Eindringtiefe eines Hydrophobierungsmittels als Funktion der Qualität, des Feuchtigkeitsgehaltes und des Alters des Betons / Penetration depth of a water repellent agent as a function of quality, humidity and age of concrete

1999 ◽  
Vol 5 (3) ◽  
pp. 289-306
Author(s):  
H.A. Moetsch ◽  
St. Meier ◽  
A. Gerdes ◽  
F.H. Wittmann
Keyword(s):  
Building Materials ◽  
Concrete Surface ◽  
Water Repellent ◽  
Protective Measures ◽  
Capillary Suction ◽  
Treatment Need ◽  
Measuring Cell ◽  
National Highway ◽  
Different Types ◽  
Concrete Elements

Abstract Service life and lifetime of a concrete structure are not only depending on mechanical but also on chemical loads. Therefore precautions are often taken into account already in the planning- or construction phase. Certain protective measures such as water repellent treatment need preliminary tests on the finished concrete surface, in order to be applied in an optimal way . The present paper describes the preliminary tests performed on three tunnels of the second section of the Swiss National Highway N5 (Grenchen - Zuchwil) in the area of Solothurn. For the construction of the three tunnels different qualities of concrete and different types of form work were used. Furthermore the selected sections of the tunnels differ also from age and environmental conditions. A new two-chamber measuring cell developped at the Institute for Building Materials of ΕΤΗ-Zurich was applied to determine the capillary suction capacity of selected tunnel sections. Values measured on concrete elements in practice with this new cell are much more reliable than those measured with the traditional Karsten-cell.

scholarly journals Technical and economic efficiency of reinforced concrete elements with different types of reinforcement

2018 ◽  
Vol 196 ◽  
pp. 02030
Author(s):  
Ekaterina Efimenko ◽  
Liya Mailyan ◽  
Viktor Muradyan
Keyword(s):  
Reinforced Concrete ◽  
Building Materials ◽  
Full Employment ◽  
Concrete Columns ◽  
Longitudinal Force ◽  
Reinforcement Steel ◽  
Different Types ◽  
Effective Use ◽  
Concrete Elements ◽  
Economic Use

The article presents data on the bearing capacity of columns with various combinations of prestressed and conventional reinforcement. The areas of the most effective use of such structures with different eccentricities and flexibilities are shown. The ecology of reinforcement steel is an important task that the designers of reinforced concrete structures face. The creation of effective constructive solutions, that allow to combine high technical characteristics with economic use of reinforcement steel, has become urgent and is necessary for today's development of the construction industry. In the works [1,2,3,4,5] it was shown that the solution of these problems was possible by creating conditions for the full employment of building materials properties - reinforcement and concrete. The working reinforcement is characterized by its application in the conventional and prestretched forms. At the same time, the works done in the recent years show that reinforcement, subjected to precompression, can be used in the compressed zone [6,7,8]. It is most effective in rigid reinforced concrete columns. Thus, precompression of all longitudinal reinforcement or its part allows to increase the strength of non-flexible columns with not high relative eccentricities of the external longitudinal force. At the same time, in order to obtain the greatest effect caused by the precompression of the reinforcement, certain conditions must be observed.

Scanning electron microscopy of asbestos-containing material where the asbestos fibers are considered locked in a binder

1993 ◽  
Vol 51 ◽  
pp. 472-473
Author(s):  
J. R. Millette ◽  
R. S. Brown
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Environmental Protection Agency ◽  
Building Materials ◽  
The United States ◽  
Protection Agency ◽  
Asbestos Fibers ◽  
Different Types ◽  
Binder Material ◽  
Scanning Electron

The United States Environmental Protection Agency (EPA) has labeled as “friable” those building materials that are likely to readily release fibers. Friable materials when dry, can easily be crumbled, pulverized, or reduced to powder using hand pressure. Other asbestos containing building materials (ACBM) where the asbestos fibers are in a matrix of cement or bituminous or resinous binders are considered non-friable. However, when subjected to sanding, grinding, cutting or other forms of abrasion, these non-friable materials are to be treated as friable asbestos material. There has been a hypothesis that all raw asbestos fibers are encapsulated in solvents and binders and are not released as individual fibers if the material is cut or abraded. Examination of a number of different types of non-friable materials under the SEM show that after cutting or abrasion, tuffs or bundles of fibers are evident on the surfaces of the materials. When these tuffs or bundles are examined, they are shown to contain asbestos fibers which are free from binder material. These free fibers may be released into the air upon further cutting or abrasion.

