Study On Preparation Technology Of Cement-based And Phosphogypsum-based Foam Materials

With the rapid development of our country's economy and the improvement of people's material living standards,urbanization has become an inevitable trend.Nearly70%of our country's house building materials are wall materials,and the traditional"Qin brick and Han tile"model of wall materials is not suitable for the development needs of today's society because of its high energy consumption,environmental pollution,and waste of land.Actively developing and applying new wall materials is of great significance in promoting my country's urbanization.Cement-based and phosphor-gypsum-based foam material is a light-weight porous material foamed in cement or phosphor-gypsum slurry by physical or chemical methods,coagulated and hardened.Due to its unique porous structure,the material is endowed with the characteristics of light weight,heat preservation,heat insulation,sound insulation,fire prevention and earthquake resistance.Applying cement-based and phosphor-gypsum-based foam materials to wall materials can significantly improve building functions,improve living comfort,save energy and reduce emissions,and has good social and economic benefits.It is an ideal material to replace traditional wall materials.This article takes the preparation of dry density 700 foam material as the research goal,and systematically studies the commonness and difference of cement-based and phosphor-gypsum-based foam materials from laboratory preparation to industrial preparation.The main conclusions are as follows:(1)The moldability of cement-based foam materials is studied by changing the type of foaming agent,water-cement ratio and foam content.The results show that when vegetable protein foaming agent is selected,the fluidity of cement paste is controlled to 170±5 mm.When the amount of foam is around 6.0%,the cement-based foam prepared has good formability,dry density of 724 kg/m3,initial setting time 12.0h,final setting time 15.5 h,3 d compressive strength 1.35 MPa,28 d compressive Strength 3.83 MPa.(2)On the basis of complete molding,Polycarboxylate Superplasticizer,naphthalene water reducer and melamine water reducer are used as single and mixed modified cement-based foam materials.The results show that the modification effect of the mixed optimal group is better than the single mixed optimal group,but the improvement is not large.Choose 0.4%Polycarboxylate Superplasticizer alone to prepare cement-based foam materials,initial setting time 14.0 h,final setting time 16.0h,3 d compressive strength 2.15 MPa,28 d compressive strength 6.37 MPa.(3)On the basis of complete molding,sodium carbonate,select aluminum sulfate and triethanolamine as the reinforcing agent to modify the cement-based foam material.The results show that the optimal dosage of sodium carbonate is 0.4%,the optimal dosage of aluminum sulfate is 1.0%,and the optimal dosage of triethanolamine is 0.14%,the initial setting time of the cement-based foam material is 6.0 h,the final setting time is 11.0 h,the 3-day compressive strength is 1.85 MPa,and the 28-day compressive strength is 5.65 MPa.(4)When using P.0 42.5 cement as the main raw material to prepare cement-based foam materials,the best modification scheme is water-cement ratio 0.4,foam content 6.0%,Polycarboxylate Superplasticizer 0.4%,sodium carbonate content 0.4%,sulfuric acid aluminum content is 1.0%,and the triethanolamine content is 0.14%.After testing,the prepared cement-based foam has a dry density of 711 kg/m~3,an initial setting time of 7.0 h,a final setting time of 8.5 h,a 3-day compressive strength of 2.63MPa,and a 28-day compressive strength of 7.52 MPa.Its performance conforms to the JG/T 266-2011 FC A07-C7.5 regulations.(5)An industrial pilot study on the cement-based foam material cast-in-place wall was conducted.The results show that too long agitation time and unbalanced foam-to-pulp ratio will cause the cast-in body to collapse.By controlling the mixing time of the cement slurry to 10 to 15 minutes,reducing the foaming rate to 1/4 of the original foaming flow rate,increasing the amount of cementing material to more than2 times the original,and raising the mixing bucket to its height and the foam mixer equal measures,effectively avoid the collapse of the casting body.(6)When the specific surface area of phosphor-gypsum-based construction gypsum is 300 g/cm~2,the content of?-type hemihydrate gypsum is 7.0%,the content of PP fiber is 1.0%,and the content of melamine water-reducing agent is 0.3%.Initial setting time 10?30?,final setting time 19?30?,2 h flexural strength 3.52 MPa,2 h compressive strength 8.41 MPa,its performance reaches the highest 3.0 in the national standard GB/T 9776-2008"Building Gypsum"standard.(7)Select cement and waterproof mortar to modify the phosphor-gypsum-based foam material.The results show that the modification effect is the best when the cement content is 15%(external mixing).Compared with the blank group,the absolute dry flexural strength increases by 55.9%.The absolute compressive strength increased by 16.9%,the water absorption decreased by 25.4%,and the softening coefficient increased by 110%.The thickness of waterproof mortar should be greater than 3 mm,but the dry density of phosphor-gypsum and foam will not meet the design requirements.(8)When the phosphor-gypsum-based construction gypsum is used as the main raw material to prepare the phosphor-gypsum-based foam material,the best modification scheme is a water-cement ratio of 0.43,a foam content of 4%,and a phosphor-gypsum-based construction gypsum specific surface area of 300 g/cm2,?Type hemihydrate gypsum content is 7.0%,PP fiber content is 1.0%,melamine water reducer content is 0.3%,and cement content is 15%.After testing,the prepared phosphor-gypsum-based foam has a dry density of 730 kg/m3,a required water-cement ratio of 0.43,an initial setting time of 25 min,a final setting time of 43 min,an absolute dry compressive strength of 5.44 MPa,and a water absorption rate of 36%.The performance meets the requirements of FC A07-C5.0-W40 in the line standard JG/T 266-2011.