Research On The Application Of Ultra-fine Limestone Powder In RPC

RPC is a kind of high performance concrete material, with high mechanical properties, excellent durability and toughness, good economy and friendly environment.but the large dosage of cement in the RPC makes it uneconomical and useless to the strength of RPC. A lot of unhydrated cement particles exists in the hardening structure,which is a waste to resources.it is a potential trouble for stability of volume. Therefore, looking for a cheap mineral fine powder to replace the RPC component and establish a low-cost and simple-process production line is still our aim. The limestone powder has lower surface energy, and good dispersion. so, the addition of limestone powder can reduce the viscosity of reactive powder concrete and change the physical properties of RPC with high dosage of cement. The preparation process requirement too high, because of high viscosity of RPC, but the use of Limestone powder in RPC with a lot of mineral powder can effectively solve a technical problems.which also provides a technology selection to reduce the mixture viscosity for the mass production of RPC with a lot of mineral powder. other admixtures haven't this characteristics. What's more, RPC has very low water/cement ratio, and their quantity demand of highly active components in gelled material is limited.those characteristics provide technical feasibility for the application of limestone powder.Through the optimization of reactive powder concrete mixing proportion,This topic study the performance of RPC,because ultra-fine limestone powder replace gelled material(cement, silica fume) and the fine aggregate(quartz powder), it also Study the microscopic structure and interface properties of ultra-fine limestone powder RPC, and analyse the relationship between pore structure and strength of the ultra-fine limestone powder RPC. Experiments show that the optimum mixture ratio is cement, silica fume, quartz sand, quartz powder = 1:0. 25:1. 1:0. 37. The mixed ultra-fine limestone powder can effectively improve the performance of mixture. when using 400 mesh of limestone powder completely to replace quartz powder(replace rate 100%), 1250 mesh limestone powder to replace 15% gelled material(cement, silica fume), In the standard curing condition, the 28days' flexural strength and compressive strength are 20.1 MPa, and 107.7 MPa. In 90 ? hot water curing condition, the 28days' flexural strength and compressive strength are 27.2Mpa and 136 Mpa. The use of ultra-fine limestone powder not only greatly reduces the production cost of RPC, improves the economic benefit, but also play a positiverole in environmental protection. The cost of 1 m3 ultra-fine limestone powder RPC will reduce 146 yuan.After mixing with ultra-fine limestone powder, natural gas hydrates of RPC distribute more uniformly and more densely. The ultra-fine limestone powder within the RPC accelerate the process of cement hydration reaction, provides plenty of space for for the C- S – H gel, improve the uniformity of the distribution of hydration products, and improve the interface area performance of Fine quartz sand aggregate and cement, which make the hydration gel product tightly bonding. Ultra-fine limestone powder desalt the Interfacial transition zone between aggregate with cement paste and improve Compactness and structural compactness of Cement interface area. what's more, mixing ultra-fine limestone powder improve the internal pore structure of RPC, refine the aperture and make RPC structure more compact.