Vitrified microsphere is a kind of inorganic heat preservation material, often as a lightweight aggregate added to plaster thermal insulation mortar. It has the thermal insulation, high temperature resistant, fire prevention, the characteristics of low density, and low cost. Vitrified microsphere, table surface height vitrified closed, internal to the porous cavity structure, due to the special microstructure, it is mixed with cement mortar can effectively reduce the thermal conductivity of mortar. Vitrified beads packing density is 80 ~ 120 kg/m3, far less than the density of the slurry, in the process of slurry mixing, existence of vitrified microsphere, aggregate buoyancy, sinking tendency of the coating. Influenced by mixing broken, damage of vitrified beads aggregate also absorb moisture in the slurry, causing its density rise, causing damage and intact vitrified beads aggregate density differences between different density of aggregate because of stress in the process of mixing different layers, the uneven distribution of aggregate, produced when the new mixing mortar material construction in the differences of aggregate distribution density, mortar hardened structure presents the macroscopic and mesoscopic structure uneven, thus affecting mortar strength, durability, etc. In order to promote the construction quality of vitrified microsphere, mortar, design suitable mixing process, to ensure the using performance of vitrified microsphere, mortar, this paper vitrified beads mortar mixing uniformity of the aggregate distribution in the process of the experiment and theoretical study, in order to get the optimal mixing effect, makes the new mixing vitrified beads mortar in meet the performance requirements of construction at the same time, also has good aggregate distribution uniformity.
Raw materials and test methods
1.1 the raw material
(1) the vitrified beads: henan xinyang, particle size, respectively for 20 ~ 30 yard and 30 ~ 50 two kinds.
(2) the cement: p. O cement 42.5 magnitude.
(3) to disperse latex powder.
(4) polypropylene fibre: 30 microns in diameter, length of 12 mm. Experiment with vitrified beads mortar with us than according to the former research results to determine, in line with the JG/T 283-2010 "expansion vitrified beads lightweight sand pulp" requirement. Mortar mixing ratio are shown in table 1.
1.2 test method
(1) aggregate pretreatment by preliminary screening out of production process and the transportation link as well as the damage of vitrified microsphere, aggregate has not expanded perlite particles completely, reduce the test error. Screen is the use of vibration sieve machine to strictly control test with vitrified microspheres particle size.
(2) mortar mixing this experiment study the influence of vitrified beads aggregate points cloth uniformity of mixing conditions include: mixer type, agitator rotational speed, stirring time, aggregate investment opportunity. Therefore, choose the following three kinds of mortar stirring mixer: SJ 15 type mixer: mixing blade rotation speed (80 + 4) r/min (clockwise); Mixing drum speed (60 + 2) r/min. HJW - 60 type stirrer, stirring shaft speed 45 r/min. JJ - 5 type mixer, the mixer speed adjustable, low speed mode mixing blade rotation speed (140 + 5) r/min, the revolution speed of stirring shaft (6)