Polymer Paving Starter Guide

Illustrated Technical Manual

Introduction

This manual is intended to serve as a guideline for those interested in planning,

financing, managing or executing soil improvement and ground modification projects,

such as building hard driving surfaces using copolymers as particle binders. One of the

most common applications when using polymers to harden soil and rock mix, is to build

hard driving surfaces. Every project where a structure of any kind must be built on the

ground (soil) must follow certain rules, for example the expected loads must be

supported without ground failure. While these rules are not inherently complicated, it is

imperative that they are well understood before proceeding with a project.

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Prologue

Nothing is more important when engaging in building roads than a clear understanding

of soil improvement and ground modification techniques. Fortunately, this knowledge

is easy to acquire and the fundamentals are easy to understand. I hope you can use this

short introduction as a springboard to build your own library on the subject and continue

to learn in depth about the rules of working with soils. Having this knowledge, and with it

the ability to spot and avoid problems, will help you deliver many successful projects,

and give you much satisfaction in your professional career. It is very important that you

request on site help from someone experienced with polymer paving on your projects as

you start, or that you work with experienced geotechnical engineers. Skipping the proper

expertise is not the place to save money. The savings is inherent to the process and it

comes from the reduced logistics when possible, depending on the situation.

Soil Considerations

When a site is selected for raising a structure, such as a road or a building, special

consideration must be given to the ground's ability to support and respond to the load

that will be imposed upon it. This knowledge generally falls in the domain of

geotechnical engineers, and much of what you need to know to work with polymers is

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basic soil behavior knowledge. Over time, a number of soil behaviors and responses

has been observed, which are now well understood by civil engineers. These soil

behaviors occur in response to man-made loads or to other natural / environmental

factors. Before raising any structure on soil / with soil / made of soil, we should gain a

basic understanding of how to best prepare a work site, select an aggregate, and

conduct a job by minimizing or counteracting possible negative soil behavior in

accordance with the load requirements and guidelines of each project.

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Driving Surface - Assorted Size Particles

One of the quickest ways to raise the likelihood of success in any paving project, is to

ensure the particle mix has the proper gradation to interlock during compaction. The

ratio of the various sizes of soil particles determines the suitability and effectiveness of

the soil in a weight bearing application. The best soils for supporting weight are made of

a mixture of different size particles.

Sufficient Fine Particles and Mixing

If your soil has an adequate mix of particles of different sizes, then your next concern is

ensuring you have sufficient fine particles to cover all the spaces between the larger

rocks so that the mix of water and polymer, when thoroughly mixed, will not flush

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through the rocks to the bottom, but rather remain suspended well mixed in the well-

graded aggregate with the help of these fine particles (allow water surface tension), and

provide lubrication to the compaction process, and then later harden into place in

between the rocks, locking all the individual rocks into place, for a solid and long lasting

hard driving surface.

Preparing a Road Base

Jusl like a building needs a proper foundation, a proper road requires a road base. At a

minimum, if working on top of excellent soil, the soil on which you build the road (the

subgrade, the lowest layer in the picture) needs to be well compacted. If certain soil

weaknesses are to be expected, a base layer should be added, preferably made of

larger rocks. If you separate the subgrade (native compacted soil) and base layer (large

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rocks) with a layer of geofiber (thin, light color in the picture), it will prevent "pumping".

The water table will be able to raise and lower through the larger base rocks (the

thickest middle layer in the picture) without driving subgrade sediment into the road

structure. An additional low cost measure to compensate for a weak subgrade is to

encase the base layer (larger rocks) into a geocell grid (height of geocell you order must

match the estimated height of this layer). This additional support creates a matrix that

has been proven to provide excellent road performance even on some of the weakest

subgrades. Adding geosynthetics (geocell, geogrid, geofiber, gabion mesh, etc) to your

project ensures substantially superior performance and longevity at low cost.

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Polymer Considerations

Considering the number of variables you need to streamline in order to get your soil to

play nice, we firmly believe that it would be smart to avoid additional concerns or doubts

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about the performance of your polymer. That is why PolymerPaving.com offers you the

most suitable polymer that you can possibly find, at a competitive price. When you use

the KompaFlex MX formula, you can rest assured you are already using a product that

will give you top notch repeatable performance time after time. Having the peace of

mind that comes with using the best product, frees you to focus on ground

improvement methods to bring your project to the desired performance standards. I

speak from experience when I tell you that if you get caught between trying to do ground

improvement while still having doubts about the performance of the binder, you will

never finish a project. So do yourself "a solid" and start with KompaFlex MX, and enjoy

the peace of mind that you already selected the best possible polymer, and the freedom

of focusing strictly on ground improvement, which is what we will discuss for the

remainder of this manual.

