DEMONSTRATION OF ELECTRO-OSMOTIC PULSE TECHNOLOGY

FOR GROUNDWATER INTRUSION CONTROL IN CONCRETE

STRUCTURES

Vincent Hock

CECER-FL-M

217-373-6753

Michael McInerney, P.E.

CECER-FL-P

217-373-6759

Erik Kirstein

CECER-FL-M

217-352-6511

ABSTRACT

Groundwater intrusion through a building's foundation can cause

serious damage. Basement dampness can ruin expensive mechanical

equipment which is often located in basement space, can increase

maintenance requirements, and can make affected areas

uninhabitable or even unusable. A system, based on electroosmosis, has been developed to prevent water intrusion through

concrete structures by applying a pulsating electric field

between the structure and the surrounding soil. Electro-Osmotic

Pulse (EOP) technology can mitigate some water-related problems

from the interior of affected areas without the cost of

excavation. The EOP alternative can further mitigate corrosion

damage to mechanical equipment and lessen mold problems by

lowering the indoor humidity.

INTRODUCTION

Groundwater intrusion through a building’s foundation can cause

serious damage. Basement dampness can ruin expensive equipment,

e.g., Heating Ventilation, and Air-Conditioning (HVAC) equipment,

which is often located in basement space; can increase

maintenance requirements (frequent repainting or cleaning to

combat mold growth); and can make affected areas uninhabitable or

even unusable (e.g., poor air quality).

In older buildings, such as those common on U.S. Army

installations, severe damp-basement problems call for immediate

action to mitigate water damage. In selective problem areas, the

usual approach is to ‘trench and drain’, in other words, to

excavate and expose the wall area and the base of the foundation,
to replace dampproofing on the wall surface, and to install a

drain tile system around the building or affected area. This

expensive process is further complicated by the fact that most

contractors limit their warrantees against future seepage in

areas with high water tables.

Electro-osmotic pulse (EOP) technology offers an alternative that

can mitigate some water-related problems from the interior of

affected areas without the cost of excavation. The EOP

alternative can further mitigate corrosion damage to mechanical

equipment and lessen mold problems by reducing the indoor

humidity.

Although new applications are still being developed, electroosmosis is not a recently discovered phenomenon. In 1809, F.F.

Reuss originally described electro-osmosis in an experiment that

showed that water could be forced to flow through a clay-water

system when an external electric field was applied to the soil.

Research since then has shown that flow is initiated by the

movement of cations (positively charged ions) present in the pore

fluid of clay, or similar porous medium such as concrete; and the

water surrounding the cations moves with them. Electro-osmosis

can be used to arrest or cause flow of water as well as the ions

in it. Electro-osmosis has been used in civil engineering to

dewater dredgings and other high-water content waste solids,

consolidate clays, strengthen soft sensitive clays, and increase

the capacity of pile foundations. It has also received

significant attention in the last five years as a method to

remove hazardous contaminants from groundwater or to arrest water

flow.

A system has been developed to apply electro-osmosis commercially

within concrete structures by applying a pulsating direct

electric field combined with an off-period. It is called

electro-osmotic pulse (EOP). The pulse sequence consists of a

pulse of positive voltage (as seen from the dry side of the

concrete wall), a pulse of negative voltage, and a period of rest

when no voltage is applied. The pulse of positive voltage has

the greatest time duration. The amplitude of the signal is

typically on the order of 20 to 40 Volts DC (VDC). The

electrical pulse causes cations (e.g., Ca++) and associated water

molecules to move from the dry side (anode) towards the wet side

(cathode) against the direction of flow induced by the hydraulic

gradient, thus preventing water penetration through the buried

concrete structure. One of the most critical aspects of this

technology is the negative voltage pulse. This allows control of

the amount of moisture within the concrete which prevents

overdrying of the concrete matrix and subsequent degradation.

Field tests were conducted to assess the feasibility and cost

effectiveness of EOP technology at selected Army installations.
BACKGROUND

If ions of one sign are preferentially adsorbed1 at a solidsolution interface, a net charge or electric potential difference

develops across the interface. This phenomenon is referred to as

electro-osmosis. (The basic physics and chemistry of electroosmosis can be found in several textbooks and treatises. 1, 2, 3)

It was found that when a potential difference is applied to

electrodes immersed into an electrolyte solution on opposite

sides of a porous plug or fine capillary tube, a flow of the

solution results. Similarly, when a solution is forced through

such a barrier by hydrostatic pressure, a potential difference

develops between the solution on one side of the barrier and that

on the other. This is called the streaming potential.

