Method for improving deformability of cementitious composite by using polyethylene terephthalate powder

Abstract

A method for improving deformability of a cementitious composite by using PET powder is provided. The aggregate in the cementitious composite is replaced with PET powder at a volume replacement ratio of 0-25%, and the value of the volume replacement ratio is not 0%. The method including following steps: mixing components of the raw materials to obtain the cementitious composite.

Claims

1. A cementitious composite based on PET powder, wherein quartz powder aggregate in the cementitious composite is replaced with the PET powder at a volume replacement ratio of 10-20%; wherein the cementitious composite based on the PET powder consists of following raw materials in terms of unit volume mass: cement 936.7 kg/m.sup.3; fly ash 401.4 kg/m.sup.3; quartz powder 301.1-401.4 kg/m.sup.3; PET powder 0-52.3 kg/m.sup.3; water 335.1 kg/m.sup.3; water reducer 5.4 kg/m.sup.3; PE fiber 19.4 kg/m.sup.3; thickener 0.54 kg/m.sup.3; and defoamer 2.01 kg/m.sup.3, wherein a dosage of the PET powder is not 0 kg/m.sup.3; particle size grades of the PET powder and the aggregate are same; and particle sizes of the quartz powder and the PET powder are 20-310 m.

2. The cementitious composite according to claim 1, wherein the cement is P.II 52.5R ordinary portland cement; and a particle size of the fly ash is 0-200 m.

3. The cementitious composite according to claim 1, wherein the PE fiber has a density of 0.97 g/cm.sup.3, a tensile strength of 3000 MPa, and an elastic modulus of 116 GPa.

4. The cementitious composite according to claim 1, wherein the water reducer is a polycarboxylate ether superplasticizer.

5. A preparation method of the cementitious composite according to claim 1, comprising a following step: mixing components of the raw materials to obtain the cementitious composite.

6. The preparation method according to claim 5, comprising following steps: mixing the cement, the fly ash, the quartz powder, the PET powder, the thickener and the defoamer to obtain a mixed material; mixing the water with the water reducer to obtain a mixed slurry; and adding the mixed slurry into the mixed material, and then adding the PE fiber to obtain the cementitious composite.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order to explain the embodiments of the present disclosure or the technical solution in the prior art more clearly, the drawings needed in the embodiments will be briefly introduced below. Apparently, the drawings in the following description are only some embodiments of the present disclosure. For one of ordinary skill in the art, other drawings may be obtained according to these drawings without creative effort.

(2) FIG. 1 shows particle size distribution curves of raw materials in embodiments of the present disclosure.

(3) FIG. 2 shows electron microscope images of raw materials in embodiments of the present disclosure.

(4) FIG. 3 is a mixing flow chart of concrete samples in embodiments of the present disclosure.

(5) FIG. 4 is a dimension diagram of specimens in embodiments of the present disclosure.

(6) FIG. 5 shows specimen failure modes of axial tensile tests in embodiments of the present disclosure.

(7) FIG. 6 shows specimen failure modes of axial compression tests in embodiments of the present disclosure.

(8) FIG. 7 shows stress-strain curves of axial tensile tests in embodiments of the present disclosure.

(9) FIG. 8 shows an interaction principle between PET and matrix.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(10) A number of exemplary embodiments of the present disclosure will now be described in detail, and this detailed description should not be considered as a limitation of the present disclosure, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present disclosure.

(11) It should be understood that the terminology described in the present disclosure is only for describing specific embodiments and is not used to limit the present disclosure. In addition, for the numerical range in the present disclosure, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Intermediate values within any stated value or stated range, as well as each smaller range between any other stated value or intermediate values within the stated range are also included in the present disclosure. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

(12) Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure relates. Although the present disclosure only describes the preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present disclosure. All documents mentioned in this specification are incorporated by reference to disclose and describe methods and/or materials related to the documents. In case of conflict with any incorporated document, the contents of this specification shall prevail.

(13) It is apparent to those skilled in the art that many improvements and changes may be made to the specific embodiments of the present disclosure without departing from the scope or spirit of the present disclosure. Other embodiments will be apparent to the skilled person from the specification of the present disclosure. The description and embodiments of the present disclosure are exemplary only.

