Method for predicting plastic shrinkage cracking of cement mortar material

A technology of shrinkage cracking and cement-based materials, which is applied in the field of material science and engineering, and can solve problems such as the failure to give multivariate constitutive equations for plastic shrinkage cracking

Inactive Publication Date: 2013-10-16
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, so far, a multi-component constitutive equation for plastic shrinkage cracking including cement-based material composition, environmental conditions, initial structural parameters and constraints has not been given, so it is expected to be used for early prediction of plastic shrinkage cracking of mortar

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] The water-cement ratio Wc of a certain cement mortar is 0.45, the lime-sand ratio is 1, and the fiber content Fc is 0.9kg / m 3 , Fiber length F 1 It is 12mm, and the water evaporation rate of the mortar under certain environmental conditions is 0.250Kg / (m 2 h) The stratification degree is 0.1cm and the constraint degree is 0.66. The calculated K=1.60, which is greater than 1.41. It is predicted that the mortar will not crack under this environmental condition.

[0032] The actual measured K value is 1.82, the relative error is 12.1%, and the mortar does not crack.

Embodiment 2

[0034] A certain cement mortar water-cement ratio Wc is 0.40, lime-sand ratio is 0.67, fiber content Fc is 0, fiber length F 1 Is 0, the water evaporation rate of the mortar under certain environmental conditions is 0.296Kg / (m 2 h), the stratification degree is 0.1cm, the constraint degree is 0.83, and K=2.11 is calculated with the constitutive equation, which is greater than 1.41. It is predicted that the mortar will not crack under this environmental condition.

[0035] The actual measured K value is 2.33, the relative error is 9.44%, and the mortar does not crack.

Embodiment 3

[0037] The water-cement ratio Wc of a certain cement mortar is 0.45, the lime-sand ratio is 1, and the fiber content Fc is 0.9kg / m 3 , Fiber length F 1 It is measured that the moisture evaporation rate of the mortar under certain environmental conditions is 0.30Kg / (m2h), the stratification degree is 0.4cm, and the constraint degree is 0.83. It is calculated by incorporating into the constitutive equation K=0.97, which is less than 0.99. It is predicted that the mortar will crack under this environmental condition.

[0038] The actual measured K value was 1.07, the relative error was 9.34%, and the mortar cracked.

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Abstract

The invention relates to a method for predicting plastic shrinkage cracking of a cement mortar material. The method comprises the following step of: substituting four cement-based material composition parameters comprising water cement ratio (Wc), cement sand ratio (Cs), fiber content (Fc) and fiber length (F1), water evaporation speed (Er) and demixing degree (Dd) and restraint degree (Rd) of the cement-based material into the following formula: K = 13.8822 - 14.0949Wc - 2.8247Cs + 0.5293Fc + 0.0022F1 - 17.0650Er + 0.2582Dd + 0.9436Rd, wherein the K is anti-cracking index. When the K value is more than 1.41, the cement-based material test piece is not cracked; when the K value is less than 0.99, the test piece is cracked; and when the K value is between 0.99 and 1.41, the test piece is cracked in certain probability. A multiplex constitutive equation of plastic shrinkage cracking of the mortar is constructed by using the parameters with great influence on the cement-based plastic shrinkage cracking, the tendency of early plastic shrinkage cracking of the cement-based material can be accurately predicted, and the method can be widely applied to early prediction of the plastic shrinkage cracking of the mortar.

Description

Technical field [0001] The invention relates to a method for plastic shrinkage cracking of cement-based materials. It can be used for the early qualitative prediction of plastic shrinkage cracking tendency of cement mortar materials. It belongs to the field of materials science and engineering. technical background [0002] Cement concrete is one of the largest and most widely used building materials in the world. Because cement concrete has the advantages of wide application range, low price, easy pouring and forming, relatively durable, and can effectively use some industrial solid wastes to make energy-saving and environmentally-friendly building materials, it will still be irreplaceable in modern engineering construction in my country in the 21st century. Main building materials. [0003] However, it is undeniable that cement concrete has disadvantages such as self-weight, low tensile strength, small ultimate tensile strain, poor impact strength, and easy plastic loss, shrink...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N33/38
Inventor 马一平张乐李国友杨晓杰
Owner TONGJI UNIV
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