Descriptions of these phenomena are based on the concept of

electric double layer. A layer of ions, which is approximately a

single ion in thickness, of one sign is firmly adsorbed on the

solid surface or particle, the sign of the charge depending on

the nature of the surface and other conditions. The region as a

whole is electrically neutral, and an equal number of opposite

electric charges are present in an adjacent ionic atmosphere

which, as the term implies, becomes more attenuated as distance

from the surface increases. This is called the diffuse layer.

When the solid surface and fluid are in relative motion, there

exists a velocity gradient, and a thin film of solution, together

with the ions it contains, is immobilized near the wall. Part of

the ion atmosphere moves with the solution, and part (together

with adsorbed ions) effectively belongs to the surface. As a

result, the liquid phase and the wall have different net electric

charge, and the application of an external electric field

produces relative motion.

For example, electro-osmosis occurs in clay soils when cations in

the diffuse layer are driven by the application of an external

electric field. As a result, a velocity field in the pore fluid

develops (Figure 1). The velocity distribution changes rapidly

near the particle’s surface, but then becomes flat at the edge of

the diffuse layer. Hence, electro-osmotic flow appears as plug

flow through the pores of soil.

 

1

 To adsorb is to collect in condensed form on a surface.
FIGURE 1. Movement of cations in a soil pore by electro-osmosis.

The velocity profile reaches a constant value (Vo) a short

distance from the particle’s surface. To determine Vo, a steadystate equation of motion is written as:

where:

μ = the viscosity of the solution;

Vx = the velocity of the solution parallel to the

particle surface;

y = the distance orthogonal to the particle surface;

Ex = the externally applied electric field gradient;

ε = the permitivity of the solution; and,

φ = the electrical potential gradient.

By the Debye-Hückel approximation, φ is written as

φ ξ ε = −

















∞

exp y

nZF

RT

2 i i

2 2

(2)

μ

∂

∂ ε φ 2

x

2 x

2

2

d

d

0

V

y

E

y

+ = (1)
where:

ξ = the zeta potential2

;

ni

∞ = the concentration of constituent i in free

solution;

Zi = the equivalents/mole of constituent i;

F = Faraday’s constant;

R = the universal gas constant; and,

T = the absolute temperature.

When (1) is solved using the boundary conditions,

V at y

V V at y

x

x

= =

= >>

0 0

0 0 (3)

The velocity Vo is then obtained:

V E 0 x = ε ξ

μ

(4)

Of the four independent variables in (4), Ex can be controlled to

redirect the movement of the solution.

One example of the pulsating electro-osmotic technique consists

of a positive voltage pulse, a negative voltage pulse, and a

period of zero voltage. Figure 2 shows this example waveform for

the pulsating electro-osmotic pulse or EOP system. The positive

voltage pulse has the longest interval and the negative voltage

pulse has the shortest interval. As a result of this, the pore

fluid moves (on the average) in one direction.

 

2

 The zeta potential is the difference of potential between the plates of a hypothetical capacitor used to model the diffuse layer.
t + t - t 0

+V

-V

0

2 sec < T < 10 sec

FIGURE 2. Example EOP voltage waveform.

Currently, the reasons for the increased performance of the EOP

system over standard dc electro-osmosis for drying concrete are

not well understood. However, it is speculated that the change

in polarity results in the reversal of some of the chemical

reactions occurring during electrolysis. It is also believed

that the rest phase (period of zero voltage) allows the system to

equilibrate. As a result of these effects, undesirable side

effects such as acid production and increased corrosion are

avoided. Also, use of a pulse sequence might prevent the

concrete from becoming too dry.

An EOP system is realized by inserting anodes (positive

electrodes) into the concrete wall or floor on the inside of the

structure and by placing cathodes (negative electrodes) in the

soil directly outside the structure. The density of the anode

and cathode placement is determined from an initial resistivity

test of the concrete and soil. The objective is to achieve a

certain current density and thus create an electric field

gradient in the concrete.

TECHNOLOGY DEMONSTRATIONS

Two sites were selected for EOP technology demonstrations,

Building 3265, a guest barracks at Fort Jackson, SC and Building

5, the Health Clinic at McAlester AAP, OK. In both cases, the

location of the groundwater intrusion was through the floor and

walls of poured concrete basements.
FT JACKSON

Building 3265 had a history of water seepage into the concrete

basement mechanical room. The mechanical room had experienced

water levels within the structure as high as 36 cm. On the

average, there existed about 5 cm of standing water. In

addition, there was seepage from cracking in the wall,

efflorescence, and poor air quality as a result of the high

indoor humidity. This seepage initiated corrosion of the

mechanical equipment located in the basement, requiring

replacement as often as every two years.

