1
Mix of gelled material system
30-40%
High alumina cement
Ordinary Portland cement
A - half water gypsum/anhydrite
2
Mineral filler
55-68%
Quartz sand
Calcium carbonate powder
3
The coagulant
~ 0.5%
Retarder tartaric acid
Coagulant - lithium carbonate
4
The rheological modifier
~ 0.5%
Super plasticizer - water reducing agent
Defoaming agent
stabilizer
5
Enhanced components
1-4%
To disperse powder
6
20% - 25%.
Three, formulation and functional materials
/ self-leveling cement mortar is one of the most complex formula of cement mortar. Generally made up of more than 10 kinds of components, the following is cement-based self-leveling formula (pad)
The Self - Leveling Underlay Mortar
Cement-based self-leveling (pad)
Raw Material of Raw materials
Dosage proportion
OPC silicon cement 42.5 R
28
CA - 50 HAC625 high alumina cement
10
Quartz Sand Quartz Sand (70-140 mesh)
41.11
Calcium Carbonate Calcium Carbonate (500 mesh)
16.2
Hemihydrate Gypsum half water stone paste
1
Anhydrite Anhydrite (Anhydrite)
6
Latex Powder emulsion Powder HP8029 AXILAT TM
Cellulose Mr Cellulose Ether MHPC400
0.06
Superplasticizer jianshuiji SMF10
Defoamer defoaming agent DF AXILAT TM 770 DD
Tartaric Acid Tartaric Acid 200 mesh
0.18
Lithium Carbonate Lithium Carbonate 800 mesh
0.15
Calcium Hydrate ripe stone ashes
1
The Total amount
Note: more than 5 ℃.
(1) the gelled material system generally consists of ordinary Portland cement (OPC), high alumina cement (CAC) and mixture of calcium sulfate, and to provide enough calcium, aluminum, and sulfur to form calcium vanadium stone. This is because the formation of calcium vanadium stone has three main characteristics, namely, (1) forming speed, (2) the high combined water capacity, and (3) the ability to add shrinkage, fully meet/self-leveling cement mortar must provide macro performance requirements.
(2) self-leveling cement mortar/grading need to packing, such as quartz sand) and coarser grinding more fine filler (such as ground calcium carbonate powder), density of in order to achieve the best effect.
(3)/self-leveling cement mortar of calcium sulphate is used inside a - half water gypsum (a - CaSO4 1/2 level H2O) or hardened gypsum (CaSO4); , which can fast enough to release sulfuric acid root without the need for increased water consumption. A question is often asked why not use the b - half water gypsum (with a - half water gypsum has the same chemical composition), it is more easy than a - half water gypsum and the price is cheap. But the problem is b - half water gypsum high void fraction of water will increase significantly, resulting in the decrease in the strength of hardened mortar.
(4) to disperse powder is the key element of the/self-leveling cement mortar. It can improve the liquidity, the surface wear resistance, drawing strength and flexural strength. In addition, it also can reduce the modulus of elasticity, so as to reduce internal stress of the system. To spread powder must be able to form solid polymer film. High performance mortar self-leveling cement/products containing up to 8% can be dispersed powder, and give priority to with high alumina cement. This product can guarantee fast condense sclerosis and 24 hours after the high early strength, to meet the requirements of the next day for construction work, such as renovation.
(5)/self-leveling cement mortar is needed by coagulant (such as lithium carbonate) to achieve early strength of cement condensation, need through the retarder gypsum condensation (such as tartaric acid) to slow speed.
(6) super plasticizer (poly carboxylic acid water reducing agent) in/self-leveling cement mortar water reducing effect and thus provide flow and leveling performance.
(7) defoaming agent can not only reduce the air content improve final later strength, can also get even, smooth and solid surface.
(8) a small amount of stabilizer (such as cellulose ether) can prevent the segregation of slurry and the formation of the skin, causing negative impact on the performance of the final surface. To spread powder can further improve flow performance and to promote the strength.
Four, the quality of the product requirements and its key technology
1, the basic requirement of/self-leveling cement mortar
(1) have good liquidity, in the case of a few millimeters thick and has a good flow property, and
Slurry has good stability, reduce segregation, stratification, bad phenomena such as exudation, bubble,
And make sure have enough available time, usually in more than 40 minutes, in order to facilitate operation.
(2) the flatness is better, and no obvious surface defects.
(3) as the ground material, its compressive strength, abrasion resistance, impact resistance, water resistance and other physical mechanics
Performance should meet the requirements of general indoor building on the ground.
(4) the durability is better.
(5) the construction is simple, fast, saving time and Labour.
2, the main technical performance/self-leveling cement mortar
(1) the fluidity
Mobility is an important index/self-leveling cement mortar performance. The general flow is greater than 210 ~ 260 mm.
(2) the stability of the slurry
The index is reflect self-leveling cement/mortar on the stability of target. Pour mixed slurry in horizontal glass, 20 minutes after the observation, should be no obvious exudation, stratification and segregation, double bubble phenomenon. The indicator on the material forming the surface condition and had a greater influence on the durability.
(3) the compressive strength
As the ground material, the index must conform to the cement ground construction specifications, domestic ordinary cement mortar
Ground floor demands for more than 15 mpa compressive strength, compressive strength of cement concrete pavement for more than 20 mpa.
(4) flexural strength
Industrial/self-leveling cement mortar flexural strength should be greater than 6 mpa.
(5) setting time
/ mortar self-leveling cement setting time, determine the slurry mixing evenly, ensure its use time in more than 40 minutes, interoperability is not affected.
(6) impact resistance
/ self-leveling cement mortar should be tolerated normal traffic in human body and handling items produced by the collision, the impact resistance is greater than or equal to 4 joule.
(7) wear resistance
/ self-leveling cement mortar as a material of ground surface, must be resistant to normal ground traffic exchanges. Due to its flow leveling layer is thinner, under the condition of the ground solid at the grass-roots level, the main bearing force on the surface, rather than on the volume. So its wear resistance is important than compressive strength.
Bonding tensile strength (8) to the local level
/ self-leveling cement mortar bond strength with base, directly related to the slurry after hardening will appear empty drum, fall off phenomenon, larger influence on the durability of the material. In actual construction process, besmear brushs interface agent on the ground, to a more adapt to self-leveling material construction conditions. Domestic self-leveling material bonding tensile strength of the cement floor is usually more than 0.8 MPa.
(9) crack resistance
Crack resistance is a key index of the/self-leveling cement mortar, after its size is related to self-leveling material hardening, whether cracks, empty drum, fall off wait for a phenomenon. Whether the correct evaluation of self-leveling
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