阅读说明：本技术 一种氧化石墨烯改性再生混凝土及其制备方法 (Graphene oxide modified recycled concrete and preparation method thereof ) 是由 刘裕 暴宁钟 李东旭 王凯 刘明乐 宫燨宝 于 2021-11-16 设计创作，主要内容包括：本发明公开了一种氧化石墨烯改性再生混凝土及其制备方法,包括200-230份硅酸盐水泥、1100-1250份再生骨料、20-35份氧化石墨烯、10-20份乙烯基三乙氧基硅烷、3-5份双氧水、0.2-0.5份氢氧化钠、1.5-4.5份氧化石墨烯改性聚羧酸减水剂和150-180份水。其中的制备本发明的氧化石墨烯改性再生混凝土的方法包括：包括以下步骤：a、将0.5-1.5份氧化石墨烯改性聚羧酸减水剂、3-5份双氧水、0.2-0.5份氢氧化钠和50-100份水倒入搅拌机混匀,再加入1100-1250份再生骨料搅拌15-30秒；b、将20-35份氧化石墨烯、10-20份乙烯基三乙氧基硅烷和50-75份水搅拌均匀加入搅拌机后搅拌15-30秒,再加入200-230份硅酸盐水泥搅拌30-50秒；c、将1-3份氧化石墨烯改性聚羧酸减水剂和50-80份水搅拌均匀后加入搅拌机,再搅拌60-120秒。(The invention discloses graphene oxide modified recycled concrete and a preparation method thereof, wherein the graphene oxide modified recycled concrete comprises 230 portions of 200-1250 portions of silicate cement, 20-35 portions of graphene oxide, 10-20 portions of vinyl triethoxysilane, 3-5 portions of hydrogen peroxide, 0.2-0.5 portion of sodium hydroxide, 1.5-4.5 portions of graphene oxide modified polycarboxylic acid water reducer and 180 portions of 150-180 portions of water. The method for preparing the graphene oxide modified recycled concrete comprises the following steps: the method comprises the following steps: a. pouring 0.5-1.5 parts of graphene oxide modified polycarboxylic acid water reducing agent, 3-5 parts of hydrogen peroxide, 0.2-0.5 part of sodium hydroxide and 50-100 parts of water into a stirrer for uniformly mixing, and then adding 1100-1250 parts of recycled aggregate and stirring for 15-30 seconds; b. uniformly stirring 20-35 parts of graphene oxide, 10-20 parts of vinyl triethoxysilane and 50-75 parts of water, adding the mixture into a stirrer, stirring for 15-30 seconds, adding 200-230 parts of portland cement, and stirring for 30-50 seconds; c. and (2) uniformly stirring 1-3 parts of graphene oxide modified polycarboxylic acid water reducing agent and 50-80 parts of water, adding into a stirrer, and stirring for 60-120 seconds.)

1. The graphene oxide modified recycled concrete is characterized by comprising 230 parts of 200-1250 parts of Portland cement, 1250 parts of recycled aggregate, 20-35 parts of graphene oxide, 10-20 parts of vinyl triethoxysilane, 3-5 parts of hydrogen peroxide, 0.2-0.5 part of sodium hydroxide, 1.5-4.5 parts of graphene oxide modified polycarboxylic acid water reducer and 180 parts of 150-180 parts of water.

2. The preparation method of the graphene oxide modified recycled concrete is characterized by comprising the following steps:

a. pouring 0.5-1.5 parts of graphene oxide modified polycarboxylic acid water reducing agent and 30-60 parts of water into a stirrer for uniformly mixing, and then adding 1100 and 1250 parts of recycled aggregate for stirring for 15-30 seconds; 3-5 parts of hydrogen peroxide, 0.2-0.5 part of sodium hydroxide and 20-70 parts of water are stirred for 4-10 seconds, added into a stirrer and stirred for 15-30 seconds;

b. uniformly stirring 20-35 parts of graphene oxide, 10-20 parts of vinyl triethoxysilane and 50-75 parts of water, adding the mixture into a stirrer, stirring for 15-30 seconds, adding 200-230 parts of portland cement, and stirring for 30-50 seconds;

c. and (2) uniformly stirring 1-3 parts of graphene oxide modified polycarboxylic acid water reducing agent and 50-80 parts of water, adding into a stirrer, and stirring for 60-120 seconds.

