Composite cement mortar for nodular cast iron pipe lining layer and preparation method of composite cement mortar

Abstract

The invention discloses composite cement mortar for a nodular cast iron pipe lining layer and a preparation method of the composite cement mortar. The composite cement mortar comprises the following raw material components: cement, sand, a polycarboxylic acid dispersing agent, a powder defoaming agent, a powder expanding agent, a retarder, redispersible latex powder and water. The invention can be widely applied to ordinary Portland cement, sulfate-resistant cement and high-alumina cement mortar, does not need additional additives during use, can be coated only by adding water into dry mortar and stirring, and has the advantages of convenience in use, high efficiency, crack resistance, low air entraining, strong adhesive force and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of ductile iron pipe inner linings and relates to a composite cement mortar for ductile iron pipe inner linings and a preparation method thereof. Background Art

[0002] At present, metal pipes are widely used as a fluid transport medium in the construction field, among which ductile iron pipes are widely used and play an increasingly important role. The performance of ductile iron pipes has changed greatly because they are fused with spheroidized graphite. Usually, a layer of cement mortar is centrifugally coated on the inner wall surface of the pipe after casting. The ductile iron pipe with cement mortar lining is easy to use, has a long service life, and has good corrosion resistance and mechanical properties.

[0003] In the existing technology, cement mortar is usually produced by mixing cement sand and then adding liquid admixtures and stirring with water. The liquid admixtures mainly contain polycarboxylic acid, aminosulfonate water reducer, sodium gluconate, sugar and other retarders. When using, cement and sand are evenly mixed, and then the liquid admixture and the specified amount of water are fully mixed and then centrifuged for coating. However, this material has the problems of cumbersome use, easy generation of bubbles during coating that affects the surface smoothness, easy shrinkage to produce cracks, and insufficient adhesion to the metal pipe wall, which has a great impact on production and use. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a composite cement mortar for the inner lining of a ductile iron pipe and a preparation method thereof. The mortar has the advantages of crack resistance, shrinkage resistance, strong adhesion and is easy to use.

[0005] The present invention is achieved through the following technical solutions:

[0006] A composite cement mortar for the inner lining of a ductile iron pipe is made of the following raw materials in parts by mass:

[0007] Cement: sand: polycarboxylic acid dispersant: powder defoamer: powder expansion agent: retarder: redispersible latex powder: water = (1-1.5): (0.2-0.4): (0.003-0.008): (0.0003-0.001): (0.00015-0.0004): (0.01-0.02): (0.0005-0.001): (0.25-0.3);

[0008] The water reduction rate of the polycarboxylic acid dispersant is ≧25%.

[0009] The cement is one or more of silicate cement, sulfate-resistant cement or high aluminate cement;

[0010] The mud content of sand is ≤2%, and the fineness modulus is 1.0-2.0.

[0011] The powder defoamer is a silicone or polyether defoamer;

[0012] The powder expansion agent is a calcium sulphoaluminate powder expansion agent;

[0013] The retarder is one or both of sodium tripolyphosphate and sodium hexametaphosphate.

[0014] The method for preparing the composite cement mortar for the inner lining of the ductile iron pipe comprises the following operations:

[0015] 1) Turn on the mixer, add cement and sand into the mixing tank in sequence and stir;

[0016] 2) Then add polycarboxylic acid dispersant, powder defoamer, powder expander, retarder, and redispersible latex powder in sequence and stir thoroughly;

[0017] 3) Discharging of dry composite mortar;

[0018] 4) Weigh a certain amount of dry mortar material and pour it into the mixer and stir;

[0019] 5) Add a matching amount of water, stir for 3-10 minutes, and then obtain a composite mortar.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] The composite cement mortar for the inner lining of a ductile iron pipe provided by the present invention optimizes the existing mortar, adds a powder admixture for premixing, reduces the step of adding liquid admixtures during production, and makes the production process simpler and more efficient. At the same time, the added defoaming agent and redispersible latex powder are further optimized to solve the problems of a large number of bubbles, easy shrinkage and cracks, and low adhesion to the pipe wall when the mortar is coated on the inner lining of the ductile iron pipe.

