Method for preparing accelerator for sprayed mortar/concrete

Abstract

A method for preparing an accelerator for sprayed mortar/concrete is provided. The accelerator includes an organic component, inorganic component aluminum sulfate, an initiator, and a reductant. The organic component in the form of a polymer monomer is added to concrete and polymerized into a polymer network structure in the presence of the initiator and the reductant; and the inorganic component aluminum sulfate promotes rapid hydration of the concrete to form an inorganic network structure. Such organic-inorganic interpenetrating network thickens a cement-based material rapidly to achieve strong adhesion, fast-setting and hardening properties and effectively reduces resilience of the sprayed mortar/concrete. The accelerator prepared by the method is well compatible with all sorts of cement, efficient and environmentally friendly. The organic-inorganic interpenetrating network is formed by polymerization and cement hydration, and therefore, the toughness of the sprayed mortar/concrete is improved by the organic polymer-inorganic compound accelerator.

Claims

1. A method for preparing an accelerator for sprayed mortar/concrete, comprising: obtaining a polymer monomer by conducting an amine-epoxide ring-opening polymerization on a diepoxy organic matter with a structural formula of R.sub.1[CH(O)CH.sub.2].sub.2 and a primary amine with a structural formula of R.sub.2NH.sub.2, wherein the polymer monomer comprises a plurality of alkenyls and has a structural formula of ##STR00006## wherein R.sub.1 is an alkylene, an ether or a phenyl derivative, R.sub.2 is an unsaturated olefin group, and n≥2; and combining aluminum sulfate, the polymer monomer, an initiator and a reductant to form the accelerator, wherein the accelerator comprises: 40-45 parts by weight of the aluminum sulfate; 5-10 parts by weight of the polymer monomer; 0.5-1.2 parts by weight of the initiator; and 0.2-0.5 parts by weight of the reductant.

2. The method for preparing the accelerator for the sprayed mortar/concrete according to claim 1, wherein the polymer monomer has a weight average molecular weight of 400-5,000 g/mol.

3. The method for preparing the accelerator for the sprayed mortar/concrete according to claim 1, wherein the diepoxy organic matter is at least one selected from the group consisting of 1,3-diglycidyl glyceryl ether, 1,3-butadiene diepoxide, diepoxy-(+)-1,3-butadiene-D6, 1,2-bis(4-(oxiran-2-ylmethoxy)diphenylsulfone, bis(glycidoxypropyl)dibenzene, 2-[2-(oxiran-2-yl)ethyl]oxirane, glycerol diglycidyl ether, diglycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, and neopentyl glycol-1,4-butanediol diglycidyl ether.

4. The method for preparing the accelerator for the sprayed mortar/concrete according to claim 1, wherein the primary amine is at least one selected from the group consisting of allylamine, 4-aminostyrene, 3-aminostyrene, 3,3-Dimethylallylamine, but-3-en-1-amine, and 4-penten-1-amine.

5. The method for preparing the accelerator for the sprayed mortar/concrete according to claim 1, wherein the initiator is at least one selected from the group consisting of sodium persulfate and potassium persulfate.

6. The method for preparing the accelerator for the sprayed mortar/concrete according to claim 1, wherein the reductant is N,N,N′,N′-tetramethylethylenediamine.

7. The method for preparing the accelerator for the sprayed mortar/concrete according to claim 1, wherein the initiator and the reductant are an alkali-resistant redox complex initiation system.

