Utilization of Unqualified Crushed Rocks for Use as Road Construction Materials

Abstract

Abstract

Crushed rock is an important material for road construction. It is generally a mixture of various grain sizes of limestone obtained from mountain explosion. During the past recent years, the activity of mountain explosion is legally prohibited in many areas by Thai Government laws due to environmental conservation issues. This causes the shortage in supplying the materials for road construction. This problem leads to the study for substitutive materials with environmental friendly concerns. This study aims to propose the possible uses of cement stabilization for improving unqualified crushed rock (i.e., gap-graded crushed rocks). In this study, the gap-graded crushed rocks were sampled from rock crushing plant in Saraburi. It was stabilized using cement. The effect of cement and water causes hydration reaction which results in cementation materials within soilmass. The cementation materials cement particles and dust together resulting in larger grain-sized particles with durable resistance. This improvement process provides the materials good enough for being sub-base and base course for roads.  Experimental results show that physical properties of the untreated soils with appropriate has potentiality for the uses as sub-base and base courses according to the standards of Department of Highways (DOH) of Thailand. Results also show that the unconfined compressive strength (q_u) and soaked California bearing ratio (CBR) was obviously developed with the increased amount of cement.