The re-use of normally discarded existing pavement material is an attractive concept and an economic proposition. This paper examines the available options for hot in situ recycling, discusses their applicability, recommends differentiation of the options into clearly defined categories, and suggests the adoption of procedures for making fair comparisons between conventional and recycling options.
Die hergebruik van bestaande plaveiselmateriaal wat normaalweg weggegooi word, is 'n aanloklike konsep en 'n ekonomiese voorstel. In hierdie verslag word die beskikbare keuses vir warm in situ hersiklering ondersoek, die toepasbaarheid daarvan bespreek, die differensiëring van die keuses in duidelik afgebakende kategorieë aanbeveel, en die aanvaarding van prosedures vir die uitvoering van billike vergelyking tussen konvensionele en hersikleringskeuses voorgestel.
The value of the coefficient of earth pressure at rest, ko and the stress-strain characteristic of soils at rest condition are important engineering considerations in the solution to problems involving pressure on stiff retaining structures, soil pressure on buried structures, and stability of excavations or settlement of large fills. The lateral soil pressure ring, a new instrument, which allows laboratory determination of the lateral soil pressure response to vertical loading without lateral strain and with limited lateral strain, is introduced in this paper. A series of tests performed on uniform and poorly graded sand specimens is described.
Test results show that ko is affected by the particle size, particle size distribution, stress history, overconsolidation ratio, the level of vertical pressure and the lateral strain. The elastic parameters of the material were also determined using the lateral soil pressure ring. Some comparative triaxial ko tests were performed using Bishop and Henkel's ko belt and it was found that when the vertical stress was low the ring yielded higher ko values and when the vertical pressure increased both methods yielded similar ko values.