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1、 ACI 304.2R-96 This report describes pumps for transporting and placing concrete. Rigid and flexible pipelines are discussed and couplings and other accessories described. Recommendations for proportioning pumpable concrete suggest optimum gradation of aggregates; outline water, cement, and admixtur
2、e requirements; and emphasize the need for evaluation of trial mixes for pumpability. The importance of saturating lightweight aggregates is stressed. Suggestions are given for layout of lines; for maintaining uniform delivery rate, as well as uniform quality of concrete at the end of the line; and
3、for cleaning out pipelines. This report does not cover shotcreting or pumping of nonstructural insu- lating or cellular concrete. Keywords: admixtures; aggregate gradation; aggregates; cement content; coarse aggregates; concrete construction; concretes; conveying; couplings; fine aggregates; finenes
4、s modulus; lightweight aggregate concrete; light- weight aggregates; mix proportioning; pipeline; placing; placing boom; pozzolans; pumped concrete; pumps; quality control; water content. CONTENTS Chapter 1Introduction, p. 304.2R-2 Chapter 2Pumping equipment, p. 304.2R-2 2.1Piston pumps 2.2Types of
5、valves 2.3Trailer pumps 2.4Truck-mounted concrete pumps 2.5Placing booms 2.6Specialized equipment 2.7Safety Chapter 3Pipeline and accessories, p. 304.2R-5 3.1General description 3.2System pressure capacity 3.3Rigid placing lineStraight sections, bends, and elbows 3.4System connection 3.5Flexible sys
6、temHose types and applications 3.6Concrete placing system accessories Chapter 4Proportioning pumpable concrete, p. 304.2R-10 4.1Basic considerations 4.2Normal weight aggregate 4.3Lightweight aggregate concrete 4.4Water and slump 4.5Cementitious materials 4.6Admixtures 4.7Fiber reinforcement 4.8Trial
7、 mixes 4.9Testing for pumpability Chapter 5Field practices, p. 304.2R-20 5.1General 5.2Pipeline concrete placement 5.3Powered boom placement Placing Concrete by Pumping Methods Reported by ACI Committee 304 Neil R. Guptill, Chairman David J. AkersRobert A. Kelsey*James S. Pierce Casimir Bognacki*Joh
8、n C. KingPaul E. Reinhart James L. CopeWilliam C. KrellRoyce J. Rhoads* Michael GardnerGary R. MassKenneth L. Saucier Daniel J. Green*Patrick McDowellPaul R. Stodola Terrence C. HollandDipak T. ParekhWilliam X. Sypher* Thomas A. Johnson*Roger J. Phares*Robert E. Tobin* Samuel A. KalatKevin Wolf *Mem
9、ber of subcommittee that prepared this report. Chairman of subcommittee that prepared this report. ACI 304.2R-96 supersedes ACI 304.2R-91 and became effective January 1, 1996. Copyright 1996, American Concrete Institute. All rights reserved including rights of reproduction and use in any form or by
10、any means, including the making of copies by any photo process, or by any electronic or mechanical device, printed or written or oral, or recording for sound or visual repro- duction or for use in any knowledge or retrieval system or device, unless permission in writing is obtained for the copyright
11、 proprietors. 304.2R-1 ACI Committee Reports, Guides, Standard Practices, Design Handbooks, and Commentaries are intended for guidance in planning, designing, executing, and inspecting construction. This document is intended for the use of individuals who are competent to evaluate the significance a
12、nd limitations of its con- tent and recommendations and who will accept responsibility for the application of the material it contains. The American Con- crete Institute disclaims any and all responsibility for the appli- cation of the stated principles. The Institute shall not be liable for any los
13、s or damage arising therefrom. Reference to this document shall not be made in contract docu- ments. If items found in this document are desired by the Archi- tect/Engineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the Ar- chitect/Engin
14、eer. 304.2R-2ACI COMMITTEE REPORT Fig. 1Piston pump and powered valve pumping train Chapter 6Field control, p. 304.2R-24 Chapter 7References, p. 304.2R-24 7.1Recommended references 7.2Cited references 7.3Other references Appendix 1Metric (SI) system adaptation, p. 304.2R- 25 CHAPTER 1INTRODUCTION AC
15、I defines pumped concrete as concrete that is transport- ed through hose or pipe by means of a pump. Pumping con- crete through metal pipelines by piston pumps was introduced in the United States in Milwaukee in 1933. This concrete pump used mechanical linkages to operate the pump and usually pumped
16、 through pipelines 6 in. or larger in diameter. Many new developments have since been made in the con- crete pumping field. These include new and improved pumps, truck-mounted and stationary placing booms, and pipeline and hose that withstand higher pumping pressures. As a result of these innovation
17、s, concrete placement by pumps has become one of the most widely used practices of the construction industry. Pumping may be used for most concrete construction, but is especially useful where space for construction equipment is limited. Concrete pumping frees hoists and cranes to de- liver the othe