(14) The terms including, comprising, having and containing used in this article are all open terms, which means including but not limited to.

(15) In the following embodiments of the present disclosure, the flowability test flow of concrete mixture is carried out by jumping table test according to GB/T 2419, and the mixture width in two vertical directions is measured after the mixture stops flowing.

(16) The dimensions of the concrete mixture specimens obtained in the embodiments are a cube of 50 mm50 mm50 mm and a dog bone shape of 330 mm60 mm13 mm, and the shapes are shown in FIG. 4.

(17) The cement used in the embodiments of the present disclosure is P.II 52.5R ordinary portland cement. The water reducer used is polycarboxylate ether superplasticizer.

(18) The PE fiber (UHMWPE fiber) used in the embodiments of the present disclosure has a length of 18 mm, a diameter of 24 m, a density of 0.97 g/cm.sup.3, a tensile strength of 3000 MPa, an elastic modulus of 116 GPa and an elongation of 1-3%. The density of quartz powder used is 2.68 g/cm.sup.3, and the density of PET powder is 1.38 g/cm.sup.3.

(19) The main component of the thickener used in the embodiments of the present disclosure is methyl cellulose, and the defoamer is polyether modified silicon defoamer.

(20) The particle size distribution curves of raw materials in the embodiments of the present disclosure are shown in FIG. 1.

Embodiment 1

(21) According to a cementitious composite with PET powder replacing quartz powder at a 0% replacement ratio, the raw material ratio (material usage of 1 cubic meter (m.sup.3) concrete) is shown in Table 1:

(22) TABLE-US-00001 TABLE 1 Mix proportion design of cementitious composite (kg/m.sup.3) Quartz PET Water PE Cement Fly ash powder powder Water reducer fiber Thickener Defoamer 936.7 401.4 401.4 0.0 335.1 5.4 19.4 0.54 2.01

(23) The preparation method is as follows: (1) adding cement, fly ash, quartz powder, thickener and defoamer into a concrete mixer, and mixing at a low speed of 75 revolutions per minute (rpm) for 3 min to uniformly mix dry materials to obtain a concrete powder premix; (2) adding water and water reducer which are mixed uniformly in advance while mixing at a low speed (75 rpm) for 1 min, and then mixing at a low speed (75 rpm) for 3 min, and then mixing at a high speed (135 rpm) for 1 min to make the mixture uniform into slurry, thus obtaining a flowing matrix; (3) adding PE fiber while mixing at a low speed (75 rpm) for 3 min, and then mixing at a low speed (75 rpm) for 4 min, and mixing at a high speed (135 rpm) for 5 min to uniformly disperse the fiber to obtain concrete slurry; and (4) quickly pouring the mixed concrete into the mold (making three cubes and three dog bones, and pouring six specimens in total), vibrating with a vibration table to eliminate bubbles in the specimens to make the specimens compact, and completing the flowability test. The specimens are covered with a film to prevent water evaporation, and then demoulded after 24 hours of indoor curing, and normally cured for 28 days in a sealed environment. After the expiration, the specimens are taken out for mechanical properties test.

Embodiment 2

(24) According to a cementitious composite with PET powder replacing quartz powder at a 5% replacement ratio, the raw material ratio (material usage of 1 m.sup.3 concrete) is shown in Table 2:

(25) TABLE-US-00002 TABLE 2 Mix proportion design of cementitious composite (kg/m.sup.3) Quartz PET Water PE Cement Fly ash powder powder Water reducer fiber Thickener Defoamer 936.7 401.4 381.3 10.5 335.1 5.4 19.4 0.54 2.01

(26) The preparation method is as follows, as shown in FIG. 3: (1) adding cement, fly ash, quartz powder, PET powder, thickener and defoamer (as shown in FIG. 2) into a concrete mixer, and mixing at a low speed of 75 rpm for 3 min to uniformly mix dry materials to obtain a concrete powder premix (dry material mixture); (2) adding water and water reducer which are mixed uniformly in advance while mixing at a low speed (75 rpm) for 1 min, and then mixing at a low speed (75 rpm) for 3 min, and then mixing at a high speed (135 rpm) for 1 min to make the mixture uniform into slurry, thus obtaining a flowing matrix (fresh mortar); (3) adding PE fiber while mixing at a low speed (75 rpm) for 3 min, and then mixing at a low speed (75 rpm) for 4 min, and mixing at a high speed (135 rpm) for 4 min to uniformly disperse the fiber to obtain concrete slurry; and (4) quickly pouring the mixed concrete into the mold (making three cubes and three dog bones, and pouring six specimens in total), vibrating with a vibration table to eliminate bubbles in the specimens to make the specimens compact, and completing the flowability test. The specimens are covered with a film to prevent water evaporation, and then demoulded after 24 hours of indoor curing, and normally cured for 28 days in a sealed environment. After the expiration, the specimens are taken out for mechanical properties test.

