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GUIDE TO USE OF THE FHA SOIL PVC METER

Including Results of Nationwide

Soil Tests and Correlation

With Climatic Factors

I. INTRODUCTION

Severe damage to building foundations can result from \"swelling\" or

\"expansive\" soils. These soils, usually cohesive clays, can swell

or shrink as they go from the dry to the wet state or vice versa.

This alteration in moisture can cause a volume change which creates

large differential movements within the structure and thus causes

excessive cracking of floors, walls, and foundations.

Soils with expansive characteristics must be recognized in order to

evaluate properly their stability as foundation material. The maximum

potential volume change that a soil can undergo due to shrinking

or swelling is known as Potential Volume Change or PVC. PVC cannot

always be determined accurately by visual inspection. For this

reason, a relatively simple device was needed which could be used by

soil engineers as well as others less familiar with soil problems

to provide quick identification of expansive soils. Therefore, the

Federal Housing Administration, through its Technical Studies Program,

contracted with Dr. T. William Lambe of the Massachusetts Institute

of Technology to design such an instrument. This guide presents a

simplified explanation of the instrument, which is known as the FHA

Soil PVC Meter.

This meter is used to test volume change caused by moisture changes

and their effects upon inherent clay minerals. Some soils, however,

contain significant amounts of alkalies, salts, or soil chemicals

in a free state. These free chemicals can also cause soils to swell

upon the addition of water. For example, some of the soils containing

free chemicals which are located in the western section of the

United States become unstable upon the addition of moisture. This

type of volume change cannot be determined through the use of the

FHA Soil PVC Meter.

II\. ENVIRONMENT AND MOISTURE CONDITIONS

Environment affects volume changes by influencing the moisture

condition of the soil. In order to predict trends of volume change,

one must ascertain which elements of the overall physical environment

around a soil mass are most important to the moisture conditions in

the soil. It is only when the usual climate is inconstant and the

moisture condition goes from wet to dry or vice versa that significant

volume change occurs.

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A. General

The principal environmental factors which affect-the

moisture conditions of soil are:

1\. Climate \-- Wind, rain, temperature, drought.

2\. Pedology \-- Inherent chemical and physical

characteristics of soils.

3\. Hydrology \-- Location of water table, natural

drainage, and conditions of seepage.

4\. Man-placed structures.

Man-placed structures affect moisture conditions by

such changes as artificially introducing water into

the soil from lawn watering,and increasing capillary

activity by covering the soil.

B. Environment and Shrinkage

The principal cause of soil shrinkage is evaporation

of water from the soil pores. Thus, periods of warm

weather with relatively little rainfall favor shrinkage.

During such periods, the situation may be aggravated

by the presence of vegetation. This affects the

moisture condition by modification of the drainage

pattern and by transpiration of water from plants,

which extract water from the soil. On the other hand,

large amounts of rainfall and/or low temperatures will

not favor shrinkage. Hence, it can be misleading to

attempt to judge whether a soil is expansive after

considering only mean temperatures or average yearly

rainfall. One must consider the net effect of all

climatic factors over long periods of time.

C. Environment and Swelling

The swelling of dry soil occurs when a change in environment

results in a supply of water which can be

absorbed by the clay. There are many ways that water

can enter and move through soil:

1\. Seepage, or the flow of water due to the force

of gravity. Seepage may result from natural

phenomena such as infiltration of rainfall or

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as a result of man-made phenomena; for

example, irrigation ditches or faulty water

mains.

2\. Capillarity, or the movement of water into

or through soils due to attractive forces

between two unlike molecules. Capillarity

is regulated by such factors as grain size

of soil, water supply and depth, and temperature

changes. The capillary movement of

water in soils above the water table is often

a contributing cause of soil instability.

3\. Vapor transfer, or the flow of water in vapor

form through air voids in soils. This is

caused by differences in water vapor pressure.

The vapor pressure of water in air voids increases with

increased temperature and water content of the soil.

Thus, water vapor will flow from soil of high temperature

or high water content or both to soil of low temperature

or low water content or both. However, this method of

moisture movement is usually only of concern in soils at

low degrees of saturation (usually below 80 per cent)

under high temperature gradients. Vapor flow through

air voids can also contribute to the shrinkage of soil,

but this is usually of secondary importance Since most of

the volume decrease of wet soil occurs at a high degree

of saturation.

D. Climate Studies

In order to understand the relationship between climatic

factors and volume changes in the United States, studies

have been made for FHA of United States Weather Bureau

data (1). These studies indicate at least five variables

affecting constancy of climate:

1\. Yearly annual precipitation;

2\. Degree of uniformity in distribution of precipitation

through the year;

3\. Number of times precipitation occurs;

4\. Duration of each occurrence;

5\. Amount of precipitation at each occurrence.