3. The preparation method of the graphene oxide modified recycled concrete according to claim 2, wherein the preparation steps of the graphene oxide modified polycarboxylic acid water reducer are as follows:

a. weighing 1000 parts of graphene oxide, carrying out ultrasonic treatment for 2 hours, then placing the graphene oxide in a reaction kettle for stirring, and heating the graphene oxide to 70 ℃ in a water bath; weighing 4 parts of vinyltriethoxysilane, and reacting for 2 hours to obtain coupling agent grafted graphene oxide;

b. weighing 400 parts of 300-part allyl polyoxyethylene ether and 2-3 parts of hydrogen peroxide according to the mass ratio, sequentially adding 300 parts of 100-part coupling agent grafted graphene oxide obtained in the step (1) into a four-neck flask, controlling the reaction temperature to be 60 ℃, and stirring for 2 hours at the rotating speed of 300 r/min;

c. then adding 15-25 parts of acrylic acid and 40-60 parts of hydroxyethyl acrylate which are weighed according to the mass ratio, and controlling the dripping time within 2-2.5 h; continuously dropwise adding 1-3 parts of ascorbic acid, 1.5-3.5 parts of thioglycollic acid and 90-120 parts of water which are weighed according to the mass ratio, wherein the dropwise adding time is controlled within 2.5-3 h;

d. 5mol/L of sodium hydroxide solution is dripped, and 300 parts of water supplement of 150-. And adjusting the pH value to 6.8-7.2, and uniformly mixing to obtain the graphene oxide modified polycarboxylic acid water reducer.

Technical Field

The invention belongs to the field of building materials, relates to recycled concrete, and particularly relates to graphene oxide modified recycled concrete and a preparation method thereof.

Background

Along with the continuous acceleration of the urbanization process in China, a large amount of construction waste is generated in the removal of old buildings, the reconstruction of houses and the construction of new buildings. The quantity of construction waste which is continuously increased nowadays reaches 30% -40% of that of urban waste, and the utilization rate of the construction waste in China is less than 5%. The accumulated construction waste occupies a large amount of land, damages a soil structure, causes ground surface settlement, influences the quality of air and water, and brings serious consequences to the environment, so that the recycling of the construction waste is a common struggle target of people in many industries.

At present, the resource utilization approach of the construction waste mainly focuses on the aspect of recycling coarse/fine aggregates. Research has shown that the fracture of the recycled cement-based composite material occurs at the interface junction of the lightweight aggregate and the cementing material, the mechanical properties and the durability of the recycled concrete and the recycled mortar are reduced along with the increase of the replacement rate of the recycled aggregate, and the graphene oxide is used as one of the main representatives of the development of the nano material, so that the graphene oxide has good dispersibility and unique physical properties in water, and is widely applied to the cement-based composite material.

However, the existing recycled concrete has the defects of large frictional resistance between aggregate and cement particles, thick aperture and unstable mechanical property of a recycled cement-based composite material, wherein the recycled aggregate mainly comprises a small amount of stones for stripping mortar, a part of stones for wrapping the mortar and a small amount of independently agglomerated cement mortar. A large amount of fine cracks and rough and angular surfaces of cement mortar can appear in the aggregate when the waste concrete is subjected to a large external force in the crushing process, so that the apparent density of the recycled aggregate can be as low as 85% of that of the natural aggregate, and the water absorption rate is as high as 6-8 times of that of the natural aggregate, thereby causing the low compactness of the recycled concrete structure and the poor mechanical and durable properties.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide graphene oxide modified recycled concrete and a preparation method thereof.