Concrete Surface Quality Improvement Technique Using Highly Water Repellent Sealing Method

2016 ◽  
Vol 54 (11) ◽  
pp. 1105-1110
Author(s):  
K. Watanabe ◽  
G. Sakai ◽  
N. Sakata ◽  
T. Ishida
Keyword(s):  
Quality Improvement ◽  
Surface Quality ◽  
Concrete Surface ◽  
Water Repellent

Self-Healing and Repairing Concrete Cracks Based on Bio-Mineralization

2014 ◽  
Vol 629-630 ◽  
pp. 494-503 ◽  
Author(s):  
Chun Xiang Qian ◽  
Mian Luo ◽  
Li Fu Ren ◽  
Rui Xing Wang ◽  
Rui Yang Li ◽  
...  
Keyword(s):  
Concrete Surface ◽  
Cellular Respiration ◽  
Self Healing ◽  
Capillary Suction ◽  
Water Permeation ◽  
Carbonate Ions ◽  
Micro Cracks ◽  
Small Cracks ◽  
The Common ◽  
The One

In this paper, three bio-mineralization mechanisms were proposed to repair cement-based materials cracks. The common feature is that the three are all induced by bacterial. A type of bacterial which can decompose urea and release carbonate ions could be applied to repair micro cracks on concrete surface when combining calcium ions. But what need to be noted is that the way of repairing cracks is passive. Some alkaliphilic bacterial spores could be added to concrete when casted and two different types of bacterial were used to realize the function of self-healing. The sources of carbonate ions made them different, the one release carbonate dioxide through its own cellular respiration, the other could transfer carbon dioxide in air to bicarbonate. Coefficient of capillary suction, apparent water permeation coefficient and area repairing rate were applied to characterize the repairing effectiveness. The tests results were that all three bio-mineralization mechanisms showed excellent repair effect to small cracks formed at early ages. When the bacteria were immobilized by ceramsite, the self-healing effect could be improved for the cracks formed at late ages.

scholarly journals LiNbO3Coating on Concrete Surface: A New and Environmentally Friendly Route for Artificial Photosynthesis

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Ranjit K. Nath ◽  
M. F. M. Zain ◽  
Abdul Amir H. Kadhum
Keyword(s):  
Building Materials ◽  
Artificial Photosynthesis ◽  
Reaction Pathway ◽  
Research Work ◽  
Pollution Prevention ◽  
Environmentally Friendly ◽  
Concrete Surface ◽  
Concrete Material ◽  
Gas Phases ◽  
Work Done

The addition of a photocatalyst to ordinary building materials such as concrete creates environmentally friendly materials by which air pollution or pollution of the surface can be diminished. The use of LiNbO3photocatalyst in concrete material would be more beneficial since it can produce artificial photosynthesis in concrete. In these research photoassisted solid-gas phases reduction of carbon dioxide (artificial photosynthesis) was performed using a photocatalyst, LiNbO3, coated on concrete surface under illumination of UV-visible or sunlight and showed that LiNbO3achieved high conversion of CO2into products despite the low levels of band-gap light available. The high reaction efficiency of LiNbO3is explained by its strong remnant polarization (70 µC/cm2), allowing a longer lifetime of photoinduced carriers as well as an alternative reaction pathway. Due to the ease of usage and good photocatalytic efficiency, the research work done showed its potential application in pollution prevention.

Ruling out Change: Institutional Impediments to Transfer of Technology in Ship Building and Design in the Far East

Itinerario ◽  
1995 ◽  
Vol 19 (3) ◽  
pp. 142-152
Author(s):  
Bao Leshi
Keyword(s):  
Coastal Waters ◽  
Building Materials ◽  
Far East ◽  
Local Conditions ◽  
Ship Building ◽  
The Past ◽  
Transfer Of Technology ◽  
Construction Techniques ◽  
Different Types ◽  
Technological Tradition

In the Chinese technological tradition, no sector, apart from that of agriculture, is as rich in original ideas as naval architecture. Over the past three millennia, hundreds of different types of craft have been developed for use on China's shallow lakes, on its fast flowing rivers and along its often stormy coastal waters. Each type was developed for specific use as a means of transportation, and would seem to represent the ultimate answer to the challenges posed by local conditions. Ultimate answer, that is, within the limitations of the traditional building materials with which these boats were constructed and fitted out. Nor was ingenuity confined to construction techniques.

Nanocomposite Photocatalyst Based on Layered Double Hydroxides (LDHs) Associated with TiO2

2014 ◽  
Vol 92 ◽  
pp. 100-109 ◽  
Author(s):  
Jonjaua Ranogajec ◽  
Andrijana Sever-Skapin ◽  
Ognjen Rudic ◽  
Snezana Vucetic
Keyword(s):  
Photocatalytic Activity ◽  
Layered Double Hydroxides ◽  
Direct Contact ◽  
Building Materials ◽  
Specific Problem ◽  
The Self ◽  
Different Types ◽  
Double Hydroxides ◽  
Positive Effect ◽  
Material Porosity