18、r materials of construction concurrently with concrete placing. Also, other crafts can work unhampered by concrete operations. A steady supply of pumpable concrete is necessary for sat- isfactory pumping.1 A pumpable concrete, like conventional concrete, requires good quality control, i.e., uniform,
19、 proper- ly graded aggregate, materials uniformly batched and mixed thoroughly.2 Concrete pumps are available with maximum output capacities ranging from 15 to 250 yd3/hr. Maximum volume output and maximum pressure on the concrete cannot be achieved simultaneously from most con- crete pumps because
20、this combination requires too much power. Each foot of vertical rise reduces the horizontal pumping distance about 3 to 4 ft because three to four times more pressure is required per foot of vertical rise than is nec- essary per foot of horizontal movement. Pumped concrete moves as a cylinder riding
21、 on a thin lu- bricant film of grout or mortar on the inside diameter of the pipeline.3-5 Before pumping begins, the pipeline interior di- ameter should be coated with grout. Depending on the nature of material used, this initial pipeline coating mixture may or may not be used in the concrete placem
22、ent. Once concrete flow through the pipeline is established, the lubrication will be maintained as long as pumping continues with a properly proportioned and consistent mixture. CHAPTER 2PUMPING EQUIPMENT 2.1Piston pumps The most common concrete pumps consist of a receiving hopper, two concrete pump
23、ing cylinders, and a valving sys- tem to alternately direct the flow of concrete into the pump- ing cylinders and from them to the pipeline (Fig. 1). One concrete cylinder receives concrete from the receiving hop- per while the other discharges into the pipeline to provide a relatively constant flow
24、 of concrete through the pipeline to the placing area. Pistons in the concrete cylinders create a vacuum to draw in concrete on the intake stroke and mechan- ically push it into the pipeline on the discharge stroke. These pistons are driven by hydraulic cylinders on most pumps, but may be driven mec
25、hanically. Primary power is provided by diesel, gasoline, or electric motors. The cost of concrete pumps and their maximum pumping capacity and pressure applied to the concrete vary greatly. Components are sized to provide the desired output, volume, and pressure on the con- crete in the pipeline. T
26、he hydraulic pumps on most units are equipped with horsepower limiters that protect the power unit by destroking or reducing displacement to reduce the volume output of the hydraulic pump so it can provide the pressure required to move concrete at the maximum height or distance of the concrete pumps
27、 capability. Receiving hop- pers vary in size to match the volume capacity of the pump and are usually equipped with agitators which prevent aggre- gate segregation and stacking in the hopper. The hopper de- PLACING CONCRETE BY PUMPING METHODS304.2R-3 sign should maintain a head of concrete at the i
28、ntake to the concrete cylinders. 2.2Types of valves 2.2.1 Hydraulically powered valvesPumps in this class use different types of valves, but all of them are operated hy- draulically and have the ability to crush or displace aggre- gate which becomes trapped in the valve area. The size of the maximum
29、 size aggregate (MSA) which can be pumped by these units is controlled by the diameter of the concrete pas- sages within the pump and the diameter of the pipeline into which concrete is being pumped (see Section 4.2.1). Most of these pumps have an outlet port 5 in. or larger in diameter and utilize
30、reducers to reach smaller pipeline size as is nec- essary. Fig. 1 is typical of these units. The capacity of these pumps may vary from 20 to 250 yd3/ hr. They handle the broadest possible range of concrete mix- tures that can be pumped. 2.2.2 Ball-check concrete pumpsThis type of pump uti- lizes ste
31、el balls and mating seats to control the flow of con- crete from the hopper into the pumping cylinder and out of the pumping cylinder into the pipeline. The ball is forced into its seat by the concrete being pumped and has a very limited ability to displace or break aggregate which may be trapped in
32、 the valve area. Failure of the ball to seat results in loss of pumping efficiency (Fig. 2). These units are limited to pumping concrete with smaller than 1/2 in. MSA. The con- crete pistons in these units are frequently mechanically driv- en although there are hydraulically powered units available.
33、 They are usually rated at 20 yd3/hr or less. Because they are Fig. 2Ball check pump schematic Fig. 3Ball check concrete pump -,-,- 304.2R-4ACI COMMITTEE REPORT limited to small aggregate and low volume, they are fre- quently used for grouting and may pump through pipeline or hose as small as 2 in.
