The use of lime-treated British clays in pavement construction. Part 2: The effect of mellowing on the stabilization process

The USA field experiences in the 1960s with lime treatment of marginal materials for pavement layers resulted in the introduction of a ‘mellowing’ period of between 24 and 72 hours, after mixing and prior to final compaction. This period facilitates reaction between the soil and the lime so that pulverization criteria and compact-ability can be achieved. As a result of these early experiences, the ‘mellowing’ period has become an integral part of specifications for lime-treatment processes used globally but it has been based on limited scientific justification. Under the Department of Transport (DoT) Specification for Highway Works (1991 and 1993 amendments) a ‘mellowing’ period of between 24 and 72 hours is mandatory. This period of mellowing is also recommended in volume 4 of the Design Manual for Roads and Bridges HA/74/95.1 Part 1 of this paper,2 also presented in Transport, discussed results of a research programme that investigated the effect of mellowing on the modification process of four British ...