8. A method of using the accelerator of claim 1 for sprayed motar/concrete, comprising adding the accelerator to the mortar/concrete, wherein the polymer monomer polymerizes and forms a polymer network structure in the presence of the initiator and the reductant, and the aluminum sulfate promotes rapid hydration of the mortar/concrete to form an organic-inorganic interpenetrating network to thicken the mortar/concrete rapidly to achieve strong adhesion and fast-setting properties and reduce resilience of the mortar/concrete.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) A method for preparing an accelerator for sprayed mortar/concrete is provided. The accelerator includes an organic component, an inorganic component aluminum sulfate, an initiator, and a reductant. The organic component in the form of a polymer monomer is added to concrete and polymerized into a polymer network structure in the presence of the initiator and the reductant. The inorganic component aluminum sulfate promotes rapid hydration and hardening of the concrete to form an organic-inorganic interpenetrating network that thickens a cement-based material rapidly to achieve strong adhesion and fast-setting properties and reduces rebound loss of the sprayed mortar/concrete.

(2) Further, the accelerator may include the following specific components:

(3) 40-45 parts by weight of aluminum sulfate,

(4) 5-10 parts by weight of a polymer monomer,

(5) 0.5-1.2 parts by weight of an initiator,

(6) 0.2-0.5 parts by weight of a reductant.

(7) Further, a method for synthesizing the polymer monomer may be to conduct amine-epoxide ring-opening polymerization on a diepoxy organic matter with a structural formula of R.sub.1[CH(O)CH.sub.2].sub.2 and a primary amine with a structural formula of R.sub.2NH.sub.2 to obtain the polymer monomer. The polymer monomer includes a plurality of alkenyls and has a structural formula of

(8) ##STR00002##
where R.sub.1 is an alkylene, an ether or a phenyl derivative, R.sub.2 is an unsaturated olefin group, and n≥2. Nitrogen and hydroxyl groups are contained in the molecular structure of the polymer monomer, which is similar to an alkylol amine structure, showing an early strength.

(9) Further, the polymer monomer may have a weight average molecular weight of 400-5,000 g/mol.

(10) Further, the diepoxy organic matter may be at least one selected from the group consisting of 1,3-diglycidyl glyceryl ether, 1,3-butadiene diepoxide, diepoxy-(+)-1,3-butadiene-D6, 1,2-bis(4-(oxiran-2-ylmethoxy)diphenyl sulfone, bis(glycidoxypropyl)dibenzene, 2-[2-(oxiran-2-yl)ethyl]oxirane, glycerol diglycidyl ether, diglycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, and neopentyl glycol-1,4-butanediol diglycidyl ether.

(11) Further, the primary amine may be at least one selected from the group consisting of allylamine, 4-aminostyrene, 3-aminostyrene, 3,3-Dimethylallylamine, but-3-en-1-amine, and 4-penten-1-amine.

(12) Further, the initiator may be at least one selected from the group consisting of sodium persulfate and potassium persulfate.

(13) Further, the reductant may be N,N,N′,N′-tetramethylethylenediamine.

(14) Further, the initiator and the reductant may be an alkali-resistant redox complex initiation system.

Embodiment 1

(15) An accelerator for sprayed mortar/concrete was prepared with the following components:

(16) 45 parts by weight of aluminum sulfate,

(17) 10 parts by weight of a polymer monomer,

(18) 1.4 parts by weight of potassium persulfate, and

(19) 0.5 parts by weight of N,N,N′,N′-tetramethylethylenediamine.

(20) The polymer monomer had a structural formula of

(21) ##STR00003##
and a weight average molecular weight of 3,000 g/mol.

Embodiment 2

(22) An accelerator for sprayed mortar/concrete was prepared with the following components:

(23) 40 parts by weight of aluminum sulfate,

(24) 5 parts by weight of a polymer monomer,

(25) 1.2 parts by weight of potassium persulfate, and

(26) 0.5 parts by weight of N,N,N′,N′-tetramethylethylenediamine.

(27) The polymer monomer had a structural formula of

(28) ##STR00004##
and a weight average molecular weight of 400 g/mol.

Embodiment 3

(29) An accelerator for sprayed mortar/concrete was prepared with the following components:

(30) 45 parts by weight of aluminum sulfate,

(31) 8 parts by weight of a polymer monomer,

(32) 0.8 parts by weight of potassium persulfate, and

(33) 0.5 parts by weight of N,N,N′,N′-tetramethylethylenediamine.

