ASTM_D_2325_-_68_2000.pdf

Designation:D 2325 68(Reapproved 2000)Standard Test Method forCapillary-Moisture Relationships for Coarse-and Medium-Textured Soils by Porous-Plate Apparatus1This standard is issued under the fixed designation D 2325;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of capillary-moisture relationships for coarse-and medium-textured soils asindicated by the soil-moisture tension relations for tensionsbetween 10 and 101 kPa(0.1 and 1 atm).Under equilibriumconditions,moisture tension is defined as the equivalentnegative gage pressure,or suction,corresponding to a soilmoisture content.This test method determines the equilibriummoisture content retained in a soil subjected to a givensoil-water tension.This test method is not suitable for veryfine-textured soils.NOTE1For determination of capillary-moisture relationships forfine-textured soils,refer to Test Method D 3152.1.2 This standard does not purport to address all of thesafety problems,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 421 Practice for Dry Preparation of Soil Samples forParticle-Size Analysis and Determination of Soil Con-stants2D 698 Test Method for Laboratory Compaction Character-istics of Soil using Standard Effort(12,400 ftlbf/ft3(600kNm/m3)D 3152 Test Method for Capillary-Moisture Relationshipsfor Fine-Textured Soils by Pressure-Membrane Appara-tus23.Summary of Test Method3.1 Saturated soil samples are placed in contact with asaturated porous plate installed within a pressure chamber.Thebottom of each plate is covered by a rubber membrane,orotherwise sealed to be airtight.The bottom of each plate ismaintained at atmospheric pressure by means of a small draintube or opening through the side of the pressure chamber.Adesired air pressure admitted to the pressure chamber,andconsequently to the top of the porous plate,creates a pressuredrop across the porous plate.The saturated soil samples on theplates establish equilibrium with the water in the plate.Thewater,held at a tension less than the pressure drop across theporous plate,will then move out of the soil,through the plate,and out through the drain tube.When water has ceased to flowfrom the sample and porous plate(indicating equilibrium forthat particular tension),the moisture content of each sample isdetermined.A series of these tests at various tensions isrequired to prepare a complete curve of the capillary-moisturerelationship for any particular soil.4.Apparatus4.1 An assembly of the apparatus is shown in Fig.1.4.1.1 Porous Plate Apparatus,consisting of the following:4.1.1.1 Pressure Container,(such as a pressure cooker),ofapproximately 15-L(16-qt)capacity.4.1.1.2 Porous Ceramic Plates,1 to 4(see Fig.2),approxi-mately 280 mm(1114in.)in diameter and 6 mm(14in.)inthickness,with an air entry value of 203 kPa(2 atm).4.1.1.3 Brass SpoutThe brass spout(one per porous plate)shall consist of a brass tube and associated washers,gaskets,and brass nuts.It shall provide an airtight joint when insertedthrough the porous plate 38 mm(1.5 in.)from the edge of theplate.The length of the unthreaded portion of the brass tubeshall be 9.5 mm(38in.);the length of the threaded portion shallbe 15.8 mm(58in.);the inside diameter of the tube shall be 1.7mm(116in.);the outside diameter of the upper unthreadedportion shall be 4 mm(532in.);the outside diameter of thelower threaded portion shall be 4.8 mm(316in.).The tap sizefor the hole through the porous plate shall be 5.5 mm(732in.).4.1.1.4 Disks of 10-mesh Brass Screen,from 1 to 4,ofslightly smaller diameter than bottom of porous ceramic plates.4.1.1.5 Rubber MembraneThe membrane shall consist ofsheet neoprene,0.79 mm(132in.)in thickness,with a hardnessof 35 by the Shore Durometer.Place a disk of brass screen overthe bottom of each porous ceramic plate to provide space forthe flow of water between the membrane and the ceramic plate(see Fig.2).Then place the rubber membrane snugly over thebrass screen,glue it securely to the outer edge of the ceramicplate,and wrap the edge tightly with wire(see Fig.2).4.1.1.6 TubingA flexible tubing tube,3 mm(18in.)in1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.04 on HydrologicProperties of Soils and Rocks.Current edition approved Sept.13,1968.Originally issued as D 2325 64 T.Last previous edition D 2325 64 T.2Annual Book of ASTM Standards,Vol 04.08.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.diameter,to carry