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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>DESIGN OF A DIFFERENTIAL PORE PRESSURE MANOMETER AND ITS TIME LAG CHARACTERISTICS</title>
      <link>https://trid.trb.org/View/118182</link>
      <description><![CDATA[A NEW DIFFERENTIAL PORE PRESSURE MANOMETER HAS BEEN DESIGNED WHICH CAN REGISTER SIMULTANEOUSLY THE DIFFERENCE OF PORE PRESSURE AT BASE AND ANY OTHER POINT INSIDE THE TRIAXIAL SOIL SPECIMEN. THE DESIGN CRITERIA OF THE ABOVE DEVICE HAVE BEEN DISCUSSED. THE DIFFERENTIAL PORE PRESSURE MANOMETER IS USEFUL FOR SATURATION BY BACK PRESSURE AND MEASUREMENT OF PORE PRESSURE IN THE TRIAXIAL SPECIMEN WHERE THERE IS NO CONTROL OF CELL PRESURE. EXPERIMENTS HAVE BEEN CARRIED OUT TO MEASURE TIME LAG IN PORE PRESSURE MEASUREMENT AT BASE AS WELL AS CENTRE OF THE SPECIMEN. EXPERIMENTAL RESULTS CONFIRM GIBSONS THEORETICAL ANALYSIS FOR TIME LAG IN BASE PORE PRESSURE MEASUREMENT. PORE PRESSURES IN THE CENTER OF THE SPECIMEN WERE MEASURED THROUGH A PLASTIC PROBE CONTAINING A FILTER TIP AT ITS END. SUITABILITY OF OTHER TYPES OF PROBE HAVE ALSO BEEN DISCUSSED. TIME LAG IN PORE PRESSURE MEASUREMENT THROUGH PROBE HAS BEEN COMPARED WITH THE THEORETICAL VALUE FOR PIEZOMETER BURIED IN SEMI-INFINITE SOIL. IT IS PREDICTED THAT IF THE DIMENSIONSLESS FACTOR IS GREATER THAN 1000, THE SPECIMEN MAY BE TREATED AS SEMI- INFINITE MEDIA WITH RESPECT TO THE PROBE. THE TEDIOUS DIFFERENTIAL EQUATION FOR TIME LAG HAS BEEN SOLVED NUMERICALLY BY SCHMIDTS METHOD AND SIMPLE EMPIRICAL FORMULAE HAVE BEEN OBTAINED FOR TIME LAG IN PORE PRESSURE MEASUREMENT AT BASE AS WELL AS MID-HEIGHT OF THE SPECIMEN. IN CLAYEY SOILS, THE PORE WATER HAS CONCENTRATION OF IONS. CONSEQUENTLY, OSMOTIC PRESSURE WILL COME INTO PLAY DURING PORE PRESSURE MEASUREMENT. SOURCE OF ERROR DUE TO ABOVE CAUSE AND REMEDIAL MEASURES HAVE BEEN DISCUSSED. IT WAS OBSERVED THAT THE FILTER TIP WAS OFTEN CHOKED. BACK PRESSURE WAS FOUND VERY EFFECTIVE IN REMOVAL OF CHOKING FROM THE FILTER TIP. VOLUME CHANGES IN PORE PRESSURE LOAD OF BISHOPS PORE PRESSURE APPARATUS HAVE BEEN MEASURED WITH CHANGES IN ATMOSPHERIC TEMPERATURE WHICH WERE FOUND TO BE OF CONSIDERABLE MAGNITUDE AND WOULD AFFECT THE PORE PRESSURE MEASUREMENT SUBSTANTIALLY. /AUTHOR/]]></description>
      <pubDate>Sun, 15 Aug 2004 01:49:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/118182</guid>
    </item>
    <item>
      <title>MOVEMENT OF WATER THROUGH SOIL AS INFLUENCED BY OSMOTIC PRESSURE AND TEMPERATURE GRADIENTS</title>
      <link>https://trid.trb.org/View/125338</link>