According to one aspect of the present invention, in order to achieve the above object, the graphene oxide modified recycled concrete of the present invention is formed by adopting the following technical scheme: comprises 230 portions of 200-1250 portions of Portland cement, 1250 portions of 1100-1250 portions of recycled aggregate, 20-35 portions of graphene oxide, 10-20 portions of vinyl triethoxysilane, 3-5 portions of hydrogen peroxide, 0.2-0.5 portion of sodium hydroxide, 1.5-4.5 portions of graphene oxide modified polycarboxylic acid water reducer and 180 portions of 150-180 portions of water.

According to another aspect of the present invention, a method for preparing graphene oxide modified recycled concrete of the present invention comprises: the method comprises the following steps:

a. pouring 0.5-1.5 parts of graphene oxide modified polycarboxylic acid water reducing agent, 3-5 parts of hydrogen peroxide, 0.2-0.5 part of sodium hydroxide and 50-100 parts of water into a stirrer for uniformly mixing, and then adding 1100-1250 parts of recycled aggregate and stirring for 15-30 seconds;

b. uniformly stirring 20-35 parts of graphene oxide, 10-20 parts of vinyl triethoxysilane and 50-75 parts of water, adding the mixture into a stirrer, stirring for 15-30 seconds, adding 200-230 parts of portland cement, and stirring for 30-50 seconds;

c. and (2) uniformly stirring 1-3 parts of graphene oxide modified polycarboxylic acid water reducing agent and 50-80 parts of water, adding into a stirrer, and stirring for 60-120 seconds.

The preparation method of the graphene oxide modified polycarboxylate superplasticizer comprises the following steps:

a. weighing 1000 parts of graphene oxide, carrying out ultrasonic treatment for 2 hours, then placing the graphene oxide in a reaction kettle for stirring, and heating the graphene oxide to 70 ℃ in a water bath; weighing 4 parts of vinyltriethoxysilane, and reacting for 2 hours to obtain coupling agent grafted graphene oxide;

b. weighing 400 parts of 300-part allyl polyoxyethylene ether and 2-3 parts of hydrogen peroxide according to the mass ratio, sequentially adding 300 parts of 100-part coupling agent grafted graphene oxide obtained in the step (1) into a four-neck flask, controlling the reaction temperature to be 60 ℃, and stirring for 2 hours at the rotating speed of 300 r/min;

c. then adding 15-25 parts of acrylic acid and 40-60 parts of hydroxyethyl acrylate which are weighed according to the mass ratio, and controlling the dripping time within 2-2.5 h; continuously dropwise adding 1-3 parts of ascorbic acid, 1.5-3.5 parts of thioglycollic acid and 90-120 parts of water which are weighed according to the mass ratio, wherein the dropwise adding time is controlled within 2.5-3 h;

d. 5mol/L of sodium hydroxide solution is dripped, and 300 parts of water supplement of 150-. And adjusting the pH value to 6.8-7.2, and uniformly mixing to obtain the graphene oxide modified polycarboxylic acid water reducer.

Due to the adoption of the technical scheme, compared with the existing recycled concrete, the recycled concrete has the following advantages: (1) the recycled concrete has large water demand due to rough surface and porous structure of the recycled aggregate, and a large amount of free water is adsorbed in the pores of the recycled aggregate in the stirring and forming process, so that the interface transition area is thick and the performance is poor. The comb-shaped structure composed of the polyelectrolyte main chain of anions and the nonionic side chain in the graphene oxide modified polycarboxylate superplasticizer is adsorbed on the inner surface of the pores of the recycled aggregate. The hydrogen peroxide foams under the excitation of an alkaline environment in which sodium hydroxide is dissolved, and the charge layer of the bubble interface enables the bubble interface to be attached to the outer layer of the water reducing agent, so that the pore filling water is reduced, the interface transition area is thinned, and the performance of the concrete is improved. (2) The vinyl triethoxysilane is attached to the charge layer of the bubbles to form coupling pressure with the side chain of the water reducing agent, and the foaming size of the hydrogen peroxide is controlled at micro-nano level, so that the fluidity of cement paste can be effectively improved, and the water demand can be reduced. Meanwhile, graphene oxide in the condensation body of vinyl triethoxysilane and graphene oxide serves as a seed crystal to promote hydration products to gather on the outer layer of the bubbles, so that the microstructure inside the hardening body is adjusted, and an interface transition region is thinned. (3) The vinyl triethoxysilane is hydrolyzed in the water solution to generate silanol, the silanol and hydroxyl on the surface of the graphene oxide are subjected to dehydration condensation reaction to generate-Si-O-C-, so that the vinyl triethoxysilane and the graphene oxide are stably and covalently connected, and the dispersibility of the graphene oxide in the cement slurry is improved. (4) The graphene oxide modified polycarboxylate water reducer provided by the invention not only enhances the water reducing effect because the nano graphene oxide modifies the space structure of the polycarboxylate water reducer, but also enables a silane coupling agent to be hydrolyzed in an aqueous solution to generate silanol, and the silanol and hydroxyl on the surface of GO to generate dehydration condensation reaction to generate-Si-O-C-, so that the coupling agent and GO generate stable covalent connection. And then, polycarboxylic acid molecules are grafted on GO molecules, so that the effect of enhancing the dispersing capacity of GO is achieved.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments below:

the invention discloses graphene oxide modified recycled concrete and a preparation method thereof, wherein the graphene oxide modified recycled concrete comprises the following steps:

example 1

A graphene oxide modified recycled concrete and a preparation method thereof are disclosed: (1) weighing 1000 parts of graphene oxide, carrying out ultrasonic treatment for 2 hours, then placing the graphene oxide in a reaction kettle for stirring, and heating the graphene oxide to 70 ℃ in a water bath; and weighing 4 parts of vinyltriethoxysilane (10 ml of absolute ethyl alcohol is added to assist dissolution if necessary) and reacting for 2 hours to obtain the coupling agent grafted graphene oxide.

(2) Weighing 300 parts of HPEG allyl polyoxyethylene ether and 2 parts of hydrogen peroxide according to the mass ratio, and adding 100 parts of the coupling agent grafted graphene oxide obtained in the step (1) into a four-neck flask in sequence, controlling the reaction temperature to be 60 ℃, and stirring for 2 hours at the rotating speed of 300 r/min;

(3) then adding 15 parts of AA acrylic acid and 40 parts of HEA hydroxyethyl acrylate which are weighed according to the mass ratio, and controlling the dropping time within 2 hours; continuously dropwise adding 1 part of VC ascorbic acid, 1.5 parts of TGA thioglycollic acid and 90 parts of water which are weighed according to the mass ratio, wherein the dropwise adding time is controlled within 2.5;

(4) 5mol/L sodium hydroxide solution was added dropwise, and 150 parts of the moisturizing water was neutralized. And adjusting the pH value to 6.8, and uniformly mixing to obtain the graphene oxide modified polycarboxylic acid water reducer.

(5) Pouring 0.5 part of graphene oxide modified polycarboxylic acid water reducing agent, 3 parts of hydrogen peroxide, 0.2 part of sodium hydroxide and 50 parts of water into a stirrer, uniformly mixing, adding 1100 parts of recycled aggregate, and stirring for 15 seconds;

(6) uniformly stirring 20 parts of graphene oxide, 10 parts of vinyltriethoxysilane and 50 parts of water, adding the mixture into a stirrer, stirring for 15 seconds, adding 200 parts of portland cement, and stirring for 30 seconds;

(7) 1 part of graphene oxide modified polycarboxylate superplasticizer and 50 parts of water are uniformly stirred and then added into a stirrer, and the mixture is stirred for 6 seconds.

Example 2

A graphene oxide modified recycled concrete and a preparation method thereof are disclosed: (1) weighing 1000 parts of graphene oxide, carrying out ultrasonic treatment for 2 hours, then placing the graphene oxide in a reaction kettle for stirring, and heating the graphene oxide to 70 ℃ in a water bath; and weighing 4 parts of vinyltriethoxysilane (10 ml of absolute ethyl alcohol is added to assist dissolution if necessary) and reacting for 2 hours to obtain the coupling agent grafted graphene oxide.

