ACI 234R
Guide for the Use of Silica Fume in Concrete
سال
: 2006-01-01
چکیده: General
Silica fume, a by-product of the ferrosilicon industry, is a
highly pozzolanic material that is used to enhance mechanical and
durability properties of concrete. It may be added directly to
concrete as an individual ingredient or in a blend of portland
cement and silica fume. ACI Committee 234 estimates that at least
120,000 metric tons (130,000 tons) of silica fume are used in
concrete worldwide annually. Using this figure, more than 6 million
cubic meters (nearly 8 million cubic yards) of silica-fume concrete
are placed globally each year.
Interest in the use of silica fume resulted from the strict
enforcement of air-pollution measures designed to stop release of
the material into the atmosphere. Initial use of silica fume in
concrete was mostly for cement replacement, along with
water-reducing admixtures (WRAs). Eventually, the availability of
high-range water-reducing admixtures (HRWRAs, often referred to as
superplasticizers) allowed new possibilities for the use of silica
fume to produce high levels of performance.
This document provides basic information on using silica fume in
concrete. The document is organized as follows:
• Chapter 1 provides general information on silica fume;
• Chapter 2 describes the physical properties and chemical
composition of silica fume;
• Chapter 3 describes the mechanisms by which silica fume
modifies cement paste, mortar, and concrete;
• Chapter 4 describes the effects of silica fume on fresh
concrete;
• Chapter 5 describes the effects of silica fume on hardened
concrete;
• Chapter 6 shows how silica fume has been used on actual
projects. This chapter covers only a very small number of
applications because ACI Committee 234 is currently developing an
additional document that will provide detailed case histories of
many more projects;
• Chapter 7 discusses specifications for silica fume and
silica-fume concrete;
• Chapter 8 presents a step-by-step methodology for
proportioning silica-fume concrete for specific applications;
• Chapter 9 presents recommendations for working with silica
fume in field concrete;
• Chapter 10 summarizes research needs for using silica fume in
concrete; and
• Chapter 11 presents all of the references from the other
chapters.
Note that the coverage in Chapters 7, 8, and 9 is somewhat
brief. More details on working with silica-fume concrete in actual
applications may be found in a guide published by the Silica Fume
Association (Holland 2005).
As with other concrete constituent materials, potential users of
silica fume should develop their own laboratory data for the
particular type and brand of cement, aggregates, and chemical
admixtures to be used with the silica fume. This testing may be
supplemented by field observations of completed silica-fume
concrete and by testing of cores taken from such concrete.
Keyword(s): curing, durability, high-range water-reducing admixture, high-strength concrete, placing, plastic-shrinkage cracking, silica fume, time of setting, water-reducing admixture, workability
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آمار بازدید
ACI 234R
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date accessioned | 2020-05-27T08:34:36Z | |
date available | 2020-05-27T08:34:36Z | |
date issued | 2006-01-01 | |
identifier uri | http://libsearch.um.ac.ir:80/fum/handle/fum/3225670 | |
description abstract | General
Silica fume, a by-product of the ferrosilicon industry, is a
highly pozzolanic material that is used to enhance mechanical and
durability properties of concrete. It may be added directly to
concrete as an individual ingredient or in a blend of portland
cement and silica fume. ACI Committee 234 estimates that at least
120,000 metric tons (130,000 tons) of silica fume are used in
concrete worldwide annually. Using this figure, more than 6 million
cubic meters (nearly 8 million cubic yards) of silica-fume concrete
are placed globally each year.
Interest in the use of silica fume resulted from the strict
enforcement of air-pollution measures designed to stop release of
the material into the atmosphere. Initial use of silica fume in
concrete was mostly for cement replacement, along with
water-reducing admixtures (WRAs). Eventually, the availability of
high-range water-reducing admixtures (HRWRAs, often referred to as
superplasticizers) allowed new possibilities for the use of silica
fume to produce high levels of performance.
This document provides basic information on using silica fume in
concrete. The document is organized as follows:
• Chapter 1 provides general information on silica fume;
• Chapter 2 describes the physical properties and chemical
composition of silica fume;
• Chapter 3 describes the mechanisms by which silica fume
modifies cement paste, mortar, and concrete;
• Chapter 4 describes the effects of silica fume on fresh
concrete;
• Chapter 5 describes the effects of silica fume on hardened
concrete;
• Chapter 6 shows how silica fume has been used on actual
projects. This chapter covers only a very small number of
applications because ACI Committee 234 is currently developing an
additional document that will provide detailed case histories of
many more projects;
• Chapter 7 discusses specifications for silica fume and
silica-fume concrete;
• Chapter 8 presents a step-by-step methodology for
proportioning silica-fume concrete for specific applications;
• Chapter 9 presents recommendations for working with silica
fume in field concrete;
• Chapter 10 summarizes research needs for using silica fume in
concrete; and
• Chapter 11 presents all of the references from the other
chapters.
Note that the coverage in Chapters 7, 8, and 9 is somewhat
brief. More details on working with silica-fume concrete in actual
applications may be found in a guide published by the Silica Fume
Association (Holland 2005).
As with other concrete constituent materials, potential users of
silica fume should develop their own laboratory data for the
particular type and brand of cement, aggregates, and chemical
admixtures to be used with the silica fume. This testing may be
supplemented by field observations of completed silica-fume
concrete and by testing of cores taken from such concrete. Keyword(s): curing, durability, high-range water-reducing admixture, high-strength concrete, placing, plastic-shrinkage cracking, silica fume, time of setting, water-reducing admixture, workability _x000D_ _x000D_ | |
language | English | |
title | ACI 234R | num |
title | Guide for the Use of Silica Fume in Concrete | |
type | Standard | |
contenttype | Fulltext | |
pages | 63 | |
organisation abbrivate | ACI | |
standard organization | ACI - American Concrete Institute |