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1、ACI 232.1R-00 supersedes ACI 232.1R-94 and became effective December 6, 2000. Copyright 2001, American Concrete Institute. All rights reserved including rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by electronic or mechanical dev
2、ice, printed, written, or oral, or recording for sound or visual reproduc- tion or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors. ACI Committee Reports, Guides, Standard Practices, and Commentaries are intended for gui
3、dance in planning, designing, executing, and inspecting construction. This document is intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and who will accept re- sponsibility for the application of the material it con
4、tains. The American Concrete Institute disclaims any and all re- sponsibility for the stated principles. The Institute shall not be liable for any loss or damage arising therefrom. Reference to this document shall not be made in con- tract documents. If items found in this document are de- sired by
5、the Architect/Engineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the Architect/Engineer. 232.1R-1 Use of Raw or Processed Natural Pozzolans in Concrete ACI 232.1R-00 This report provides a review of the state-of-the-art use of raw or pr
6、ocessed natural pozzolans in concrete and an overview of the properties of natural pozzolans and their proper use in the production of hydraulic-cement con- crete. Natural pozzolans mixed with lime were used in concrete construc- tion long before the invention of portland cement because of their con
7、tribution to the strength of concrete and mortar. Today, natural poz- zolans are used with portland cement not only for strength, but also for economy and beneficial modification of certain properties of fresh and hardened portland-cement concrete. This report contains information and recommendation
8、s concerning the selection and use of natural pozzolans generally conforming to the applica- ble requirements of ASTM C 618 and CSA A23.5. Topics covered include the effect of natural pozzolans on concrete properties, a discussion of qual- ity control and quality assurance, and guidance regarding ha
9、ndling and use of natural pozzolans in specific applications. References are provided that offer more information on each topic. Keywords: alkali-silica reaction; cement; concrete; concrete strength; diatomaceous earth; lime; natural pozzolan; pozzolan; pozzolanic activity; sulfate attack (on concre
10、te). CONTENTS Chapter 1General, p. 232.1R-2 1.1History 1.2Definition of a natural pozzolan 1.3Chemical and mineralogical composition 1.4Classification 1.5Examples Reported by ACI Committee 232 Gregory M. Barger* Allen J. HulshizerSandor Popovics Bayard M. CallTarif M. JaberJan Prusinski Ramon L. Car
11、rasquilloJim S. JensenDan Ravina James E. Cook Elizabeth S. Jordan* D. V. Reddy Douglas W. Deno Paul Klieger* Harry C. Roof George R. DeweySteven H. KosmatkaDella Roy Edwin R. Dunstan, Jr.Ronald L. Larson John M. Scanlon William E. Ellis, Jr.V. M. Malhotra Ava Shypula* Dean Golden Oscar Manz* Peter
12、G. Snow Karen A. Gruber*Bryant Mather* Robert Sparacino William Halczak Richard C. Mielenz* Michael D. A. Thomas G. Terry Harris, Sr.Tarun R. NaikSamuel S. Tyson R. Douglas Hooton*Terry Patzias Orville R. Werner, II Paul J. Tikalsky* Chairman Morris V. Huffman* Secretary *Subcommittee members for th
13、is report. Subcommittee chairman for this report. Deceased. Note: Special thanks is extended to P. K. Mehta and Caijun Shi for their help with this document. Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for
14、Resale, 03/05/2007 01:27:36 MSTNo reproduction or networking permitted without license from IHS -,-,- 232.1R-2ACI COMMITTEE REPORT 1.6Chemical and physical properties 1.7Uses Chapter 2Effects of natural pozzolan on concrete properties, p. 232.1R-8 2.1Concrete mixture proportions 2.2Properties of fre
15、sh concrete 2.3Properties of hardened concrete Chapter 3Specifications, test methods, quality control, and quality assurance, p. 232.1R-16 3.1Introduction 3.2Chemical requirements 3.3Physical requirements 3.4General specification provisions 3.5Methods of sampling and testing 3.6Quality control and q
16、uality assurance Chapter 4Concrete production using natural pozzolans, p. 232.1R-18 4.1Storage 4.2Batching Chapter 5Concrete applications for natural pozzolans, p. 232.1R-19 5.1Concrete masonry units 5.2Concrete pipes 5.3Prestressed concrete products 5.4Mass concrete Chapter 6Other uses of natural p
17、ozzolans, p. 232.1R-20 6.1Grouts and mortars 6.2Controlled low-strength materials Chapter 7References, p. 232.1R-21 7.1Referenced standards and reports 7.2Cited references CHAPTER 1GENERAL 1.1History Lime and limestone are among the oldest materials used by mankind for construction purposes. Structu
