Stabilized Engineered 

Wood Fiber for 

Accessible Trails 

Installation and Serviceability Results: 

Governor Dodge State Park, Wisconsin 

Theodore L. Laufenberg 

United States

Department of 

Agriculture 

Forest Service 

Forest 

Products 

Laboratory 

General 

Technical 

Report 

FPL−GTR−155 
Abstract 

Trails made with wood chips are difficult for those who use 

mobility aids because the surface is soft, uneven, and shifting. This report describes the development of a concept for 

stabilizing engineered wood fiber (EWF) to improve wheelchair and walker accessibility for outdoor recreational trails 

where traditional paving would be costly and would detract 

from the natural aesthetics. The applicability and field performance of two binderñEWF systems previously developed 

for an outdoor playground were tested on a beach path and 

two bridle trails. The stabilized EWF (SEWF) system enhanced accessibility and should reduce erosion and maintenance costs for trail systems. Overall, the two systems performed well on the beach path but were not adequate for the 

bridle paths. Cost estimates and step-by-step instructions are 

provided for installing SEWF. 

Keywords: wood, fiber, surfacing, accessibility, walkways, 

paths, ADA, composite, polyurethane, playground, durability, installation, cushioning 

November 2004 

Laufenberg, Theodore L. 2004. Stabilized engineered wood fiber for 

accessible trailsóInstallation and serviceability results: Governor Dodge 

State Park, Wisconsin. Gen. Tech. Rep. FPL-GTR-155. Madison, WI: 

U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 

11 p. 

A limited number of free copies of this publication are available to the 

public from the Forest Products Laboratory, One Gifford Pinchot Drive, 

Madison, WI 53726ñ2398. This publication is also available online at 

www.fpl.fs.fed.us. Laboratory publications are sent to hundreds 

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The Forest Products Laboratory is maintained in cooperation with the 

University of Wisconsin. 

The use of trade or firm names is for information only and does not imply 

endorsement by the U.S. Department of Agriculture of any product or 

service. 

The United States Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national 

origin, sex, religion, age, disability, political beliefs, sexual orientation, or 

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Persons with disabilities who require alternative means for communication 

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Room 326-W, Whitten Building, 1400 Independence Avenue, SW, Washington, DC 20250ñ9410, or call (202) 720ñ5964 (voice and TDD). USDA is 

an equal opportunity provider and employer. 

 Acknowledgments 

We gratefully acknowledge Bill Botten, U.S. Architectural 

and Transportation Compliance Board, for guidance in 

initiating Phase III of the development of the stabilized 

engineered wood fiber (EWF) concept, and Ted Illjes and 

Bob Zeager of Zeager Bros. Inc., Middletown, Pennsylvania, 

for performing the impact tests. 

Zeager Bros. Inc. and Beneficial Designs, Inc. (Minden, 

Nevada), provided the apparatus for the impact test and the 

rotational penetrometer, as well as training in their use. 

Thanks to Zeager Bros. Inc. for the donation of EWF and 

Midwest Industrial Supply (Canton, Ohio) for the donation 

of Soil-Sement. 

We are grateful to the Wisconsin Department of Natural 

Resources for offering park areas and trails for this study. In 

particular, we appreciate the guidance and support of Anthonette Gilpatrick, ADA Coordinator; Kathy Gruentzel, 

Park Manager; and the staff of Governor Dodge State Park 

for installing and monitoring the trail and beachwalk sites. 

Special thanks to Jane and Steve Schmieding, Carl Syftestad, 

Lloyd Currier, Nancy Keen, Vicki Herian, Mary Collet, 

and other members of the FPL staff, for their support of 

this effort. 

Contents 

 Page 

Introduction........................................................................... 1

Background........................................................................... 1

Objectives ............................................................................. 2

Acceptable Trail Surfacing Requirements ............................ 2

Trail Study Sites.................................................................... 2

Beach Path ........................................................................ 2

Bridle Path ........................................................................ 3

Bonded Beach Path Installation ............................................ 3

Bonded Bridle Path Installation ............................................ 4

Test Procedures..................................................................... 5

Field Observation Reports ................................................ 5

Impact Attenuation Tests .................................................. 5

Accessibility and Durability Measures ............................. 5

Observations and Results...................................................... 7

Field Observations ............................................................ 7

Impact Attenuation............................................................ 7

Durability .......................................................................... 8

