Experimental Research On Durability Of Surface Strengthening Materials Applied In Existing Concrete Structure

With the rapid development of infrastructure construction, reinforced concrete structure has been widely used in bridge engineering, water conservancy and hydropower engineering, port channel and coastal engineering, etc.. But the durability of reinforced concrete structures is becoming more and more prominent in the hydraulic environment. On the one hand, due to the high-speed sediment flow, the concrete surface will suffer from serious abrasion, resulting in decrease of steel bar protection layer. On the other hand, due to the erosion of chloride in water, the corrosion of rebar in concrete occurs easily, resulting in the cracking and spalling of the concrete structure. If the reinforced concrete structure is not timely repaired, a vicious circle will greatly reduce the capacity and service life.To analyze the durability of polyurea elastomers, acrylic mortar and epoxy mortar, the tests for resistance to abrasion, carbonation and migration of chlorides were conducted. And the durability of acrylic-modified mortar with cement replacements of slag and fly ash at the level of 36% was also studied. At last, the feasibility of modified acrylic emulsion mortar was verified by a practical engineering example. The conclusions of this thesis are as follows:(1) Compared with acrylic mortar and epoxy mortar, polyurea elastomers has a far superior resistance to abrasion, carbonation and migration of chlorides.(2) With the increase of cement replacement of slag, the compressive strength, flexural strength and abrasion resistance of acrylic-modified mortar are all increased firstly and then decreased, and the optimum content of slag ranges from 6% to 12%. The abrasion resistance of acrylic-modified mortar with cement replacement up to 9% increased by 18%. With the increase of slag content, the chloride ion permeability coefficient of acrylic-modified mortar is decreased firstly and then increased, and the chloride ion permeability coefficient can be reduced by 59% at 36% content of slag.(3) With the increase of cement replacement of fly ash, the compressive strength, flexural strength, adhesive strength and carbonation resistance of acrylic-modified mortar are linearly decreased, and abrasion resistance is firstly increased and then decreased. The abrasion resistance of acrylic-modified mortar with cement replacement up to 6% increased by 12% approximately. The chloride ion permeability coefficient of acrylic-modified mortar is first decreased and then increased, and the optimal content of fly ash should be under 18%.(4) At the same content, the durability of slag acrylic-modified mortar is better than fly ash acrylic-modified mortar. According to engineering requirements, the better mechanical properties and abrasion resistance of acrylic-modified can be acquired when the content of slag is range from 6% to 12%, and the better resistance to chloride ion penetration can be acquired when the content of slag is 36%.