Specific Gravity is the ratio of the unit weight of solids to the unit weight of water.  Based on several studies, the specific gravity of tire shreds ranges from 1.02 to 1.27.  These values are less than half the specific gravities for other conventional soils.     Absorption capacity is the amount of water absorbed onto the surface of the particles (tire chips).  These values range from 2-4.3%.  Table 1 gives experimental values of the specific gravity and water absorption capacity of different types of tire shreds.

Table 1. Summary of Specific Gravities and Water Absorption Capacity

Tire shred	Specific gravity			Water	Reference
type	Bulk	Saturated surface dry	Apparent	absorption capacity (%)
Glass belted	----	----	1.14	3.8	Humphrey et al. (1992)
Glass belted	0.98	1.02	1.02	4	Manion & Humphrey (1992)
Steel belted	1.06	1.01	1.10	4	Manion & Humphrey (1992)
Mixture	1.06	1.16	1.18	9.5	Bressette (1984)
Mixture (Pine State)	----	----	1.24	2	Humphrey et al. (1992)
Mixture (Palmer)	----	----	1.27	2	Humphrey et al. (1992)
Mixture (Sawyer)	----	----	1.23	4.3	Humphrey et al. (1992)
Mixture	1.01	1.05	1.05	4	Manion & Humphrey (1992)
Mixture	----	0.88 to 1.13	----	----	Ahmed (1993)

Procedures

Specific gravity and absorption capacity are determined using the procedures given by ASTM C 127.  The weight of test samples can be half the value given by the standard because the specific gravity of tire shreds is less than half that of other soils.

Back to Main Engineering Page

Back to Main Materials Page