      <description><![CDATA[THE EQUATION USED TO DESCRIBE STEADY-STATE WATER FLOW THROUGH A SOIL IN RESPONSE TO HYDRAULIC PRESSURE (OR SUCTION IN UNSATURATED SOIL), OSMOTIC PRESSURE, AND TEMPERATURE GRADIENTS IS GIVEN. PUBLISHED RESEARCH RESULTS INDICATE THAT THE EFFECT OF TEMPERATURE COEFFICIENT IS RELATIVELY INDEPENDENT OF SUCTION WHEN SUCTIONS ARE GREATER THAN ABOUT 0.06 BAR, BECOMES QUITE SMALL WHEN SUCTIONS ARE LOWER THAN 0.06 BAR, AND INCREASES IN A PREDICTABLE MANNER AS THE AVERAGE TEMPERATURE INCREASES. A VALUE IS SUGGESTED FOR THE EFFECT OF TEMPERATURE COEFFICIENT FOR ESTIMATES OF WATER FLOW IN RESPONSE TO TEMPERATURE GRADIENTS. THE EFFECT OF THE OSMOTIC PRESSURE GRADIENT CAN BE CONSIDERED TO BE ZERO FOR SUCTIONS LESS THAN ABOUT 0.25 BAR EXCEPT UNDER CONDITIONS OF VERY HIGH CLAY CONTENT. THE VALUE OF THE OSMOTIC PRESSURE GRADIENT IS NOT LIKELY TO BE GREATER THAN 10 PER CENT OF THE COEFFICIENT OF HYDRAULIC CONDUCTIVITY (3 PER CENT IS SUGGESTED FOR APPROXIMATE CALCULATIONS) AT SUCTIONS BETWEEN 0.25 AND 1 BAR. THE OSMOTIC PRESSURE GRADIENT WOULD MORE NEARLY EQUAL THE COEFFICIENT OF HYDRAULIC CONDUCTIVITY AT GREATER SUCTIONS, BUT NO DATA ARE AVAILABLE ON THIS RELATIONSHIP AT HIGHER SUCTIONS. /AUTHOR/]]></description>
      <pubDate>Fri, 02 Sep 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/125338</guid>
    </item>
    <item>
      <title>OSMOTIC INTERPRETATION OF THE SWELLING OF EXPANSIVE SOILS</title>
      <link>https://trid.trb.org/View/126941</link>
      <description><![CDATA[VARIOUS FACTORS INVOLVED IN THE SWELLING OF EXPANSIVE SOILS ARE DISCUSSED. AVAILABLE KNOWLEDGE ON THE FIXATION OF WATER BY SOILS IS DISCUSSED: (1) DRY SOIL FIXES WATER VAPOR FROM THE ATMOSPHERE OR LIQUID WATER BY POLAR ABSORPTION, (2) CLAY SOILS AT MOISTURE CONTENTS AT OR ABOVE THEIR HYGROSCOPICITIES AT H = 100 ARE ABLE TO SORB MORE LIQUID WATER WITH LESS ENERGY BUT IN LARGER QUANTITY. OSMOSIS WITHOUT MEMBRANE AND OSMOTIC PRESSURE OF THE SOIL-WATER SYSTEM ARE MATHEMATICALLY ANALYZED. CONSIDERING WATER SUCTION IN CLAY SOILS AS AN OSMOTIC PHENOMENON WITHOUT MEMBRANE DUE TO THE EXCHANGE IONS, LEADS TO THE FOLLOWING CONCLUSIONS: (1) THE DIRECT APPLICATION OF VAN T'HOFF'S LAW IMPLIES THAT THE HYDROSTATIC OR OSMOTIC PRESSURE DEVELOPED IS DIRECTLY PROPORTIONAL TO THE BASE EXCHANGE CAPACITY AND INVERSELY TO THE VALENCE OF THE EXCHANGE IONS, (2) THE BASIC HYPOTHESIS IS THE INTRODUCTION OF THE CONCEPT OF THE OSMOTIC ACTIVITY OF THE EXCHANGE IONS, WHICH IS A DIRECT AND NECESSARY CONSEQUENCE OF THE FACT THAT OSMOTIC WATER SUCTION IN THE CASE OF CLAY SOILS IS OSMOSIS WITHOUT MEMBRANE, (3) BIVALENT CATIONS AND HYDROGEN, WHICH ALSO HAS A FLOCCULATING EFFECT, EXHIBIT AGGREGATION TENDENCIES AND FORM A STRUCTURE AS THE MOISTURE CONTENT DECREASES AND THE PARTICLES COME CLOSER TOGETHER, (4) IN THE RANGE IN WHICH THE LINEAR FUNCTION HOLDS, ONE CAN CONSIDER THE CONSOLIDATION CELL AS AN OSMOMETER AND CALCULATE THE MOISTURE CONTENT FROM THE DATA OBTAINED IN THE CONSOLIDATION TEST, AND (5) THE