Research on influencing factors of compressive strength of foam concrete

Definition and preparation method of foam concrete

Foamed concrete is prepared by introducing it into a cement (sand) slurry with a certain fluidity and using a physical method. The uniform and small air bubbles are made of cement-based porous materials with a large number of pores made by mixing, shaping, and curing.

There are two methods for introducing air bubbles in foam concrete:

(1)Add the foaming agent directly to a certain flow. In the dynamic and viscous slurry, use mechanical high-speed stirring to make the air directly wrap into the slurry to form a foam slurry; Then, the foam and the prepared slurry are thoroughly mixed to make a slurry with uniform pore distribution.

(2) First, the foaming liquid is prepared into a fine and uniform foam by mechanical high-speed stirring or compressed air, and then the foam and the prepared slurry are fully mixed to make a slurry with uniform pore distribution.

Research on influencing factors of compressive strength of foam concrete

Compared with ordinary concrete, foam concrete is a special porous material with a large number of pores. Its mechanical properties are also different from ordinary concrete, and its influencing factors are also relatively special. In general, the main mechanical properties of foamed concrete-compressive strength, its size is affected by many factors, such as cement strength, mineral admixture activity, type of additives, curing system, age, water-cement ratio, bulk density, slurry Body density, moisture content, light aggregate strength and its content, pore distribution, and structure type, etc.

Among these factors:

(1) cement strength grade, maintenance system, age, moisture content, etc. are mainly affected by The strength of the foamed concrete is affected by the strength of the pulp;

(2) The bulk density mainly affects the pore content of the foamed concrete and has a great impact on the strength of the foamed concrete;

(3) The water-cement ratio and the admixture affect the strength of the slurry and change The density of the paste affects the porosity of the foam concrete, and also affects the degree of fluidity and thus the uniform distribution of the bubbles. Therefore, its mechanism of action is the most complex and has special rules of action.

(4) Light aggregates are different according to the way they are incorporated. It will have a certain influence on the foam concrete pore system, the original foam concrete density, and strength, and finally, make the composite system have a special strength law.

(5) Admixtures have an important effect on the porosity of foam concrete, especially at low bulk density, the impact is particularly obvious.

The following conclusions can be drawn through research

(1) For the foam concrete with the same bulk density and the same cell ratio, the compressive strength of the paste is directly

Affecting the compressive strength of foam concrete, there is a proportional relationship between the two.

(2) At low water-cement ratio, the introduction of EPS particles can improve the compressive strength of EPS composite foam concrete

Degree and a higher water-cement ratio will reduce the strength of the composite system.

(3) There is an optimal interval for the influence of pore size on the compressive strength of foam concrete.

In the range of 3.63-4.11. the strength is high. When it exceeds this range, the proportion of large holes or small holes increases, and the strength is low.

(4) The opening is not conducive to the strength of foam concrete, especially when the porosity is high and the bulk density is low.

(5) When the pore orientation in foam concrete is mostly distributed in a certain direction, the compressive strength performance

It has anisotropy, higher compressive strength in the direction of orientation, and lower compressive strength in the vertical direction. The difference in strength between the two directions is related to bulk density.

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