Reasearch On The Preparation And Properties Of Alkali Slag Foamed Concrete

Slag cementitious material is a low-carbon,environmentally friendly,energy-saving and green building material.The preparation of it into alkali slag foamed concrete insulation material can provide a new type of energy-saving material for national building energy conservation and can further expand the application range of alkali slag cementitious materials.Existing reports mostly use physical foaming methods to prepare alkali slag foamed concrete,and there are a few reports on the preparation of chemical foaming alkali slag foamed concrete.The main purpose of this paper is to prepare chemically foamed alkali slag foamed concrete with a dry density of 250kg/m~3.The effects of different foam stabilizers,water-binder ratio,alkali equivalent and other basic ratio parameters on the basic physical and mechanical properties of alkali slag foam concrete were studied;In order to solve the cracking phenomenon during the drying process of foamed concrete and improve the performance of foamed concrete,the influence of polymer fiber on the basic properites of alkali-slag foamed concrete was studied.On this basis,the influence of the the basic ratio parameters on the water absorption rate of the alkali slag foam concrete mixed with polymer fiber was studied.The main findings were as follows:(1)Although the foam stabilizer with vegetable protein alone could prepare the alkali slag foamed concrete with a dry density that meets the requirements,its 28d compressive strength was too low,indicating that the foam stabilizer has poor compatibility with the slag.When only calcium stearate foam stabilizer was added,the28d compressive strength of foam concrete is higher,but at the same time its dry density was too large.When self-made foam stabilizer,silicone amide,tea saponin were mixed alone,the dry density of alkali slag foam concrete met the requirements.(2)Combine calcium stearate with self-made foam stabilizer,silicone amide and tea saponin in two combinations.The test results showed that when calcium stearate was compounded with silicone amide or self-made foam stabilizer,the foamed concrete had a higher 28d compressive strength and a higher dry density;when calcium stearate was mixed with tea saponin,the dry density of the foamed concrete met the requirements,and the compressive strength was better than that when the tea saponin was added alone.The best combined dosage was that 6‰calcium stearate and 1‰tea saponin.At this time,the 28d compressive strength of foamed concrete was 0.21 MPa and the dry density was251 kg/m~3.(3)As the alkali equivalent increaseed,the dry density of the foamed concrete decreased,and the 28d compressive strength increased;with the increase of the foaming agent aluminum powder content,the 28d compressive strength of the foamed concrete decreased.(4)Incorporating polymer fibers could delay the cracking of the alkali slag foamed concrete during drying to a certain extent,but it would reduce the fluidity of the alkali slag foamed concrete slurry and increase its dry density.Compared with PVA fiber,PP fiber was more beneficial to the 28d compressive strength of foamed concrete.As the length of the fiber decreased and the volumetric content decreased,the strength of the foamed concrete increased.When blended with 0.6 kg/m~3 PP fiber with a length of 9 mm,the 28d compressive strength of the alkali slag foamed concrete was 0.34 MPa and the dry density is 268 kg/m~3.(5)Compared with other combinations of foam stabilizers,when the content of calcium stearate was 6‰and the content of tea saponin was 1‰,the water absorption rate of polymer fiber foam concrete was reduced to the lowest,which was 96.3%;As the ratio,alkali equivalent,and aluminum powder content increased,the water absorption rate of polymer fiber foamed concrete increased.