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1、ACI 230.1R-90 (Reapproved 1997) State-of-the-Art Report on Soil Cement reported by ACI Committee 230 Wayne S. Adaska, Chairman Ara Arman Richard L. De Graffenreid Robert T. Barclay John R. Hess Theresa J. Casias Robert H. Kuhlman David A. Crocker Paul E. Mueller Harry C. Roof Dennis W. Super James M
2、. Winford Anwar E. Z. Wissa Soil cement is a denseiy compacted mixture of portland cement, soil/ aggregate, and water. Used primarily as a base material for pave- ments, soil cement is also being used for slope protection, low- permeability liners, foundation stabilization, and other applications. T
3、his report contains information on applications, material proper- ties, mix proportioning, construction, and quality-control inspection and testing procedures for soil cement.This report s intent is to pro- vide basic information on soil-cement technology with emphasis on current practice regarding
4、design, testing, and construction. Keywords: aggregates; base courses; central mixing plant; compacting; con- struction; fine aggregates; foundations; linings; mixing; mix proportioning; moisture content; pavements; portland cements; properties; slope protection; soil cement; soils; soil stabilizati
5、on; soil tests; stabilization; tests; vibration. CONTENTS Chapter 1-Introduction 1.1 -Scope 1.2-Definitions Chapter 2-Applications 2.1 -General 2.2-Pavements 2.3-Slope protection 2.4-Liners 2.5-Foundation stabilization 2.6-Miscellaneous applications Chapter 3-Materials 3.1-Soil 3.2-Cement 3.3-Admixt
6、ures 3.4-Water Chapter 4-Properties 4. l-General 4.2-Density 4.3-Compressive strength ACI Committee Reports, Guides, Standard Practices, and Commentaries are intended for guidance in designing, plan- ning, executing, or inspecting construction and in preparing specifications. References to these doc
7、uments shall not be made in the Project Documents. If items found in these doc- uments are desired to be a part of the Project Documents, they should be phrased in mandatory language and incorporated into the Project Documents. 4.4-Flexural strength 4.5-Permeability 4.6-Shrinkage 4.7-Layer coefficie
8、nts and structural numbers Chapter 5-Mix proportioning 5.1-General 5.2-Proportioning criteria 5.3-Special considerations Chapter 6-Construction 6.1-General 6.2-Materials handling and mixing 6.3-Compaction 6.4-Finishing 6.5-Joints 6.6-Curing and protection Chapter 7-Quality-control testing and inspec
9、tion 7.1 -General 7.2-Pulverization (mixed in place) 7.3-Cement-content control 7.4-Moisture content *7.5 -Mixing uniformity 7.6-Compaction 7.7-Lift thickness and surface tolerance Chapter 8-References 8.1-Specified references 8.2-Cited references 1-INTRODUCTION 1.1-Scope This state-of-the-art repor
10、t contains information on applications, materials, properties, mix proportioning, design, construction, and quality-control inspection and Copyright 0 1990, American Concrete Institute. All rights reserved, including rights of reproduction and use in any form or by any means, including the making of
11、 copies by any photo process, or by any electronic or mechanical device, printed, written, or oral, or recording for sound or visual reproduction for use in any knowledge or retrieval system or device, unless permission in writng is obtained from the copyright proprietors. 230.1 R-l 230.1 R-2 ACI CO
12、MMITTEE REPORT testing procedures for soil cement. The intent of this report is to provide basic information on soil-cement technology with emphasis on current practice regarding mix proportioning, properties, testing, and construc- tion. This report does not provide information on fluid or plastic
13、soil cement, which has a mortarlike consistency at time of mixing and placing. Information on this type of material is provided by ACI Committee 229 on Controlled Low-Strength Material (CLSM). Roller- compacted concrete (RCC), which is a type of no-slump concrete compacted by vibratory roller, is no
14、t covered in this report. ACI Committee 207 on Mass Concrete has a report available on roller-compacted concrete. 1.2-Definitions Soil cement-AC1 116R defines soil cement as “a mixture of soil and measured amounts of portland ce- ment and water compacted to a high density.” Soil ce- ment can be furt
15、her defined as a material produced by blending, compacting, and curing a mixture of soil/ag- gregate, portland cement, possibly admixtures includ- ing pozzolans, and water to form a hardened material with specific engineering properties. The soil/aggregate particles are bonded by cement paste, but u
16、nlike con- crete, the individual particle is not completely coated with cement paste. Cement content-Cement content is normally ex- pressed in percentage on a weight or volume basis. The cement content by weight is based on the oven-dry weight of soil according to the formula Cw = weight of cement O
17、ven-dry weight of soil x 100 The required cement content by weight can be con- verted to the equivalent cement content by bulk vol- ume, based on a 94-lb U.S. bag of cement, which has a loose volume of approximately 1 ft3, using the follow- ing formula c Y = D - I+ liners for channels, reservoirs, a
18、nd lagoons; and mass soil-cement placements for dikes and foundation stabilization. 2.2-Pavements Since 1915, when a street in Sarasota, Fla. was con- structed using a mixture of shells, sand, and portland cement mixed with a plow and compacted, soil cement has become one of the most widely used for
19、ms of soil stabilization for highways. More than 100,000 miles of equivalent 24 ft wide pavement using soil cement have been constructed to date. Soil cement is used mainly as a base for road, street, and airport paving. When used with a flexible pavement, a hot-mix bituminous wear- ing surface is n
