Study On Additives Used In Foam Concrete Block

As a new type of foam material,foam concrete has many good characteristis including heat insulation,light weight and inflaming retardance,which makes foam concrete being a better candidate for energy-saving buildings compared with other conventional heat-preservation products.However,some defects of this material,such as high water absorption,low strength,and intrisic brittleness,hamper its practical application in the field of construction industry to some extent.Based on the mentioned problems and related references,author has carried out a series of experimental research arround the additives of highdensity foam concrete,and identified the type and dosage of several conventional-function additives.A kind of enhanced polycarboxylic acid water reducing agent(HD-ZQ)was synthesized,and the effect of the synthetic process on the properties of foam concrete was furtherly studied.Meanwhile,the influence of the complex of water-resisted organic silicon(SHP60+)and ordinary polycarboxylic acid water reducing agent(HD-PCA)on the water absorption,ratio of strength to density,drying shrinkage value and the coefficient of thermal conductivity of the foam concrete were investigated as well.The results showed that:Various functional additives were selected by single factor method.The optimal coagulation effect can be achieved when 0.6 wt% sodium aluminate was used in combination with 0.9 wt% aluminum sulfate.2.0 wt% calcium formate probably produced stabilized-structure bubbles with excellent early strength.And also,0.2 wt%calcium stearate could effectively reduce the ratio of water absorption,increase the stability of bubble hole,but the excessive would destroy its strength.A kind of enhanced polycarboxylic acid water reducing agent HD-ZQ was synthesized by free radical polymerization.The influence of the functional monomer AM(Acrylamide)and AMPS(2-Acrylamido-2-methylpropane sulfonic acid)on the dispersion of HD-ZQ,also the hydration and strength of foam concrete were studied and discussed.When the replace ratio of AM and AMPS to AA(Acrylic acid)was 10mol% and 35 mol%,respectively,the HD-ZQ displayed the best comprehensive performance.KPS(Potassium Persulfate)and SMAS(Sodium Methylallyl Sulfonate)would affect the dispersion property of water reducing agent,and SMAS played a positive role in the cement hydration,but no obvious evidence on the strengthpromotion of foam concrete.The molecular weight of polyether was closely related to the performance of water reducing agent,and this agent with the number average molecular weight of 2400 g/mol could result in the best main performance of foam concrete.1.5 wt% SHP60+ and 0.5 wt% HD-PCA could improve the hydrophobicity,reduce the shrinkage of foam concrete and the coefficient of thermal conductivity under the condition of low ratio of water to cement,so as to enhance the comprehensive performance of foam concrete.