Accessibility Measures ..................................................... 8

Costs and Personnel Time for Beach Path Installation ....... 10

Preliminary Guidelines for SEWF Installation ................... 10

Literature Cited ................................................................... 11
Stabilized Engineered Wood Fiber 

for Accessible Trails 

Installation and Serviceability Results: 

Governor Dodge State Park, Wisconsin 

Theodore L. Laufenberg, Research General Engineer

Forest Products Laboratory, Madison, Wisconsin 

Introduction 

Wood chip surfaces on trails create difficulties for those who 

use mobility aids, such as wheelchairs and walkers, due to 

their softness, shifting, and uneven surface. This report is 

part of the third phase of research in pursuit of an accessible 

stable and smooth surface based on wood fiber. The study 

originally targeted the use of engineered wood fiber (EWF) 

(ASTM 2004) for playgrounds. In Phase I, processing techniques and material properties were evaluated in small 

benchtop and full-depth laboratory tests (Laufenberg and 

others 2003). Phase II involved further development of the 

best Phase I system in 6-month outdoor field testing 

(Laufenberg and Winandy 2003). 

In Phase III of this project, we investigated the applicability 

and field performance of the two best candidate resin/EWF 

systems. The previous phases had shown that our new resin/EWF systems can enhance mobility as related to the 

Americans With Disabilities Act (ADA) and can perform in 

an outdoor environment. This report describes the development of a concept for stabilizing EWF to improve wheelchair and walker accessibility for outdoor recreational trails 

where traditional paving would be costly and would detract 

from the natural aesthetics. In this portion of the Phase III 

study, we installed our two most promising EWF stabilizing 

binders on a walkway across a sandy beach extending down 

to the waterís edge. This surfacing material concept was to 

mix a binder with EWF to create a stiff (firm) and scuffresistant (stable) composite. Stabilized EWF (SEWF) is a 

system that has enhanced accessibility and should reduce 

erosion and maintenance costs for trail systems. 

Background 

The initial research effort included a variety of resin (e.g., 

latex, silicone, and polyurethane) binders and various types 

of EWF. We chose adhesive binders for their inert and 

non-toxic nature in the environment and the retention of a 

natural look for the surface. Consideration was given to the 

need to add material or patch the surfaces after major damage. Use of a trail surface for 3 to 5 years was considered 

adequate time for the binder to fulfill its function. These 

adhesive systems have not been previously used in this 

application with EWF, therefore there is no experience with 

their functioning for that extended period. The preliminary 

evaluation included laboratory testing of energy absorption 

and surface firmness and stability on trial surfaces in 0.5- by 

0.5-m (18- by 18-in.) plywood boxes; the surfaces had a 

uniform depth of 0.3 m (12 in.). Seven systems were identified as having reasonable performance and thence recommended for Phase II outdoor field evaluations. 

Phase II research focused on outdoor evaluation of the 

binder and fiber options identified as minimally acceptable 

and promising in the Phase I evaluations. The Phase II work 

studied field durability and looked at changes in performance by quantifying the impact and accessibility of these 

novel surfaces after field exposure. This series included 

seven surface treatments, and a control surface, installed in a 

series of outdoor test beds in Madison, Wisconsin, to gather 

field experience on long-term performance and durability. 

The binders evaluated were (a) synthetic latex emulsion, 

(b) a low molecular weight silicone, and (c) foaming and 

non-foaming resilient polyurethane. Systems were evaluated 

over a 6-month period, from April to October 2002. 

Tests were performed at regular intervals to provide a quantitative measure of accessibility. The results indicate that 

latex and polyurethane stabilizers consistently met the 

requirements for accessibility on playgrounds (Laufenberg 

and Winandy 2003). The foaming polyurethane formulation 

produced a hard brittle shell that became even harder with 

exposure/age and would increase the injury rate for falls on 

the surface. The silicone system did not maintain its integrity 

adequately during the rain/dry cycles in this outdoor test. 
2 

Monitoring of the Phase II test plot continued for 2 years 

after the initial 6-month evaluation reported by Laufenberg 

and Winandy (2003). In those 2 years, the synthetic latex 

emulsion and the non-foaming polyurethane continued to 

performed acceptably. As anticipated, the foaming polyurethane system continued to harden with exposure, rendering it 

unsuitable for meeting the impact absorption requirements 

for playground surfaces. 