18、res built of limestone include the pyramids of Egypt. Long before the in- vention of portland cement in 1824, mortars and concretes composed of mixtures and fillers and raw or heat-treated lime were used for construction throughout the world (Mali- nowski 1991). Malinowski et al. (1993) report that
19、the oldest example of hydraulic binder, dating from 5000-4000 B.C., was a mixture of lime and natural pozzolan, a diatomaceous earth from the Persian Gulf. The next oldest reported use was in the Mediter- ranean region. The pozzolan was volcanic ash produced from two volcanic eruptions: one, sometim
20、e between 1600 and 1500 B.C. on the Aegean Island of Thera, now called Santorin, Greece; the other in 79 A.D. at Mt. Vesuvius on the bay of Na- ples, Italy. Both are volcanic ashes or pumicites consisting of almost 80% volcanic glass (pumice and obsidian). According to the Roman engineer Marcus Vitr
21、uvius Pollio (Vitruvius Pollio 1960), who lived in the first century B.C., the cements made by the Greeks and the Romans were of su- perior durability, because “neither waves could break, nor water dissolve” the concrete. In describing the building tech- niques of masonry construction, he indicated
22、that the Ro- mans developed superior practices of their own from the techniques of the Etruscans and the Greeks. The Greek ma- sons discovered pozzolan-lime mixtures sometime between 700-600 B.C. and later passed their use of concrete along to the Romans in about 150 B.C. During the 600 years of Ro-
23、 man domination, the Romans discovered and developed a variety of pozzolans throughout their empire (Kirby et al. 1956). During archaeological excavations in the 1970s at the an- cient city of Camiros on the Island of Rhodes, Greece, an an- cient water-storage tank having a capacity of 600 m3 (785 y
24、d3) was found. Built in about 600 B.C., it was used until 300 B.C. when a new hydraulic system with an underground water tank was constructed. For almost three millennia this water tank has remained in very good condition, according to Ef- stathiadis (1978). Examination of the materials used for thi
25、s structure re- vealed that the concrete blocks and mortar used were made out of a mixture of lime, Santorin earth, fine sand (2 mm 0.08 in.) and siliceous aggregates with sizes ranging be- tween 2 and 20 mm (0.08 and 0.79 in.). The fresh concrete was placed into wooden sidewall molds. The compressi
26、ve strength of a 20 mm (0.79 in.) cubic specimen was found to be 12 MPa (1740 psi). Mortars like these were known to have a composition of six parts by volume of Santorin earth, two parts by volume of lime, and one part by volume of fine sand. These mortars were used as the first hydraulic cements i
27、n aqueducts, bridges, sewers, and structures of all kinds. Some of these structures are still standing along the coasts of Italy, Greece, France, Spain, and in harbors of the Mediter- ranean Sea. The Greeks and Romans built many such struc- tures over 2000 years ago. Examples of such structures are
28、the Roman aqueducts as well as more recent structures such as the Suez Canal in Egypt (built in 1860) (Luce 1969), the Corinthian Canal (built in 1880), the sea walls and marine structures in the islands of the Aegean Sea, in Syros, Piraeus, Nauplion, and other cities, and the harbors of Alexandria
29、in Egypt, Fiume, Pola Spalato, Zara on the Adriatic Sea, and Constanta (Romania) on the Black Sea. All of these struc- tures provide evidence of the durability of pozzolan-lime mortar under conditions of mild weathering exposure. Ro- man monuments in many parts of Europe are in use today, standing a
30、s a tribute to the performance of lime-pozzolan mortars (Lea 1971). 1.2Definition of a natural pozzolan Pozzolan is defined in ACI 116R as: “.a siliceous or siliceous and aluminous material, which in itself possesses little or no cementitious value but will, in finely divided form and in the presenc
31、e of moisture, chemically react with calcium hydroxide at or- dinary temperatures to form compounds possessing ce- mentitious properties.” Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007
32、01:27:36 MSTNo reproduction or networking permitted without license from IHS -,-,- USE OF RAW OR PROCESSED NATURAL POZZOLANS IN CONCRETE232.1R-3 Natural Pozzolan is defined as: “.either a raw or calcined natural material that has poz- zolanic properties (for example, volcanic ash or pumicite, opalin
33、e chert and shales, tuffs, and some diatomaceous earths).” ASTM C 618 and CSA A23.5 cover coal fly ash and nat- ural pozzolan for use as a mineral admixture in concrete. The natural pozzolans in the raw or calcined state are designated as Class N pozzolans and are described in the specifications as:
