An investigation of the strength evolution of lime-treated London clay soil

The paper investigates the effect of hydrated lime on shear strength properties and behaviour of London clay, a soil extensively encountered in construction in the London area and the South Eastern England. Unconsolidated Undrained (UU) tests were performed to identify the effect of lime dosage, compaction water content and curing time on the shear strength and stress-strain behaviour of the treated soil. The mineralogical and physicochemical transformations occurring during the curing stage of the soil were also monitored to support the interpretation of the triaxial testing results and verify hypotheses made on the evolution of the chemical reactions and the development of cementation bonds. The results showed that strengths gain was strongly influenced by lime content and the curing period, whereas the compaction water content was less influential. An interesting finding of practical relevance is that the strength evolution is likely to continue over long periods of time and result in very considerable strength gains upon the hardening of pozzolanic reaction products. At the same time, adequate early strength gains and adequate soil treatment can be obtained with reduced use of material consumption, thus further increasing the sustainability of the treatment processes.  The paper has also highlighted the importance for engineering design of considering the brittle stress-strain response of the lime treated soil, and the benefit of using lower amounts of lime to alleviate this undesirable effect. The implications of various aspects of soil brittleness in different situations merit further attention and should be explored via modelling in future work.