The Research And Application Of Using Mineral Admixtures To Inhibit The Creep Of Bridge Concrete

Since the reform and opening-up, the public transportation in our country had the enterprise vigorous development and the growing surge in traffic. However, some important highway bridges have premature aging and low service life of bridge due to excessive load and environmental corrosion. Bridge premature performance degradation is mainly composed of load fatigue, and the roles of environmental corrosion and cause the loss of prestress concrete creep than design value of multiple factors, among them, the creep is largely accelerated the degradation process of prestressed concrete bridges.With the continuous development of concrete technology, the application of mineral admixtures in cement base material has a great progress, and its applied varieties and content has increased much, which purpose is not only confined to save cement dosage and utilization of waste, more focusing on improving the various performance of concrete. Granulated blast furnace slag has a certain activity, and part of ground slag in concrete will produce pozzolanic effect and occurs secondary hydration reaction with the density, filling effect, and it is helpful to improve the strength of concrete, improve its durability.This research topic is to Qinhuangdao regions(G102) Qing Long He bridge maintenance renovation project for actual engineering background. To research the effect of ground slag on the properties of concrete creep, this study tested the creep of different ground slag dosage(15%, 30%, 45% and 30%) concrete and concrete without ground slag benchmark in the environment of(20±1)℃ and relative humidity of(60±5)% under the load level of 40%. At the same time, to explore the influence mechanism of the technology, applying the nano indentation test the elastic modulus of cement and ground slag particles and scanning electron microscopy(SEM) observation of ground slag particles under different dosage and the combination of the matrix. The test results show that the ground slag can have significant inhibition on concrete creep. When slag content is lower than 30%, its ability to inhibit the concrete creep increase with the increase of dosage, and the concrete creep degree of 360 d is only 80.1% and 70.6% of the baseline group; When the dosage of slag is higher than 30%, its ability to inhibit the concrete creep weakened with the increase of the content, and the degree of creep is 81.2% and 86.2% of the baseline group. At the same time, combining the concrete creep tests of the actual project, the concrete creep of 7 d and 28 d age of mixed with 20% ground slag 180 d was significantly less than the benchmark concrete creep degree, and the degree of creep to reduce quantity of up to 40%. The creep of concrete used in practical engineering prestressed bridge had been controlled by the groud slag, verifying the feasibility of the use of reasonable dosage of fine grinding slag effectively reducing the prestressed concrete bridge creep.