Objectives 

The original development work, though targeted toward 

playground improvements, was eventually seen as a potential improvement for trail surfacing. Following the preliminary field trials, professionals involved in recreational surface development encouraged us to investigate the concept 

for trails. For trails, the primary emphasis was accessibility 

and natural aesthetics, and impact performance was a 

secondary characteristic. However, many processing and 

handling issues for playgrounds were also considerations for 

trail construction and use. Several such issues were considered. This study explores the use of the resin/EWF system as 

a surfacing material for accessible outdoor recreation trails. 

Acceptable Trail Surfacing 

Requirements 

Current trail design considerations include quantity of traffic 

and type of use, such as walking and wheelchair use, biking, 

horse riding, and other allowed uses. Trail surfaces are 

currently considered accessible only if the surfacing material 

is firm, stable, and slip-resistant and the trail has the engineered attributes of adequate width, moderately short slopes, 

passing spaces, and appropriate signage. A traditional paving 

material such as asphalt and concrete may be appropriate, 

but this type of surface is expensive to construct, requires the 

use of heavy materials and equipment, and may detract from 

the aesthetics of the trail. 

The Americans with Disabilities Act (ADA 1990) states that 

accessible surfaces shall be stable, firm, and slip-resistant. 

These three criteria have not been defined adequately within 

the ADA Accessibility Guidelines for quantitative measurement on any specific surface. Currently, the only objective 

method that is suitable for assessing the firmness and stability of playground surfacing systems is the rotational 

penetrometer (Axelson and Chesney 1999). 

As when constructing trails with native soils, it is very desirable to drain water quickly away from the surface of a 

SEWF trail. This is critical in maintaining the stability of 

native soils and for reducing the biodeterioration potential of 

a wood fiber based surface. Keeping water off the surface 

also maintains adequate friction on the stabilized EWF 

during sub-freezing temperatures. The rotational penetrometer, a portable measurement device that simulates a 

wheelchair caster negotiating the test surface, was used to 

assess the level of accessibility. 

We also needed to consider several practical aspects for 

processing the SEWF material and maintaining a safe work 

environment. Based on our experience in field applications, 

stabilizing binders needed to be applied on site or mixed 

with the EWF no longer than 1 h prior to placement on the 

ground surface. The practical considerations were 

(a) cure/set time prior to surface use, (b) range of EWF 

moisture and temperature conditions acceptable for use, 

(c) emission of fumes or odors, workable exotherms, and 

toxic or other chemical release/concerns from the binder/ 

EWF mixture, and (d) deleterious effects of SEWF on 

trail users. 

Trail Study Sites 

An Access Board solicitation for potential playground study 

sites yielded numerous responses for trail work as well. An 

accessibility coordinator for the Wisconsin State Parks offered us an opportunity not far from the Forest Products 

Laboratory, at Governor Dodge State Park in Dodgeville, 

Wisconsinóto extend an accessible beach path and to 

attempt to stabilize two short sections of a severely eroded 

bridle path. 

Beach Path 

Our prototype test location for the SEWF concept on trails 

was an accessible beach path to Cox Hollow Lake. The 

existing path was 1.2-m- (4-ft-) wide blacktop asphalt 

extending 50 m (165 ft) from accessible parking to the beginning of the sand beach, 30 m (100 ft) from the water. Our 

task was to provide accessibility over the sand to the water, 

retaining the aesthetic quality of the area (National Center on 

Accessibility 2003). 

Discussions with the park staff provided insight to the usage 

of the beach path. The desire was for park users to be able to 

maneuver a wheelchair directly to the waterís edge, where 

they could access the beach and a boat landing (Fig. 1). 

Another consideration was the proximity of the path to the 

beach volleyball area. The SEWF surfaces were originally 

developed for use as impact-sensitive playground surfaces. 

Thus, their impact behavior was considered much more 

forgiving than that of an asphalt path. 

