Abstract: The engineering properties of newly hydraulic reclamation mud in liquid state are poor. Their bearing capacity is almost zero. After it is improved with vacuum preloading technology (VPT), its soil strength increases only a little and its effective depth is very small. A new idea of vacuum preloading combined with nonpolluting chemical reinforcement technology (VPCT) is proposed. Three kinds of vacuum preloading combined with chemical reinforcement technologies (VPCT1, VPCT2 &VPCT3) and one kind of chemical improvement technology (CT) are compared with VPT in laboratory tests. The test results show that: (1) when the effective chemical agent adding, the deposition of newly hydraulic reclamation mud finishes after a short standing time before vacuum preloading; (2) the effective chemical agent can promote the improvement effect; (3) in macrocosmic aspects, the mud of VPCT3 has uniform improvement, the clay content obviously decreases, the wet density is the biggest, the void ratio obviously decreases, and the unconfined compression strength is the biggest (66.7 kPa) which is 3.5 times that of VPT; (4) in microcosmic aspects, the mud of VPCT3 has the smallest total region (void) area, average perimeter, region(void) number, void ratio, porosity, and has good directionality, intimate contact with mainly surface-to-surface connection, and has most noticeable agglomerate phenomenon. Therefore, comparing with VPT, VPCT3 has the best effect for improving the mud. It is advisable & necessary that VPCT3 is further researched in field trial.

Key words: hydraulic reclamation mud, high clay content, vacuum preloading technology (VPT), chemical reinforcement technology (CT), vacuum preloading combined with chemical reinforcement technology (VPCT)