Pavel Mec

Alkali-Activated Building Materials Based on Blast Furnace Slag and Non-Standard Aggregates

Alkali-Activated Building Materials Based on Blast Furnace Slag and Non-Standard Aggregates This paper deals with alkali activated materials based on fine grained granulated blast furnace slag. Waste aggregates from building materials and building demolition are used as the filler. Its mechanical and durability parameters are tested. Results may contribute to further alkali activated system development and research focused on practical applications in the building industry. Alkalicky Aktivované Stavební Hmoty na Bázi Vysokopecní Strusky a Nestandardního Kameniva Příspěvek se zabývá alkalicky aktivovanými materiály na bázi jemně mleté granulované vysokopecní strusky. Současně jsou v těchto hmotách jako plnivo použity odpadní suroviny jak z výroby a úpravy stavebních surovin a hmot, tak také z oblasti demolic staveb. Vytvořený materiál je testován na mechanické a trvanlivostní parametry. Výsledky mohou přispět k dalšímu výzkumu a vývoji alkalicky aktivovaných systémů se zaměřením na praktické využití ve stavebnictví.

Stiffness analysis of glued connection of the timber-concrete structure

Abstract This paper presents results of experimental and mathematical analysis of stiffness characteristics of a composite timber-concrete structure. The composite timberconcrete structure presented herein is non-typical compared to similar types of building structures. The interaction between the timber and concrete part of the composite cross-section is not based on metal connecting elements, but it is ensured by a glued-in perforated mesh made of plywood. The paper presents results of experimental and mathematical analysis for material alternatives of the solution of the glued joint. The slip modulus values were determined experimentally. Data obtained from the experiment evaluated by means of regression analysis. Test results were also used as input data for the compilation of a 3D model of a composite structure by means of the 3D finite element model. On the basis of result evaluation, it can be stated that the stress-deformation behaviour at shear loading of this specific timber-concrete composite structure can be affected by the type of glue used. Parameters of the 3D model of both alternative of the structure represent well the behaviour of the composite structure and the model can be used for predicting design parameters of a building structure.

Analysis of the high way tunnels monitoring using an optical fiber implemented into primary lining

Abstract This article is focused on the analysis of the use of distributed fibre-optic technology for security monitoring of road tunnel and motorway tunnel structural load. The authors focused on the measurements of deformation utilizing Brillouin Time Domain Reflectometry (BOTDR). The principle is based on the measurement of stimulated Brillouin scattering. The article describes and analyses real measurements within a period of 5 months, which were carried out during the tunnelling and the whole process of building a new tunnel in Žilina, Slovakia. The performed experimental measurements were carried out using a standard optic telecommunication cable with water-absorbing aramid yarns and a jacket with a diameter of 4.2 mm. The contribution of this article lies in the introductory analysis of the implementation and use of the fibre-optic technology for security monitoring of road tunnel and motorway tunnel structural load.

Preparation and Properties of Pressed Metakaolin and Fly Ash Based Alkali-Activated Binders

Metakaolin, fly ashes and other secondary raw materials serves as suitable input in preparation of alkali-activated binders. This work deals with preparation of alkali-activated materials based on metakaoline and fly ash. Mixtures were prepared with a minimum of mixture water, ready for pressing. Prepared specimens were tested for tensile strength and pressure strength, resistance to high temperatures, frost resistance and resistance to water and salt.

Application of Thermal Analysis for the Quantification of Mineralization in Surface Wooden Layers

Natural and artificial wooden mineralization leads to mineral particles deposition which positively affects certain properties. An evaluation of mineral content is therefore important. This study is focused on the application of thermal analysis for quantification of mineral content in surface wooden layers. Suitability of methodology used for specimen preparation and testing, and also derived relationships are confirmed by the example of artificial mineralized wood by organosilane.

Sensor system based on the Mach-Zehnder interferometer for the rail transport

The article describes the use of fiber-optic interferometer in the rail transport. We proposed a measuring sensor system based on the Mach-Zehnder interferometer. The basic tracked parameter of vehicles are detection (count of vehicles). The proposed system was tested in the real tram traffic. Altogether, 435 vehicles were detected with 100 % success. The basic advantages of the solution include immunity to electromagnetic interference (EMI) and the ability to remotely evaluate information about the traffic.

FBG strain sensor mounted on plastic carrier

Fiber optic Bragg gratings are among the most widely used fiber optic sensors. It uses in dangerous explosive environments thanks to the electrical passivity of the sensor itself, but also in applications with high electromagnetic disturbance. Maintaining immunity of the sensor to electromagnetic interference requires non-electrical encapsulation material. This paper describes the encapsulation of the FBG sensor on a plastic plate fixed by gluing to the monitored structure. The proposed FBG sensor is suitable for measuring deformations or vibrations of iron and concrete structures. Due to the material used, the FBG sensor keeps resistance to electromagnetic interference, humidity, and corrosion. The results show the almost equal sensitivity of FBG strain sensors mounted on a metal carrier when measuring very small deformations and vibrations. The proposed FBG sensor concept reduces the cost of its manufacturing by using a 3D printer to produce the plastic carrier.

Standard optical fibers for load measuring of concrete structures using BOTDR

Distributed fiber optic systems based on Brillouin Time Domain Reflectrometry BOTDR offer an exclusive solution for monitoring the load of large building structures such as buildings, bridges, tunnels, etc. Deformation measurements use special optical cables with added reinforcement element and a closer bond between cable jacket and fiber optic to achieve high sensitivity to mechanical deformation. Alternatively, cheaper standard optical fiber cables with single-fiber optic fibers are used. Alternatively, there is possible to use cheaper standard optical cables with single mode optical fibers. The paper deals with the analysis of the suitability of standard optical cables for the deformations measurement using a distributed BOTDR system. Several standard types of telecommunication optical cables were implemented into concrete beams and bent in a hydraulic press. The main result of this paper is the deformation sensitivities determination of optical cables for load measurement and the suitability analysis for embedding into the concrete beam with regard to long life.

Standard optical cables for building structures monitoring with BOTDR in harsh environments

A fiber optic distributed system based on Brillouin scattering (BOTDR) is an interesting alternative for the load monitoring of building structures and line structures. For the purpose of monitoring deformations, special fiber optic cables with a close bond between optical fibers and cable protective elements are specified. It turns out that standard telecommunication optical cables can be used for some applications in the civil engineering. This paper provides an analysis of the impact of using these cables in harsh environments that is an integral part of engineering structures. The primary interest of this paper is the study of the influence of excessive humidity and temperature variation on the life and optical properties of standard cables implemented in building structures for measurement applications. The results are derived from long-term testing of standard fiber optic cables implemented in concrete structures in harsh environments to determine the suitability of using these cables for the reliability of long-term monitoring of building structures such as buildings, bridges or tunnels.

Numerical modeling and measurement of polydimethylsiloxane deformation with fiber Bragg grating sensor

This paper deals with mechanical properties of polydimethylsiloxane (PDMS) as material for preparation of deformation sensors. PDMS is widely used especially in medical area. Some application of PDMS as material for preparation of deformation sensors with fiber optics has been prepared. Due to its hyper-elastic and viscoelastic of this material is complicate to use it with long time and large deformation mechanics. In this paper authors compare the numerical models of prepared sensor using hyper-elastic models and mechanical experiment at large deformation.