Layout of the path across the beach was sloped so that the 

edge of the path would not hold water. Park personnel were 

concerned that sand would wash or get kicked over the path 

surface, which would decrease accessibility and increase 

maintenance requirements. Slope along the upper edge was a 

minimum of 1%. Nearer the waterline the slope of the path 

increased to a maximum of approximately 5% for the final 

few meters (feet). The amount of waterline fluctuation was 

considered minimal at this beach because of the proximity of 

water control structures. 
3

We first lowered and leveled the existing sand surface to a 

depth of 0.06 m (2.4 in.) (Fig. 2). Any stones and vegetation 

near the waterline were removed. Within 1.5 m (5 ft) (horizontal distance) of the waterline, the stability of the sand was 

deemed inadequate for supporting the SEWF. We removed 

0.1 m (4 in.) of sand in this area and replaced it with 20 mm 

(3/4 in.) of angular stone to provide a well-drained and 

stable base, which would also reduce the amount of scour 

from wave action on the lake. The work crew consisted of 

employees of the park, the Wisconsin Department of Natural 

Resources, and the USDA Forest Service. 

A lightweight landscaping geotextile fabric was placed on 

the sand and drainage rock. Handfuls of sand were thrown 

on the fabric to keep the wind from blowing it out of place. 

The geotextile fabric bonded to the SEWF and improved 

overall stability of the surface layer. 

Bridle Path 

Both bridle path sections were remote sites that required the 

use of hand tools for surface preparation. The surfaces were 

prepared by removing large rocks and woody forest debris. 

One site consisted of two parallel ruts approximately 0.1 to 

0.2 m (4 to 8 in.) deep and 0.2 to 0.3 m (8 to 12 in.) wide. 

The ruts were within 1 m (3 ft) apart on a 15% to 20% slope. 

Native soil was exposed along the ruts. The soil was firm 

with little loose soil or unstable rock. 

The other site was a 3-m (12-ft) wide section on a bridle trail 

with a 20% to 25% slope leading to a level wash that carried 

water during heavy rains for very short periods. 

The primary objective was to stabilize the soil from the 

erosive forces of horse hooves and water running across the 

wash. 

Bonded Beach Path Installation 

The two binder systems used to fabricate the beach path 

surface were 

1. an acrylic and polyvinyl acetate polymer emulsion, SoilSement (Midwest Industrial, Canton, Ohio), mixed 30% 

by dry weight of solids to unit weight of dry EWF and 

applied 63 mm (2-1/2 in.) thick, and 

2. a non-foaming polyurethane, Vitri-Turf (Vitricon, Polymer Plastics Corp., Commack, New York), mixed 30% by 

weight with unit dry weight of EWF and applied 37 mm 

(1-1/2 in.) thick. 

Because the installation occurred in the fall, we monitored 

air temperature; both stabilizing binders required 4°C (40°F) 

for proper curing. On the date of installation, the overnight 

temperature was 7°C (44°F). The binders had been stored at 

room temperature. When the binders were mixed with EWF, 

the temperature of the mixture was well above 10°C (50°F). 

The EWF was shoveled directly from the truck into a 160-L 

(40 gal) portable mortar mixer. The amount of binder added 

was determined as a proportion (30%) of EWF dry weight 

(volumetrically equivalent to 0.041 m3

 (1.45.ft3) of EWF to 

5.3 L (1.25 gal) of Vitri-Turf or 10.6 L (2.5 gal) of SoilSement. Weight proportion was 77:23. The binder and EWF 

were mixed for approximately 2 min and transported to the 

target pad in polyethylene tray wheelbarrows (Fig. 3). The 

binderñEWF mixture was spread with hand tools to an even 

thickness (Figs. 4 and 5). The area was then compacted and 

flattened with a 1.2-m by 1.2-m by 16-mm (4-ft by 4-ft by 

Figure 1óSchematic plan of Governor Dodge State Park Cox Hollow beach path site (not to scale). 
4 

5/8-in.) piece of plywood covered with a polyethylene release sheet. A 90-kg (198-lb) person walked on the plywood 

in each quadrant to apply firm compaction pressure. At the 

termination of the path at the waterline a 0.1-m (3.5-in.) curb 

was formed to reduce any inadvertent rolling of the path into 

the water and to stiffen the edge directly in contact with 

wave action. 

The two SEWF surfaces were allowed to cure or bond for 

5 days prior to use (Fig. 6). Because rain was not predicted, 

the entire surface was left exposed. Overnight temperatures 

stayed above 4°C (40°F) for 2 days after installation. Within 

2 h of installing the Vitri-Turf, the surface was somewhat 

rigid to hand pressure. The Soil-Sement surface was slower 

to stiffen and was deemed stiff within 48 h. Five days after 

installation, the barriers were removed and the edge of the 

path was backfilled with beach sand using rakes. The completed beach path after 2 months of weathering is shown in 

Figure 7. 

