FACULTY OF CIVIL ENGINEERING AND BUILDING SERVICES. Eng. Hans-Udo KRASSER. Ph.D THESIS -ABSTRACT-

Transcription

1 FACULTY OF CIVIL ENGINEERING AND BUILDING SERVICES Eng. Hans-Udo KRASSER Ph.D THESIS -ABSTRACT- APPLICATIONS OF LIGHT WEIGHT AGGREGATE CONCRETE FOR EXTERIOR WALLS IN CIVIL BUILDINGS Doctorate graduate: Doctorate coordinator, Eng. Hans Udo KRASSER Eng. Traian ONEł, PhD proffesor C.M of Romanian Academy of Technical Sciences Doctor Honoris Causa - 1 -

2 CONTENT CHAPTER 1 INTRODUCTION. OBJECTIVES OF THE DOCTORATE THESIS CHAPTER 2 TYPES OF LIGHTWEIGHT AGGREGATE CONCRETE CHAPTER 3 TECHNOLOGY OF MIXTURE AND CHARACTERISTICS OF LIGHT WEIGHT AGGREGATE CONCRETE CHAPTER 4 DESIGN SPECIFICATIONS CHAPTER 5 EFICIENCE OF USING LIGHT WEIGHT AGGREGATE CONCRETE CHAPTER 6 EXPERIEMENTAL ANALYSIS ON STRUCTURES AND ELEMENTS CHAPTER 7 CONCLUSION AND FINAL REMARKS ANNEXES ANNEX 1 Published paper 1 - Hans Udo Krasser : Realizarea pereńilor exteriori prefabricańi la construcńii de locuinńe, social culturale şi industriale din betoane uşoare, omogene cu agregate de zgură expandată şi scorie bazaltică. ConferinŃa a patra de betoane, Braşov ANNEX 2 - Published paper 2 - Hans-Udo Krasser, Ioan Pop Evolution and Improvement of Lightweight Aggregate Concrete Technique, Acta Technica Napocensis ANNEX 3 - Published paper 3 - Hans-Udo Krasser, Dan Bompa Specific Behaviour of Lightweight Aggregate Concrete, Acta Technica Napocensis The Ph.D. Thesis is structured on 7 chapters developed on 122 pages

3 CHAPTER 1 - INTRODUCTION Concrete is known to be the most widespread structural material due to its quality to shape up in various geometrical configurations. In some conditions, one might assume that normal weight concrete is inconvenient due to its density ( kg/ m 3 ). Replacing partially or entirely the coarse part of normal weight aggregate concrete with lower weight aggregates produces lightweight aggregate concrete to a density between kg/m 3 and can reach compressive resistence of 50N/mm 2. Lightweight agregates used in structural lightweight concrete are fly ash, expanded clay or any other porous material. Lightweight aggregate concrete was first used in in Ancient Rome during the building of Panthenon dome under the well known name opus caementitim. LWAC known a wide development in the entire world becoming famous around CHAPTER 2 TYPES OF LIGHTWEIGHT AGGREGATE CONCRETE The second chapter presents at length several types of lightweight aggregates of different origins such as: blast-furnance slag, scoria and fly ash. An scrutiny research is made upon the use wood aggregates in producing concrete. The author presents the characteristics and usage of sawdust and shivers in order to create masonry concrete framework. A thorough presentation regarding the process of producing the aformentioned masonry blocks. Few practical adivces are also given. The author, then, makes an incursion upon LWAC made of expanded clay such as: whitestone, liapor, haydite, leca, keramsit. Several other lightweight aggregates are than presented: synthtised slate, spongious volcanic lava or coal mining waste. The last part of the second chapter is dedicated to plastic granules having the maximum diameter 3 mm, used for thermoenergetic optimized mortars. The blast-furnance slag represents an secondary product of the iron ore industry. Due to this fact the material needs crushing, to be fractured, granulated and then expanded. One of the inconveniences using this aggregate is the different porosity from one granule to another and that implies variable volumetric weight. Slag and volcanic tufa (pozzolana) have been formed during the time through natural expansion. Along the similar disadvantages present in the description of the previous aggregate: variable porosity, this ones might become expensive being situated far from construction site. Sawdust and shiver aggregate are used in combination with cement grout for the producing of precast masonry blocks. Expanded clay aggregates the most popular and used aggregates in the entire world due to their peculiar positive characteristics. The raw material is fractured and granulated then burned at 1200 degrees in rotary ovens. Through this process - 3 -