[0022] The composite cement mortar for the inner lining of a ductile iron pipe provided by the present invention comprises the following steps: after cement and sand are mixed, a powdered polycarboxylic acid high-performance dispersant is added to replace a liquid water reducing agent; a powdered defoaming agent is added to eliminate bubbles generated during stirring and centrifugal coating, thereby making the mortar denser and reducing bubbles; a powdered expansion agent (plastic expansion agent) is added to eliminate the volume shrinkage generated during cement hydration, thereby reducing the generation of cracks after the mortar is solidified; a retarder such as sodium tripolyphosphate and sodium hexametaphosphate is added to adjust the setting time of the mortar; and a redispersible latex powder is added to increase the viscosity of the system, improve the adhesion, and make the mortar more firmly bonded to the pipe wall.

[0023] The present invention can be widely applied to ordinary Portland cement, sulfate-resistant cement and high-alumina cement mortars. No additional additives are needed during use. The mortar dry material only needs to be added with water and stirred for coating. The invention has the advantages of easy use, high efficiency, crack resistance, low air entrainment, strong adhesion, etc., and can effectively solve the defects of existing mortars. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the embodiments, which are intended to explain the present invention rather than to limit it.

[0025] The composite cement mortar for the inner lining of a ductile iron pipe provided by the present invention has the following mass fraction ratios of the components:

[0026] Cement: sand: polycarboxylic acid dispersant: powder defoamer: powder expander: retarder: redispersible latex powder: water = (1-1.5): (0.2-0.4): (0.003-0.008): (0.0003-0.001): (0.00015-0.0004): (0.01-0.02): (0.0005-0.001): (0.25-0.3).

[0027] Wherein, the cement is one or more of silicate cement, sulfate-resistant cement or high aluminate cement;

[0028] The sand content is ≤2%, and the fineness modulus is 1.0-2.0;

[0029] Polycarboxylic acid dispersant, water reduction rate ≧25%;

[0030] Powder defoamer, which is silicone defoamer or polyether defoamer;

[0031] Powder expansion agent, calcium sulphoaluminate type powder expansion agent;

[0032] Retarder, which is one or both of sodium tripolyphosphate and sodium hexametaphosphate;

[0033] Redispersible latex powder, average particle size 80-100μm;

[0034] The present invention provides a method for preparing a composite cement mortar for an inner lining layer of a ductile iron pipe, comprising the following steps:

[0035] 1) Turn on the mixer, add cement and sand into the mixing tank in sequence according to the production formula and stir for 2 minutes.

[0036] 2) Add polycarboxylic acid dispersant, powder defoamer, powder expander, retarder, and redispersible latex powder in sequence according to the production formula and stir for 10 minutes;

[0037] 3) Discharging of dry composite mortar material.

[0038] 4) Weigh the specified amount of dry mortar material into the mixer and stir for 2 minutes.

[0039] 5) Add a matching amount of water, stir for 3 minutes and discharge the material to complete the production of the composite mortar of the present invention.

[0040] The following three embodiments are used to prepare the composite mortar of the present invention and perform performance tests.

[0041] Example 1

[0042] Allocation ratio of each group:

[0043] Cement (ordinary Portland cement): sand (mud content ≦2%, fineness modulus 1.0-2.0): polycarboxylic acid dispersant (water reduction rate ≧25%): powder defoaming agent (silicone defoaming agent): powder expansion agent (calcium sulfoaluminate type): retarder (sodium tripolyphosphate): redispersible latex powder: water = 1.0: 0.4: 0.003: 0.0003: 0.00015: 0.01: 0.0005: 0.25.

[0044] Specifically, the polycarboxylic acid dispersant was purchased from Shanghai Yingshan New Material Technology Co., Ltd., model PC-100.

[0045] Powder defoamer, purchased from Shanghai Yingshan New Material Technology Co., Ltd., model DF-07;

[0046] Powder expansion agent, purchased from Yantai Zhuorun New Building Materials Co., Ltd., model ZR;

[0047] Retarder, which is one or both of sodium tripolyphosphate and sodium hexametaphosphate;

[0048] Redispersible latex powder, purchased from Shaanxi Xutai Technology Industry Co., Ltd., model BMYF-211.