Bonded Bridle Path Installation 

The same two binder systems used to fabricate the beach 

path surface (Soil-Sement and Vitri-Turf) were used for the 

bridle path trials. 

Prior to the date of installation, the overnight temperature 

was 9°C (48°F). The binders had been stored at room temperature; when mixed with EWF, the resultant mixture was 

well above 10°C (50°F). 

Figure 2óGrading of beach path to waterline. 

Figure 3óLoading of binderñEWF mixture from mortar 

mixer into wheelbarrow. 

Figure 4óLeveling and compaction of binderñEWF 

mixture near junction with asphalt path. 

Figure 5óTermination of Soil-Sement portion of beach 

path. Geotextile fabric visible under completed SEWF 

surface. 
5

For both systems, the layer of EWF placed on the soil surface was 0.05 to 0.07 m (2 to 3 in.) deep and was raked 

smooth. A backpack sprayer and drip-bucket were used to 

apply the Soil-Sement (approximately 50% solids content) 

with a target application proportion of 30% binder based on 

the weight/volume of EWF (Figs. 8 and 9). The Vitri-Turf 

was much more viscous (100% solids) and thus only a drip 

bucket approach was used to apply the binder (Fig. 10). 

With a known weight of EWF at an application proportion 

of 30%, 19 L (5 gal) of binder was applied by moving a 

perforated bucket (holes 6 mm (0.2 in.) in diameter) quickly 

over the surface. Immediately after applying the binder, the 

binder was mixed into the EWF with forks and garden rakes. 

On the narrow bridle path, the SEWF was compacted using 

the flat end of a rake. The wider path was compacted using a 

polyethylene-covered 1.2-m by 1.2-m by 16-mm (4-ft by 4-ft 

by 5/8-in.) piece of plywood; a 90-kg (198-lb) person 

walked on the plywood in each quadrant to apply firm compaction pressure (Fig. 11). The SEWF areas were roped off 

for 5 days to provide time for curing prior to usage.

Test Procedures 

Field Observation Reports 

The sites were not under direct supervision or observation by 

park staff or other responsible personnel. However, on-duty 

staff noted any public concerns and changes at the site and 

reported them when we visited. Forest Products Laboratory 

staff visited the sites at least weekly for the first 2 months 

and at least monthly thereafter (if the ground was thawed) to 

complete the rotational penetrometer testing and to observe 

and annotate any maintenance needs. 

Impact Attenuation Tests 

Impact tests were completed on the beach path only as an 

adjunct to tests conducted at a playground at another park. 

For the beach path, we were interested if the impact standard 

could be met when SEWF was placed over sand. The impact 

was conducted by a cooperator (Zeager Bros. Inc., Middletown, Pennsylvania) 8 weeks after installation. ASTM F 

1292ñ99 test specifications (ASTM 1999a) and F355ñ95 test 

methods (ASTM 1995) were used at a test drop height of 

3.05 m (10.0 ft) and 1.83 m (6.0 ft), respectively. Maximum 

g levels and head injury criteria (HIC) were measured. 

Accessibility and Durability Measures 

The beach path surfaces were periodically measured with a 

rotational penetrometer. This device subjects the test surface 

to a low-speed rotational bearing test meant to simulate the 

weight and action of a front caster wheel on a wheelchair. 

The procedures are based on the draft national standard test 

method for the firmness and stability of ground and floor 

surfaces (RESNA 2000), which uses an average of five 

Figure 6óCompleted beach path area looking west, 

shown with temporary barrier for 5-day SEWF curing 

period. 

Figure 7óBeach path after 2 months of weathering. 

Junction of Soil-Sement and Vitri-Turf surfaces is just 

above the shadow cast by the picnic bench. 
6 

readings. This test provides objective measures of surface 

firmness and stability. Although no literature has been published on this subject, the use of the rotational penetrometer 

data allows an inference to the durability of the binderñEWF 

surface. The test effectively detects the loss of bond strength 

during the stability (rotation of caster wheel) portion of the 

test. The firmness measure is a means of inferring changes in 

overall stiffness of the bonded layer as well. It has been 

correlated to the work measurement of ASTM F1951 

(ASTM 1999b), ìAccessibility of Surface Systems,î for a 

wide array of surfacing and floor coverings. The test was 

performed 1 week after surface installation and as often as 

Figure 8óInstallation of Soil-Sement surface on bridle 

path: (a) application of Soil-Sement by backpack-type 

sprayer; (b) trail crew mixed, leveled, and compacted the 

narrow trail filled with SEWF. 