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FIGURE 1

UNITED STATES WEATHER BUREAU SOIL-CLIMATE RATING MAP

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The United States Weather Bureau studies have further

disclosed that the amount of rainfall during any particular

period cannot be directly correlated with the

number of rains during that period. Without going into

a detailed explanation\$ for this guide it suffices to

say that the frequency function provides an excellent

measure of the potential for soil activity by giving a

sound indication of the likelihood of extended periods

during which soil-moisture balance may be upset either

through a small amount of rainfall and evaporation or

through a great amount of rainfall In fewer-than-normal

occurrences. In any instance, cohesive soils can be

expected to shrink with loss of moisture and swell with

moisture gain.

The rate at which moisture is lost or gained by soils

is not at this time thoroughly understood. It is generally

accepted, however, that air movement accelerates

loss of soil moisture. Since air movement is independent

of rainfall, it can be assumed that air movement

increases loss of soil moisture especially during

extended periods of little or no precipitation.

Using the variables mentioned above, the U.S.W.B. developed

a climatic rating (Cw) for all points in the

continental United States (Figure 1). These climatic

ratings range from a numerical value of 15, which signifies

those areas where the climate exerts the most

severe adverse influence on the soils, to 45, which

signifies those areas where the climate is least influential

on the soils. The Cw for any particular locality

not directly on an isoline can be determined simply by

interpolation to the nearest whole number; for example,

Columbia, Missouri, would be about 33.

The climatic rating chart can be used to indicate potential

problem areas where climatic variations are significant;

however, to determine the potential volume change

of any particular soil sample, a swell index test using

the FHA Soil PVC Meter can be made.

III\. USING THE FHA SOIL PVC METER

A. General

The FHA Soil PVC Meter is used to perform a swell index

test. This test is essentially a measurement of the

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4075.15 6

pressure exerted by a sample of compacted soil when

it swells against a restraining force after being

wetted. The FHA Soil PVC Meter, in addition to

yielding PVC values, can be used to estimate the

plasticity index and shrinkage behavior of soils.

These values are determined by comparing the results

of the swell index test with appropriate values contained

in Figures 3, 4, 5, and 6 in this guide and

reading the corresponding extrapolations.

The following categories of PVC have been established:

PVC Rating Category

Less than 2 Noncritical

2 to 4 Marginal

4 to 6 Critical

Greater than 6 Very critical

These ratings were established on the basis of the

swelling and shrinking behavior of the soil.

B. Equipment (See Figure 2 for Pictures of Equipment)

1\. PVC Meter

2\. Spacers, plate, and clamp for alternate

compaction method

3\. No. 10 Sieve

4\. Teaspoon

5\. Compaction Hammer and Sleeve

6\. Two Dry Porous Stones

7\. Knife, (preferably serated)

8\. Straight Edge

9\. Water in Squirt Bottle with Pointed End

10\. Wrenches

C. Preparation of Sample

For the test sample, take about a pint of soil from the

soil layer in which the foundation member will rest.

Although samples can be tested at three relative water

contents (dry, moist, or wet), it is suggested that those

being tested for FHA purposes be tested in the air dried

condition only. The samples can be sufficiently air

dried by breaking the soil into small lumps and leaving

it in the sun for a few hours. The following procedures

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are for soil in the air dried condition. For

information about soil in other conditions, see

Bibliography reference (2).

D. Preparation for Compaction

Disassemble the PVC Meter with exception of the

rods which can remain screwed into the base.

Place proving ring and top bar where it will not

be jarred during compaction. Wipe equipment with

clean cloth.

E. Compaction

Definitions:

Compaction ring \-- larger ring; identified

by letter \"c\" etched on outside periphery.

Spacer ring \-- smaller ring; identified by

letter \"s\" etched on outside periphery.

1\. To assemble meter for compaction, fit compaction

ring on base so that \"c\" is backwards and at the

top. Align bolt holes with those in base. Place

spacer ring on compaction ring so that \"s\" is at

the top (radial grooves are at top). Align bolt

holes with those in base. Insert the 3 bolts

through both the rings and the base and tighten

firmly to base.

2\. The soil sample is to be placed in the ring assembly

in 3 layers of equal amounts. Each layer is to be

compacted separately. Compaction it accomplished by

use of the hammer, which is a tamping device encased

in a metal sleeve.

3\. Compact each layer of the sample in the following

manner:

a\. Place 3 heaping teaspoonsfull of sample in

ring assembly and smooth lightly with hammer

to firm up the surface before applying the

blows (This reduces the amount of soil

\"Jumping\" out of the mold during compaction.).

Place apparatus on a solid level floor.

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b\. Before each blow, lift sleeve 1/8 inch

from soil and hold firmly against the

inside of the spacer ring. Make sure

sleeve of hammer rests inside rings so

that hammer does not damage them in

falling. Be sure to hold sleeve and

hammer perpendicular and in line with

supporting rods. Raise hammer to top

of sleeve and let it fall free (not

striking sides of sleeve). Space blows

evenly over surface of sample by shifting

hammer after each blow. Compact

the first two layers with 7 blows each

of the compaction hammer and the last

with 8 blows. Repeat this process for

each layer. (See F for Alternate

Compaction Method.)

