SECTION 32 12 43 — POROUS FLEXIBLE PAVING

PART 1 — GENERAL

1.1 SUMMARY

This section includes the requirements for constructing stabilized aggregate pathways, trails, and low-volume roads using POLYFIRM Trail Binder CPx-2900 Series Stabilizer Binder.

1.2 RELATED SECTIONS

• Section 31 20 00 - Earth Moving
• Section 32 11 23 - Aggregate Base Courses
• Section 32 15 40 - Decomposed Granite Surfacing

1.3 REFERENCES

• ASTM C136 - Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates
• ASTM D1557 - Standard Test Methods for Laboratory Compaction Characteristics of Soil
• ASTM D2419 - Standard Test Method for Sand Equivalent Value of Soils and Fine Aggregate
• ADA Standards for Accessible Design

1.4 SYSTEM DESCRIPTION

The stabilized aggregate system consists of a specified aggregate material treated with POLYFIRM Trail Binder water-based vinyl acrylic copolymer emulsion to create a permeable, natural-appearing surface that remains firm and stable under traffic and weather exposure.

1.5 SUBMITTALS

Submit the following in accordance with Section 01 33 00:

1. Product Data: Manufacturer's technical data sheets for stabilizer binder.
2. Samples: Submit 1-pound samples of proposed aggregate material.
3. Sieve Analysis: Certified laboratory analysis of aggregate materials demonstrating compliance with gradation requirements.
4. Manufacturer's Instructions: Application procedures and recommendations.

1.6 QUALITY ASSURANCE

1. Manufacturer Qualifications: Provide products from a company specializing in stabilized aggregate systems with a minimum of 5 years documented experience.
2. Installer Qualifications: Company experienced in performing work of this section with a minimum of 3 years documented experience.
3. Mock-up: Construct on-site 4' x 4' sample panel using proposed materials and installation methods. Approved mock-up may remain as part of the work.

1.7 DELIVERY, STORAGE, AND HANDLING

1. Deliver stabilizer binder in original, unopened containers with manufacturer's labels intact.
2. Store in clean, dry area between 40°F and 90°F (4°C and 32°C). Protect from freezing.
3. Store aggregate materials in a clean, well-drained area. Prevent contamination with foreign materials.

1.8 PROJECT/SITE CONDITIONS

1. Environmental Requirements:
   1. Do not install in rainy conditions or when rain is forecast within 48 hours.
   2. Do not install when ambient temperature is below 50°F (10°C) or above 95°F (35°C).
   3. Do not install on frozen subgrade.
2. Existing Conditions: Verify subgrade preparation, compaction, and elevation are proper before beginning installation.

PART 2 — PRODUCTS

2.1 MANUFACTURERS

1. Acceptable Manufacturer: POLYFIRM, Seattle, WA
2. Substitutions: Not permitted without prior approval.

2.2 MATERIALS

1. Stabilizer Binder:
   1. Product: POLYFIRM Trail Binder CPx-2900 Series
   2. Description: Water-based vinyl acrylic copolymer emulsion
   3. Physical Properties:
      • pH: 4.0-5.5
      • Solids Content: 47-51% by weight
      • Specific Gravity: 1.05-1.10
      • VOC Content: Less than 50 g/L
      • Color: Milky white (when wet), clear (when dry)
2. Surface Course Aggregate:
   1. Description: Clean, crushed, angular granite, quartzite, or similar durable stone.
   2. Gradation: 1/4" minus with the following sieve analysis:

      Sieve Size	Percent Passing
      3/8" (9.5 mm)	100
      1/4" (6.3 mm)	90-100
      No. 4 (4.75 mm)	75-95
      No. 8 (2.36 mm)	50-80
      No. 16 (1.18 mm)	30-60
      No. 30 (0.6 mm)	20-45
      No. 50 (0.3 mm)	10-30
      No. 100 (0.15 mm)	5-15
      No. 200 (0.075 mm)	0-5

   3. Sand Equivalent: Minimum 35 per ASTM D2419
   4. Color: As selected by Landscape Architect from manufacturer's range.
3. Base Course Material (Optional):
   1. Clean, crushed angular aggregate, 5/8" minus gradation.
   2. Comply with requirements of Section 32 11 23 - Aggregate Base Courses.
4. Mixing Water: Clean, potable, free from contaminants.

PART 3 — EXECUTION

3.1 EXAMINATION

1. Verify that subgrade has been prepared according to specifications with proper drainage and compaction.
2. Verify that aggregate materials meet specification requirements.
3. Do not begin installation until unsatisfactory conditions have been corrected.

3.2 PREPARATION

1. Protect adjacent surfaces, structures, and vegetation from contamination during installation.
2. Prepare subgrade in accordance with Section 31 20 00 - Earth Moving.
3. Ensure proper slope for drainage (minimum 1% cross slope recommended).
4. Install base course material (if specified) to required thickness and compact to 95% Modified Proctor Density per ASTM D1557.

3.3 MIXING

1. Dilute stabilizer binder with clean water at a ratio of 1 part binder to 5 parts water by volume, or as specified by manufacturer based on site conditions.
2. For extremely hot and dry conditions, add 1/2 part extra water to compensate for evaporation.
3. Mix thoroughly until well blended.

3.4 INSTALLATION

1. Place surface course aggregate in loose, uniform layer to achieve a final compacted thickness of 3 inches (75 mm), or as specified in drawings.
2. Moisten aggregate lightly if excessively dry.
3. Work in manageable sections approximately 4 feet long (or 4' x 4' areas).
4. Apply diluted stabilizer binder solution using a pressurized sprayer at a rate sufficient to thoroughly saturate the aggregate without causing runoff.
5. Immediately rake the solution through the full depth of the aggregate layer.
6. Compact surface with a plate vibrator, roller, or by boot-tamping for small areas.
7. Apply an additional coat of stabilizer solution along edges and high-traffic zones.
8. Continue process until entire surface is complete.
9. Final compacted surface shall be smooth, uniform, and tightly bound.

3.5 FIELD QUALITY CONTROL

1. Verify final surface meets ADA accessibility guidelines for firm, stable, slip-resistant surfaces.
2. Check finished grade for compliance with drawings.
3. Ensure proper drainage with no standing water or depressions.

3.6 PROTECTION AND CURING

1. Protect newly installed surface from traffic for a minimum of 24-48 hours, depending on temperature and humidity conditions.
2. Cover surface if rain is forecast within 48 hours of installation.
3. Do not allow heavy traffic until surface has fully cured (typically 3-5 days).

3.7 MAINTENANCE

1. Touch up high-wear areas annually or as needed with diluted stabilizer solution.
2. Remove debris and organic material from surface as needed.
3. Follow manufacturer's recommendations for long-term maintenance.