Figure 9óApplication of Soil-Sement to bridle trail by 

drip-bucket method. Rakes were used to mix binder 

with EWF and level the trail. 

Figure 10óApplication of Vitri-Turf to bridle trail by dripbucket method. Holes drilled in bottom of 19-L (5-gal) 

container allowed uniform application over 0.4- by 20-m 

(1.3- by 66-ft) trail. 
7

once a week initially, using a Beneficial Designs, Inc. 

(Minden, Nevada) rotational penetrometer and protocol for 

assessing the bearing/rotational indentation on each surface 

(Axelson and Chesney 1999). 

Observations and Results 

Field Observations 

A wheelchair user on the beach path described the Vitri-Turf 

surface as ìnice and firmî and the Soil-Sement surface as 

ìkind of softî (Fig. 12). Maneuvering the chair was noted to 

be ìeasyî on the Vitri-Turf and ìnot as easyî on the SoilSement. The user also noted that the raised curb made her 

feel comfortable about moving to the end of the path. Without the curb, she felt she would have had to stop a few feet 

back from the waterís edge. 

The bridle paths suffered near total loss of integrity within 

the first 2 months of installation. Shoed horse hooves broke 

the thin 50- to 70-mm (2- to 3-in.) surfaces. Material was 

first broken into dinner-plate-sized pieces and then smaller 

pieces. The horses did not avoid the SEWF area and were 

clearly comfortable walking on it. Although a thicker surface 

would have lasted longer, the clear implication is that equestrian traffic requires a much tougher surface to resist the 

forces applied. Because this system failed prematurely due to 

mechanical loads, it did not remain in place long enough to 

confirm its ability to control trail erosion. 

Impact Attenuation 

Impact testing (ASTM F1292, ASTM 1999)) of the Vitri 

Turf and Soil-Sement surfaces was conducted 8 weeks after 

installation (Fig. 13). 

For the second and third drop tests at 3.05 m (10 ft), 

• average g readings were 223 for Vitri-Turf and 

238 for Soil-Sement and 

• average HIC readings were 1679 for Vitri-Turf and 1752 

for Soil-Sement. 

For the second and third drop tests at 1.82 m (6 ft), 

• average g readings were 214 for Vitri-Turf and 

196 for Soil-Sement and 

• average HIC readings were 1370 for Vitri-Turf and 

1214 for Soil-Sement. 

Figure 11óTreatment of wide bridle trail (site 2): spray 

application of Vitri-Turf in background and drip-bucket 

application of Soil-Sement in foreground. Note use of 

polyethylene-covered plywood for compaction and 

leveling of Vitri-Turf SEWF. 

Figure 12óTesting bonded beach path with (a) batterypowered and (b) hand-powered wheelchairs. Shadow 

near the waterline indicates terminal curb of beach path. 
8 

Recall that these recreational trails were installed directly on 

the sand and not on the 0.3 m (12 in) of EWF found at a 

typical playground site. If the trails were evaluated as play 

surfaces, both beach path SEWF surfaces would fail the 

criteria of <200 for g and <1,000 for HIC. When using the 

1.82-m (6-ft) fall height (which would be appropriate for 

people of average height playing volleyball), the SoilSement surface was just able to meet the g criteria but failed 

the HIC. However, given the alternatives available, both 

surfaces are softer and less likely to cause injury than is 

an asphalt path. 

Durability 

Measures of surface durability are quite subjective unless the 

loss of durability is a dramatic failure. The curing of SoilSement, as evidenced by the stiffening of the SEWF mixture, was slower than that of the Vitri-Turf, and the SoilSement surface was ìsofterî according to one wheelchair 

user. In the rotational penetrometer test, the Soil-Sement 

SEWF showed some indication for the top surface particles 

to detach from the overall top layer faster than did the VitriTurf SEWF top particles. The rotational penetrometer readings also reflected changes in stability and firmness of the 

Soil-Sement surface. 