4\. At completion of the compaction of both the first

and second layers, scratch the top surface of the

layer with a knife to assure proper bond with the

next layer. After compaction, the last layer

should extend approximately 1/4 inch into the spacer

ring. If it is significantly below this point, remove

entire sample and recompact.

5\. Put assembly on table and remove the 3 bolts. Rotate

spacer ring (to break bond between ring and soil) and

remove carefully from base. Remove compaction ring

containing sample in same way. Do not tilt compaction

ring or spill soil.

6\. Trim top of the sample with a knife. Hold knife

against the compaction ring at all times during

trimming to avoid dislodging sample. Trim in a

sawing motion taking off only a small amount of

soil at a time. Rotate the ring as you trim. Work

from the edge toward the center. When sample is

almost level, do final leveling by drawing a metal

straight edge over sample.

7\. The final surface of the soil sample should be firm

and smooth. Any voids should be filled by pressing

additional soil into them with the knife or spoon.

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8\. Clean soil from base and from all holes in rings

and base. Remove soil in the groove of the spacer

ring and from the holes in the spacer ring and the

compaction ring with a toothpick or paperclip.

F. Alternate Compaction Method

1\. After fitting rings to base as explained in E, paragraph

1, place one spacer on each rod, then set the

plate on the spacers. Bolt these securely to the

rods. Attach the clamp to the sleeve so that the

sleeve extends about 1/4 inch inside the spacer ring.

Place the soil sample in the ring assembly in the

same manner as explained in E, paragraphs 2 and 3a.

2\. Before each blow, turn the \"foot\" of the clamp so that

it points in the direction of the spot to be compacted.

The sleeve and hammer must be held perpendicular and in

line with the supporting rods. To assure this, the

sleeve should be held firmly against the inside of the

plate and the spacer ring. Raise hammer to top of

sleeve and let it fall free (not striking sides of

sleeve). Space blows evenly over surface of sample by

shifting hammer after each blow. Compact the first two

layers with 7 blows each of the compaction hammer and

the last with 8 blows. Repeat this process for each

layer.

3\. The remaining compaction process is the same as E,

paragraphs 4 through 8.

G. Swelling

1\. Place spacer ring on base with \"s\" (and radial grooves)

on top. Align bolt holes with those on base. Place

thoroughly dry porous stone in spacer ring. Move

assembled base to edge of working table. Place thumb

under base and other fingers over spacer ring and stone,

holding them firmly in place. Turn base upside-down

retaining firm hold on stone and spacer ring. Pick up

compaction ring containing sample \-- trimmed side up

\-- and place flush against porous stone in spacer ring

aligning bolt holes in the two rings. Move compaction

ring with as little disturbance of sample as possible.

Turn base with rings, stone, and sample rightside-up.

Bolt rings tightly to base.

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2\. Place a dry porous stone on top of sample inside

compaction ring. Place the rubber O-ring on the

base and screw the lucite container onto it tightly

to insure water seal. Place metal cover on porous

stone with the center indentation at the top.

3\. Place top bar with proving ring on the steel rods

(Be sure that the adjustable rod which extends down

from the proving ring dial does not strike the cover.).

Add washers and nuts and tighten firmly.

4\. Set proving ring dial to zero by moving the band

around the dial. Tighten dial with the screw on

band. Push up on proving ring dial to see that it

appears to work properly. Turn adjustable rod

exactly into the center of the indentation on top

of the cover. Be sure that the cover is centered

exactly over the stone. Tighten lock nut on adjustable

rod firmly. Be sure adjustable rod does not

stick in cover (receptable for adjustable rod may

require slight enlargement). Turn adjustable rod

until dial reads one division past zero. Tighten

lock nut firmly again until adjustable rod has no

play.

5\. Record the time and the proving ring reading. Add

water to sample by squeezing from squirt bottle into

the holes located at the top of compaction ring until

water level in lucite container has covered the spacer

ring and tops of the bolts. (This procedure is used to

reduce the amount of air entrapped in the ring assembly

and thus insures that the sample has uniform access to

water over its entire top and bottom surfaces.)

H. Reading

1\. Allow soil to expand until completely stabilized or for

a maximum of 2 hours, then read dial to obtain PVC swell

index value. On the dial the number 1 equals 10 divisions,

the number 2 equals 20, etc.

2\. Next, find the number corresponding to the proving ring

dial reading on Figure 3 and subtract the one division

that registered on the dial prior to swell. Read horizontally

to intersection with sloping line. From point

of intersection, read downward to baseline which indicates

pressure in lbs./sq. ft.

