Norlite Corporation 628 S. Saratoga Street Cohoes, NY 12047 Phone (518) 235-0030 Fax (518) 235-0233 E-mail: farchambault@norliteagg.com
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Norlite Structural Lightweight Fill Soil Fill Applications Engineers Design Table Standard Specification

Soil Fill Applications

Norlite inert aggregate, with a minimum angle of internal friction (O) of 40· and a maximum wet density of 65 PCF (ASTM D 2049) aids Geotechnical engineers in reclaiming land which would otherwise go unused. Norlite is continually being specified for backfill behind retaining walls and bulkheads, pipe covering, footings and subbase for roads and parking lots.

Norlite lightweight structural fill has been successfully placed on several construction sites in the Northeast.

Concrete slab over lightweight fill.

Back fill behind retaining wall.

Subbase under roadway.

Earth Retaining Structures

Problem 1

Low Safety Factor against Deep-Seated Failure

Design of the Capital Center Project in Providence, Rhode Island included a pile-supported 35' high cantilever retaining wall adjacent to the Providence River. The weight of the proposed structure, including the backfill soil, would significantly increase loads on the underlying soft silt. The designers wanted to avoid triggering a deep-seated failure of an old bulkhead along the river bank.

Solution

Engineers specified over 10,000 cubic yards of Norlite Lightweight Aggregate for placement behind the cantilever wall. Because of its light weight, Norlite reduced the loads on the foundation soils and behind the retaining wall, and increased the safety factor against deep-seated failure to acceptable levels.

In another application, 5,500 cubic yards of Norlite maintained stability of an existing bulkhead along Long Wharf in Boston.

Problem 2

Increased Lateral Loads and Overturning Moments

MBTA's renovations to a railway bed in Natick, Massachusetts required increasing the bridge clearance. This would involve raising both abutments and adjacent elevation. The increased lateral loads and overturning moments could have damaged the bridge's old masonry abutments.

Solution

Norlite Lightweight Aggregate was used to both raise the adjoining area to the desired elevation and to replace some of the heavier existing backfill. Because Norlite aggregate is lighter than natural soils, it maintained the same lateral loads and overturning moments behind the abutments.

Soft Ground Improvements

Problem 1

Excessive Differential Settlements

The underlying soils at the Vermont Cheese Factory warehouse in Hinesburg, Vermont consisted of soft clay and peat. Engineers wanted to avoid structurally damaging differential settlements between the existing warehouse and a proposed new addition

Solution

Several feet of existing soft soils were replaced with Norlite Lightweight Aggregate.  Because the aggregate weighs only half as much as the existing soil, Norlite reduced the total foundation load of the new structure and kept differential settlements well within tolerable limits.

Engineers have used Norlite in soil replacement techniques for many years on a variety of structures, including the Massachusetts Institute of Technology Arts and Media Facility

Problem 2

Potential Settlements, Pipe Damage

A 12" utility line in the town of New London, Connecticut had to be placed across a swampy, two-acre site. Settlement in the soft organic soils induced by the trench backfill could damage the pipe.

Solution

Norlite Lightweight Aggregate was used to solve several problems.   The aggregate limited the amount of ground settlement to levels that the utility line could safely tolerate and its light weight reduced loads on the pipe.  In addition, the aggregate's thermal insulating properties provided protection from freezing.

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Engineers Design Table

Norlite Lightweight Fill and Ordinary Granular Fill
Range of Unit Weights for Dry and Submersed Conditions

NOTES: Multiply pcf by 0.157 to obtain kN/m³
a) "Loose" indicates minimum dry unit weight from ASTM D2049, and "Compacted" indicates maximum dry unit weight from the Standard Compaction Test, ASTM D698.

d) Certified test reports available.

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The following is a standard specification which has been used or incorporated in a number of job specifications.

Materials
Lightweight aggregate fill shall be Norlite or approved rotary kiln substitute meeting the requirements of ASTM C-330. No by-product slags, cinders or by-products of coal combustion shall be permitted. Lightweight aggregate shall have a proven record of durability, as determined by ASTM C-88 and ASTM C-131, and be non-corrosive, as determined by CAL DOT 422 with the following physical properties:

1. Delivered Gradation:

   Sieve Size	% Passing
   1"   (25.0mm)	100
   3/4" (19.0mm)	90 - 100
   3/8" (9.5mm)	10 - 50
   #4   (4.75mm)	0 - 15

2. The dry loose density shall be less than 50 pcf (801 kg/m³).
3. The maximum in situ density (moist, surface dry) shall be less than 60 pcf (961 kg/m³). The minimum compacted dry density shall be equal to 65% relative density as determined by ASTM D-4253 and D-4254, or as otherwise specified by the engineer.
4. The maximum soundness loss when tested with 5 cycles of magnesium sulfate shall be 10% (ASTM C-88).
5. The maximum chloride content (CAL DOT 422) shall be 100 ppm.
6. The minimum strength of loosely placed material, as determined from drained triaxial tests, shall equal that of cohesionless soil with an angle of internal friction of 36º. Minimum strength of material compacted to 65% relative density shall equal that of a cohesionless soil with an angle of internal friction of 40º.

Method of Construction
Lightweight fill can be placed in approximately uniform layers not to exceed 12 inches loose thickness. Each layer shall be compacted using vibratory compaction equipment weighing not more than 12 tons static weight. The actual lift thickness, exact number of passes, and need for vibrating the roller will be determined by the engineer, depending on the project requirements (i.e., strength, compressibility, unit weight) and equipment used. The contractor shall take all necessary precautions during construction activities in operations on or adjacent to the lightweight fill to ensure that the material is not over-compacted. Construction equipment, other than for compaction, shall not operate on the exposed lightweight fill.

Measurement
Lightweight Fill shall be measured by the cubic yard complete in place. Measurement for payment shall occur following completion of all excavation as approved by the Engineer but prior to placement of Lightweight Fill. Payment
The work under this item will be paid for by the cubic yard at the unit price designated as "Lightweight Fill" listed in the proposal. This price and payment shall be full compensation for all labor, materials and equipment required to complete the work.

NOTE: Lightweight aggregate is sold by the ton, supplier should be contacted regarding conversion from tons to yards.

Material Properties of Norlite Lightweight Aggregate