| 摘要 |
Prodn. of lightweight cement with compensated shrinkage involves treating a mixt. of sand (particle size 0-2 mm), Portland cement, (I) and 200-270 l/m3 water with 1.5-3 pts. wt. hydroxypropylmethylcellulose (II) with a viscosity of over 70 000 cP and 2-4 pts. modified Ca-Na lignosulphonate (III), both per 1000 pts. (I) and also with 7-9 wt. % Ca sulphoaluminate (IV) w.r.t. (I) and 500-950 l/m3 expanded polystyrene beads (V), with a particle size distribution of 1-3mm. For lightweight concrete, a mixt. of gravel, sand (I) and 200-250 l/m3 water is treated with 1-2 pts. (II) and 2-4 pts. (III) per 1000 pts. (I) and with 300-500 l (V)/m3. Mortar with density 0.4-1.1 kg/l and specific compressive strength 30-90 kg/cm2 after 28 days is made from 150-500 kg/m3 sand, 300-400 kg/cm3 (I) 425/525 1.5-3 pts. (II)/1000 pts. (I), 2-4 pts. (III)/1000 pts. (I), 7-9% (IV), 550-950 l(v)/m3 and 200-270 l water/m3. Concrete with density 1.3-1.7 kg/l and compressive strength 100-160 kg/cm2 can also be made. Used for sub-floors and thermal and acoustic insulation. The distribution of (V) in the compsn. remains constant for long periods before setting. Even thin sections do not show cracks, since (II) not only coats (V) but also prevents sudden water loss and increases the elasticity and resistance to compressive and flexural stresses. |