Polymer Mix-In Methods

The best way to achieve a perfect mixing of aggregate and polymer is by pre-mixing

(image 2). However, when the size of the job makes pre-mixing too slow, in order to

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work faster you can also do the following 4 step procedure: apply aggregate (soil or rock

mix) and spread to 1 inch thick (2-3 cm); Use a spraybar to apply the proper amount of

liquid (water and polymer in the correct ratio) to reach optimum moisture (image 1).

Then immediately mix the liquid into the aggregate using a scarifier or power rake

(image 3). Repeat this process (add soil, spread, spray, scar/mix) until the desired road

surface thickness is achieved, then grade the surface to the correct angles, compact,

and allow it to cure. Follow-up with a sealing coat, regardless of the method used. After

8-24 hours, clean remaining debris (loose rock and dust) from the surface with a power

broom, and apply a second and final sealer coat to the surface.

Another fast method is to use a reclaimer connected to a water tank truck preloaded

with the water and polymer mix; this combination vehicle can wet and scar/mix the soil

at the same time while advancing without the need to stop, except to reload the tank.

Optimum Moisture Content is a humidity level that ensures all particles will receive

polymer treatment, and compaction is well lubricated. If you see liquid on the compactor

wheel or puddles, you have exceeded OMC. Never work below OMC. Exceeding it a

little is not critical, but exceeding it by a lot can reduce ability to achieve high

compaction. Try to make a ball in your hand with the mixed soil; if it crumbles in your

hand it is too dry. If you have liquid seeping through your fingers you are applying too

much liquid. When it holds shape without excess liquid showing, it is perfect for

compaction.

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"Poor" Soil Contingencies

A soil is considered "poor" if it has been determined or tested to have inadequate or

insufficient engineering characteristics to meet the minimum requirements of the

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application. Another term commonly used is "marginal" and it applies when a soil comes

very close to meeting these requirements but doesn't quite make the cut. Here are

common methods for approaching these situations:

• Excavate the "poor" soil and replace it with good aggregate.• Redesign the project to be able to work with the poor soil (for example reinforce with

geocell or a similar mechanical reinforcement).• Modify the soil through soil remediation methods (mixing with other available soils / rocks,

mechanical or chemical, etc).• Abandon the project - this approach is selected when you can pick a more suitable

alternative location, or when the cost of fixing the soil insufficiencies exceeds theallocated budget.

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Soil Type Classification by Particle Size

1. Gravel2. Sand3. Silt4. Clay

A "sieve analysis" is a process where a given quantity of soil is passed through a certain

size of mesh to see how much passes and how much remains, determining whether a

soil has a "variety" or a "uniformity" of particle sizes. Generally speaking, soils with a

variety of particle sizes are called "well-graded" and are desirable for their ability to

be cohesive and to compact well. Soils with mostly uniform particle size do not have

good cohesion or compaction characteristics and should be avoided or modified.

Crushed rock (angular) is desirable in the mix. Round particles (river rock, beach sand)

are to be avoided; they may pass for "acceptable" when paving with asphalt because it

is a full ring aromatic, but round particles will not work when paving with polymer as your

binder because there isn't enough surface in contact with the particles surrounding it.

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Shear Strength

Soil is different from other engineering materials because it tends to fail in shear

rather than from direct tension or compression. With this fact in mind, imagine how much

stronger and resilient to shear forces the soil on the left is (compacted, mixed size [well

graded], interlocked, angular rocks) compared to the soil on the right (silt / clay).

Foundation: Bearing Capacity & Slope Stability

Nothing is more important or critical to success than a strong foundation, whether

you construct a road or a building. This becomes particularly important when the

foundation soil (subgrade) is poor or marginal. When the soil and the climate are

optimal, you can throw a road surface right on top of a good soil compaction without

problems. Many roads in Arizona and California are built just like that and they perform

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to acceptable levels for the desired lifespan. These regions rarely see bad weather or

rain, or the deleterious effects of water penetration or frost heave. Building a road in

most other regions require a properly designed foundation to compensate for the natural

forces that work against you. For instance many tropical areas see non-stop rain for six

months out of the year. In such an instance, a large portion of your effort and budget

should be aimed at effective drainage and building the road above the water table.

