Study On Anchorage Performance Of Magnesium Phosphate Cement Mortar

Technology of bar planting and anchoring is drilling holes on structures or elements and planting reinforcing steel bars into holes with anchorage agent. The other side of bars can connect with a new element, which transmits the load to the old structures or elements. This simple and high-effective method, with its security and reliability, has being wildly used in reinforcement of constructions, connection of the new and existing elements or between preformed members and so on. Nowadays most of the anchorage agent are organic materials, with good anchorage effect, low fire-resistance and high cost.This thesis aims at the method of bar planting and anchoring, which is using in the world-wild phenomenon renovation and reinforcement and realistically, raises a new anchorage agent named Magnesium Phosphatic Cement(MPC) mortar agent. This early strength agent which offers strength after hardening has suitable fluidity and viscosity, also is fire resistant better than traditional organic materials, consequently the field of bar planting and anchoring can well served by MPC mortar agent.Four experiments of basic performances are goes primarily: flow and expansion ability; setting time; compressive strength and contraction performance. Then I investigated the hole characteristics with methods of MIP and XCT. After that is comparing MPC mortar agent with other anchorage agents and found the suitable anchorage depth to offer foundation in practical use. Then tested the long-term ability of anchorage with cyclic loading. At last, using actual anchoring and drawing method to test MPC mortar agent at a building site to distinguish the differences between actuality and lab.The consequences of experiments of basic performances show that:1. the flow and expansion abilityof MPC mortar agent is fit for both vertical and horizontal holes. 2.The setting time is suitably for anchoring. 3.The compressive strength is high enough and the contraction performance is not good enough. 4.The microcosmic analysis shows that MPC cement has good cementing action between it and aggregates, concrete and steels. Distribution of holes shows has two peaks on curve and the results of method of MIP are more accuracy than method of XCT.Anchoring experiments shows that :1.at the age of 28 days steels can yield by drawing, which can fit the perfect failure mode of anchoring. 2.Comparing with OPC mortar agent, organic agent, inorganic agent and beforehand-planting steel, at the age of 1 day, 3 days and 7 days the anchorage effect of inorganic agent is the best and MPC mortar agent ranks only second to it. But at the age of 28 days, MPC mortar agent became the best one. 3.The suitable anchorage depth of anchoring is 17.5d(diameter of steel bars). 4.The relationship of drawing strength and anchoring depth can be described by quartic polynomial by five items while anchoring depth is lower than 17.5d and constant while it is higher than and equal to 17.5d. This formula can be used in design and checking. 5.MPC mortar agent can not suffer periodic load well in a long run service under the load value is between 1kN and 15 kN when 100 days due to its shrinkage, and drawing strength of 100 days has reduce from the one of 28 days. 6.Experiments in lab have proved that MPC mortar agent is a kind of anchorage agent with good capabilities because 5 of the 6 groups of steels are yield when drawing at the age of 12 days. At last this thesis summarizes the works I have done and gives some suggests that should do further study on modified MPC mortar agent, which can prevent this anchorage agent in a long run service.