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3\. Take this figure to Figure 4. Find the number

corresponding to it on left hand side of the

chart. Read horizontally to intersection with

the sloping line Marked \"Dry and Moist.\" From

point of intersection, read downward to the

baseline, which indicates PVC category.

4\. Take the reading in lbs./sq. ft. to Figure 5 to

determine the plasticity index.

5\. It is also possible to obtain the approximate

PVC category and plasticity index by taking the

reading from the proving ring dial directly to

Figure 6.

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FIGURE 2

PICTURES OF EQUIPMENT

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FIGURE 3

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FIGURE 4

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FIGURE 5

SWELL INDEX VS. PLASTICITY INDEX

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FIGURE 6

TABLE FOR CONVERTING PROVING RING READINGS TO

PVC CATEGORY AND APPROXIMATE PLASTICITY INDEX

Proving Swell PVC Plasticity

Ring Index Category Index (%)

Reading (#/SF)

5 775 0.8 8.5

6 925 1.0 9.5

7 1075 1.2 10.7

8 1250 1.4 11.7

9 1375 1.6 12.7

10 1550 1.8 13.8

10.8 1675 2.0 14.6

11 1700 2.0 14.8

12 1875 2.2 15.8

13 2025 2.4 17.0

14 2175 2.65 18.0

15 2350 2.85 19.0

16 2500 3.05 20.0

17 2675 3.3 21.5

18 2800 3.45 22.5

19 2975 3.7 23.8

20 3150 3.9 25.0.

20.3 3200 4.0 25.5

21 3300 4.1 26.0

22 3450 4.3 27.5

23 3600 4.5 28.5

24 3775 4.75 29.8.

25 3925 4.95 30.8

26 4075 5.15 31.8

27 4225 5.4 33.0

28 4375 5.55 34.0

29 4525 5.75 35.3

30 4700 5.95 37.0

30.2 4725 6.00 37.1

31 4850 6.2 38.0

32 4975 6.35 39.0

33 5125 6.5 40.4

34 5275 6.7 41.7

35 5425 6.9 43.4

36 5575 7.1 44.2

37 5725 7.25 45.5

38 5850 7.4 46.6

39 6000 7.5 48.0

40 6150 7.65 49.5

40.5 6225 7.7 50.0

Prepared by

6/74 the Architectural Section,

Federal Housing Administration Insuring Office

San Antonio, Texas

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IV\. FHA SOIL PVC METER SWELL INDEX TEST RESULTS FROM SELECTED LOCATIONS
IN

THE UNITED STATES

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

ALABAMA

1\. Houston clay, Montgomery, Alabama Very

(sampled and tested by Elvin F. Henry). 8300 Critical 65

2\. Houston clay, Montgomery, Alabama Very

(sampled and tested by Elvin F. Henry). 6400 Critical 53

3\. Houston clay, Montgomery, Alabama Non

(sampled and tested by Elvin F. Henry). 1400 -Critical 13

4\. Eroded Sumpter clay mixture of subsoil

and chalky soil material, Montgomery,

Alabama (sampled and tested by Elvin

F. Henry). 3700 Critical 29

5\. Sumpter clay, Montgomery, Alabama Very

(sampled and tested by Elvin F. Henry). 9000 Critical 67

6\. Sumpter clay, Montgomery, Alabama Very

(sampled and tested by Elvin F. Henry). 5700 Critical 45

7\. Vaiden soil overlying Selma chalk,

Montgomery, Alabama (sampled by Elvin

F. Henry and Ray Dawson). 4000 Critical 31

ARIZONA

1\. Clay soil, Holbrook, Arizona (sampled

by Lloyd Leslie). 4800 Critical 38

ARKANSAS

1\. Soil, Fayettsville, Arkansas (sampled

and tested by Elvin F. Henry). 2025 Marginal 17

6/74

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

4075.15

18

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

CALIFORNIA

1\. Soil, Brawley, California (sampled and

tested by Ray Sherman). 3200 Marginal 25

2\. Soil, Silty clay, Calexico, California

(sampled and tested by Elvin F. Henry). 4075 Critical 32

3\. Soil, El Cajon, California (sampled and Non

tested by Ray Sherman). 500 -Critical 8

4\. Soil, El Cajon, California (sampled and Non

tested by Ray Sherman). 1200 -Critical 12

5\. Soil, El Cajon, California (sampled and Non

tested by Ray Sherman). 500 -Critical 8

6\. Soil, El Cajon, California (sampled and Non

tested by Ray Sherman). 500 -Critical 8

7\. Soil, El Centro, California (sampled and

tested by Ray Sherman). 4100 Critical 32

8\. Soil, El Centro, California (sampled and

tested by Ray Sherman). 2800 Marginal 21

9\. Soil, El Centro, California (sampled and Very

tested by Ray Sherman). 4800 Critical 38

10\. Soil, El Centro, California (sampled and

tested by Ray Sherman). 2500 Marginal 20

11\. Soil, El Centro, California (sampled and

tested by Ray Sherman). 3200 Marginal 25

12\. Soil, Poway, California (sampled and

tested by Ray Sherman). 2250 Marginal 18

13\. Soil, Poway, California (sampled and Non

tested by Ray Sherman). 600 -Critical 8

14\. Soil, Poway, California (sampled and Non

tested by Ray Sherman). 100 -Critical 5

6/74

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

4075.15

19

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

CALIFORNIA (Continued)