For the EOP system, eighty-three (83) rubber-graphite anodes were

coated with a graphite-mortar mixture and inserted into holes

drilled into all four walls, approximately 13 cm from the floor

and 46 cm apart. Twenty-four feet of rubber-graphite conductive

cable was installed around the base of a concrete pad that

supported steel water tanks in the room. Three copper-clad steel

ground rods (cathodes) were driven into the soil adjacent to the

exterior side of the concrete wall. The EOP Control Unit was

mounted on one wall and all wiring from the anodes and cathodes

was enclosed and wired into the unit. Figure 3 presents a layout

of the EOP installation at Ft. Jackson.

MCALESTER AAP

The basement of Building 5 had standing water in several areas.

Problems similar to the basement at Fort Jackson were prevalent;

water seepage from cracking in the wall, efflorescence and high

indoor relative humidity (70 percent). In this case the

reduction of the indoor air humidity is very important, as one of

the rooms is the Industrial Hygiene Office, occupied by an

individual 40 hours a week.

Analysis of water infiltration revealed that only about half the

basement was leaking, therefore the EOP system was installed only

in the areas of infiltration. Rubber-graphite anodes were

installed 13 cm above the floor and 28 cm on center. The total

number of anodes used was 95. Four copper-clad steel ground rods

(cathodes), 2.44 m long, were driven into the soil in the crawl

spaces adjacent to the concrete wall in selected areas. Figure 4

shows the arrangement of the EOP installation at McAlester AAP.
FIGURE 3. Layout of EOP installation at Ft. Jackson.
FIGURE 4. Arrangement of EOP installation at McAlester AAP.
EOP OPERATIONAL DATA

FT Jackson

The EOP dc output current was within acceptable limits, varying

from 0.75 amps for a high humidity environment to less than 0.2

amps for a low humidity environment. Direct variation of current

with humidity is a result of the characteristics of the EOP

system. The EOP power supply produces a voltage pulse of

constant amplitude (i.e. a constant voltage power supply).

Since the resistivity of the concrete is inversely proportional

to the amount of water present in the concrete, as the water is

slowly driven out, the resistivity of the concrete increases,

decreasing the current load of the power supply. (Recall Ohm’s

Law, current is inversely proportional to resistance.) Table 1

shows measured current and voltage outputs of the EOP power

supply. The slight increase in output current is due to the

higher water table during July and August 1996.

TABLE 1. Ft. Jackson EOP power supply dc output current.

Date of Reading DC Volts DC Amps

1995/01/10 +37 0.20

1996/08/15 +30 0.75

Concrete moisture readings were taken at different locations on

the walls. Table 2 lists the moisture measurements that were

taken at three different times; at the time of installation, at

the 5-month performance check, and 2 years after installation.

The data are presented as percent relative humidity. All

measurements were made at the concrete surface, not internally.

The most suitable humidity for concrete structures is ≈70

percent. Note the direct correspondence between the power supply

current (Table 1) and the concrete humidity (Table 2).

TABLE 2. Concrete moisture readings in Building 3265, Ft.

Jackson.

% Relative Humidity at Surface

Date of Reading A B C D

1994/08/23 94 92 98 98

1995/01/10 44 43 68 64

1996/08/15 73 72 76 77

The corrosion potential of rebar specimens was investigated.

Several small (~5-cm long) sections of 1.27-cm steel rebar were

embedded in various locations in the basement walls. The purpose
of these specimens was to document whether any change occurred in

the native corrosion potential of rebar that might be embedded in

a concrete structure when an EOP system is operating. The

corrosion potential of the specimens was tracked and compared to

the average corrosion potential for reinforcing steel in

concrete, which is approximately -0.2 VDC. Table 3 lists the

corrosion potentials for some of the specimens. These potentials

were taken at the 5-month performance check on 10 January 1995.

This data shows no significant difference in the corrosion

potential from the native potential. However, this is just one

time sample of a dynamic system, a larger record will be needed

to fully document the EOP system effect on rebar corrosion

potential.

TABLE 3. Rebar specimen corrosion potentials.

