The slag slag aerated concrete and technical requirements

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Granulated blast furnace slag

Ironmaking process, the liquid discharged from the blast furnace slag of molten state, rapid cooling by water quenching become loose porous fine glassy particles, called granulated blast furnace slag is a good activity, commonly known as water quenched slag or water residue, materials. With the development of industrial technology, water residue has a large number of cement industry as an active admixture. Aerated concrete industry, more extensive use of the former Soviet Union, in China, only a few factories still in use.

The physical properties and chemical composition of a slag

Granulated blast furnace slag for the appearance of white, gray, yellow or yellow-green loose small particles. Its color and chemical composition of the slag and water quenching conditions. The particle size is usually below 10mm, mostly between 0.5 ~ 5mm, a bulk density of 500 to 800kg/m3, a density of about 2.95g/cm3. The chemical composition of the slag CaO, SiO2, A12O3 of MgO and Fe2O3, there is a small amount of sulfide (CaS, MnS, FeS), a small number of slag there TiO2, P2O5. Table 2-2 lists the fluctuation range of the chemical composition of China's general slag.

Chemical composition of the general slag and cement clinker

SiO2 CaO Al2O3 Fe2O3 MgO SO3 MnO

Water quenched slag 26 ~~ 42 38 to 48 7 to 20 0.2 to L 4 13 1 ~~ 2 0.1 ~~ 1

Portland cement clinker 20.50 63.93 6.25 5.48 0.37

2 slag activity

Since the chemical composition of the slag and similar to the cement clinker (CaO content), and solidified in the quenching process, having a higher content of vitreous. Therefore, has potential activity, the role of a small amount of activating agent (lime or cement) can exhibit a discharge condensable. This activity of the slag, depending on its chemical composition, the mineral composition and the water quench conditions, also related to the method and environment of the application slag.

3 slag quality evaluation

The chemical composition of the slag, mineral composition is more complex, the structural differences are also generated due to the different conditions of granulation essentially affect the quality of the slag. Different excitation agent is present, but also affect the activity of the slag to play, it demonstrated the activity is not the same, which resulted in the complexity of the quality of the assessment of slag.

With the chemical composition analysis was used to test the activity of the slag, although still not comprehensive enough, and is not related to the slag of the internal structure, but with this method has been described the nature of the slag characteristics. So, is the main method of the the domestic evaluation blast furnace slag.

GB GB302, slag quality is good or bad to be evaluated according to the following three aspects:

Quality coefficients of (1) [(CaO + MgO + Al2O3) / (SiO2 + MnO + TiO2)] not less than 1.2 mass coefficient reflects the slag of the active ingredient of CaO, MgO, A12O3 and non-active component - SiO2, MnO, TiO2, ratio, the quality coefficient is larger, the higher the activity of the slag.

(2) as MnO, the content of manganese compound is not more than 4%; with TiO2 of the titanium compound content of not greater than 10%; as F, fluorine compounds content of not greater than 2%.

(3) quenching process must be fully the bulk density to greater than 1.lkg / l; inadequately quenching massive slag, intuitive tick weight of not more than 5%, the maximum size of not more than 100 mm.

4 slag aerated concrete

Milled water quenched slag in a saturated Ca (OH) 2 solution, will produce a significant hydration reaction, gelling properties, i.e., the potential activity of the slag is excited and released, showing the ability of water and hardening .

In the aerated concrete in the slurry, when the raw quicklime, quicklime hydration to form Ca (OH) 2; generated in the cement as its calcareous materials, cement C3S, C2S silicate minerals hydration CA (OH) 2, the slurry is alkaline, which can stimulate the activity of the slag, thereby starting the hydration reaction.

5 slag quality requirements

(1) loose particles, uniform appearance of yellowish or gray, shiny glass, no iron slag and grit bulk.

(2) The chemical composition

Ca (OH) 2 ≥ 40%

Al2O3 9 ~ 16%

SO3 0.8 ~ 1.6%

Cl-<0.02%

CaO/SiO2> 1