34、 “Raw or calcined natural pozzolans that comply with the applicable requirements for the class as given herein, such as some diatomaceous earth; opaline chert and shales; tuffs and volcanic ashes or pumicites, any of which may or may not be processed by calcination; and various materials requiring c
35、alcination to induce satisfactory properties, such as some clays and shales.” Similar materials of volcanic origin are found in Europe, where they have been used as an ingredient of hydraulic-ce- ment concrete for the past two centuries. Raw or processed natural pozzolans are used in the pro- ductio
36、n of hydraulic-cement concrete and mortars in two ways: as an ingredient of a blended cement, or as a mineral admixture. This report deals with the second case. Blended cements are covered in ACI 225R. Fly ash and silica fume are artificial pozzolans and are covered in ACI 232.2R and 234R. 1.3Chemic
37、al and mineralogical composition The properties of natural pozzolans vary considerably, de- pending on their origin, because of the variable proportions of the constituents and the variable mineralogical and phys- ical characteristics of the active materials. Most natural poz- zolans contain substan
38、tial amounts of constituents other than silica, such as alumina and iron oxide, which will react with calcium hydroxide and alkalies (sodium and potassium) to form complex compounds. Pozzolanic activity cannot be de- termined just by quantifying the presence of silica, alumina, and iron. The amount
39、of amorphous material usually deter- mines the reactivity of a natural pozzolan. The constituents of a natural pozzolan can exist in various forms, ranging from amorphous reactive materials to crystalline products that will react either slowly or not at all. Because the amount of amorphous materials
40、 cannot be determined by standard techniques, it is important to evaluate each natural pozzolan to confirm its degree of pozzolanic activity. There is no clear distinction between siliceous materials that are considered pozzolans and those that are not. Generally, amorphous sili- ca reacts with calc
41、ium hydroxide and alkalies more rapidly than does silica in the crystalline form (quartz). As is the case with all chemical reactions, the larger the particles (the lower the surface area per unit volume) the less rapid the rate of reaction. Therefore, the chemical composition of a pozzolan does not
42、 clearly determine its ability to combine with calcium hydroxide and alkalies. Volcanic glasses and zeolitic tuffs, when mixed with lime, produce calcium silicate hydrates (CSH) as well as hydrated calcium aluminates and calcium aluminosilicates. These ma- terials were proven to be good pozzolans lo
43、ng ago. Natural clays and shales are not pozzolanic, or only weakly so, as clay minerals do not react readily with lime unless their crys- talline structure is partially or completely destroyed by cal- cination at temperatures below 1093 C (2000 F). High-purity kaolin may be processed to form a high
44、-qual- ity pozzolan called high-reactivity metakaolin. Italian re- searchers who have studied volcanic glasses and the relationship to pozzolanic activity believe that “reactive glass originated from explosive volcanic eruptions” like the ones from the volcanoes of Thera and Mount Vesuvius, which pr
45、oduced the natural pozzolans with unaltered alumi- nosilicate glass as their major component (Malquori 1960). Both are pumicites, one third of which is in the amorphous state (glass), and are highly reactive with lime and alkalis at normal temperatures 1.4Classification Mehta (1987) classifies natur
46、al pozzolans in four catego- ries based on the principal lime-reactive constituent present: unaltered volcanic glass, volcanic tuff, calcined clay or shale, and raw or calcined opaline silica. This classification is not readily applicable to pozzolans of volcanic origin (cat- egories 1 and 2) becaus
47、e volcanic tuffs commonly include both altered and unaltered siliceous glass. These are the sole or primary sources of pozzolanic activity in siliceous glass, opal, zeolites, or clay mineralsthe activity of the last two being enhanced by calcination. In Table 1.1, the chemical Table 1.1Typical chemi
48、cal and mineralogical analysis of some natural pozzolan (Mehta 1987) Pozzolan %Estimated Ignition Loss, % Non- crystalline matter, % Major crystalline minerals SiO2Al2O3Fe2O3 CaOMgOAlkalies* Santorin earth65.114.55.53.01.16.53.565 to 75Quartz, plagioclase Rhenish trass53.016.06.07.03.06.050 to 60Qua
49、rtz, feldspar, analcime Phonolite55.720.22.04.21.110.83.6 Orthoclase, albite, pyroxene, calcite Roman tuff44.718.910.110.34.46.74.4 Herschelite, chabazite, phillipsites Neapolitian glass54.518.34.07.41.011.03.150-70Quartz, feldspar Opaline shale65.410.14.24.62.71.46.3 Diatomite86.02.31.80.60.45.2 Rhylolite pumicite65.715.92.53.41.36.93.4 Jalisco pumice68.714.82.30.59.35.690Sanidine *%Na2O + 0.658% K2O Copyright American Concrete Institute Provided by I