4 spherical expanded granules, having therir surface sintered. CHAPTER 3 TECHNOLOGY OF MIXTURE AND CHARACTERISTICS In the third chapter is presented the characteristics and preparation process and technology of lightweight aggregate concrete. A thorough comparison regarding preparation process is made between normal and lightweight aggregate concrete. The characteristics compared are: compressive strength, tension strength, elasticity modulous, shrinkage, creep, bond between bars and concrete, the resistance under long term loadings, aggregates density and the thermal strength depeding on the pore prercentage inside the aggregate. Two of the most important characteristics are then presented to length: the reduced selfweight of structural elements which than modifies the strength capacity and cost price in a positive manner; and the thermal insulating capacity of the lightweight aggregate concrete used for exterior walls at civil buildings. CHAPTER 4 DESIGN SPECIFICATIONS Chapter four presents design specifications for lightweight aggregate concrete. There are presented those aspects that must be accounted in the process of design and use of LWAC for the process of preparation and casting in situ. A large description is given upon the construction of several blocks of flats in Sibiu between under the surveilance of the author. The end of the chapter presents the physical and mechanical characteristics of Eurocod 2 section 11. Design basis for LWAC from section 2 of Eurocode 2 can be applied as well as for normal aggregate concrete with no modifications. CHAPTER 5 EFICIENCE OF USING LIGHT WEIGHT AGGREGATE CONCRETE The appication efficience domains are presented in chapter five and are given several examples such as: civil buildings, drains for bridge works, sound-proof walls or other art works

5 CHAPTER 6 EXPERIEMENTAL ANALYSIS ON STRUCTURES AND ELEMENTS First experimental tests on lightweight concrete in Romania were made by the author between as a need for the increasing demand for civil buildings. Sibiu was the first town where civil buildings for residential use made of lightweight aggregate concrete were built. The structures were made out of precast panels on an permanent site polygon. The polygon was the first in the country. Lightweight aggregate concrete was chosen instead normal one with the purpose of improving termotechnical and economical aspects. An reduction of 20% of the initil cost have been obtained replacing the normal sand. The aggregates used were basaltic scoria. The second most important experimental test represents the Model House built in Heidelberg, Germany between It comes as a follow-up for the previous experiments regarding the use of lightweight agreggate concrete. A detailed presentation concerning the future settelment of the house, type of construction, description of all erection phases (groundwork, plumming, paving, masonry work and walls and slab moldings). In the end, the legal thermoenergetic card is presented. CHAPTER 7 CONCLUSION AND FINAL REMARKS The thesis represents the history of four decades of insistence and perseverence for the usage of lightweight aggregate in concrete mixture. The first experimental tests carried out by the author in Romania were developed between on precast panels designed for civil buildings in Sibiu for Hipodrom area. During the future years he stayed faithfully connected to the promotion of new technology and science in construction area. Further concernment for expansion of the lightweight aggregate concrete, more exactly the one made of wood waste continued in Germany during Its pursuit for new findings and developments have been placed through the construction of an experimental house. Time confirmed mentation and solutions chosen by the author. The buldings that have been build under the surveilance of the author, namely the experimental house in Germany and the blocks of flats in Sibiu have validated his thoughts through their behaviour in time characterized by a similar durability to the normal weight aggregate structures

6 Work and research actions of the author are presented in this doctorate thesis. The paper apply himself as a structural engineer with openings to innovation, fitter with intelligence and passion for research. Personal contribuitions of the author are: a synthesis of techical-economical effects in usage the lightweight aggregate concrete in civil structures design and production of the first precast station from Romania, at Sibiu colaboration to the development of technical instructions for production and usage of the light weight aggregate concrete with expanded foam and slag stone use of lightweight aggregate concrete for the construction of several blocks of flats in Hipodrom Area in Sibiu concept, design and construction for a (model) experimental house in Germany at Hidelberg sustained activities in applied research and experimental teste carried out during the four decades of experience in the field - 6 -