MARKED DIFFERENCE IN OSMOTIC ACTIVITY BETWEEN SODIUM AND THE OTHER CATIONS, WHICH IS REFLECTED IN THE RESPECTIVE K VALUES, COINCIDES WITH THAT SHOWN BY WINTERKORN AND BAVER IN THEIR EXPERIMENTS ON FREE SWELLING WITHOUT SURCHARGE OF PUTNAM AND BENTONITE CLAY COLLOIDS. THE OSMOTIC INTERPRETATION OF THE CONSOLIDATION AND SWELLING PHENOMENA OCCURRING IN SATURATED CLAY SOIL SYSTEMS PERMITS THE RECOGNITION AND ORGANIZATION OF THE CAUSATIVE FACTORS IN THE FOLLOWING MANNER: (1) THE ACTIVE SWELLING FORCE IS THE OSMOTIC PRESSURE OF THE AQUEOUS PHASE OF THE SOIL-WATER SYSTEM, (2) OPPOSED TO THIS ACTIVE FORCE IS AN INTERNAL RESISTANCE OF THE SOIL-WATER SYSTEM EXPRESSED BY THE COEFFICIENT, (3) THE CAPACITY FOR SWELLING AND FOR DEVELOPING A SWELLING PRESSURE THAT IS ABLE TO PERFORM EXTERNAL WORK DEPENDS ON THE RELATIVE MAGNITUDE OF THE SWELLING PRESSURE AND THE INTERNAL RESISTANCE, (4) REMOLDED, NONCEMENTED, EXPANSIVE SOILS POSSESS A LOW RESISTANCE TO DEFORMATION AND A HIGH ONE TO VISCOUS FLOW, (5) UNDISTURBED OR CEMENTED, STRUCTURE-ENDOWED, EXPANSIVE SOILS POSSESS A HIGH RESISTANCE TO DEFORMATION AND MAY ABSORB A LARGE PART OF OSMOTIC PRESSURE, (6) WHEN THE CLAY FRACTION OF A SOIL OCCUPIES THE SPACES BETWEEN THE COARSE GRANULAR COMPONENTS OF A SOIL, THEN THE SWELLING OF THE CLAY RESULTS IN EXPANSION OF THE SYSTEM IF THE COMBINED VOLUME OF CLAY PARTICLES AND OSMOTIC WATER EXCEEDS THAT OF THE INTERGRANULAR PORE SPACE, AND (7) WHEN THE INITIAL SOIL- WATER SYSTEM IS NOT WATERSATURATED, THEN WATER INTAKE CAN TAKE PLACE BY DISLOCATING AIR WITHOUT INCREASE IN TOTAL VOLUME. A THEORY IS DEVELOPED THAT PERMITS THE INTERPRETATION OF SWELLING PRESSURE WITH INCREASE IN INITIAL MOISTURE CONTENT.]]></description>
      <pubDate>Sun, 28 Aug 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/126941</guid>
    </item>
    <item>
      <title>MOVEMENT AND EQUILBRIUM OF WATER IN HETEROGENEOUS SYSTEMS WITH SPECIAL REFERENCE TO SOILS</title>
      <link>https://trid.trb.org/View/123786</link>
      <description><![CDATA[A THERMODYNAMIC STUDY OF WATER IN HETEROGENEOUS SYSTEMS WAS CONDUCTED TO OBTAIN AN EQUATION TO PRESENT A UNIFIED PICTURE OF THE THERMODYNAMICS OF SOIL MOISTURE. A THERMODYNAMIC FUNCTION, THE TOTAL POTENTIAL, WHICH WAS SHOWN TO BE EQUIVALENT TO THE PARTIAL MOLAR FREE ENERGY AND WHICH WAS APPLIED TO THE MOVEMENT AND EQUILIBRIUMS OF CONSTITUENTS IN HETEROGENEOUS SYSTEMS WAS USED. A GENERAL EQUATION WAS DEVELOPED, SHOWING THE CHANGE IN THE TOTAL POTENTIAL OF A CONSTITUENT DURING ANY PROCESS TO BE DUE TO CHANGES IN THE POSITIONAL POTENTIAL ENERGY OF THE CONSTITUENT AND TO CHANGES IN CONCENTRATION, PRESSURE AND TEMPERATURE OCCURRING IN THAT PROCESS. THE PRESENCE OF GRAVITATIONAL, ELECTROSTATIC, AND VAN DER WAALS FORCE FIELDS IN THE SYSTEM WAS CONSIDERED TO BE