COMPARISON OF THE PENETRABILITY OF SMOOTH AND CRUSHED SAND BY SUBTERRANEAN TERMITES (ISOPTERA, RHINOTERMITIDAE)

A natural beach sand with smooth rounded particles and a crushed limes tone sand with angular particles were evaluated to test the effect of particle shape on the particle size limits for termite barriers. For b oth materials, four sieve fractions were impenetrable: Mesh 8, 10, 12, and 14 (2.8 to 2.36, 2.36 to 2.0, 2.0 to 1.7, and 1.7 to 1.4 mm respe ctively). The tested sieve fractions on the margins of this range (Mes h 7+8, 2.36 to 3.35 mm; and Mesh 16, 1.18 to 1.4 mm) were partially pe netrated at a slow rate or not penetrated depending on particle shape. There were significant differences in the depth of penetration for th ese marginal sieve fractions for the smooth and crushed materials. The smooth sand was less deeply penetrated than the crushed angular sand in the Mesh 7+8 (2.36 to 3.35 mm) sieve fraction. Conversely, the crus hed sand was less deeply penetrated than the smooth sand in the Mesh 1 6 (1.18 to 1.4 mm) sieve fraction. Thus the effective particle size ra nge appears to be shifted toward slightly larger particles for smooth rounded aggregate, This could be an important consideration for aggreg ate producers who want to develop a termite barrier product by sieving natural alluvial deposits.