Cement Deep mixing method applied in Lowland areas, is mostly set to a value of water-cement ratio equal to one (W/C =
1.0). Also, W/C is determined based on empirical experience so far, and Engineers seem reluctant to increase the amount of water
(W/C > 1). They have concerns over the possibility of insufficient mechanical strength of improved soil columns due to the amount of
water. So, based on X-ray fluorescence data analysis instrument, our research is dealing with the evaluation of the chemical
composition of elements responsible for soil-cement hardening on six specimens with parameters such as W/C ratio, the amount of
cement C, the curing, and the mixing times. Then, the main components identified and quantified that interest us are silicon dioxide,
calcium oxide, alumina, iron oxide and magnesium oxide. Especially about the amount of silica and calcium oxide which most
influence the hardening process of the soil cement, we have the uniform tendencies of its percentage for W/C = 1.5 after 10min of
mixing time and when the curing time becomes important (28 days). Then, combined with the strength 𝑞 distribution at 100 different
points of each specimen, taken by needle penetration, the one with W/C = 1.5 and C = 110 kg/m3 is more uniform than the others.
Finally, W/C = 1.0 is not the most effective ground improvement specification to consider when performing deep mixing treatment
on cohesive soft soil such as Ariake clay.

physico-chemical evaluation, soil-cement, Ariake clay, X-ray fluorescence, W/C