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Die Zeichnung ist die Sprache des
Architekten – die Visualisierung seiner
entwerferischen Gedanken und CONSTRUCTION
beabsichtigten Konstruktionslösungen.
Basics Technisches Zeichnen vermittelt
CONCRETE
Studenten gebündelt das Wissen für die
Entwicklung professioneller Dar stellungen
CONSTRUCTION
von Planungen in allen Projektphasen.
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www.birkhauser.com
Katrin Hanses
Concrete
C onstruction
KBaetrrti nB iHelaenfeselds - Sebastian El Khouli
CEnotnwcruertfesi dee
C onstruction
Birkhäuser
BIRKHÄUSER
Basel
BASEL
Contents
Foreword _7
INTrodUCTIoN _8
BUILdING maTerIaL _9
Constituent materials _9
Kinds of concrete _12
Reinforcement _14
Material properties _20
Deformations _22
Defects _23
CoNsTrUCTIoN meThod _25
In-situ concrete _28
Formwork _28
Concreting process _36
Precast elements _39
Surfaces _41
BUILdING parTs _47
Footings/foundations _47
Wall _53
Column _54
Beam _55
Ceiling/floor slab _58
Roof and roof parapet _65
Thermal separation _65
Staircases _69
IN CoNCLUsIoN _73
appeNdIx _74
Standards and guidelines _74
Literature _75
Picture credits _75
The author _75
Foreword
As a monolithic, cast material with a high loadbearing capacity, con-
crete is used in many areas of building. When combined with reinforce-
ment steel in the form of reinforced concrete the material can bridge
large spans and is very durable. Surfaces that differ in terms of structure
and colour can be produced using different formwork elements and
admixtures. A good knowledge of this material, its properties and the
process by which it is made is indispensable for the architect’s creative
process.
Reinforced concrete has been tried and tested over a long period and
is widely used in both architecture and civil engineering. Generations
of architects have discovered ever new and creative ways of using the
material. In recent years, thanks to innovative reinforcement elements
and processing methods, marked progress has been made in building
with concrete, so that the diversity of this material has increased sub-
stantially, and it has proved possible to develop new areas of use.
It is at this point that this new book Basics Concrete Construction
begins and gives the reader an understanding of the special qual ities of
concrete and the constructional possibilities that it offers. From the
development of knowledge about the material, to the special production
methods of concrete building parts, to the connections between these
parts, it gives the architecture student the means for reflecting on crea-
tive solutions and developing new approaches to the construction of
buildings.
Bert Bielefeld, Editor
7
Introduction
Concrete is one of the most important materials in architecture and
civil engineering. As a poured material it offers a variety of possibilities
for architectural design and in making loadbearing building parts. Con-
crete allows monolithic ways of building – i.e. buildings which are “poured
in one cast” and through the use of various additives and composite
materials its abilities are extremely varied. The concrete mix has a great
influence on the later qualities of the material and can be adapted to meet
the individual demands made on the building element. In designing con-
crete a great deal is possible – from the small to the extremely large scale.
As a material it has a strength that allows it to be used in primary
and secondary constructions as prefabricated elements so that, with con-
sistent planning, economic, high-quality execution is possible. When de-
signing concrete buildings various building parts must be fitted together,
different means of production combined, and the relationship between
the details and the structure of the whole must be resolved. A wide range
of knowledge about the fabrication, construction and later treatment is
indispensable. To explore the potential and possibilities of the material
this basic knowledge about concrete is conveyed here, opening the way
for an intensive examination of the material.
8
Building material
CoNsTITUeNT maTerIaLs
Concrete is traditionally made of water, cement and aggregate. To
these can be added air and various additives and admixtures, which are
being continuously developed. Consequently, concrete’s capacity and
the range of areas in which it can be used are growing all the time.
The proportion of water to cement and the consistency of the cement
paste produced in this way have a major influence on the quality and
workability of the fresh concrete. Mixing causes the concrete to become
malleable. The duration of the mixing process is strictly laid down for
each kind of concrete mix. The cement paste must surround the aggre-
gate, holding the pieces together and filling any hollows.
In terms of amount, the aggregate plays the major role in concrete, Aggregate
and is most important for the quality of the concrete. A fine-grained
aggregate should be chosen particularly for exposed concrete building
elements or those on which great demands are made.
The aggregate can consist of broken or unbroken pieces. Natural
mineral materials are traditionally used but waste products or byprod-
ucts from industry can often also be employed. They need to have a cer-
tain grain strength and it must be possible to combine them with the
paste so that the durability of the concrete is not impaired.
The aggregate is differentiated according to its origins, structure,
unit weight, grain form and grain size. There are also different demands
in terms of durability and the geometrical, chemical and physical prop-
erties of the grain, as well as with regard to frost resistance. In this re-
spect there are special grain groups, compositions or forms.
Depending on the nature of the particular material, the aggregate Grain size distribution
must be processed for use in making concrete. The grain size distribu- curve
tion curve (a diagram depicting the composition of grain mixes) is de-
cisive for the quality of the concrete produced. This distribution curve is
produced by sieving the aggregate through sieves of different mesh sizes.
Standard distribution curves for grain mixes are 8 mm, 16 mm, 32 mm
and 63 mm, the maximum grain size, which in certain circumstances must
be produced by fragmenting, sieving or washing.
Up to a grain size of 0.125 mm we are dealing with powder. This fine
material has a positive effect on the workability of fresh concrete and en-
sures a dense structure, which is particularly important for exposed or
watertight concrete. However, the higher amount of cement also makes
it more expensive to produce.
One of the further main ingredients of concrete is cement, which can Cement
be subdivided into five main kinds (CEM I–V). > Tab. 1 Cement is a hy draulic
binder that holds the concrete together.
9
Tab. 1: Kinds of cement
Kind of cement Definition
CEM I Portland cement: strength class 32.5R (high initial strength)
CEM II Portland composite cement: various main ingredients (slag sand and
limestone), strength class 42.5N
CEM III Blast furnace cement (Portland cement, clinker and slag sand), strength
class 32.5N
CEM IV Pozzolanic cement
CEM V Composite cement
Blast furnace cement (CEM III) is used for the production of ultra high
performance concrete (UHPC). Alongside its low porosity (which protects
against ingress of liquid) it has numerous other positive qualities. Less
primary energy is required to produce it, and it saves on natural resources.
Cracking due to thermal stress is rare and it is more resistant to chem-
icals and salts.
Water-cement value What is called the w/c value should be determined at the planning
stage in accordance with the appearance required and the particular
function. This describes the proportion of water to cement and influences
the properties of the concrete. The higher the w/c value, the lower the
strength. The proportion of water to cement can also have an effect on
the colour: a lower w/c value makes the surface appear darker, whereas
a higher value produces a lighter-coloured surface.
In order for concrete to cure (= hydration), it must have a w/c value
of at least 0.4 (which represents 40% water). If more water is added the
cement can no longer bind the water, and the liquid emerges (“bleeds”).
If the proportion of cement is too high there is a danger of too rapid dry-
ing and shrinking.
Admixtures Admixtures can be in liquid or powder form or can also be added as
granulate or a paste. They influence the quality of the fresh or solid concrete
by chemical or physical processes. For example, they can change workabil-
ity or air content. > Tab. 2 The admixtures have only a minor effect on the mass
● of the fresh concrete and their volume can therefore be ignored.
Additives Additives are different materials that are added to concrete to influ-
ence or achieve certain properties. A distinction is made between two
different groups:
Type I: Almost inactive concrete additives (stone dust, pigment)
Type II: Pozzolanic or latent hydraulic concrete additives (fly ash,
silica dust)
10
