Material: Recycled
Glass
Issue:
Recycled glass aggregate is a relatively new construction material. To promote its use, studies have been conducted
to determine its engineering performance and environmental impact.
The studies suggest that cullet aggregate is strong, clean,
and safe to use. However,
because cullet aggregate remains a relatively unfamiliar material,
safety concerns surrounding the use of “crushed glass” may discourage
its use. These concerns generally
involve the potential for skin cuts and punctures, and exposure to
glass dust during transportation, handling, and placement. In order to ease concerns and to maintain a safe working environment,
information about necessary precautions is needed. Best Practice: The most common health concern regarding the use of
cullet aggregates is the potential for skin cuts or penetration. Workers may come into physical contact with
cullet particles during transportation or placement of the cullet. Experience has shown that cullet 3/4 inch or
smaller presents no greater cut or penetration hazard than fractured
natural aggregates such as crushed rock.
Therefore, the same safety precautions for working with natural
aggregates should also be followed when working with cullet. Exposure to glass dust is another
health concern with cullet aggregate.
Studies have been conducted to determine whether glass dust
contains crystalline silica, a known carcinogen.
These studies have found that glass aggregate dust typically
contains less than 1% crystalline silica by weight and is not considered
hazardous by federal standards. This
places cullet in the category of “nuisance dust” with a Permissible
Exposure Limit (PEL) of 10 mg/m3. Glass cullet dust can be a
skin and eye irritant. Cullet
dust is abrasive due to the high angularity of its particle shapes,
and appears to be more irritating than dust from natural aggregates
or soils. However, experience from construction sites
indicates that cullet dust, and the irritations associated with the
dust, can be easily prevented using simple measures.
For information regarding construction site dust control measures,
refer to the Best Practices Dust Control with Glass Aggregate at Construction Sites
and . Analysis of
Glass Dusts The following safety precautions
are based on the field experience of construction site personnel: Before every construction project, the use of cullet aggregate should
be discussed with the owner, engineers, general contractor, contractor’s
earthwork sub-contractor, labor foremen and laborers. The discussion should include but not be limited to the following
items:
1.
The advantages
and disadvantages of using cullet as a construction aggregate and
the merit of cullet fill. The
awareness of the rationale for using a new construction material at
all levels of the crew tends to mitigate concern, and to facilitate
the cost-effective use of the material. 2.
Proper procedures
for handling, placing and compacting glass. This discussion will allow project team members
and workers to realize that glass aggregate will behave similarly
to a natural aggregate; and, that the cullet aggregate has good workability
in terms of handling and compaction. All personnel should know that
direct skin contact with glass cullet should be avoided. To protect against possible cuts or penetration
injuries, site personnel working with cullet should wear long sleeves,
pants, gloves, work boots, hard-hats, ear protection, and eye protection.
Shirt sleeves and pant legs can be taped for additional protection.
Site personnel should also be instructed not to sit, kneel,
or lay on cullet surfaces, or work surfaces containing cullet. Furthermore, working surfaces should be kept clean of cullet particles
by sweeping. Although all personnel should have
knowledge of dust control measures, responsibilities should be clearly
assigned. Minimizing cullet
dust hazards should begin with a dust control program. As with any aggregate, the need for dust control
is most obvious during dry weather.
Since glass has a specific gravity less than that of natural
aggregate, the fines from cullet aggregate may be more prone to becoming
airborne. On construction sites, cullet dust can be generated
when the cullet is delivered and end-dumped from trucks. Handling and stockpiling of cullet aggregate
on-site can also create a dust cloud.
Site personnel involved in handling or stockpiling cullet should
monitor for potential cullet dusting, and be prepared to implement
dust control measures. Wet
suppression using a garden hose is the most common and effective measure
of dust control. Since cullet aggregates are generally free-draining,
the application of water to cullet generally does not adversely impact
its compaction characteristics. Cullet may draw the attention of curious onlookers or passers-by. For maximum safety, take measures to minimize
public access to areas where cullet is being used or stockpiled. These areas should be surrounded by cautionary
tape, and cullet stockpiles should be placed in low visibility or
minimum access areas. Benefits: Understanding the safety issues
of cullet aggregate and implementing preventative measures will help
create a safe worksite and minimize environmental impact in the site
vicinity. Implementing safety
procedures also reduces injuries and increases productivity. Application Sites: Construction sites Contact: For more information about this Best Practice, contact
CWC, mailto:info@cwc.org. References: Glass
Feedstock Evaluation Project: 1) Environmental
Suitability Evaluation, Rpt GL-93-3; Evaluation of Cullet as a Construction
Aggregate, Rpt GL-93-6, Clean Washington Center, 1994. These reports are available only in hardcopy. Contact CWC. Case Studies for the Use of Post Consumer
Glass as a Construction Aggregate, CWC, 1997. Shin,
C.J., and Sonntag, V., Using
Recovered Glass as Construction Aggregate Feedstock, 1994, Transportation
Research Board, National Research Council, Record No. 1437;
Issue
Date / Update: March
1997
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