Research Of The Properties Of High Performance And Low Density Aerated Concrete

As a kind of porous lightweight materials, aerated concrete, which is widely used in building energy efficiency and reducing loads of structure and so on, has various kinds of excellent properties such as sound insulation,heat insulation,seismic energy absorption and so on. Due to introducing a large volume of air bubbles by Hydrogen peroxide,the compressive strength of aerated concrete is generally lower than normal concrete’s, which limit its application fields. How to improve the compressive strength of aerated concrete has become the mission of research workers.First of all, forming process of high performance and low density aerated concrete is mainly studied in this experiment. Adding a small amount of calcium sulfoaluminate cement and trace amounts of lithium carbonate, at the same time increasing the water temperature, is to shorten the setting time. This method can prevent the collapse of mold.The results show that adding7.5%sulfur aluminate cement mixed with0.03%lithium carbonate can significantly shorten the setting time of aerated concrete. In addition, adjustment of water temperature has great influence on setting time.Then, this experiment mainly studies the methods of improving compressive strength of aerated concrete. We choose two kinds of common mineral admixture, which are Silica fume and fly ash, to research the best mixing ratio by test. In addition, this paper researched the influence of water temperature, age and curing conditions on the compressive strength of aerated concrete.Next, this paper investigates the effects of Hydrogen peroxide in different types on the dry apparent density and compressive strength of aerated concrete. The air-void structures of the aerated concrete are investigated by a reading microscope and image process software. The relationship between the compressive strength and the air-void structures is mainly studied. The results show that the compressive strength of the aerated concrete is highly correlated to the air-avoid structure factors. The models describing the relationship between compressive strength and air-void structure parameters of the aerated concrete are proposed.Last, this paper also investigates the properties of high performance and low density aerated concrete, including dry bulk density, water absorption, moisture and thermal conductivity. Potassium permanganate can significantly increase the amount of foaming. For the aerated concrete of the same density grade, not only compressive strength under the condition of low water to binder ratio is obviously higher, but its thermal conductivity and water absorption properties are also lower.On this basis, an ultra low density of aerated concrete is prepared.