Wyniki wyszukiwania - BazTech

1

Design principles and testing of internal frost resistance of concrete for road structures critical review

Glinicki M. A., Jaskulski R., Dąbrowski M.

Roads and Bridges - Drogi i Mosty

|

2016

|

Vol. 15, no. 1

21--43

PL

Przedstawiamy przegląd wymagań na beton mrozoodporny zgodny z normami europejskimi oraz specyfikacjami krajowymi, stosowanymi w budownictwie drogowym. Rozpatrujemy zasady doboru składników mieszanki betonowej. Omawiamy lokalne zróżnicowanie agresywności klimatu w zimie i zasięg oddziaływania mrozu w elementach konstrukcji drogowych. Analizujemy charakterystyczne parametry procedury bezpośredniego oznaczania wewnętrznej mrozoodporności, zwłaszcza szybkość ochładzania. Rozkład temperatury w próbkach w trakcie normowych testów mrozoodporności został wyznaczony w dwóch różnych laboratoriach akredytowanych. Przedstawiamy też dyskusję kryteriów oceny mrozoodporności oznaczanej metodą pośrednią - na podstawie charakterystyki porów w betonie napowietrzonym. Na podstawie pomiarów rozkładu temperatury w próbkach postulujemy modyfikację procedury normowej, aby jednoznacznie ustalić szybkość ochładzania. Pożądane jest wyróżnienie stref agresywności oddziaływania mrozu i soli odladzających na beton w obiektach drogowych.

EN

We present a review of freeze-thaw durability requirements laid down in both European standards and in the national specifications in relation to concrete for road structures. The principles of material selection for concrete mix are presented. We discuss local variations in the severity of the winter season and the extent of frost action in the components of road structures. The characteristic parameters of the test procedure for direct assessment of the resistance of concrete to internal damage are analysed, with particular attention paid to the specimen cooling rate. The temperature distribution in specimens was determined in standard freeze-thaw resistance tests carried out at two accredited laboratories. We discuss the criteria used in indirect assessment of freeze-thaw durability of air-entrained concrete on the basis of air void characteristics. Based on the determined temperature distribution in concrete specimens we postulate an improvement of the standard test procedure to clearly specify the cooling rate. It would be beneficial to distinguish frost impact zones depending on the severity of action of frost and de-icing salts on concrete in road structures.

2

Protective clothing for pesticide operators: part II – data analysis of fabric characteristics

Shaw A., Schiffelbein P.

International Journal of Occupational Safety and Ergonomics

|

2016

|

Vol. 22, No. 1

7--11

EN

Development of objective measurements is an important requirement for establishing performance-based standards for protective clothing used while handling pesticide. This study, the second in a two-part series, reports on the work completed to evaluate the performance of approximately 100 fabrics that are either used or have the potential to be used for garments worn by operators while applying pesticides. Part I, published separately, provides an overview of these issues and describes research undertaken to select a test chemical for use in subsequent studies. The goals of this study were first to develop a comprehensive approach to evaluate the performance of garments currently being used by pesticide operators, and second, to use the laboratory and field data in the development of performance specifications.

3

Protective clothing for pesticide operators: part I – selection of a reference test chemical for penetration testing

Shaw A., Schiffelbein P.

International Journal of Occupational Safety and Ergonomics

|

2016

|

Vol. 22, No. 1

1--6

EN

A systematic approach was taken to develop a database for protective clothing for pesticide operators; results are reported as a two-part series. Part I describes the research studies that led to identification of a pesticide formulation that could serve as a reference test chemical for further testing. Measurement of pesticide penetration was conducted using different types of pesticide formulations. Six fabrics were tested using 10 formulations at different concentrations. Three formulations were subsequently selected for further testing. Analysis of the data indicated that, when compared with other formulations, mean percent penetration of 5% Prowl 3.3 EC [emulsifiable concentrate diluted to 5% active ingredient (pendimethalin)] is either similar to or higher than most test chemicals. Those results led to choosing 5% Prowl 3.3 EC as a reference test liquid. Part II of the study, published as a separate paper, includes data on a wide range of textile materials.