Preparation And Properties Of Alkali-activated Slag Foamed Concrete

The alkali-activated slag cementing material has high strength,low hydration heat,fast hydration speed,and excellent durability.In this paper,the slag is used as the base material to develop the alkali-activated slag foamed concrete to overcome the problems such as the inability of both light and high strength and the large dry shrinkage.In this paper,the experiment starts from two aspects of optimizing the cementitious materials and the pores.Firstly,the new excitation agent is used for excitation,which effectively improves the strength of the cementitious materials.Based on this cementitious material,foamed concrete is introduced by means of physical foaming.The effects of water-cement ratio,foam content and foam stabilizer content on the performance,strength and pore structure of alkali-activated slag foamed concrete were studied systematically by single factor experiment and orthogonal design experiment,and the alkali activated slag foam concrete with high strength is obtained.Finally,on this basis,study the effects of fiber and little-weight aggregate on strengthening,toughening and shrinkage of fomed concrete.The results show that:(1)The alkali slag cementitious material with good performance can be obtained by using the new activator.The ASJ activator used in this paper has better excitation effect than the traditional activator,Na OH and water glass.Its 28-day compressive strength is 48.6MPa and its flexural strength is 11.6MPa.(2)The water cement ratio,the amount of foam and the amount of stabilizer affect the structure of alkali-activated slag foamed concrete,and then affect the performance of concrete.The effect of water-cement ratio and foam content is the most obvious.With the increase of the two,porosity,average pore diameter and roundness of holes increase,and dry density and strength decrease correspondingly.By optimizing the composition,the foamed concrete was obtained,which dry density is 542kg/m3,fluidity is 179 mm,flexural strength is 0.570 MPa and 28 d compressive strength is 3.92 MPa.(3)The properties of alkali-activated slag foamed concrete can be improved by fiber and lightweight aggregate.On the premise that the fluidity,water content and dry density of alkali-activated slag foam concrete have not been greatly affected,basalt fiber has the best reinforcing effect,which can increase the compressive strength by 17% and the compressive strength by 180%.PVA and wood powder can increase compressive strength by 16% and flexural strength by 46%.PVA and wood powder have a good effect on reducing shrinkage and can reduce the dry shrinkage rate by about 50%.The effect on reducing shrinkage of basalt is slightly weaker,but also can reduce the dry shrinkage rate by 43%.The toughening effects of basalt fiber,wood powder and PVA are also significant,and the toughening effects can reach 641%,252% and 98% respectively.