Research On Low Price Eps Thermal Insulation Mortar With High Performance

For lack of energy sources and energy consumption of buildings in China is much higher than the average value of the world, it is extremely urgent to implement building energy saving tasks. EPS thermal insulation mortar is becoming the mainstream of the thermal insulation layer in building energy saving systems for desired properties, and can meet the requirement of "Eleventh Five-Year Plan" which proposes building energy efficiency by 65%. However some problems existed in the application of EPS thermal insulation mortars are as follow: (1) easily hollowing and cracking, (2) high thermal conductivity and high cost, (3) the mechanisms of etherified cellulose and re-dispersible emulsion powder in EPS thermal insulation mortars even unclear.The effects of etherified cellulose, re-dispersible emulsion powder and polypropylene fiber on the consistency,water retention,strength and other performance of EPS thermal insulation mortar were studied in this paper. The results show that the effect of domestic etherified cellulose on increasing consistency and water retention is worse than imported one's at the same dosage; compared with imported one's at low dosage (below 1%), domestic re-dispersible emulsion powder has the same tensile binding strength; but the ability of domestic re-dispersible is weaker, so the tensile binding strength of domestic re-dispersible emulsion powder is lower at dosage above 1%.Scanning electronic microscopy (SEM) and fluorescence test were used to investigate the mechanisms of etherified cellulose and re-dispersible emulsion powder. The results show that etherified cellulose is characteristic with air entraining, and the size of pore is 0.3-0.7mm; etherified cellulose can improve the rate of cement paste hydrate cured in air; dosage of etherified cellulose is more, hydration degree is higher. Etherified cellulose can form film in cement mortar, and can become thin after drying. The mechanism could be that etherified cellulose adsorbs a great deal of water, and forms a continuous film structure; with the hydration of cement, moisture releases and the film becomes thin and forms lots of pores. Re-dispersible emulsion powder forms film structure in cement mortar, the mortar with higher dosage of re-dispersible emulsion powder, forms a thicker film structure; after 12 hours, the film is not stable; the film might becomes thin after immerging into water. Bentonite might adsorb some powders, so that the film turns thin. XRD results show that the mixing of re-dispersible emulsion powder does not change the type of hydration products, but reduced the orientation of calcium hydroxide and amount. With the increasing of the content of re-dispersible emulsion powder,the structure of hydration products become more compact.By adjusting the dosage of EPS, mineral admixture types and their ratios, thermal conductivity EPS thermal insulation mortar can decrease and meet the requirement of national standard——0.06 W/(m·K), and guarantee the strength of the mortar. Proper dosage of hydrophobic agent can reduce the saturated water absorption of EPS thermal insulation mortar, reduce its compressive strength and tensile adhesive strength loss after immerging into water, increases the adhesion strength between EPS and paste. The results indicate that the influence of water retention rate on the ability of crack resistance of mortar is outstanding, except for drying shrinkage. When the water retention rate of EPS thermal insulation mortar is above 85%, the mortars have good crack resistance ability and good weather durability. So EPS thermal insulation mortar of high performance can be made according to this method. The adhesive strength of EPS thermal insulation mortar of high performance is 1 time greater than that of common EPS thermal insulation mortar.The influence of Lignocellulose, modified bentonite and modified polyethylene oxide powder on water retention rate, mechanical properties of EPS thermal insulation mortar were determined. After addition of 0.3% (by mass of binder) Lignocellulose, 4%, modified bentonite and 0.5% modified polyethylene oxide powder substituted for 0.2% etherified cellulose and 1% re-dispersible emulsion powder, the properties of EPS thermal insulation mortar meet the requirements of national standards ofⅠtype EPS thermal insulation mortar, the cost of this EPS thermal insulation mortar can be as low as 450 yuan per cubic meter (reduced by 4.7%). while the market price of EPS thermal insulation mortar of typeⅠis 800-1200 yuan per cubic meter. It would have good prospects.Lignocellulose, modified bentonite and lime were selected as water retention agents, effects of water retention agents on the properties (epically cracking resistance) of base coat mortar by orthogonal test. Comparison of the prepared mortar and commercial mortar was conducted. The results showed that the optimum dosage is: Lignocellulose 0.4%, modified bentonite 4% and lime 15%. Compared to commercial mortar, mortar prepared according to above dosage has better cracking resistance, water retention and higher mechanical properties, while the cost of the mortar is only about 78% of that of commercial mortar, Thus this base coat mortar has broad market prospects.