RESPONSIBLE FOR THE POSITIONAL POTENTIAL ENERGY OF THE WATER IN THE SOIL. THE HYPOTHESIS WAS MADE THAT THE RATE OF MOVEMENT OF THE WATER IN THE SOIL IS DIRECTLY PROPORTIONAL TO THE DRIVING FORCE, WHICH WAS REGARDED AS EQUAL TO THE NEGATIVE GRADIENT OF THE TOTAL POTENTIAL OF THW WATER. AN EQUATION FOR THE VELOCITY OF WATER IN A HETEROGENEOUS SYSTEM WAS DEVELOPED ON THE BASIS OF THIS HYPOTHESIS AND THE GENERAL EQUATION FOR THE TOTAL POTENTIAL. THIS EQUATION YIELDED DARCY'S LAW. INTEGRATION OF THE GENERAL EQUATION PRODUCED A SECOND GENERAL EQUATION EXPRESSING THE EQUILIBRIUM PRESSURE DIFFERENCE BETWEEN ANY TWO PHASES AS A FUNCTION OF THE CONCENTRATION RATIO AND POSITIONAL POTENTIAL ENERGY DIFFERENCE FOR ANY CONSTITUENT DISTRIBUTED BETWEEN THE TWO PHASES. THE CAPILLARY RISE AND VAN'T HOFF'S LAW EMERGED AS SPECIAL CASES. THE GENERAL EQUATION WAS APPLIED TO THE WATER IN THE INTERFACIAL REGION OF THE CLAY PARTICLE, WITH THE RESULT THAT THE HYDROSTATIC PRESSURE WAS SHOWN TO BE GREATER IN THE MICELLAR SOLUTION THAN IN THE INTERMICELLAR SOLUTION, THE MAGNITUDE OF THE DIFFERENCE DEPENDING ON THE SALT CONCENTRATION IN THE INTERMICELLAR SOLUTION, THE ELECTROSTATIC POTENTIAL IN THE MICELLAR SOLUTION, AND THE DISTANCE FROM THE PARTICLE. SIMPLIFICATION RESULTED IN AN EQUATION FOR EQUILIBRIUM OSMOTIC PRESSURE DIFFERENCES ORIGINALLY DUE TO LANGMUIR.]]></description>
      <pubDate>Fri, 12 Aug 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/123786</guid>
    </item>
    <item>
      <title>PARALLEL PLATE INTERACTION IN CLAY-WATER SYSTEMS</title>
      <link>https://trid.trb.org/View/127978</link>
      <description><![CDATA[TWO RANGES MAY BE DISTINGUISHED IN THE DISCUSSION OF THE INTERACTION BETWEEN PARALLEL CLAY PLATES IN A CLAY-WATER SYSTEM, I.E. A SHORT RANGE AND A LONG RANGE. IN PRACTICE, THESE REGIONS DOMINATE THE PROBLEMS ENCOUNTERED IN FOUNDATION ENGINEERING /LONG RANGE INTERACTION/ AND IN THE STUDY OF THE COMPACTION OF SEDIMENTARY ROCKS /SHORT RANGE INTERACTION/. THE QUANTITATIVE TREATMENT OF THE LONG RANGE INTERACTION /OR OSMOTIC SWELLING/ DEALS WITH THE EVALUATION OF THE ELECTRIC DOUBLE LAYER REPULSION AND OF THE VAN DER WAALS ATTRACTION FORCES AND OTHER POSSIBLE SOURCES OF ATTRACTION. THE TREATMENT OF THE SHORT RANGE INTERACTION INVOLVES THE EVALUATION OF VAN DER WAALS, ELECTROSTATIC AND ADSORPTION FORCES. THE NET EFFECT OF THESE THREE FORCES IS ACCESSIBLE TO MEASUREMENT FROM ADSORPTION-DESORPTION ISOTHERMS OF WATER VAPOR ON AN EXPANDABLE CLAY. AN ANALOGOUS TREATMENT CAN BE GIVEN FOR CLAY-ORGANIC-HYDROCARBON SYSTEMS, AND APPLIED TO THE PROBLEM OF RETENTION OF HYDROCARBONS BY SOURCE ROCKS. /AUTHOR/]]></description>
      <pubDate>Thu, 11 Aug 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/127978</guid>
    </item>
    <item>