Potential (Volts DC)

Specimen Minimum Maximum Average

3 -0.190 -0.200 -0.195

5 -0.204 -0.224 -0.214

9 -0.145 -0.154 -0.150

The water table level is a good indication of EOP system

performance: if the water table is above the floor of the

basement and the basement remains dry, then the EOP system is

fulfilling its purpose. A monitoring well was installed just

outside the basement wall for the purpose of tracking the level

of the water table relative to the basement floor. (It’s

location is shown in Figure 3.) Figure 5 shows the hydrograph

for the monitoring well from September 1995 until September 1996.

(Groundwater temperature just happened to be included in the

standard monitoring well ‘package’, it was not used in this

study.) Note there are several times during the recording period

when the water table exceeded the basement floor level. In

previous years the basement would have flooded during these

periods, however now because of the EOP system the basement

remains dry.
FIGURE 5. Hydrograph from monitoring well at Fort Jackson, SC.

Rainfall data was obtained to track the months when there would

be a greater potential for a higher water table. This data can

be correlated to the monitoring well data points, specifically,

note the correlation between the high rainfall during March 1996

and the rise in the water table during that month. Table 4 shows

the rainfall data at Fort Jackson up until May 1996.

TABLE 4. Monthly precipitation data for Columbia, SC.

Month

Total

Precipitation

(cm)

Month

Total

Precipitation

(cm)

1994/08 13.49 1995/07 19.96

1994/09 8.31 1995/08 16.99

1994/10 12.04 1995/09 14.00

1994/11 7.82 1995/10 9.17

1994/12 14.81 1995/11 7.34

1995/01 11.40 1995/12 5.56

1995/02 17.02 1996/01 7.37

1995/03 4.32 1996/02 2.95

1995/04 2.49 1996/03 16.56

1995/05 4.29 1996/04 6.04

1995/06 27.28 1996/05 6.81
McAlester AAP

Many of the same parameters that were documented at Fort Jackson

were recorded at McAlester AAP. The corrosion potential of rebar

was sampled using a 33-cm long piece of 1.27-cm steel rebar which

was grouted into the wall along with a Ag/AgCl reference half

cell. The half cell was installed so as to be behind the rebar,

and separated from it by about 5 cm of concrete. The humidity of

the concrete was sampled using a dual humidity/temperature probe

which was sealed in a small cavity in the concrete wall. Since

the cavity is sealed, this probe monitors the temperature and

humidity of the cavity. The humidity of the cavity should be

proportional to the moisture content of the concrete, giving an

indication of the effectiveness of the EOP system as it operates.

Ambient room humidity and temperature sensors monitored the

Industrial Hygiene Office. The level of the water table outside

the basement was also monitored. In addition to these sensors

and probes, the electrical power consumption of the EOP system

was tracked to monitor the power output of the power supply. The

locations of these sensors are indicated in Figure 4.

All these monitoring devices except the rebar corrosion potential

were fed into a datalogger that was installed on site and was

remotely accessible via modem. The data was collected and stored

in the datalogger until downloaded to a computer.

The daily rainfall, average outdoor temperature, and average

outdoor relative humidity at McAlester AAP were obtained from the

Oklahoma Climatological Survey. Data was downloaded monthly from

their INTERNET site.

Figure 6 shows some of the recorded data, and highlights the

power consumption of the EOP system in relation to the relative

humidity of the wall cavity, as measured by the wall probe.

Figure 6 shows that, as the power consumption drops (as a result

of the decrease in current as the water is driven out), the

concrete humidity drops as well. This shows that the EOP system

is decreasing the moisture content in the concrete with a

corresponding decrease in power requirements, both excellent

indicators that the system is working properly.

Figure 7 shows the water table with respect to the basement

floor. Unlike FT Jackson the water table never rose above the

basement floor, confirming that the water intrusion problem at

McAlester was mainly through the floor-wall cold joints, that

manifested itself with the periodic saturation of the nearby soil

following a heavy rainfall.
0

5

101520253035404550

96/11/06

96/11/13

96/11/20

96/11/27

96/12/04

96/12/11

96/12/18

96/12/25

97/01/01

97/01/08

97/01/15

97/01/22

97/01/29

97/02/05

97/02/12

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97/03/05

97/03/12

97/03/19

97/03/26

97/04/02

97/04/09

97/04/16

97/04/23

97/04/30

Date

EOP Power Supply DC Output Power 

(Watts)

80828486889092949698100

Relative Humidity within Wall (%) Wall RH DC Power

FIGURE 6. Power consumption of EOP system in relation to relative humidity of the wall.
0