15\. Soil, Poway, California (sampled and Non

tested by Ray Sherman). 100 -Critical 5

16\. Soil, Poway, California (sampled and Non

tested by Ray Sherman). 650 -Critical 9

17\. Clay, San Diego, California (sampled Very

and tested by Elvin F. Henry). 6000 Critical 48

18\. Soil, San Diego, California (sampled

and tested by Ray Sherman). 2750 Marginal 21

19\. Soil, San Diego, California (sampled Very

and tested by Ray Sherman). 5500 Critical 43

20\. Soil, San Diego, California (sampled

and tested by Ray Sherman). 4000 Critical 31

21\. Soil, San Diego, California (sampled Very

and tested by Ray Sherman). 5500 Critical 45

22\. Soil, San Diego, California (sampled Non

and tested by Ray Sherman). 1400 -Critical 13

23\. Soil, San Diego, California (sampled

and tested by Ray Sherman). 2500 Marginal 20

24\. Soil, San Diego, California (sampled

and tested by Ray Sherman). 4000 Critical 31

25\. Soil, San Diego, California (sampled

and tested by Ray Sherman). 2200 Marginal 18

26\. Soil, Spring Valley, California Non

(sampled and tested by Ray Sherman). 650 -Critical 8

27\. Soil, Spring Valley, California Non

(sampled and tested by Ray Sherman). 750 -Critical 9

28\. Soil, Spring Valley, California

(sampled and tested by Ray Sherman). 2500 Marginal 20

29\. Soil, Spring Valley, California

(sampled and tested by Ray Sherman). 3000 Marginal 20

6/74

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

4075.15

20

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

COLORADO

1\. Clay, Denver, Colorado (sampled by Very

Charles Bigler). 7600 Critical 55

2\. Clay, Denver, Colorado (sampled by

Charles Bigler). 3950 Critical 31

3\. Silty clay, Denver, Colorado (sampled

by Charles Bigler). 2350 Marginal 19

4\. Silty clay, Denver, Colorado (sampled

by Charles Bigler). 2400 Marginal 19

5\. Silty clay, Denver, Colorado (sampled Non

by Charles Bigler). 450 -Critical 6

6\. Silty clay, Northwest Pueblo, Colorado Non

(sampled by Charles Bigler). 900 -Critical 9

HAWAII

1\. Dark clay Foam basalt, Manilani, Oahu,

Hawaii (sampled and tested by Elvin F. Very

Henry). 5500 Critical 43

2\. Soil sample, (fill area), Aikahi

Hillside, Oahu, Hawaii (sampled and Very

tested by Elvin F. Henry). 7400 Critical 56

3\. Soil sample, Halawa Hill, Oahu, Hawaii

(sampled and tested by Elvin F. Henry). 2200 Marginal 18

4\. Soil sample, (subsoil), (Kalihi) Wilson

Tract, Oahu, Hawaii (sampled and tested Very

by Elvin F. Henry). 8000 Critical 63

5\. Soil Sample, (fill area), Waiolu

Subdivision, Oahu, Hawaii (sampled and

tested by Elvin F. Henry). 3400 Marginal 27

6/74

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

4075.15

21

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

LOUISIANA

1\. Colfax soil, Olla, Louisiana (sampled Non

and tested, by Elvin F. Henry). 1550 -Critical 14

2\. Clay, Shreveport, Louisiana (sampled Very

and tested by Elvin F. Henry). 5725 Critical 45

3\. Clay, Shreveport, Louisiana (sampled

and tested by Elvin F. Henry). 4075 Critical 32

4\. Clay, Shreveport, Louisiana (sampled

and tested by Elvin F. Henry). 3000 Marginal 24

5\. Bladen clay, St. Joseph, Louisiana

(sampled and tested by Elvin F. Henry). 4700 Critical 37

MARYLAND

1\. Montalto silty clay (Experimental House),

Rockville, Maryland (sampled by Ralph

Johnson, NAHB). 2675 Marginal 21

MISSISSIPPI

1\. Yazoo clay, Jackson, Mississippi Very

(sampled and tested by Elvin F. Henry). 9500 Critical 68

OKLAHOMA

1\. Parsons clay, Tulsa County, Oklahoma

(sampled and tested by Elvin F. Henry). 2000 Marginal 17

2\. Summit clay, Tulsa County, Oklahoma

(sampled and tested by Elvin F. Henry). 2400 Marginal 19

TEXAS

1\. Soil, NE of San Antonio, Bexar County,

Texas (sampled by John Turner). 3300 Critical 26

2\. Soil, NE of San Antonio, Bexar County,

Texas (sampled by John Turner). 2175 Marginal 18

6/74

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4075.15

22

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

TEXAS (Continued)