      <title>REACTIVITY OF RICE HUSK ASH</title>
      <link>https://trid.trb.org/View/276345</link>
      <description><![CDATA[Effect of lime:silica ratio on the kinetics of the reaction of silica with saturated lime has been investigated.  A parameter, lime reactivity index, has been defined to quantify the reactive silica present in rice husk ash.  The product of the reaction between rice husk ash and saturated lime is a calcium hydrosilicate.  The fibrilar structure and the hollow tubular morphology of the fibers of C-S-H, have been explained by a growth mechanism, where the driving force is osmotic pressure.  (Edited author abstract)]]></description>
      <pubDate>Fri, 31 Oct 1986 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/276345</guid>
    </item>
    <item>
      <title>USE OF THE OSMOTIC TENSIOMETER TO MEASURE NEGATIVE PORE WATER PRESSURE</title>
      <link>https://trid.trb.org/View/147872</link>
      <description><![CDATA[The osmotic tensiometer was developed to provide a method of direct measurement of tension in the pore water of soils. A study was undertaken at the University of Saskatchewan to investigate the instrument's operational characteristics and its applicability to practical engineering problems. The study covered long-term stability, response time to changes in pore water pressure, and response to changes in ambient temperature.  It was found that the internal prestress pressure tended to diminish with time, probably due to leakage of the confined solute through the semipermeable membrane.  However, it was possible to individually calibrate each instrument to correct for this effect.  Second, the pressure response of the osmotic tensiometers indicated that a transient flow process was occurring; the equilibration time of the device was primarily a function of the configuration and materials of the unit and the compressibility of the solution in the chamber.  Third, it was found that changes in ambient temperature considerably affected the internal reference pressures.  These results indicate that osmotic tensiometers may be useful to measure negative pore water pressures, providing that the temperature is controlled and the pore water pressure is constant.  This may restrict their usefulness to research applications.  (Author)]]></description>
      <pubDate>Tue, 30 Dec 1980 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/147872</guid>
    </item>
    <item>
      <title>SHEAR STRENGTH PROPERTIES OF A SODIUM ILLITE</title>
      <link>https://trid.trb.org/View/140076</link>