2468

101214161820

96/11/06

96/11/13

96/11/20

96/11/27

96/12/04

96/12/11

96/12/18

96/12/25

97/01/01

97/01/08

97/01/15

97/01/22

97/01/29

97/02/05

97/02/12

97/02/19

97/02/26

97/03/05

97/03/12

97/03/19

97/03/26

97/04/02

97/04/09

97/04/16

97/04/23

97/04/30

Date

Rainfall (centimeters)

-10-9-8-7-6-5-4-3-2-10

Depth of water table (meters) Rainfall Basement Floor Water Table

FIGURE 7. Water table with respect to basement floor, Bldg. 5, McAlester AAP.
COST/BENEFIT ANALYSIS

How to best estimate the initial cost savings of EOP over

standard dampproofing methods for purposes of decision making

must be based on experience and standard construction industry

cost-estimating reference guides. 4, 5, 6 The comparison of the

standard waterproofing technology to EOP technology is based on

field experience at Fort Jackson and at McAlester AAP.

The standard estimate is drawn from construction cost guides,

assuming a basement about 2.44 m deep with a concrete exterior.

It is then compared to the results of the Army test sites.

Table 5 gives the breakdown of the costs for each facet of the

standard dampproofing method, as an approximate cost per linear

meter (lm). The assumption is a contract for the whole building

and a standard depth of 2.44 m with average, but wet soil

conditions.

TABLE 5. Standard approach cost estimate.

Action Cost per lm ($)

Site dewatering 221.55

Wood shoring 34.78

Excavation and backfill 728.34

Drain tile installation 13.78

Dampproofing 26.25

Backfilling 3.61

Landscape restoration 6.10

Total 1,034.41

The original contracts to the EOP installer were analyzed and

adjustments were made to the contract prices to reflect generic

installations (i.e., travel, monitoring wells, report

requirements, and certain extra experimental requirements were

eliminated from the base costs). The price of the EOP system was

calculated, based on installed costs, and expressed as linear

meter of wall. As for installation, both sites required some

degree of interior access to the basement, but neither excavation

nor dampproofing were required. The cost includes the EOP

Control Unit, the anodes, ground rods, and all the wiring and

labor for installation (Table 6).
TABLE 6. Calculation of EOP System Based on Installed Costs and

lm of Wall.

Location Lineal Meters

Installed

Cost per lm

($)

McAlester AAP 29.0 624.07

Fort Jackson 34.5 612.69

Average Cost of EOP Installation

for Both Sites

618.38

The manufacturer of the EOP system estimates the life cycle of

the system be 10 years. Therefore, one could assume a normal

cycle with almost zero maintenance for that period of time.

However, the system does consume energy roughly equivalent to

that of a 60W light bulb left on all the time. This cost is

minimal and is neglected in these calculations.

The percent savings based on capital costs is basically a

comparison between the cost of trenching, dampproofing,

backfilling, and installed EOP technology. The percent savings

comparison is computed as:

% first cost saved

EOP per lm

Trench & Drain per lm

$618.38

$1,034.41

= ×− = ×− = 



 



 



 

 100 1 100 1 40%  (5)

Payback is based on a calculation of time taken to recoup the

original investment. This is usually based on the overall

reduction in maintenance and repair costs over time. The two

possible approaches are Payback Upon Price Comparison and Payback

Over Time. With payback upon price comparison (PPC) one

determines how long it would take to save investment moneys for

EOP over a comparable expenditure for a trench and drain system.

P

PC

1

Trench & Drain per lm - EOP per lm

EOP per lm

$416.03

$618.38

1

0.67 = = ==1.49 years

1

(6)

Note that this is an internal return-on-investment, but does not

represent the savings over time.

The payback over time (POT) calculation very much depends on

individual circumstances. Some questions regarding these

circumstances are: whether the treated area can be used in the

future for habitable area; whether corrosion degradation of

valuable mechanical equipment will be stopped; and whether
elimination of painting mold will reduce the number of cycles of

painting in the future. Table 7 summarizes the savings over ten

years at FT Jackson and McAlester AAP for these circumstances.

TABLE 7. Payback over time savings estimates.

Situation Savings ($)

Usable space return (at McAlester) 21,225.00

Painting avoidance (at McAlester) 748.80

Reduced mechanical maintenance (at Jackson) 20,000.00

Total 41,3973.80

P

OT = Total Installation Cost

Sum of Annual Cost Avoidances

$38,800.00

10 years = = 9.24 years $41, . 973 80 (7)

This value for POT should be used only as a guideline because two

different sites were combined to determine this estimate, however

it is both a good estimate of final returns, and a reasonable

payback over time. Some reasons for this conclusion are:

1) The life cycle for the full return-on-investment is

almost equal to the expected life of the system, i.e. any

life after ten years will represent a higher return-oninvestment.

