ACI-547R-1983-R1997.pdf
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1、ACI 547R-79 Refractory Concrete: Abstract of State-of-the-Art Report Reported by ACI Committee 547 Refractory concretes are cur- rently used in a wide variety of industrial applications where py- reprocessing and/or thermal con- tainment is required. The service demands of these applications are bec
2、oming increasingly severe and this, combined with the constant demand for refractories with en- hanced service life and more ef- ficient means of installation, has resulted in an ever expanding re- fractory concrete technology. ACI Committee 547 has prepared this state-of-the-art report in order to
3、547R-5 meet the need for a better under- standing of this relatively new technology. The report presents back- ground information and per- spective on the history and cur- rent status of the technology. Composition and proportioning methods are discussed together with a detailed review of the con- s
4、tituent ingredients. Emphasis is placed on proper procedures for the installation, curing, drying, and firing. The physical and engi- neering properties of both normal weight and light weight refractory concretes are reported, as are state-of-the-art construction de- tails and repair/maintenance tec
5、h- niques. Also included is an in- depth review of a wide variety of applications together with the committees assessment of future needs and developments. Keywords: abrasion; accelerating agents; admixtures; aggregates; aluminate cement and concretes; anchorage (structural); ce- ment-aggregate reac
6、tions; chemical analy- sis; construction; corrosion: curing; drying; failure mechanisms; formwork (construc- tion); hydration; insulating concretes; kilns; lightweight concreetes; mechanical proper- ties; mix proportioning; packaged concrete; physical properties; placing; pumped con- crete; quality
7、control; refractories; refrac- tory concretes; reinforcing materials: re- pairs; research; shotcrete; spalling; structural analysis; temperature; thermal properties; water; welded wire fabric. (Revised 1983) (Reapproved 1997) This abstract first appeared in Concrete International: Design T-Troweling
8、; S-Shotcretinq; E-Extruding. All measurements except thermal conductivity taken *2000 F (For back-up material) at room temperature. SI conversion factors DegF = 1.8 C + 32 1 pcf = 16.02 kg/m 1 lb = 0.4536 kg 1 psi = 0.006895 MPa 1 Btu-in./hr-sq ft - deg F Copyright American Concrete Institute Provi
9、ded by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 01:17:56 MSTNo reproduction or networking permitted without license from IHS -,-,- REFRACTORY CONCRETE 547R-5 Plastics are generally placed without use of forms. With the exception o
10、f some specialized tabular alu- mina castables, plastics have a somewhat higher ser- vice limit than castable refractories. Their main dis- advantages are greater shrinkage and crack development. Except for phosphate bonded mate- rials cured above 600 F (315 C), plastics generally have lower cold an
11、d hot strengths than refractory concretes. In addition, plastics tend to have a rela- tively low strength zone on the cool side of the lin- ing. Ramming mixes usually have higher density and less shrinkage than plastic refractories. With their low water content, they must be forced into place and re
12、quire strong well-braced forms. Some of the dryer medium grind ramming mixes are suitable for gunning, and are used for patching and maintenance materials. 1.6.4 Gunning mixes other than refractory con- cretes12,13 - As used in this section, the term “gun- ning mixes” does not refer to refractory co
13、ncrete and should not be confused with gunned refractory materials which produce refractory concrete. Gun- ning mixes are mixtures of non-hydraulic setting in- gredients which are installed hot or cold, usually by the shotcrete method. Gunning mixes generally have low rebound loss, are predominately
14、 used for patching or resurfacing brick or other refractories, have a strong internal bond, and exhibit excellent adhesion or bond to the existing refractory lining. They find extensive use in basic oxygen, electric arc and open hearth furnaces, among other applications. Chapter 2 - Criteria for ref
15、ractory concrete selection Refractory castables are plant packaged mixes composed of ingredients that are weighed, blended and usually bagged in convenient sizes for shipping and handling. They require only mixing with water on the job to produce refractory concrete. Field mixes are made from materi
16、al components which are proportioned and mixed on the site just prior to the addition of water. 2.5 Load bearing considerations Most application designs of refractory concrete con- sider that there is a thermal gradient through the material with heat conducted from the hot face to the cold face. A c
17、ross section of the refractory will usually have a layer at the hot face that has a ce- ramic bond, an intermediate section with a weaker combination of ceramic and a partial hydraulic bond, and a cold face section that retains most of its hy- draulic bond. Refractory concrete linings in this type o
18、f situation are usually well anchored and self-sup- porting. Castables containing high proportions of coarse ag- gregates produce refractory concrete with good load bearing characteristics. Certain types of refractory concrete tend to have low strengths in the inter- mediate temperature zones 1500-2
19、250 F (820-1230 C) and should not be subjected to excessive mechanical abuse or dead load. Generally, lightweight concretes designed for insulating purposes should not be sub- jected to impact, heavy loads, abrasion, erosion or other physical abuse. Normally, both the strength and the resistance to
20、destructive forces decline as the bulk density of the refractory concrete de- creases. There are a number of special refractory castables available which have better than average load-bear- ing capabilities and withstand abrasion much better than the standard types. orerosion 2.1 Introduction 2.7 Co
21、rrosion influences Refractory concrete is usually made with high alu- mina cement. It is not generally used as a structural material and its primary purpose is as a protective lining for steel, concrete or brick structures. It is Some of the destructive forces that refractory con- cretes withstand a
22、re abrasion, erosion, physical considered a consumable material requiring replace- abuse, high temperatures, thermal shock, hot and molten metals, clinker, slag, alkalies, mild acid or ment after an appropriate service life. acid fumes, expansion, contraction, carbon monoxide, and flame impingement.
23、 Refractory concretes are categorized as either nor- mal weight or lightweight. The former are also re- ferred to as “heavy refractory concretes” and the latter are often called “insulating refractory con- cretes.” Table 2.la shows the characteristics of a typical range of normal weight refractory c
24、oncretes; Table 2.lb shows the characteristics of lightweight refractory concretes. 2.2 Castables and field mixes Refractory concretes are usually prepared at the job site from materials supplied to the user in either of two ways: (1) prepackaged so-called “refractory cast- ables;” (2) field mixes.
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