      <description><![CDATA[Osmotic repulsive forces between clay particles appears as a component of the effective normal stress, but do not withstand shearing stresses; hence, the osmotic forces reduce the effective angle of internal friction.  This was determined from a series of effective-stress triaxial compression tests that were performed on sedimented samples of 0.1N sodium illite and the results were compared with a similar series of tests on 0.01N calcium illite. The tests also suggested that the size of the hysteresis loop in the effective-stress Mohr-Coulomb failure envelope is a function of the strain at failure rather than the void ratio and that the failure strain depends on the initial soil structure and the type and relative magnitude of interparticle physico-chemical forces.  The shear-induced pore-water pressures for normally consolidated samples at 30 psi were functions only of strain, not being effected by a wide range in strain rate.]]></description>
      <pubDate>Wed, 29 Jan 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/140076</guid>
    </item>
    <item>
      <title>OSMOTIC STUDIES AND HYPOTHESIS CONCERNING ALKALI-AGGREGATE REACTION</title>
      <link>https://trid.trb.org/View/96654</link>
      <description><![CDATA[AN OSMOTIC CELL TECHNIQUE FOR THE STUDY OF THE CHEMISTRY AND PHYSICS OF THE ALKALI-AGGREGATE REACTION IS DESCRIBED. THE EXPERIMENTAL DATA INCLUDE THE EFFECT UPON OSMOTIC PRESSURE OF (1) THE PERMEABILITY OF THE NEAT CEMENT PASTE MEMBRANE, (2) ALKALI CONCENTRATION, (3) DIFFERENT ALKALIES, (4) CALCIUM HYDROXIDE, (5) PARTICLE SIZE OF AGGREGATE, AND (6) REACTION TEMPERATURE. APPLICATION OF THESE RESULTS HAS LED TO THE DEVELOPMENT OF A HYPOTHESIS CONCERNING THE REACTION OF ALKALIES IN CONCRETE OR MORTAR WITH REACTIVE SILICEOUS AGGREGATES.]]></description>
      <pubDate>Tue, 01 Jun 1971 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/96654</guid>
    </item>
    <item>
      <title>SOIL MOISTURE CHARACTERISTICS BY OSMOSIS WITH POLYETHYLENE GLYCOL: A SIMPLE SYSTEM WITH OSMOTIC PRESSURE DATA AND SOME RESULTS</title>
      <link>https://trid.trb.org/View/128271</link>
      <description><![CDATA[THE USE OF POLYETHYLENE GLYCOL (PEG) SOLUTIONS TO EXTRACT WATER FROM SOIL BY OSMOSIS MAKES IT POSSIBLE TO OBTAIN MOISTURE RELEASE CURVES OVER A WIDE SUCTION RANGE WITH A SINGLE SYSTEM. MATRIC SUCTIONS---MATRIC POTENTIAL EXPRESSED ON A UNIT VOLUME BASIS WITH THE SIGN REVERSED, I.E., NEGATIVE POTENTIAL IS POSITIVE SUCTION---UP TO 25 BARS ARE EASILY OBTAINED WITH PEG-6000 DIALYZING TUBING SYSTEMS. UNITS ARE DESCRIBED, MADE WITH SIMPLE, INEXPENSIVE, OFF-THE- SHELF LABORATORY EQUIPMENT WHICH WHEN USED WITH A TABLE OF OSMOTIC PRESSURES GIVEN IN THE ARTICLE, PROVIDE A SINGLE SYSTEM FOR DETERMINING MOISTURE CHARACTERISTICS FROM 0.16 TO 24.8 BARS WITHOUT RESORT TO EXPENSIVE PRESSURE AND SUCTION DEVICES AND THEIR ASSOCIATED PRESSURE SOURCES, VALVES, REGULATORS, AND GAGES. THE DESIGN OF AN OSMOTIC EXTRACTION UNIT AND OF AN OSMOMETER FOR DETERMINING PEG-6000 OSMOTIC PRESSURE IS SHOWN IN DETAIL IN FIGURES, AND PROCEDURES FOR THEIR USE ARE DESCRIBED IN THE TEXT. THE CHARACTERISTICS OF FIVE MINERAL SOIL AND ONE ORGANIC SOIL ARE PLOTTED AS WATER CONTENT AGINST MATRIC SUCTION.]]></description>
