Abstract:
The aims of this research was to investigate the relationships of laboratory test results of soils mixed cement for using as a subgrade material. Four types of testing ware conducted, comprised of unconfined compression test, soaked CBR test, third point loading test, and plate bearing test. The soil samples were derived from three different sources: 1) a laterite soil from Ban Pong District, Ratchaburi Province, 2) a sand from Kamphaeng Saen District, Nakhon Pathom Province, and 3) a clay from Meuang District, Samut Sakhon Province. The cement used was Portland Cement Type I.
The soil sample mixed with cement ware compacted into the molds by the method of Modified Proctor Test. The quantity of water mixed in the soil sample during compaction was adjusted to the optimum moisture content. The four types of molds were used, comprised of 1) a cylinder mold (diameter 3.5 cm; height 7.00 cm) for the unconfined compression test, 2) a cylinder mold (diameter 15.10 cm; height of 17.7 cm) for the soaked CBR test, 3) a beam mold (size 7.5x7.5x35 cm3,and 4) a box mold (size 150x150x1 5 cm3)for the plate bearing test. The curing period was 28 days.
The results, revealed that the increasing of cement being mixed could significantly increase the values of the soaked CBR, the undrained shear strength, the modulus of rupture, and the modulus of subgrade, The relationships of these testing results have been demonstrated.