Long-term Performance and Durability of Masonry Structures

Degradation Mechanisms, Health Monitoring and Service Life Design

Bahman Ghiassi, Paulo B. Lourenco

• Publisher: Woodhead Publishing
• Year: 2018
• Print ISBN: 9780081021101
• eBook ISBN: 9780081021118
• Topic: Technology & Engineering
• Subtopic: Construction & Architectural Engineering
• Index: Technology & Engineering

Long-Term Performance and Durability of Masonry Structures: Degradation Mechanisms, Health Monitoring and Service Life Design focuses on the long-term performance of masonry and historical structures. The book covers a wide range of related topics, including degradation mechanisms in different masonry types, structural health monitoring techniques, and long-term performance and service life design approaches. Each chapter reflects recent findings and the state-of-the-art, providing practical guidelines. Key topics covered include the theoretical background, transport properties, testing and modeling, protective measures and standards and codes. The book's focus is on individual construction materials, the composite system and structural performance.- Covers all issues related to durability, including degradation mechanisms, testing and design, monitoring and service life design- Focuses on different masonry construction types- Presents a 'one-stop' reference for advanced postgraduate courses that focuses on the durability of masonry and historical constructions

Part One

Durability and degradation mechanisms of bare and strengthened masonry

Outline

1. 1. Clay bricks
2. 2. Concrete block
3. 3. Stone
4. 4. Earth masonry
5. 5. Timber
6. 6. Mortars
7. 7. FRP-strengthened masonry

1

Clay bricks

Francisco M. Fernandes Faculty of Engineering and Technologies, Universidade Lusíada - Norte, Vila Nova de Famalicão, Portugal

Abstract

Clay bricks were amongst the first artificial materials produced by men for building purposes that proved to be easy to produce, resistant, and durable, as attested by the numerous examples that can be seen all around the world that endured centuries of rough climacteric conditions and wars. Clay bricks are simply produced by mixing clay and water. Hardening methods evolved from sun drying to industrial ovens, which allowed strength and durability to increase. While clay brick's durability was initially affected by inadequate raw materials and usage contamination, today, urban pollution and incorrect use of materials fosters an even more rapid deterioration of existing bricks, adding to the general lack of maintenance observed in most buildings. Nevertheless, only by understanding how bricks deteriorate was a series of methods and materials established for the repair of these bricks, extending their life expectancy.

Keywords

Brick; Durability; Firing; Moisture; Pollution; Raw clay; Salts; Strength

Chapter Outline

1. 1.1 Introduction
2. 1.2 Origin and properties of clay bricks
   1. 1.2.1 Raw material characteristics
   2. 1.2.2 Production process
   3. 1.2.3 Properties of final clay bricks
3. 1.3 Decay and degradation factors and mechanisms
   1. 1.3.1 Production/manufacture
   2. 1.3.2 Moisture and soluble salts
   3. 1.3.3 Temperature
   4. 1.3.4 Biological deterioration
   5. 1.3.5 Atmospheric contamination
4. 1.4 Durability of clay bricks
5. 1.5 Treatments to improve/extend brick's durability
6. References

1.1. Introduction

Since man began to establish himself and replace nomad hunting by local farming and agriculture, he sought to protect himself from the aggressions of the environment (snow, rain, cold, heat, etc.) and wild animals. The first protections were natural caves, and the first huts and houses were built with what nature provided, such as tree trunks, animal fur, straw, clay, etc. With the appearance of the first civilizations, around 9000–7000 BC, the construction techniques evolved, and stone, adobe, wood, and clay brick began to be used. The first vestiges of brick masonry buildings were found in the region of Israel (Mesopotamia) and dated from 9000 to 8000 BC. Masonry-fortified walls in Jericho (7000 BC) and rectangular brick houses in Çatal-Hüyük, Anatolia, (6500 BC) were also found.

Clay brick masonry is, effectively, one of the finest and most durable construction techniques ever invented by man. Masonry consists of building stable bonded stacks of small pieces by hand (Vekey, 1998). Used since the time of the first villages and cities built by man, masonry application has been growing and evolving to new uses all over the entire civilized world. It was a fundamental building material in Mesopotamian, Egyptian, and Roman periods. During Roman period, the use of clay brick increased and become specialized to maximize its benefits. Moreover, clay brick masonry was used as well during medieval and modern times. Despite several modifications of the clay brick use, shape, and manufacture along thousands of years of constant evolution, the simplicity that made its success remained. Numerous buildings built with clay bricks prevailed until the 21st century, which testifies to the strength and durability of this material through centuries of rainstorms, snow, thaw-freezing cycles, high temperatures (sunlight, fire), and human-induced deterioration.

Durability, according to Cooper (1994), is the ability of a product to perform its required function over a lengthy period under normal conditions of use without excessive expenditure on maintenance or repair. Therefore, the main pillars that affect the durability of clay bricks are (1) the quality of the raw material; (2) the manufacture process and firing conditions and, consequently, (3) the properties of hardened bricks; (4) the usage conditions to which bricks were exposed since construction; and (v) the rate of maintenance and repair as well as the types of treatments carried out.

1.2. Origin and properties of clay bricks

1.2.1. Raw material characteristics

In the natural state, raw clay is a complex and heterogeneous material, formed by a variable proportion of different minerals, known as clay minerals. A general definition of raw clay is given in Álvarez de Buergo and Limón (1994), where it is referred to as a material constituted by fine grain, with a size lower than 0.1 mm. These minerals are found to be in the range of 2–4 m soil depth, with earthen texture, and acquiring plasticity when mixed with water. Additionally, clay is a grain-sized term enclosing all the sediments where the dominant particles have an equivalent spherical diameter lower than 2 μm (Gomes, 1988).

In geologic terms, clay is classified as a clastic sedimentary rock, originated by the mechanic accumulation of individual fragments of rocks and mainly constituted by clay minerals and quartz. The word sediment has its origin in Latin sedere (to accumulate), and it is a reference to the process of formation of clays, while the term clastic (from the Greek klastos, which means broken) describes the fragments of rocks and sediments that constitute raw clay. The formation process of sedimentary rocks is composed of four stages: alteration, transport, sedimentation, and lithification. These rocks derive from the consolidation of rock fragments a...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of contributors
• Preface
• Part One. Durability and degradation mechanisms of bare and strengthened masonry
• Part Two. Health monitoring and testing
• Part Three. Long-term performance and service life design
• Index