The surfaces of building materials are constantly exposed to the actions of environmental factors, pollutants of inorganic and organic origin as well as to microorganisms, which significantly contribute to corrosion phenomena.The application of coatings decreases the negative action of the pollutants minimizing their direct contact with the substrate. Different types of coatings with additional functions have been developed. A specific problem of these applications is the lack of compatibility of the photocatalysts with the surface of the building materials and the detachment of potentially toxic TiO2nanoparticles. In the present study, this problem was solved by the proper immobilization of TiO2nanoparticles onto the photocatalyst support, layered double hydroxides (LDHs). The newly formed coating possesses acceptable porosity for a porous building material (porosity within the range of 30-46 %) and satisfied photocatalytic activity, as well as mineralogical compatibility with the substrates (mortars, renders, bricks). Additionally, a positive effect considering the self-cleaning phenomenon was attained.

scholarly journals Effects of Concrete Core Technological Defects on the Strength of Tube Confined Concrete Elements

2018 ◽  
Vol 7 (3.2) ◽  
pp. 376
Author(s):  
Oleksandr Semko ◽  
Olga Gukasian ◽  
Serhii Skliarenko
Keyword(s):  
Concrete Strength ◽  
Experimental Studies ◽  
Fracture Pattern ◽  
Confined Concrete ◽  
Concrete Core ◽  
Different Types ◽  
Technological Defects ◽  
Concrete Elements ◽  
Core Production ◽  
Physical And Mechanical Characteristics

The paper sums up a series of experimental studies describing the influence of most types of concreting common defects, such as core weakening: weak compression inclusions, voids, height heterogeneity of concrete. The basis of the experimental study is the research on the concrete core production conditions influence on tube confined concrete elements and the change in physical and mechanical characteristics of the elements. The concrete strength is estimated based on the results of the study of specially shaped samples with given dimensions. According to the results of concreting samples with different types of modeled defects (abnormalities) inspection, the most dangerous damages of the concrete core were identified and different variants of the height strength retrogression of the elements under study were analyzed. As a result, the degree and type of damage to the tube confined concrete elements core of the samples, which affect the fracture pattern, was established. 

Influence of TiO2 on Selfclean Bio Coating

2013 ◽  
Vol 315 ◽  
pp. 399-403 ◽  
Author(s):  
Nurulsaidatulsyida Sulong ◽  
Anika Zafiah Mohd Rus
Keyword(s):  
Contact Angle ◽  
Organic Contaminants ◽  
Concrete Surface ◽  
Waste Cooking Oil ◽  
Water Repellent ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
The Difference ◽  
Micro Features ◽  
Coated Surfaces

Treatment on the exposed surface to the environmental attack was studied based on biopolymer coating from waste cooking oil doped with a superhydrophilic filler of Titanium Dioxide (TiO2), known as TOP. TOP was found to affect the physical properties of the coated concrete surface in a systematic way. Contact angle measurements are interpreted with respect to nanoand micro-features existing on the surface of the water repellent superhydrophilic filler filled bio-polymer composite coating. The smooth coated surfaces of polymer filled or doped with superhydrophobic filler shows the systematic increasing static Waste Contact Angle, WCA (θst) and revealed that polymer filled superhydrophobic fillers by only 2.0 % shows the ability to form superhydrophobicity property. Scanning Electron Microscope (SEM) pictures revealed the difference between the concrete surface roughness of concrete biopolymer with and without TOP coating is to provide self-cleaning concrete biopolymer coating based on two principal ways: (1) the development of surface coating of semiconducting photocatalytic superhydrophilic. (2) If such a superhydrophilic is illuminated by light, then grease, dirt and organic contaminants will be decomposed and can easily be swept away by rain.

ASSESSMENT OF NATURAL RADIOACTIVITY LEVELS AND RADIOLOGICAL HAZARDS IN BUILDING MATERIALS

2020 ◽  
Vol 188 (3) ◽  
pp. 316-321
Author(s):  
Fei Tuo ◽  
Xuan Peng ◽  
Qiang Zhou ◽  
Jing Zhang
Keyword(s):  
Building Materials ◽  
Gamma Ray ◽  
Absorbed Dose ◽  
Gamma Ray Spectrometry ◽  
Absorbed Dose Rate ◽  
Radium Equivalent Activity ◽  
Radiological Hazards ◽  
Radium Equivalent ◽  
Different Types ◽  
Radioactivity Levels

Abstract Radioactivity of 226Ra, 232Th, and 40K were measured in a total of 92 samples, including eight commonly used types of building materials that were obtained from local manufacturers and suppliers in Beijing. Concentrations were determined using high-purity germanium gamma-ray spectrometry. The 226Ra, 232Th, and 40K activity concentrations in all samples varied from 10.1 to 661, 3.3 to 555 and 3.2 to 2945 Bq per kg with an average of 127.8, 114.8, and 701.5 Bq per kg, respectively. The potential radiological hazards were estimated by calculating the absorbed dose rate (D), radium equivalent activity (Raeq), external hazard (Hex), and internal hazard (Hin) indices. The investigated building materials were classified into different types according to the radioactivity levels. Results from this research will provide a reference for the acquisition, sales, and use of building materials. Attention should be paid to the use of coal cinder brick, ceramic, and granite in the construction of dwellings.

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