[0049] Example 2

[0050] Allocation ratio of each group:

[0051] Cement (sulfate-resistant cement): sand (mud content ≦2%, fineness modulus 1.0-2.0): polycarboxylic acid high-performance dispersant (water reduction rate ≧25%): powder defoamer (polyether defoamer): powder expansion agent (calcium sulfoaluminate type): retarder (sodium hexametaphosphate): redispersible latex powder: water = 1.5: 0.2: 0.008: 0.001: 0.0004: 0.02: 0.001: 0.3.

[0052] The use / purchase of polycarboxylic acid dispersant, powder defoamer, retarder, and redispersible latex powder are the same as in Example 1.

[0053] Example 3

[0054] Allocation ratio of each group:

[0055] Cement (high aluminate cement): sand (mud content ≦2%, fineness modulus 1.0-2.0): polycarboxylic acid high-performance dispersant (water reduction rate ≧25%): powder defoamer (silicone defoamer: polyether defoamer = 1:1): powder expansion agent (calcium sulfoaluminate type): retarder (sodium tripolyphosphate: sodium hexametaphosphate = 1:1): redispersible latex powder: water = 1.3: 0.3: 0.006: 0.0006: 0.00028: 0.015: 0.0007: 0.28.

[0056] The composite cement mortars and ordinary mortars prepared in the above three embodiments were tested for air content, adhesion, strength and roughness according to GB 8076-2008, GB175-2007, GB / T 17671-2021 and GB / T 1031-2009 standards. The test and comparison data are shown in Table 1.

[0057] Table 1 Air content, adhesion, strength and roughness test of mortar in lining of ductile iron pipe

[0058] Serial number Test items Technical indicators Existing mortar Example 1 Example 2 Example 3 1 28d strength ≥42.5MPa 44.3 55.8 56.7 57.6 2 Roughness k≦0.05mm 0.04mm 0.02mm 0.02mm 0.02mm 3 Gas content ≦3％ 2.1％ 0.8％ 0.7％ 0.5％ 4 Adhesion / 4.3MPa 6.8MPa 6.7MPa 6.4MPa

[0059] The present invention optimizes the existing mortar, adds powder admixtures for premixing, reduces the step of adding liquid admixtures during production, and makes the production process simpler and more efficient. The defoamer and redispersible latex powder added at the same time can effectively solve the problems of cumbersome use during coating of the existing mortar, low surface smoothness, easy shrinkage and cracking, and insufficient adhesion to the metal pipe wall due to the bubbles appearing in the later stage, and the performance is greatly improved compared with the existing composite cement mortar for the inner lining of ductile iron pipes.

[0060] The above embodiments are preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential additions and substitutions made by those skilled in the art based on the technical features of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A composite cement mortar for the inner lining of a ductile iron pipe, characterized in that: It is made of the following raw materials by weight: Cement: sand: polycarboxylic acid dispersant: powder defoamer: powder expansion agent: retarder: redispersible latex powder: water = (1-1.5): (0.2-0.4): (0.003-0.008): (0.0003-0.001): (0.00015-0.0004): (0.01-0.02): (0.0005-0.001): (0.25-0.3); The water reduction rate of the polycarboxylic acid dispersant is ≧25%.

2. The composite cement mortar for the inner lining of a ductile iron pipe according to claim 1, characterized in that: The cement is one or more of silicate cement, sulfate-resistant cement or high aluminate cement; The mud content of sand is ≤2%, and the fineness modulus is 1.0-2.

0.

3. The composite cement mortar for the inner lining of a ductile iron pipe according to claim 1, characterized in that: The powder defoamer is an organosilicon defoamer or a polyether defoamer; The powder expansion agent is a calcium sulphoaluminate powder expansion agent; The retarder is one or both of sodium tripolyphosphate and sodium hexametaphosphate.

4. The method for preparing the composite cement mortar for the inner lining of the ductile iron pipe according to claim 1, characterized in that: The following operations are included: 1) Turn on the mixer, add cement and sand into the mixing tank in sequence and stir; 2) Then add polycarboxylic acid dispersant, powder defoamer, powder expander, retarder, and redispersible latex powder in sequence and stir thoroughly; 3) Discharging of dry composite mortar; 4) Weigh a certain amount of dry mortar material and pour it into the mixer and stir; 5) Add a matching amount of water, stir for 3-10 minutes, and then obtain a composite mortar.