(34) The polymer monomer had a structural formula of

(35) ##STR00005##
and a weight average molecular weight of 5,000 g/mol.

(36) Performance Testing:

(37) Reference cement was used, and main compositions of the reference cement are listed in Table 1. In accordance with GBT 35159-2017, setting time, flexural strength, and compressive strength were tested on Embodiments 1, 2, and 3.

(38) TABLE-US-00001 TABLE 1 Chemical and mineral compositions of reference cement Mass fraction w/ % SiO.sub.2 A.sub.2O.sub.3 F.sub.2O.sub.3 CaO MgO SO.sub.3 Na.sub.2Oeq f-CaO C.sub.3S C.sub.2S C.sub.3A C.sub.4AF 22.91 4.29 2.89 66.23 1.93 0.34 0.71 0.63 58.68 21.48 6.49 8.79

(39) Setting Time Test:

(40) 400 g of concrete and 16 g of 4% accelerator were poured into an agitator kettle of a cement paste mixer; the mixer was started to agitate for 10 s at low speed and then paused; subsequently, 140 g of water was added at one time, and the mixture was agitated at low speed for 5 s and at high speed for 15 s; after the agitation is stopped, the mixture was filled in a master stamper immediately, inserted and beaten with a knife, and shaken gently a plurality of times; redundant paste was scraped off, and the surface was trowelled; since water addition, all operations did not exceed 50 s. Setting time test was conducted.

(41) Flexural Strength Test and Compressive Strength Test:

(42) 900 g of concrete and 36 g of 4% accelerator were poured into an agitator kettle; a mixer was started to agitate for 30 s at low speed until mixed well; in a second process of 30-second low-speed agitation, 1,350 g of standard sand and 450 g of water were added evenly and agitated for 5 s at low speed and 15 s at high speed; the agitation was ended. The mortar obtained was charged into a cement mortar mold as soon as possible, and subsequent flexural strength test and compressive strength test were conducted.

(43) 1. Setting Time Test:

(44) The accelerators prepared in Embodiments 1, 2, and 3 were added and subjected to the setting time test. Results are shown in Table 2. The experimental results proved that all of the accelerators prepared in embodiments met the Chinese national standard.

(45) TABLE-US-00002 TABLE 2 Effects of accelerators on setting time of reference cement Initial setting Final setting time time Sample Dosage (%) (min:second) (min:second) 1 4.0 2:10 6:40 2 1:50 7:00 3 1:55 5:50

(46) 2. Flexural Strength Test:

(47) The accelerators prepared in Embodiments 1, 2, and 3 were added and subjected to the mortar flexural strength test. Results are shown in Table 3. The experimental results proved that all of the accelerators prepared in embodiments improved early and 28 d flexural strengths.

(48) TABLE-US-00003 TABLE 3 Mortar flexural strength test Percent flexural strength (%) Accelerator Dosage (%) 1 d 7 d 28 d None 0 100 100 100 1 4.0 152 156 168 2 165 161 173 3 163 165 175

(49) 3. Compressive Strength Test:

(50) The accelerators prepared in Embodiments 1, 2, and 3 and control sample Tianjin™ accelerator were added and subjected to the compressive strength test. Results are shown in Table 4. The experimental results proved that: there was no decrease in 28 d strength when using the accelerators; all the three accelerators prepared in embodiments met the Chinese national standard, and had better retention rate before 28 d than the Tianjin™ accelerator.

(51) TABLE-US-00004 TABLE 4 Mortar compressive strength test Percent compressive strength (%) Accelerator Dosage (%) 1 d 7 d 28 d None 0 100 100 100 1 4.0 113 103.2 101.3 2 118 104 101.5 3 116 106 102.5 Tianjin ™ 107 90.2 87

(52) Although the present invention has been described as above in the preferred embodiments, they are not intended to limit the present invention. Various alterations or modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope defined by the claims of the present application.