20、ormally placed on the soil-cement base. Under concrete pavements, soil cement is used as a base to prevent pumping of fine-grained subgrade soils un- der wet conditions and heavy truck traffic. Further- more, a soil-cement base provides a uniform, strong support for the pavement, which will not cons
21、olidate under traffic and will provide increased load transfer at pavement joints. It also serves as a firm, stable work- ing platform for construction equipment during con- crete placement. Failed flexible pavements have been recycled with ce- ment, resulting in a new soil-cement base (Fig. 2.1). R
22、ecycling increases the strength of the base without re- moving the old existing base and subbase materials and replacing them with large quantities of expensive new base materials. In addition, existing grade lines and drainage can be maintained. If an old bituminous sur- face can be readily pulveri
23、zed, it can be considered sat- isfactory for inclusion in the soil-cement mixture. If, on the other hand, the bituminous surface retains most of its original flexibility, it is normally removed rather than incorporated into the mixture. The thickness of a soil-cement base depends on var- ious factor
24、s, including: (1) subgrade strength, (2) pave- ment design period, (3) traffic and loading conditions, including volume and distribution of axle weights, and (4) thicknesss of concrete or bituminous wearing sur- face. The Portland Cement Association (PCA),2,3 the American Association of State Highwa
25、y and Transpor- tation Officials (AASHTO),4 and the U.S. Army Corps of Engineers (USACE), 5,6 have established methods for determining design thickness for soil-cement bases. Most in-service soil-cement bases are 6 in. thick. This thickness has proved satisfactory for service conditions associated w
26、ith secondary roads, residential streets, and light-traffic air fields. A few 4 and 5 in. thick bases have given good service under favorable conditions of light traffic and strong subgrade support. Many miles of 7 and 8 in. thick soil-cement bases are providing good performance in primary and high-
27、traffic second- ary pavements. Although soil-cement bases more than -,-,- SOIL CEMENT 230.1R-3 Fig.2.1-Old bituminous mat being scarified and pulverized for incorporation in soil-cement mix 9 in. thick are not common, a few airports and heavy industrial pavement project3 have been built with mul- ti
28、layered thicknesses up to 32 in. Since 1975, soil-cement base courses incorporating local soils with portland cement and fly ash have been constructed in 17 states.7 Specification guidelines and a contractors guide for constructing such base courses are available from the Electric Power Research Ins
29、ti- tute.8 2.3-Slope protection Following World War II, there was a rapid expan- sion of water resource projects in the Great Plains and South Central regions of the U.S. Rock riprap of sat- isfactory quality for upstream slope protection was not locally available for many of these projects. High co
30、sts for transporting riprap from distant quarries to these sites threatened the economic feasibility of some proj- ects. The U.S. Bureau of Reclamation (USBR) initiated a major research effort to study the suitability of soil cement as an alternative to conventional riprap. Based on laboratory studi
31、es that indicated soil cement made with sandy soils could produce a durable erosion-resis- tant facing, the USBR constructed a full-scale test sec- tion in 1951. A test-section location along the southeast shore of Bonny Reservoir in eastern Colorado was se- lected because of severe natural service
32、conditions cre- ated by waves, ice, and more than 100 freeze-thaw cycles per year. After 10 years of observing the test sec- tion, the USBR was convinced of its suitability and specified soil cement in 1961 as an alternative to riprap for slope protection on Merritt Dam, Nebraska, and later at Chene
33、y Dam, Kansas. Soil cement was bid at less than 50 percent of the cost of riprap and produced a total savings of more than $1 million for the two projects. Performance of these early projects has been good. Although some repairs have been required for both Merritt and Cheney Dams, the cost of the re
34、pairs was far less than the cost savings realized by using soil ce- ment over riprap. In addition, the repair costs may have been less than if riprap had been used.9 The origi- nal test section at Bonny Reservoir has required very little maintenance and still exists today, almost 40 years later (Fig
35、. 2.2). Since 1961, more than 300 major soil-cement slope protection projects have been built in the U.S. and Canada. In addition to upstream facing of dams, soil cement has provided slope protection for channels, spillways, coastal shorelines, highway and railroad em- bankments, and embankments for
36、 inland reservoirs. For slopes exposed to moderate to severe wave ac- tion (effective fetch greater than 1000 ft) or debris-car- rying, rapid-flowing water, the soil cement is usually placed in successive horizontal layers 6 to 9 ft wide by 6 to 9 in. thick, adjacent to the slope. This is referred t
37、o as “stairstep slope protection” (Fig. 2.3). For less severe applications, like those associated with small reservoirs, ditches, and lagoons, the slope protection may consist of a 6 to 9 in. thick layer of soil cement placed parallel to the slope face. This method is often referred to as “plating”
38、(Fig. 2.4). The largest soil-cement project worldwide involved 1.2 million yd3 of soil-cement slope protection for a -,-,- 230.1 R-4 Fig. 2.2-Soil-cement test section at Bonny Reservoir, Colo., after 34 years Mini level 3 Not to scale Fig. 2.3-Soil-cement slope protection showing layered design Fig.