When you work in muddy or volcanic silt (such as in most of Southeastern Europe) you

need to explain to your beneficiaries the importance of building roads the same way they

build their railroads (with a solid crushed rock base that allows for water drainage and

frost heave), if they want them to last as long. You should seek additional reading on

"shallow foundation design" to understand bearing capacity failure. You can imagine

the risk of slope stability failure when you think that every few square feet of your

compacted pavement surface weighs tons by itself, and there are enormous natural

shear pressures acting on a slope, especially when the pavement structure is imbibed

with water molecules in between the soil particles (a very important phenomenon that is

worth exploring in detail, to have it well understood), and subjected to additional traffic

weight. That is why we strongly recommend the use of geosynthetic materials for

reinforcement, not as a luxury, but as a way to raise project longevity and to prevent

catastrophic failure due to unforseen events (bad winter, floods, earthquakes,

liquefaction, etc). No other materials offer a better price to performance ratio for

enhancing the desirable characteristics of a road and/or road base (and also for other

soil projects - embankments, overpasses, etc).

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Soil Densification and Consolidation

Soil densification is a process by which the air pockets are removed from soil through

compaction. Soil consolidation is a process by which water is removed from soil. There

is sufficient technology available today to literally be able to say that "no soil is

unsuitable" if you have the budget, the equipment, and use the right methods to fix it, or

to compensate for the respective defficiencies.

Types of Compactors

There are various types of compactors available, each designed for specific tasks, and

some are more suitable than others for specific jobs. It is important to know what kind of

compactor to use depending on your soil type and the desired end result which you are

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trying to achieve. Different soil types will present diverse characteristics that will affect

the soil improvement decisions you make.

Smooth Drum Rollers: a static load roller used for compaction of soils and asphalts, they

provide even weight distribution over the width of the roller and a smooth finished

surface. Also good for "proof rolling" during base preparation (to identify soft spots that

need reinforcement).

Pneumatic (rubber tire) rolles: these are engineered to apply very high static loads to a

wide variety of soils, pavements, bases and subgrades. They are even better suited at

finding soft spots, particularly because individual tires have the ability to move up and

down a small distance independently.

Combination rollers: easily identifiable as having both a steel drum and a set of

pneumatic roller wheels, with the ability to use either.

Vibratory rollers: they look similar to static rollers, with the ability to provide impact and

vibration to the soil beneath. If you have granular soils (poor cohesion aggregate) a

vibratory roller will help overcome the frictional resistance and achieve better

compaction.

Sheepsfoot / Padfoot / Wedgefoot rollers can apply very high static loads by

concentrating extreme weight on a small contact surface. These are ideal for breaking

hard dry boulders inherent in clay, silt and other cohesive soils, and in this way allowing

high and uniform compaction.

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Weight and Number of Passes

Although mathematically you should get the same result by adding the weight between

the number of passes, field experience shows that if you don't get the desired

compaction after 5-7 passes, you should perhaps switch to a heavier compactor. One

exception to this rule may be saturated sands, which have shown to improve up to 15-20

passes. However, since one of the "commandments" of working with polymer is to never

use sands or other round particles, this detail is irrelevant in our context.

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Requesting a Laboratory Test

So you are interested in polymer paving, perhaps because it is eco-friendly, or because

it is affordable or maybe because it is easy to complete and maintain. Perhaps it is for a

combination of reasons, or perhaps someone asked you to look into it. Many of the

variables you need to determine, including the suitability of a soil, can be easily and

inexpensively resolved by sending a soil sample and a small fee to our laboratory, where

we can test your soil for you and provide you with a report of your general situation. This

way you have a much better idea which approach / method / procedures we would

recommend as the most suitable for your particular project.

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Conclusions

Building an eco-friendly road with in-situ soil and polymer binder is really a process of

self-development, of becoming really good at soil improvement and ground modification

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procedures. Clean, affordable, long-lasting roads are just a result of accumulating that

knowledge and experience. I hope this brief guide served to introduce you to (or to

remind you of) some of the basics of sound soil engineering. Success in polymer paving

only requires a dilligence in following these proven and time tested principles. Soil

improvement methods are generally applicable in almost any other type of construction,

not only road building. We look forward to working with you.

PolymerPaving.com is a division of Option Quest LLC, which manages the following

properties:

• www.polymerpaving.com• www.greenroadbuilder.com• www.optionquest.com• www.incentiveserver.com• www.responsiveglass.com• www.language-queen.com• www.law-register.com• www.mobileactivator.com

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Polymer Paving Starter Guide

Environment

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