3\. Soil, NE of San Antonio, Bexar County, Very

Texas (sampled by John Turner). 10,000+ Critical 70

4\. Soil, NW of San Antonio, Bexar County, Non

Texas (sampled by John Turner). 775 -Critical 8

5\. Soil, E of San Antonio, Bexar County, Very

Texas (sampled by John Turner). 6550 Critical 54

6\. Soil, S. of San Antonio, Interstate

Highway, Bexar County, Texas (sampled

by John Turner). 2500 Marginal 20

7\. Soil, S. of San Antonio\$ Texas, Bexar

County, Texas (sampled by John Turner). 1700 Marginal 15

8\. Soil, SW of San Antonio, Bexar County, Non

Texas (sampled by John Turner). 450 -Critical 4

9\. Soil, SW of San Antonio, Bexar County, Very

Texas (sampled by John Turner). 5575 Critical 44

10\. Soil, W. of San Antonio, Bexar County,

Texas (sampled by John Turner). 2025 Marginal 17

11\. Soil, W. of San Antonio, Bexar County, Very

Texas (sampled by John Turner). 8425 Critical 66

12\. Soil, W. of San Antonio, Bexar County, Very

Texas (sampled by John Turner). 4975 Critical 39

13\. Soil, W. of San Antonio, Bexar County,

Texas (sampled by John Turner). 2500 Marginal 20

14\. Soil, Cavaca, Texas (sampled by John

Turner). 4525 Critical 35

15\. Denton clay, Dallas, Texas (sampled and

tested by Elvin F. Henry). 3800 Critical 30

16\. Soil, Dallas, Texas (under the direction Very

of Mr. Herschel Smith, Dallas, Texas). 5050 Critical 39

6/74

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4075.15

23

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

TEXAS (Continued)

17\. Soil, Dallas, Texas (under the

direction of Mr. Herschel Smith,

Dallas, Texas). 2800 Marginal 22

18\. Soil, Dallas, Texas (under the

direction of Mr. Herschel Smith, Very

Dallas, Texas). 5200 Critical 42

19\. Soil, Dallas, Texas (under the

direction of Mr. Herschel Smith,

Dallas, Texas). 4050 Critical 32

20\. Soil, Dallas, Texas (under the

direction of Mr. Herschel Smith,

Dallas, Texas). 4400 Critical 34

21\. Soil, Dallas, Texas (under the

direction of Mr. Herschel Smith, Very

Dallas, Texas). 5450 Critical 43

22\. Soil, Dallas, Texas (under the

direction of Mr. Herschel Smith, Non

Dallas, Texas). 900 -Critical 9

23\. Soil, Denton, Texas (under the

direction of Mr. Herschel Smith, Non

Dallas, Texas). 700 -Critical 8

24\. Soil, Duncanville, Texas (under the

direction of Mr. Herschel Smith,

Dallas, Texas). 2200 Marginal 18

25\. Soil, Duncanville, Texas (under the

direction of Mr. Herschel Smith, Non

Dallas, Texas). 1400 -Critical 13

26\. Soil, Eagle Pass, Texas (under the

direction of Mr. Herschel Smith,

Dallas, Texas). 1875 Marginal 16

27\. Soil, Eagle Pass, Texas (under the

direction of Mr. Herschel Smith, Non

Dallas, Texas). 1250 -Critical 12

6/74

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4075.15

24

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

TEXAS (Continued)

28\. Soil, Garland, Texas (under the

direction of Mr. Herschel Smith, Very

the Dallas, Texas). 5400 Critical 43

29\. Soil, Garland, Texas (under the

direction of Mr. Herschel Smith,

Dallas, Texas). 4700 Critical 37

30\. Soil, Garland, Texas (under the

direction of Mr. Herschel Smith, Very

Dallas, Texas). 5650 Critical 44

31\. Houston clay (black), Houston,

Texas (sampled and tested by Very

Elvin F. Henry). 6000 Critical 48

32\. Katy sandy clay, Houston, Texas

(sampled and tested by Elvin F.