Embodiment 3

(27) According to a cementitious composite with PET powder replacing quartz powder at a replacement ratio of 10%, the raw material ratio (material usage of 1 m.sup.3 concrete) is shown in Table 3:

(28) TABLE-US-00003 TABLE 3 Mix proportion design of cementitious composite (kg/m.sup.3) Quartz PET Water PE Cement Fly ash powder powder Water reducer fiber Thickener Defoamer 936.7 401.4 361.3 20.9 335.1 5.4 19.4 0.54 2.01

(29) The preparation method is as follows: (1) adding cement, fly ash, quartz powder, PET powder, thickener and defoamer into a concrete mixer, and mixing at a low speed of 75 rpm for 3 min to uniformly mix dry materials to obtain a concrete powder premix (dry material mixture); (2) adding water and water reducer which are mixed uniformly in advance while mixing at a low speed (75 rpm) for 1 min, and then mixing at a low speed (75 rpm) for 3 min, and then mixing at a high speed (135 rpm) for 1 min to make the mixture uniform into slurry, thus obtaining a flowing matrix (fresh mortar); (3) adding PE fiber while mixing at a low speed (75 rpm) for 3 min, and then mixing at a low speed (75 rpm) for 4 min, and mixing at a high speed (135 rpm) for 4 min to uniformly disperse the fiber to obtain concrete slurry; and (4) quickly pouring the mixed concrete into the mold (making three cubes and three dog bones, and pouring six specimens in total), vibrating with a vibration table to eliminate bubbles in the specimens to make the specimens compact, and completing the flowability test. The specimens are covered with a film to prevent water evaporation, and then demoulded after 24 hours of indoor curing, and normally cured for 28 days in a sealed environment. After the expiration, the specimens are taken out for mechanical properties test.

Embodiment 4

(30) According to a cementitious composite with PET powder replacing quartz powder at a replacement ratio of 15%, the raw material ratio (material usage of 1 m.sup.3 concrete) is shown in Table 4:

(31) TABLE-US-00004 TABLE 4 Mix proportion design of cementitious composite (kg/m.sup.3) Quartz PET Water PE Cement Fly ash powder powder Water reducer fiber Thickener Defoamer 936.7 401.4 341.2 31.4 335.1 5.4 19.4 0.54 2.01

(32) The preparation method is as follows: (1) adding cement, fly ash, quartz powder, PET powder, thickener and defoamer into a concrete mixer, and mixing at a low speed of 75 rpm for 3 min to uniformly mix dry materials to obtain a concrete powder premix (dry material mixture); (2) adding water and water reducer which are mixed uniformly in advance while mixing at a low speed (75 rpm) for 1 min, and then mixing at a low speed (75 rpm) for 3 min, and then mixing at a high speed (135 rpm) for 1 min to make the mixture uniform into slurry, thus obtaining a flowing matrix (fresh mortar); (3) adding PE fiber while mixing at a low speed (75 rpm) for 3 min, and then mixing at a low speed (75 rpm) for 4 min, and mixing at a high speed (135 rpm) for 4 min to uniformly disperse the fiber to obtain concrete slurry; and (4) quickly pouring the mixed concrete into the mold (making three cubes and three dog bones, and pouring six specimens in total), vibrating with a vibration table to eliminate bubbles in the specimens to make the specimens compact, and completing the flowability test. The specimens are covered with a film to prevent water evaporation, and then demoulded after 24 hours of indoor curing, and normally cured for 28 days in a sealed environment. After the expiration, the specimens are taken out for mechanical properties test.