2) The extended life (i.e. after ten years) will represent a

dramatic cost saving in that the initial labor of putting

in the probes and wiring has already been expended.

3) If one considers the usable space retrieved from

dampness, then there will be at least ten years of

productivity beyond the mere acquisition of additional

space.

4) Over the expected life of a foundation wall (about 50

years) the payback could be 2-5 times the initial

investment, even assuming the purchase of replacement

electronics.

5) The estimate was acquired from real-world field test data

on existing Army installations.

One might also consider some intangible, or certainly difficult

to quantify benefits:

1) There is minimal disruption of the building activity

during the drying out process, e.g. no digging, minor

noise and a small amount of waste.

2) Illnesses caused by allergies or other sensitivities will
be reduced, thereby increasing health and productivity of

the building occupants.

In summary, both the economic benefits based on conservative

estimates from field data, and the intangible benefits, point to

a very positive return-on-investment for EOP technology.

CONCLUSIONS

In buildings with daily occupancies and mature landscaping,

retrofitting a foundation wall by ‘trenching and draining’ is not

easy. The common approach to prevent water intrusion is to

excavate and expose the wall area and the base of the foundation,

to replace the dampproofing on the wall surface, and to install a

drain tile system around the building or affected area. This is

a costly and disruptive endeavor. Any interior application that

can mitigate some of the water-related problems will save both

the cost, inconvenience, and disruption of excavation. If the

alternative can also mitigate corrosion damage to mechanical

equipment and lessen mold problems by lowering the indoor

humidity it should be highly rated.

Based on the results of the demonstration and validation, this

study concludes that the application of EOP technology for

control of moisture in concrete basement structures is an

acceptable alternative to conventional trenching and drain.

The EOP technology installed in a facility at Fort Jackson, SC

successfully prevented water seepage and reduced the relative

humidity of the concrete to 70 percent. The cost of installation

has been determined to be 40 percent lower than the cost of the

conventional ‘trench and drain’ approach. The operating, or

energy cost, of the EOP system is negligible - about that of

continuously burning a 60W light bulb.

It is recommended that the EOP technology be transferred for

Department of Defense implementation as a cost effective

alternative to the ‘trench and drain’ approach for control of

moisture in concrete basement structures.

ACKNOWLEDGMENTS

This study was conducted for the U.S. Army Center for Public

Works (USACPW) under the Facilities Engineering Application

Program (FEAP); Project Title ‘A Demonstration of Electro-Osmotic

Pulse (EOP) Technology for Control of Seepage in Concrete

Structures’. The assistance provided by Frank Cooper, Fort

Jackson, SC; Gary Reasoner, McAlester Army Ammunition Plant;

Fidel Rodriguez and Malcolm McLeod, Center for Public Works, Ft.

Bevoir, VA; Dr. Charles Lozar of Architects Equities Research
Group; and Roger Hayes, Arild Ottersen, Egil Bjerke, and Micheal

Connor, Drytronic (formerly known as Dry-Tec of North America),

was essential to the completion of this work.

REFERENCES

1. Hamill, W.H., Williams, R.R. and MacKay, C., Principles of

Physical Chemistry, 2nd edition, 1966, Prentice-Hall, Inc.,

Englewood Cliffs, N.J.

2. Glasstone, S., Textbook of Physical Chemistry, 2nd edition, 1946, D. Van Nostrand Company, Inc., Princeton, N.J.

3. Tikhomolova, K.P., Electro-Osmosis, 1993, Ellis Horwood

Limited, Chichester, West Sussex, England.

4. Means Cost Estimating Guides

5. Walker Estimating Guide

6. National Construction Estimator Handbook

AUTHOR’S ADDRESS: U.S. ARMY CONSTRUCTION ENGINEERING RESEARCH

LABORATORIES

ATTN: CECER-FL-M (V. Hock)

P.O. BOX 9005

CHAMPAIGN IL 61826-9005

U.S. ARMY CONSTRUCTION ENGINEERING RESEARCH

LABORATORIES

ATTN: CECER-FL-P (M. McInerney)

P.O. BOX 9005

CHAMPAIGN IL 61826-9005

U.S. ARMY CONSTRUCTION ENGINEERING RESEARCH

LABORATORIES

ATTN: CECER-FL-M (E. Kirstein)

P.O. BOX 9005

CHAMPAIGN IL 61826-9005