Study On The Frost Resistance Of Silica Fume To Mixed Fiber Concrete

Concrete is an important building and civil engineering material that is widely used in all aspects of modern urbanisation related projects,but as the complexity of modern projects continues to increase,the performance of traditional silicate concrete struggles to meet the relevant needs.Silica fume as a reinforcing material can effectively improve the strength,frost resistance,compactness,erosion resistance and other related properties of concrete,mainly because silica fume can react with the calcium-water compound in cement to produce a new calcium-silica hydrate cementitious substance,which can improve the porosity and chemical composition of concrete,thus enhancing the mechanical properties of concrete;at the same time,silica fume is an environmentally friendly material Silica fume is an environmentally friendly material,with low environmental pollution and low energy consumption,and it is recyclable when used to strengthen concrete materials,so that it can be recycled and reused at the end of a building’s life.Due to these advantages,silica fume is widely used in the production of high performance concrete.However,silica fume concrete has characteristics such as fast early hydration rate,and is prone to excessive cracking and other problems in cold area projects.Adding fibers can improve its toughening and cracking resistance,so this experiment chose mixed fiber modified silica fume concrete,adding mixed fibers with different contents of silica fume in the concrete,testing the basic mechanical properties and freeze-thaw resistance of mixed fiber concrete with different amounts of silica fume admixture,and conducting freeze-thaw The simulations were carried out as follows.(1)To carry out unconfined compressive test,splitting tensile test and flexural test for mixed fiber concrete with silica fume admixtures of 0%,3%,6%,9% and 12%,to obtain their unconfined compressive strength,splitting tensile strength and flexural strength,to propose a prediction model for the relevant strengths,and to analyse the activation interval of silica fume reinforced mixed fiber concrete and to derive the relevant optimum reinforcement admixture of silica fume.(2)Freeze-thaw cycle tests were carried out on mixed fiber concrete with silica fume admixtures of 0%,3%,6%,9% and 12%,and the relevant mechanical properties of mixed fiber concrete with different silica fume admixtures were tested after 50,100,150 and 200 freeze-thaw cycles.(3)The temperature field model of prismatic body under freeze-thaw environment was established by ABAQUS finite element software,and the temperature change cloud and temperature change curve were analysed to complete the numerical simulation of thermal stress field;the number of freeze-thaw cycles was used as the variable to analyse the thermal stress and thermal strain cloud;the numerical simulation of cube loading test under freeze-thaw environment was completed and compared with the test results.