Embodiment 5

(33) According to a cementitious composite with PET powder replacing quartz powder at a replacement ratio of 20%, the raw material ratio (material usage of 1 m.sup.3 concrete) is shown in Table 5:

(34) TABLE-US-00005 TABLE 5 Mix proportion design of cementitious composite (kg/m.sup.3) Quartz PET Water PE Cement Fly ash powder powder Water reducer fiber Thickener Defoamer 936.7 401.4 321.1 41.8 335.1 5.4 19.4 0.54 2.01

(35) The preparation method is as follows: (1) adding cement, fly ash, quartz powder, PET powder, thickener and defoamer into a concrete mixer, and mixing at a low speed of 75 rpm for 3 min to uniformly mix dry materials to obtain a concrete powder premix (dry material mixture); (2) adding water and water reducer which are mixed uniformly in advance while mixing at a low speed (75 rpm) for 1 min, and then mixing at a low speed (75 rpm) for 3 min, and then mixing at a high speed (135 rpm) for 1 min to make the mixture uniform into slurry, thus obtaining a flowing matrix (fresh mortar); (3) adding PE fiber while mixing at a low speed (75 rpm) for 3 min, and then mixing at a low speed (75 rpm) for 4 min, and mixing at a high speed (135 rpm) for 4 min to uniformly disperse the fiber to obtain concrete slurry; and (4) quickly pouring the mixed concrete into the mold (making three cubes and three dog bones, and pouring six specimens in total), vibrating with a vibration table to eliminate bubbles in the specimens to make the specimens compact, and completing the flowability test. The specimens are covered with a film to prevent water evaporation, and then demoulded after 24 hours of indoor curing, and normally cured for 28 days in a sealed environment. After the expiration, the specimens are taken out for mechanical properties test.

Embodiment 6

(36) According to a cementitious composite with PET powder replacing quartz powder at a replacement ratio of 25%, the raw material ratio (material usage of 1 m.sup.3 concrete) is shown in Table 6:

(37) TABLE-US-00006 TABLE 6 Mix proportion design of cementitious composite (kg/m.sup.3) Quartz PET Water PE Cement Fly ash powder powder Water reducer fiber Thickener Defoamer 936.7 401.4 301.1 52.3 335.1 5.4 19.4 0.54 2.01

(38) The preparation method is as follows: (1) adding cement, fly ash, quartz powder, PET powder, thickener and defoamer into a concrete mixer, and mixing at a low speed of 75 rpm for 3 min to uniformly mix dry materials to obtain a concrete powder premix (dry material mixture); (2) adding water and water reducer which are mixed uniformly in advance while mixing at a low speed (75 rpm) for 1 min, and then mixing at a low speed (75 rpm) for 3 min, and then mixing at a high speed (135 rpm) for 1 min to make the mixture uniform into slurry, thus obtaining a flowing matrix (fresh mortar); (3) adding PE fiber while mixing at a low speed (75 rpm) for 3 min, and then mixing at a low speed (75 rpm) for 4 min, and mixing at a high speed (135 rpm) for 4 min to uniformly disperse the fiber to obtain concrete slurry; and (4) quickly pouring the mixed concrete into the mold (making three cubes and three dog bones, and pouring six specimens in total), vibrating with a vibration table to eliminate bubbles in the specimens to make the specimens compact, and completing the flowability test. The specimens are covered with a film to prevent water evaporation, and then demoulded after 24 hours of indoor curing, and normally cured for 28 days in a sealed environment. After the expiration, the specimens are taken out for mechanical properties test.

(39) Samples of concrete specimens obtained in the above Embodiment 1-Embodiment 6 are subjected to axial tensile tests (experimental data including tensile strength and peak tensile strain) and axial compression tests (data including compressive strength) respectively, and the test results are shown in Table 7 and FIG. 5-FIG. 7.

(40) The axial tensile tests of concrete dog bone specimens are carried out according to Japan Society of Civil Engineering (JSCE) specification, and are loaded by electronic universal testing machine. The loading mode is stretching in displacement control mode, and the loading rate is 0.5 millimeter per minute (mm/min). The axial strain of the 80 mm area in the middle of each of the specimens is measured by two symmetrical displacement meters, and the stress sensor and displacement meter are combined to assist in collecting data.

