The Study Micromechanism And Mechanical Properties Of Cement Clays Strengthened By Rock Powder

A large number of stone machining enterprises distributed in Fujian provincesuch as Quanzhou and Xiamen, great quantity of rock powder produced in the processof stone machining which cause serious pollution to local environment when stackedat will. In this paper, rock powder is taken as additive agent to improve the strength ofcement-soil. The purpose of the study is to provide a new way to dispose rock powderand a new way to improve the strength of cement-soil. At first, this paper analysis thebasic physical properties of rock powder, Then, with regard to littoral mud, theinfluence of rock powder content, cement type and content, curing time and totalwater volume on the strength of cemented rock powder solidified soil is studiedthrough unconfined compressive strength tests, meanwhile, putting forward linersuperposition analysis method.After that, mix a certain amount of gypsum on the baseof strength improvement to study the further enhance effect of gypsum on cementedrock powder solidified soil. Next, observe the microscopic structure of cemented rockpowder solidified soil by scanning electron microscope aiming at revealing itsmicroscopic mechanism. Finally comparison analysis of mechanics performance ofcemented-soil mixed with rock powder and without rock powder.Study results show that the rock powder as the additive agent could significantlyincrease the strength of cemented-soil, the strength of the cemented rock powdersolidified soil overall showed a trend of increase under the different dosage of cement.For325composite Portland early strength cement, the strength of cemented-soilcould improve0.86~1.01MPa after28days of curing and0.25~1.25MPa after90days of curing; For425ordinary Portland cement, rock powder show little effectunder cement dosage of10%and15%and improve somewhat under cement dosageof20%after28days of curing, when curing time reach90days, the maximumstrength could increased by0.22MPa to1.29MPa. Gypsum has further strengtheneffect on the strength of cemented rock powder, but it is difficult to determine theoptimal proportion which is greatly influenced by the types and dosage of cement, rock powder content and curing time. Comparative analysis of mechanicsperformance of cemented-soil mixed with rock powder and without rock powdershows that, rock powder can improve compaction degree of cemented-soil andoptimize its mechanical properties, also, it reduce the compressibility and improvecohesive c, the increase amplitude increce along with the increase of cement content,however, rock powder could not increce the friction Angle, even slightly reduced.Rock powder increce the strength mainly reflects on aspects of grading effect, microaggregate filling effect, crystal nucleus effect and frame effect. Rock powdersomehow optimizes pore structure of cemented-soil and makes cemented-soil denser,it also promotes the cement hydration and induces crystallization of hydrates, strongspace frame formed because of increced hydration products on the surface of thespecimen...