplished calculations, experimental verification and analysis have showed that subtle HPC frame is the effective solution from reliability aspects as well as from environmental and economical parameters. Minimal columns cross sections enable their complete implementation into building envelope and they also contribute to high quality architectonic solution of buildings interiors.

High Performance Concrete for Environmentally Efficient Building Structures

Concrete is the most used man made material nowadays. The environmental impact associated with cement production is very significant due to the extent of concrete use. At the same moment cement production is associated with large energy consumption and high amount of greenhouse gas emissions. Development of concrete technology during last twenty years has lead to a significant quality shift of technical parameters and also of related environmental impacts. New types of optimized concrete mixes have significantly improved characteristics from the perspective of strength, mechanical resistance, durability and resistance to extreme loads. The use of alternative non-steel reinforcement from various types of fibres can increase reliability, durability and reduction of environmental impacts. Due to optimization of production technology, concrete is gradually becoming a building material appropriate and advantageous for sustainable construction of buildings. In this context increase of reliability and durability within whole life cycle is essential. New approaches in concrete technology like utilization of high performance and ultra high performance concretes, use of textile reinforcement, shape optimization and conceptual approach for integrated life-cycle assessment of concrete structures are presented in the paper. Some of principles are demonstrated on results of experimental research performed by author and his team at the Czech Technical University in Prague (CTU).

High Performance Concrete as a Sustainable Material

Concrete is after water the second mostly used material and the most widely used construction material in the world. The production of cement creates more than 7% (calculated from WBCSD data) [7] of worldwide man–made CO2 emissions. Therefore optimization of concrete structures can lead to the significant environmental savings. Experimental investigation and case studies performed by authors in the frame of long term research, focused on environmental optimization of building structures, support the expectation that it will be possible to reach factor 3 or even more through utilization of high performance concrete (HPC) while keeping structural reliability on the needed high level. Developed structural concepts have been proved not only by theoretical and experimental results, but also by practical application in construction of several buildings. Paper presents three case studies — ribbed / waffle floor structure with minimized thickness of upper deck to 30 mm, light precast RC balcony element and light ...