The Research On Preparation And Application Of Lightweight Aggregate Concrete

It is well known, the wall is one of the most important components of all buildings,whose structure and material determine its thermal performance and finally affect the energy consumption and living comfort of the buildings. However, all those performance is based on the insulation materials stuffed in the walls. Lightweight aggregate concrete, due to its good performance of small thermal conductivity, bulk density, high refractoriness, and so on,is considered to be the ideal wall materials Moreover, Lightweight aggregate concrete wall panels can be widely used for its good performance and low cost.In this thesis, lightweight aggregate concrete was prepared with shale ceramsite as lightweight aggregate which was produced from a slate mine in Yiyang, Hunan province. As the concrete panel has no exorbitant request for its strength(≥3.5MPa), it can be mixed with a certain amount of mineral admixtures and foamers, which not only reduced the cost, but also reduced the bulk density and thermal conductivityFirstly, this thesis analyzes the probability that three types of slate powder were used as mineral admixtures. The best cementitious materials ratio was determined by orthogonal design method. Then, hydrogen peroxide and FA-1cement foam as foamers were blended into cementitious materials to prepare a series of lightweight aggregate porous concretes. And their density, compressive strength, and thermal conductivity coefficient were tested. Too much foam leads to the poor strength property of lightweight aggregate porous concrete. Polypropylene fiber was mixed into the lightweight aggregate porous concrete to enhance its strength when the amount of hydrogen peroxide is27.2kg/m3. The main conclusions are as flows:1.The flexural strength and compressive strength of gel sand test blocks decreases with the increasing of mixing amount of raw slate powder, burnt slate powder or expanded slate powder. The descending order of pozzolantic activity of the three types of slate powder is burnt slate powder,raw slate powder,expanded slate powder. According to the corresponding standard,the burnt slate powder and raw slate powder can be used as mineral admixtures2.The best cementitious pastes ratio is cement:fly ash:raw slate powder:burnt slate powder:water=0.75:0.07:0.07:0.11:0.42by weight3.The bulk density of concrete, compressive strength and thermal conductivity coefficient decreases with the increasing of dosage of hydrogen peroxide or foam which made form FA-1foaming agent. The maximum amount of hydrogen peroxide in the present experimental conditions is26.6kg/m3, at the point of which the concrete dry apparent density, the compressive strength and thermal conductivity coefficient are912kg/m3,8.9MPa,0.205W/(m·K), respectively. When the foam dosage is22.1kg/m3, its dry apparent density, compressive strength and thermal conductivity coefficient are829kg/m3,4.4MPa,0.189W/(m·K). While the foam dosage reaches24.2kg/m3, the compressive strength is2.1MPa, failed to exceed3.5MPa4.The most appropriate amount of polypropylene fiber was0.2percent of cement by weight, at the point of which its compressive strength improved6.8percent and flexural strength improved13percent.