Vitri-Turf SEWF durability with exposure to weather was 

good and reflected our experience with this material during 

the past 2 years at the Phase II test site at the Forest Products 

Laboratory in Madison, Wisconsin. During the spring of 

2004 Wisconsin experienced record-setting rainfalls. This 

caused the level of Cox Hollow Lake in Governer Dodge 

State Park to rise over 0.3 m (1 ft) for a short period. Park 

staff reported that the path ìfloatedî off the gravel pad at the 

path terminus for a distance of approximately 2 m (6-1/2 ft). 

After the water had subsided, there was no evidence that the 

path had been lifted and the overall performance of the 

surface seemed comparable to that noted before the high 

water level. 

Accessibility Measures 

During the 10-month period of this testing, the firmness and 

stability of the SEWF surfaces were measured with the 

rotational penetrometer (Fig. 14). Both the Vitri-Turf and 

Soil-Sement showed good performance for accessibility 

during this period. The Vitri-Turf SEWF indicated ìfirmî 

and ìstableî during the entire period, with some fluctuation 

traceable to the changes in moisture with long rainy spells. 

Soil-Sement SEWF was rated as ìmoderately firmî and 

ìstableî during the testing period (Figs. 15 and 16). 

Figure 13óImpact testing on beach path was similar to 

impact test conducted at a playground using a 3.05-m 

(10-ft) drop-height. 

Figure 14óRotational penetrometer used to measure 

accessibility. 
9

Figure 15óFirmness of Soil-Sement and Vitri-Turf treatments on beach path over 

first 10 months of installation. 

Figure 16óStability of Soil-Sement and Vitri-Turf treatments on beach path over 

first 10 months of installation. 
10 

Costs and Personnel Time for 

Beach Path Installation 

The following summary of costs and time estimates is not 

meant to be definitive but to document data for the beach 

path installation. 

Quantity of material 

EWF 6 yd3

 

Vitri-Turf 15 gal 

Soil-Sement 35 gal (45% solids) 

Market value of material 

EWF $21/yd uncompacted 

(includes shipping) 

$126 

Vitri-Turf $18/gal 

(100% solids, 11 lb/gal) 

 270 

Soil-Sement $7/gal 

(45% solids, 9 lb/gal) 

 245 

Drainage system Geotextile 80 

 $721 

Equipment and tool rental (market value) $100 

Personnel time 

Base prep and geotextile installation, 

4 h @ $10/h 

$40 

Bonded surface install, 16 h @ $15/h 240 

The installation of the two surface treatments was completed 

during one workday. Approximate efforts for the installation 

of 200 ft2

 of each material (400 ft2 total) were 16 h (4 people 

for 4 h). 

Summary of costs for beach path surface 

 Cost ($/ft2

) 

Binder Labor Materials Surface 

w/labor 

Vitri-turf (38 mm, 1.5 in.) 0.70 1.87 2.57

Soil-Sement (63.5 mm, 

2.5 in.) 

0.70 1.74 2.44 

Preliminary Guidelines for 

SEWF Installation 

Follow manufacturerís instructions for storage and handling 

of the binder. Binder materials must be stored indoors in 

cool dry storage out of sunlight. Observe recommended 

limits on binder shelf life. Read material safety data sheets 

carefully prior to opening containers. Wear protective 

clothing and eye gear at all times. Assure a period of 48 h of 

warm and dry weather for proper curing of the binders. EWF 

should be moderately dry (less than 30% moisture content). 

Mixing Binder With EWF 

1a. Vitri-Turf binder is mixed with the EWF at the ratio of 

77/23 by weight. This equates to approximately 6 liters 

(1.25 gallons) of Vitri-Turf binder to 0.041 m3

 (1.45 ft3) 

of EWF (depending upon the density of the EWF 

 particles). 

1b. Soil-Sement is mixed 77/23 by weight (assuming 100% 

solids). If it is only 50% solids then the ratio of weights 

changes to 63/37. This equates to 10 L (2.5 gallons of 

Soil-Sement) (50% solids) to 0.041 m3

 (1.45 ft3) of 

EWF. 

2. Mixing is best done with a mechanical drum mixer. If a 

small patch is needed for repair, use a trough with a hoe. 

Be sure that the EWF particles are thoroughly coated. 

Running a typical mortar or cement mixer for 2 min is 

usually adequate to achieve good mixing. Check the 

mixer at the end of each mix to assure that binder and 

fine wood particles are not accumulating on the paddles 

or drum. 