(41) The compressive strength om of concrete cube specimens is tested according to the Standard for test method of mechanical properties on ordinary concrete GB/50081-2002, and is obtained from cube compression tests, and the compressive strength of 50 mm50 mm50 mm cubes is measured. In this experiment, YAW-5000 microcomputer controlled electro-hydraulic servo pressure testing machine MATEST material testing machine is used, and the loading rate is 1800 Newton per second (N/s). Compressive strength is calculated according to the following formula:
m=F/A, where F is the force value recorded by the testing machine, and A is the stressed cross-sectional area.

(42) TABLE-US-00007 TABLE 7 PET volume Com- replace- Flow- Tensile Peak pressive ment ability/ strength/ tensile strength/ Sample ratio/% mm MPa strain/% MPa Embodiment 1 0 175 8.53 (0.12) 3.71 (0.40) 98.2 (2.0) Embodiment 2 5 183 8.92 (0.18) 3.69 (1.04) 100.8 (1.3) Embodiment 3 10 192 8.78 (0.28) 5.22 (1.50) 95.2 (1.3) Embodiment 4 15 199 9.12 (0.32) 6.16 (0.88) 89.2 (0.9) Embodiment 5 20 191 8.91 (0.27) 6.32 (1.47) 87.0 (1.3) Embodiment 6 25 182 8.19 (0.10) 6.53 (0.97) 87.3 (2.3)

(43) Note: the PET volume replacement ratio is the volume ratio of replacing quartz powder with PET powder. The result of the test is the average of three specimens, and the value in brackets is the standard deviation of the result.

(44) The flowability is the flowability test of fresh slurry (freshly mixed concrete slurry).

(45) It may be seen from the above table that the ultimate tensile strains of Embodiment 3-Embodiment 6 doped with PET powder are better than the ultimate tensile strain of Embodiment 1 not doped with PET powder, and the axial tensile strengths of Embodiment 2-Embodiment 5 are better than the axial tensile strength of Embodiment 1, and Embodiment 5 is the best embodiment combining the two results. The compressive strengths of Embodiment 3-Embodiment 6 are lower than the compressive strength of Embodiment 1, while the compressive strength of Embodiment 2 is slightly higher than the compressive strength of Embodiment 1. In addition, it may be seen that the flowability of Embodiment 2-Embodiment 6 doped with PET powder is higher than the flowability of Embodiment 1 not doped with PET powder.

(46) The better value range of PET volume replacement ratio is 15%-20%. Under this replacement ratio range, the flowability of fresh concrete may reach above 190 mm, the tensile strength may reach above 8.9 MPa, the ultimate tensile strain may reach above 6%, and the compressive strength may also be maintained at 87 MPa.

(47) The optimal value of PET volume replacement ratio is 15%. Under this replacement ratio, the flowability of fresh concrete reaches the highest of 199 mm, the tensile strength reaches the highest of 9.12 MPa, which is 6.92% higher than the tensile strength of the control group, the ultimate tensile strain reaches 6.16%, and the compressive strength may also be maintained at 89.2 MPa.

(48) Before the performance test, the shape and distribution of cracks may be observed by applying white paint on the surface of dog bone-like specimens, and the results are as follows.

(49) TABLE-US-00008 TABLE 8 PET Density volume Ultimate Average of replace- tensile Number crack cracks/per ment strain/ of width/ millimeter Sample ratio/% % cracks m (mm.sup.1) Embodiment 1 0 5.69 17 214 0.21 Embodiment 2 5 5.64 15 241 0.19 Embodiment 3 10 6.36 23 177 0.29 Embodiment 4 15 7.76 31 160 0.39 Embodiment 5 20 7.80 32 156 0.40 Embodiment 6 25 8.56 36 152 0.45

(50) FIG. 8 shows the interaction principle between PET and matrix. Because there is a wider interface transition zone between PET and matrix, micro-defects may be created in cementitious composite (ECC) by introducing PET, so that ECC may expand more micro-cracks to enhance the deformation performance.

(51) The above-mentioned embodiments only describe the preferred mode of the present disclosure, and do not limit the scope of the present disclosure. Under the premise of not departing from the design spirit of the present disclosure, various modifications and improvements made by one of ordinary skill in the art to the technical solution of the present disclosure should fall within the protection scope of the present disclosure.