Henry). 2400 Marginal 19

33\. Lake Charles clay loam, Houston,

Texas (sampled by Elvin F. Henry

and Dr. M. M. Lemcoe). 3900 Critical 31

34\. Sandy clay loam, Houston, Texas

(sampled and tested by Elvin F. Non

Henry). 500 -Critical 7

35\. Soil, Irving, Texas (under the

direction of Mr. Herschel Smith, Non

Dallas, Texas). 1550 -Critical 14

36\. Soil, Kirby, Texas (under the

direction of Mr. Herschel Smith, Very

Dallas, Texas). 4850 Critical 38

37\. Soil, Kirby, Texas (under the

direction of Mr. Herschel Smith, Very

Dallas, Texas). 8025 Critical 63

38\. Soil, Lancaster, Texas (under the

direction of Mr. Herschel Smith,

Dallas, Texas). 4700 Critical 37

6/74

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4075.15

25

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

TEXAS (Continued)

39\. Soil, Mesquite, Texas (under the

direction of Mr. Herschel Smith,

Dallas, Texas). 2800 Marginal 22

40\. Soil, Plano, Texas (under the

direction of Mr. Herschel Smith, Very

Dallas, Texas). 6300 Critical 51

41\. Soil, Richardson, Texas (under the

direction of Mr. Herschel Smith, Very

Dallas, Texas). 5850 Critical 47

42\. Black organic clay, overlying

Taylor marl, San Antonio, Texas

(sampled by Elvin F. Henry and

John Turner). 3300 Critical 26

43\. Clay, San Antonio, Texas (sampled Very

by Dr. M. M. Lemcoe). 6300 Critical 51

44\. Clay, San Antonio, Texas (duplicate

test sampled by Dr. M. M. Lemcoe and Very

Elvin F. Henry). 6200 Critical 50

45\. Clay, San Antonio, Texas (sampled by Very

Elvin F. Henry and John Turner). 5725 Critical 45

46\. Clay, San Antonio, Texas (sampled by Very

Elvin F. Henry and John Turner). 5725 Critical 45

47\. Clay, San Antonio, Texas (sampled by Very

Elvin F. Henry and John Turner). 5425 Critical 43

48\. Clay, San Antonio, Texas (sampled by Very

Elvin F. Henry and John Turner). 5275 Critical 42

49\. Clay, San Antonio, Texas (sampled by Very

Elvin F. Henry and Dr. M. M. Lemcoe). 4900 Critical 39

50\. Clay (Bentonitic), San Antonio, Texas

(sampled by Elvin F. Henry and Very

John Turner). 5575 Critical 44

6/74

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4075.15

26

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

TEXAS (Continued)

51\. Clay soil, San Antonio, Texas

(sampled by Elvin F. Henry and

John Turner). 2500 Marginal 20

52\. Clay soil, San Antonio, Texas

(sampled by Elvin F. Henry and Non

John Turner). 0 -Critical 0

53\. Clay soil, San Antonio, Texas

(sampled by Elvin F. Henry and

John Turner). 2175 Marginal 18

54\. Clayey marl, San Antonio, Texas

(sampled by Elvin F. Henry and

John Turner). 2300 Marginal 19

55\. Dark Topsoil, silt loam, San

Antonio, Texas (sampled by Non

Dr. M. M. Lemcoe). 1400 -Critical 13

56\. Marly Material, San Antonio,

Texas (sampled by Elvin F. Henry Non

and John Turner). 0 -Critical 0

57\. Marly Material, San Antonio,

Texas (sampled by Elvin F. Henry Non

and John Turner). 925 -Critical 9

58\. Sandy Clay, San Antonio, Texas

(sampled by Elvin F. Henry and

John Turner). 1700 Marginal 15

59\. Silty clay, San Antonio, Texas

(sampled by Elvin F. Henry and

John Turner). 4225 Critical 33

60\. Silty clay, San Antonio, Texas

(sampled by Elvin F. Henry and Non

John Turner). 1550 -Critical 14

61\. Silty clay soil, San Antonio,

Texas (sampled by Elvin F. Henry

and John Turner). 2350 Marginal 19

6/74

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4075.15

27

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

TEXAS (Continued)

62\. Soil, San Antonio, Texas (sampled

by Elvin F. Henry and Dr. M. M.

Lemcoe). 4800 Critical 38

63\. Soil, San Antonio, Texas (sampled

by Elvin F. Henry and John Turner). 3150 Marginal 25

64\. Soil, Woodlawn, San Antonio, Texas

(sampled by Elvin F. Henry and

John Turner). 3950 Critical 31

65\. Soil, Summertime, San Antonio, Texas

(sampled by Elvin F. Henry and John Non

Turner). 300 -Critical 4

66\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 2025 Marginal 17

67\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 2675 Marginal 21

68\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 2800 Marginal 22

69\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 1875 Marginal 16

70\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 2675 Marginal 21

71\. Soil, San Antonio, Texas (sampled by Non

Elvin F. Henry and John Turner). 1250 -Critical 12

72\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 3775 Critical 30

73\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 2675 Marginal 21

74\. Soil, San Antonio, Texas (sampled by Very

Elvin F. Henry and John Turner). 5425 Critical 43

6/74

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

4075.15

28

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

TEXAS (Continued)