Application of SEWF 

1. Use a wheelbarrow to transport the SEWF mixture. 

Dump into place and apply the mixed Binder/EWF at a 

nominal 50% more (uncompacted) depth than the intended compacted thickness using a screed bar or rake. 

2. Compact and smooth the surface by using a large trowel 

or stiff plywood (16 mm or 5/8 in.) of dimension 1.2 by 

1.2 m (4 by 4 ft) covered with a heavy-mil sheet of 

polyethylene as a release. If material sticks, you may 

lubricate with kerosene, diesel fuel, or soapy water. 

Do not saturate surface with these lubricants. After 

compaction the thickness will be approximately 40 mm 

(1.6 in.). 

3. Apply a moderate downward pressure onto the surface 

so that the mixture compacts tightly. When using the 

4- by 4-ft plywood, a 90-kg (200-lb) person stepping in 

the four quadrants of the panel should provide adequate 

compaction. 

4. Allow to cure in the open air for a minimum of 24 h. 

Cover only for short periods to protect the surface from 

direct rainfall. 
11

Cleanup 

Clean all tools for Vitri-Turf application immediately with 

diesel fuel before the surface has dried; use water to clean 

tools for Soil-Sement application. Once binder has dried it 

will be difficult to remove from tools, surfaces, or hands. 

General Precautions 

• Wear protective clothing and eye gear. 

• Provide a minimum of 1% slope for all substrates for 

drainage. 

• Ambient air temperature should be 40°F (4°C) or greater 

and rising when SEWF is applied. Air temperature should 

remain at 40°F (4°C) or greater for at least 7 days after 

SEWF application. 

• Protect surfaces from rain for a minimum of 48 h 

after SEWF application. 

• Read all material safety data sheets very carefully. If you 

do not understand the instructions, contact the manufacturer before applying SEWF. 

• If binder accidentally comes in contact with eyes, immediately rinse with water and contact a physician. 

Literature Cited 

ADA. 1990. Public Law 101ñ336. Americans with Disabilities Act, Public Law 336, 101st Congress, enacted July 26, 

1990. 

ASTM. 1995. Standard test method for shock-absorbing 

properties of playing surface systems and materials. ASTM 

F355ñ95, Vol. 15.07. West Conshohocken, PA: American 

Society for Testing and Materials. 

ASTM. 1999a. Standard specification for impact attenuation 

of surface systems under and around playground equipment. 

ASTM F1292ñ99. West Conshohocken, PA: American 

Society for Testing and Materials. 

ASTM. 1999b. Standard specification for determination of 

accessibility of surface systems under and around playground equipment. ASTM F1951.West Conshohocken, PA: 

American Society for Testing and Materials. 

ASTM. 2004. Standard specification for engineered wood 

fiber for use as a playground safety surface under and 

around playground equipment. F2075ñ04, Vol. 15.07. 

West Conshohocken, PA: American Society for Testing and 

Materials. 

Axelson, P.W.; Chesney, D. 1999. Accessible exterior 

surfaces. Tech. rep. Washington, DC: U.S. Architectural and 

Transportation Barriers Compliance Board. 

www.accessboard.gov/research&training/Exterior%20Surfac

es/exteriorsarticle.htm 

Laufenberg T.; Winandy, J.E. 2003. Field performance 

testing of improved engineered wood fiber (EWF) surfaces 

for accessible playground areas. Gen. Tech. Rep. FPLñ

GTRñ138. Madison. WI: U.S. Department of Agriculture, 

Forest Service, Forest Products Laboratory. 10 p. 

Laufenberg T.; Krzysik, A.M.; Winandy, J.E. 2003. 

Improved engineered wood fiber (EWF) surfaces for accessible playgrounds, Gen. Tech. Rep. FPLñGTRñ135. 

Madison. WI: U.S. Department of Agriculture, Forest 

Service, Forest Products Laboratory. 15 p. 

National Center on Accessibility, Providing Access to 

Beaches. 2003. Access Today. Special Vol., Issue 9. 

(Summer).

http://www.ncaonline.org/monographs/9beach-access.shtml 

RESNA, 2000. RESNA surface, section 1: Test method for 

firmness and stability. Working draft standard. Arlington, 

VA: Rehabilitation Engineering and Assistive Technology 

Society of North America. 11ñ20. info@resna.org