The Study On Mechanical Properties Of Granulated Blast Furnace Slag As Fine Aggregate Of Concrete

With the economy continues to develop, China’s crude steel production reached 683 million tons at 2011, accounting for 45% of world production. With about 400 kg blast furnace slag produced for each one ton crude steel producing, and thus a year reached 200 million tons production of blast furnace slag which urgently needed treatment and utilization. On one hand,steel slag utilization is relatively low now, resulting in a huge inventory of blast furnace slag,which also occupy a lot of land resources and make pollution to the environment. On another hand, concrete as excellent materials have been greatly used in building and bridge structures.Until now, there is no doubt that no other material can replace the place of concrete. However,on one hand, the current system of concrete need development with the sacrifice of environment for the situation over-exploitation of natural river sand, which already facing a great of shortage. What much serious for environmental protection is continuous mining. On the basis, a method is aimed to find to make a solution of natural sand shortage and excess scrap in iron and steel smelting. Using blast furnace slag after water quenching replaced natural sand as fine aggregate that is called granulated blast furnace slag is an attempt.Analysis is made for aggregate characteristics of granulated blast slag along with investigating of mix design and mechanical strength for granulated blast furnace slag fine aggregate concrete.A more detailed analysis is conducted for granulated blast furnace slag in this paper. First of all, aggregate characteristics of granulated blast furnace slag are discussed. Maintaining a high standard quantity of pore, granulated blast furnace slag has larger water absorption than natural sand found through experiments. Compared with nature sand, it contained a higher crushed indicator for granulated blast furnace slag because of larger internal porosity and more elongated and flaky particles. Its apparent density is fully close to natural sand, which makes granulated blast furnace slag has a better advantage in replacing the natural sand as fine aggregate concrete. During mixing ratio test, it can be found in concrete preparation that slightly more water is needed to achieve the desired slump owning to the larger porosity and water absorption of granulated blast furnace slag aggregate surface. In addition,granulated blast furnace slag has a stronger affinity to superplasticizer. In the case of no changing the amount of water, concrete performance requirements of testing and engineering can be easier to meet with the efficient polycarboxylate superplasticizer taking part in. In terms of the mechanical properties, a distinctive feature of granulated blast furnace slag is that early compressive strength of concrete is slightly lower than the compressive strength of natural sand, and later compressive strength was significantly higher than the compressive strength ofnatural sand concrete. For the strength of growth, it makes no difference in the growth rate of the early strength between granulated blast furnace slag and natural sand, while the growth rate of late strength was significantly higher than natural sand concrete. Blast furnace slag concrete and natural sand concrete keep the same variation in tensile strength and elastic modulus, and the difference is very small.Using granulated blast furnace slag as fine aggregate of concrete project a bold attempt in engineering. With more research on granulated blast furnace slag fine aggregate concrete carried out in the future, granulated blast furnace slag will surely be much deeper and widespread applied in the project.