      <pubDate>Thu, 01 Apr 1971 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/128271</guid>
    </item>
    <item>
      <title>MOVEMENT AND EQUILIBRIUM OF WATER IN SOIL SYSTEMS AS AFFECTED BY SOIL - WATER FORCES</title>
      <link>https://trid.trb.org/View/127438</link>
      <description><![CDATA[A REVIEW IS PRESENTED OF RESULTS AND CONCLUSIONS TO DATE ON THE FORCES BETWEEN WATER AND SOIL MINERALS, ESPECIALLY THE CLAYS AND THEIR INFLUENCE ON WATER MOVEMENT AND EQUILIBRIUM. FICK'S LAW FOR DIFFUSION IS DEVELOPED MATHEMATICALLY, FOLLOWED BY EXPRESSIONS GIVING THE RELATIONSHIP OF OSMOTIC PRESSURE. EXPERIMENTAL PROOF IS PRESENTED OF THE LESSER DENSITY OF WATER HELD ON THE PLANAR SURFACES OF MONTMORILLONITE CLAY PARTICLES. IT APPEARS THAT CLAY-WATER FORCES ARE RESPONSIBLE FOR THE DEVELOPMENT OF A WATER STRUCTURE AT THE CLLAY-WATER INTERFACE. THIS STRUCTURE EXTENDS UPWARDS OF 60A. FROM THE CLAY SURFACE IT BECOMES LESS REGULAR, AND PROBABLY MORE FLUID, WITH DISTANCE FROM THE SURFACE. THIS ABSORBED WATER STRUCTURE AND THAT OF ICE ARE NOT IDENTICAL BUT ARE SIMILAR IN THAT BOTH ARE LESS DENSE THAN NORMAL WATER. THEY PROBABLY BOTH OWE THEIR COHERENCE TO HYDROGEN BONDS. IF CLAY-WATER FORCES GIVE RISE TO A MORE REGULAR WATER STRUCTURE IN THE VICINITY OF THE CLAY MINERAL SURFACES, THEY MUST ALSO INCREASE THE VISCOSITY OF THE WATER NEAR THESE SURFACES. SINCE WATER TENDS TO MOVE TOWARD REGIONS OF LOW POTENTIAL ENERGY, IT SHOULD ACCUMULATE IN THE INTERFACIAL REGIONS BETWEEN CLAY AND WATER, THE EXTENT OF THE ACCUMULATION BEING PROPORTIONAL TO THE MAGNITUDE OF THE FORCES. IT IS REASONABLE TO BELIEVE THAT SOIL-AND-CLAY WATER FORCES AFFECT THE MOVEMENT AND EQUILIBRIUM OF WATER IN SOIL SYSTEMS.]]></description>
      <pubDate>Mon, 17 Aug 1970 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/127438</guid>
    </item>
    <item>
      <title>PORE STRUCTURE</title>
      <link>https://trid.trb.org/View/102145</link>
      <description><![CDATA[MOST OF THE IMPORTANT PROPERTIES OF HARDENED CONCRETE ARE RELATED TO THE QUANTITY AND CHARACTERISTICS OF THE VARIOUS TYPES OF PORES IN PASTE AND AGGREGATE COMPONENTS OF CONCRETE. THE PAPER DISCUSSES THE POROSITY OF CONCRETE, CAPILLARY AND GEL PORES IN CEMENT-WATER PASTES, AGGREGATE PORES, AIR VOIDS, PERMEABILITY AND ABSORPTION OF CONCRETE, FREEZING PRESSURE, OSMOTIC PRESSURE, AND EFFECTIVE PORE AREAS. /PCA/]]></description>
      <pubDate>Mon, 01 Jun 1970 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/102145</guid>
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