The study was carried out to investigate the changes of retained strength and reaction products in the CO₂ sands obtained are as follows. 1) Higher mole-ratio sodium silicates have the lower retained compression strength. 2) Organic liquid additives make a notable decrease in the retained strength and, in case of when use the 2.7 mole-ratio sodium sillicate, the effect is remarkable at the range of temperature to 600℃. 3) Sodium silicate binder forms silica gel with very high bonding force, accompaning an exothemic reaction at the temperatures of around 200℃, and dehydrated brittle silica gel and hydrated sodium silicate glass with sands transformed at the temperature of ahout 600℃. 4) It forms dehydrated glass with sintering of the sand gain surfaces, at the temperatures of around 800℃ and has a value of high retatined strength. 5) The decreases in the retaired strength of CO₂sands are accelerated with the lots of defects resulted from the porosity and cracks in sodium silicate bond films which are caused by the evaporation or combustion of the organic additives.