39、 2.4-Soil-cement slope plating for cooling water flume at Florida power plant SOIL CEMENT 230.1R-5 7000-acre cooling-water reservoir at the South Texas Nuclear Power Plant near Houston. Completed in 1979, the 39 to 52 ft high embankment was designed to contain a 15 ft high wave action that would be
40、created by hurricane winds of up to 155 mph. In addition to the 13 miles of exterior embankment, nearly 7 miles of in- terior dikes, averaging 27 ft in height, guide the recir- culating cooling water in the reservoir. To appreciate the size of this project, if each 6.75 ft wide by 9 in. thick lift w
41、ere placed end-to-end rather than in stair- step fashion up the embankment, the total distance covered would be over 1200 miles. Soil cement has been successfully used as slope pro- tection for channels and streambanks exposed to lat- eral flows. In Tucson, Arizona, for example, occa- sional floodin
42、g can cause erosion along the normally dry river beds. From 1983 to 1988, over 50 soil-cement slope protection projects were constructed in this area. A typical section consists of 7 to 9 ft wide horizontal layers placed in stairstep fashion along 2:l (horizontal to vertical) embankment slopes. To p
43、revent scouring and subsequent undermining of the soil cement, the first layer or two is often placed up to 8 ft below the existing dry river bottom, and the ends extend approx- imately 50 ft into the embankment. The exposed slope facing is generally trimmed smooth during construction for appearance
44、. To withstand the abrasive force of stormwater flows of 25,000 to 45,000 ft3/sec at veloci- ties up to 20 ft/sec, the soil cement is designed for a minimum 7-day compressive strength of 750 psi. In ad- dition, the cement content is increased by two percent- age points to allow for field variations.
45、10 More detailed design information on soil-cement slope protection can be found in References 11 through 13. 2.4-Liners Soil cement has served as a low-permeability lining material for over 30 years. During the mid-1950s, a number of 1 to 2 acre farm reservoirs in southern Cal- ifornia were lined w
46、ith 4 to 6 in. thick soil cement. One of the largest soil-cement-lined projects is Lake Ca- huilla, a terminal-regulating reservoir for the Coachella Valley County Water District irrigation system in southern California. Completed in 1969, the 135 acre reservoir bottom has a 6 in. thick soil-cement
47、lining, and the sand embankments forming the reservoir are faced with 2 ft of soil cement normal to the slope. In addition to water-storage reservoirs, soil cement has been used to line wastewater-treatment lagoons, sludge-drying beds, ash-settling ponds, and solid waste landfills. The U.S. Environm
48、ental Protection Agency (EPA) sponsored laboratory tests to evaluate the com- patibility of a number of lining materials exposed to various wastes.14 The tests indicated that after 1 year of exposure to leachate from municipal solid wastes, the soil cement hardened considerably and cored like port-
49、land cement concrete. In addition, it became less permeable during the exposure period. The soil cement was also exposed to various hazardous wastes, includ- ing toxic pesticide formulations, oil refinery sludges, toxic pharmaceutical wastes, and rubber and plastic wastes. Results showed that for these hazardous wastes, no seepage had occurred through soil cement following 21/2 years of exposure. After 625 days of exposure to these wastes, the compressive strength of the soil ce- ment exceeded the compressi
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