34、in diameter (Fig. 3). 2.3Trailer pumps 2.3.1 GeneralTrailer-mounted pumps are available with a very wide range of capacities and pressures. These units are usually rated for maximum theoretical volume in yd3/hr based on the diameter of the concrete cylinders and the length and frequency of the pumpi
35、ng strokes and the pres- sure applied to the concrete at the piston face. The most sig- nificant comparison factor is the horsepower available to pump concrete. The effect of horsepower limiters mentioned in Section 2.1 is most pronounced on general purpose and medium-duty trailer-mounted pumps beca
36、use they use lower horsepower engines. Most trailer pumps are powered with diesel engines and fall into relatively standard horsepower ranges that are determined by the number of cylinders in the power unit and whether it is turbo-charged. 2.3.2 Small general purpose pumpsThese trailer-mount- ed pum
37、ps are generally rated from about 20 to 35 yd3/hr, are powered with up to 60 hp engines, and weigh up to 5000 lb. They may have either hydraulically powered or ball-check valves. They generally utilize 5- and 6-in.-diameter concrete cylinders and apply pressures up to about 750 psi on the con- crete
38、. They are capable of pumping up to 250 ft vertically or up to 1000 ft horizontally. They are most suitable for grout- ing masonry walls and placing concrete in floor slabs, foot- ings, walls, columns, and decks where the limitations imposed by forming or finishing requirements limit the vol- ume of
39、 concrete and the rate at which it can be placed (Fig. 4). Operators usually use the smallest possible pipeline di- ameter (Section 4.2.1) for the grout or concrete being pumped 2 in., 2 1/2 in., and 3 in. are the most popular sizes. 2.3.3 Medium duty pumpsThese units have a capacity range from abou
40、t 40 to 80 yd3/hr, are powered with engines from 60 to 110 hp, and weigh from 5000 to 10,000 lb. They generally use 6-, 7-, or 8-in.-diameter concrete cylinders and are capable of applying pressures up to 900 psi on the con- crete. This pressure allows them to pump up to 300 ft verti- cally or 1200
41、ft horizontally. They are used on larger volume concrete placements where the ability to place concrete more quickly justifies their higher cost of ownership and operation (Fig. 5). Operators generally use 4- or 5-in.-diameter pipe- lines. 2.3.4 Special application pumpsThese trailer-mounted pumps p
42、lace over 80 yd3/hr, utilize engines with 110 hp and more, and weigh over 10,000 lb. They have a wide variety of pressure and volume capacities depending on the applica- tions for which they are used. Typical applications are spe- cialty projects like high-rise buildings and tunnel projects that req
43、uire pumping long horizontal distances because of limited access (see Fig. 6). Pumps in this class have pumped concrete over 1400 ft vertically and over 4600 ft horizontal- ly. Pipeline is selected to match the volume and pressure re- quirements of the project (Chapter 3). 2.4Truck-mounted concrete
44、pumps 2.4.1 Separate engine driveSeparate engine-driven con- crete pumps mounted on trucks are used primarily for projects with capacity requirements where the horsepower required for pumping the concrete is considerably less than that required to move the vehicle over the road. Such pumps are frequ
45、ently modified versions of the general purpose trail- er pumps and have the same operating capacities. 2.4.2 Truck engine-driven pumpsThese pumps have ca- pacities ranging from about 100 to 200 yd3/hr. They general- ly use 8- and 9-in.-diameter concrete cylinders and concrete pressures range from ab
46、out 640 to 1250 psi. Many units have different ratings when pumping oil is applied to the rod side (high capacity) or to the piston side (high pressure) of the hy- draulic pumping cylinder. With such wide variations in ca- pacity, it is not possible to summarize maximum vertical and horizontal pumpi
47、ng distances. These pumps are generally used with placing booms and require a heavy-duty truck chassis to carry their combined weight. A larger engine is re- quired for highway travel than is normally required for the pumping operation. The most economical combination in this case is to use the truc
48、k engine and a split shaft or power divider that can use the truck engine to power the running gear of the truck or to drive hydraulic pumps to provide pumping power. These units have receiving hoppers much larger than those on most trailer pumps to accommodate their higher pumping rates (Fig. 7). H
49、igh-volume pumping re- quires that the receiving hopper have an effective agitator. 2.5Placing booms Placing booms support a 5-in.-diameter pipeline which re- ceives the discharge from a concrete pump and places it in the forms. Booms have three or four articulating sections. Fig. 4Pump with hydraulically powered valve PLACING CONCRETE BY PUMPING METHODS304.2R-5 The booms are mounted on a turret that rotates to enable the discharge of the pipeline to be located anywhere within a cir- cle
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