75\. Soil, San Antonio, Texas (sampled Very

by Elvin F. Henry and John Turner). 7425 Critical 52

76\. Soil, San Antonio, Texas (sampled

by Elvin F. Henry and John Turner). 2350 Marginal 19

77\. Soil, San Antonio, Texas (sampled

by Elvin F. Henry and John Turner). 2675 Marginal 21

78\. Soil, San Antonio, Texas (sampled Non

by Elvin F. Henry and John Turner). 1075 -Critical 11

79\. Soil, W. of San Antonio, San Antonio,

Texas (sampled by Elvin F. Henry and

John Turner). 3925 Critical 31

80\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 3600 Critical 28

81\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 2175 Marginal 18

82\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 4075 Critical 32

83\. Soil, San Antonio, Texas (sampled by Very

Elvin F. Henry and John Turner). 5775 Critical 46

84\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 2500 Marginal 20

85\. Soil, San Antonio, Texas (sampled by

Elvin F. Henry and John Turner). 3450 Critical 27

86\. Soil, Universal, Texas (under the

direction of Mr. Herschel Smith,

Dallas, Texas). 4250 Critical 33

6/74

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4075.15

29

Swell Approximate

Index Plasticity

Soil Sample Pounds/ PVC Index

sq. ft. Category

VIRGINIA

1\. Lenoir clay, Alexandria, Virginia

(sampled and tested by Elvin F. Henry). 3900 Critical 31

2\. Iredell sandy clay loam Roadbed

material, Centerville, Virginia Non

(sampled and tested by Elvin F. Henry). 800 -Critical 9

3\. Iredell soil, Fairfax County, Virginia

(sampled and tested by Elvin F. Henry,

repeated 6 times, results +- 300 lbs. Very

per square ft.). 5500 Critical 43

4\. Iredell clay, Fairfax County, Virginia Very

(sampled and tested by Elvin F. Henry). 6000 Critical 48

WYOMING

1\. Clay loam sample, Casper, Wyoming

(sampled and tested by Elvin F. Henry). 2200 Marginal 18

2\. Clay loam to loam sample, Casper,

Wyoming (sampled and tested by Non

Elvin F. Henry). 900 -Critical 9

3\. Yellow-Bentonitic clay, Casper,

Wyoming (sampled and tested by Very

Elvin F. Henry). 6300 Critical 51

6/74

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4075.15

30

V. GLOSSARY

Atterberg limits: Limits of soil consistency named after a

Swedish soils scientist. Used in the Unified Soil Classification

System as the basis for laboratory differentiation between

materials of appreciable plasticity (clays) and slightly plastic

or non-plastic materials (silts).

Liquid limit: The water content in percentage of dry

weight at which the soil passes from the liquid state

to the plastic state.

Plastic limit: The water content of the soil at the

boundary between the plastic state and the solid (or

semisolid) state.

Plasticity index: The numerical difference of water

contents between the liquid and plastic limits.

Clay: The term clay as used today carries with it three

implications: (1) a natural material with plastic properties,

\(2\) an essential composition of particles of very fine size

grades, and (3) an essential composition of crystalline fragments

of minerals that are essentially hydrous aluminum silicates

or occasionally hydrous magnesium silicates.

Cohesion: The capacity of sticking or adhering together.

Liquid: Soil either in suspension or behaves like a viscous fluid.

Natural Drainage Classes:

Excessively Drained: Water is removed from the soil

rapidly. Uniformily colored in surface and subsoil.

Usually sandy, porous and has thin soil layers over

parent materials.

Well Drained: Water is removed from the soil readily

but not rapidly. Uniformily colored in surface and

subsoil layers.

Moderately Well Drained: Water is removed from the soil

somewhat slowly so that the profile is wet for a small

but significant part of the time. Uniformily colored

in surface and upper subsoil layers.

6/74

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4075.15

31

Somewhat Poorly Drained: Water is removed from the

soil slowly enough to keep it wet for significant

periods but not all of the time. Has mottled subsoil

layers.

Poorly Drained: Water is removed so slowly that the

soil remains wet for a large part of the time. The

water table is commonly near or at the surface for a

considerable part of the year. Has gray or mottled

colors in both surface and subsoil layers.

Very Poorly Drained: Water is removed from the soil

so slowly that the water table remains at or near

the surface most of the time. Has black., dark gray

surface layers and dark or mottled subsoils.

Plastic: Soil can be rapidly deformed or molded without rebounding

elastically, changing volume, cracking, or crumbing.

Solid: Soil will crack when deformed or will exhibit elastic rebound.

The solid state is sometimes divided into the semisolid state and the

solid state.

Transpo-evaporation: Movement or transfer of moisture or vapor from

below ground or ground areas through vegetative media to the

atmosphere.

U. S. GOVERNMENT PRINTING OFFICE : 1974 545-713/317 6/74