Study On Concrete Mixing Lithium Slag With Other Mineral Admixtures

It is one of the requirements of preparing the high-performance concrete to mix with active mineral admixture.To mix in the concrete with the mineral powder does not only have better economic benefits,but also can improve the workability,mechanical properties and durability of the concrete.Mineral admixture is indispensable component of the high-performance concrete.Fly ash,granulated blast furnace slay and silica fume are commonly used as the mineral admixture in China,and have been already widely applied in concrete.How to fully utilize the waste residue,waste material has become the problem to be solved urgently at present in order to expand source of mineral admixture in the concrete.This subject regards super fine lithium slag as the main mineral and adopt the technology of "double-mixing" to study the workability,mechanical properties and durability(anti-Cl^--permeability,anti-carbonization) of the concrete mixing lithium slag only(LC),mixing lithium slag and silica fume(LSC),mixing lithium slag and fly ash (LFC),mixing lithium slag and slag.Results and conclusion of this thesis are as follows:â‘ The lithium slag is a kind of mineral admixture with higher potential pozzolanic activity and has good grindability.Modifying the surface of the powder through fine-grinding can increase its activity.Original state lithium slag can be made to super fine powder with specific surface area up to 14000 cm²/g after grinding for 34min. Mixing it into concrete can obviously improve the workability of the concrete.But the specific surface area of the lithium slag increases slowly at the later stage of grinding, so it is inadvisable to simplely increase grinding time and mixing the lithium slag ground for 34min is advised while preparing concrete.The mixing amount of glued material is between 650 kg/m³ with 600kg/m³ in the concrete;â‘¡Mixing super fine lithium slag can produce the concrete with good workability. The optimum single-mix amount in the concrete is 15%.With fixing the mix amount of lithium slag to 15%,the optimum double-mix amount of microsilica,fly ash and slag are 5%,30%and 25%respectly.â‘¢With mixing lithium slag only,the 3d strenth of concrete reduces with increase of mix amount gradually,but decreasing amplitude is not obvious.When the mix amount is less than 15%,the initial strength and later strength are superior than that of the blank concrete.From the compressive strengths of the concrete in different age,the optimum mix amount of lithium slag in concrete is 15%.With the optimum mix amount, the strength at every age is superior than that of the blank concrete besides initial 3d strength.â‘£Microsilica has obvious enhancement effect,and mixing it with the lithium slag can get good compound effect.With fixing the amount of super fine lithium slag to 15%, the optimum double-mix amount of microsilica is 5%.The increase of compressive strength in 3d,28d and 90d of the concrete double-mixing with microsilaca is more abvious than that of the concrete single-mixing with lithium slag.Mixing lithium slag with fly ash or slag can also get good compound effect.When fixing the amount of super-fine lithium slag to 15%,the optimum double-mix amounts of fly ash and slag are 20%and 15%respectly.In the respect of later strength,the concrete doubel-mixing is superior than the concrete single-mixing lithium slag;⑤From the results of SEM and XRD,it was found that after mixing mineral admixtures such as lithium slag,etc.,the amount of C-S-H gel increased in the concrete, the amount of Ca(OH)₂ reduced,and grain refinement took place.Meanwhile,because of the compact stacking interaction of the lithium slag and other mineral admixtures,the density of the concrete can be improved and the strength of the conrete can increase;â‘¥The ability to resist chloride ion penetration of concrete can be improved effectively by mixing super-fine lithium slag powder.Double-mixing lithium slag and microsilica can improve the ability to resist chloride ion penetration of the concrete by a wide margin,and the amplitude of the chloride diffusion coeddicient is more than 60%. The ability to resist chloride ion penetration of the concrete double-mixing with fly ash and slag respectly can also be improved effectively in 56d;⑦No carbonization took place in 56d concrete single-mixing with super-fine lithium slag.The amount of glued material has little effect on carbonization of concrete. With the amount of lithium slag fixed to 15%,no carbonization took place in the 56d concrete double-mixing with microsilica.