(2) Weighing 400 parts of HPEG allyl polyoxyethylene ether and 2-3 parts of hydrogen peroxide according to the mass ratio, and 300 parts of the coupling agent grafted graphene oxide obtained in the step (1), sequentially adding the weighed materials into a four-neck flask, controlling the reaction temperature to be 60 ℃, and stirring for 2 hours at the rotating speed of 300 r/min;

(3) then adding 25 parts of AA acrylic acid and 60 parts of HEA hydroxyethyl acrylate which are weighed according to the mass ratio, and controlling the dropping time within 2.5 h; continuously dropwise adding 3 parts of VC ascorbic acid, 3.5 parts of TGA thioglycollic acid and 120 parts of water which are weighed according to the mass ratio, wherein the dropwise adding time is controlled within 3 hours;

(4) 5mol/L sodium hydroxide solution is added dropwise, and 300 parts of moisturizing water are neutralized. And adjusting the pH value to 7.2, and uniformly mixing to obtain the graphene oxide modified polycarboxylic acid water reducer.

(5) Pouring 1.5 parts of graphene oxide modified polycarboxylic acid water reducing agent, 5 parts of hydrogen peroxide, 0.5 part of sodium hydroxide and 100 parts of water into a stirrer for uniformly mixing, and then adding 1250 parts of recycled aggregate and stirring for 30 seconds;

(6) uniformly stirring 35 parts of graphene oxide, 20 parts of vinyltriethoxysilane and 75 parts of water, adding the mixture into a stirrer, stirring for 30 seconds, adding 230 parts of portland cement, and stirring for 50 seconds;

(7) and (3) uniformly stirring the graphene oxide modified polycarboxylate superplasticizer and 80 parts of water, adding into a stirrer, and stirring for 120 seconds.

Example 3

A graphene oxide modified recycled concrete and a preparation method thereof are disclosed: (1) weighing 1000 parts of graphene oxide, carrying out ultrasonic treatment for 2 hours, then placing the graphene oxide in a reaction kettle for stirring, and heating the graphene oxide to 70 ℃ in a water bath; and weighing 4 parts of vinyltriethoxysilane (10 ml of absolute ethyl alcohol is added to assist dissolution if necessary) and reacting for 2 hours to obtain the coupling agent grafted graphene oxide.

(2) Weighing 360 parts of HPEG allyl polyoxyethylene ether and 2.2 parts of hydrogen peroxide according to the mass ratio, and 210 parts of the coupling agent grafted graphene oxide obtained in the step (1), sequentially adding the weighed materials into a four-neck flask, controlling the reaction temperature to be 60 ℃, and stirring for 2 hours at the rotating speed of 300 r/min;

(3) then adding 21 parts of AA acrylic acid and 52 parts of HEA hydroxyethyl acrylate which are weighed according to the mass ratio, and controlling the dripping time within 2.2 h; continuously dropwise adding 1.8 parts of VC ascorbic acid, 2.2 parts of TGA thioglycollic acid and 100 parts of water which are weighed according to the mass ratio, wherein the dropwise adding time is controlled within 2.8 h;

(4) 5mol/L sodium hydroxide solution was added dropwise, and 210 parts of the moisturizing water was neutralized. And adjusting the pH value to 7.0, and uniformly mixing to obtain the graphene oxide modified polycarboxylic acid water reducer.

(5) Pouring 0.9 part of graphene oxide modified polycarboxylic acid water reducing agent, 3.8 parts of hydrogen peroxide, 0.3 part of sodium hydroxide and 80 parts of water into a stirrer for uniformly mixing, and then adding 1190 part of recycled aggregate and stirring for 20 seconds;

(6) uniformly stirring 30 parts of graphene oxide, 18 parts of vinyl triethoxysilane and 65 parts of water, adding the mixture into a stirrer, stirring for 20 seconds, adding 210 parts of portland cement, and stirring for 40 seconds;

(7) and (3) uniformly stirring 2 parts of graphene oxide modified polycarboxylic acid water reducing agent and 70 parts of water, adding into the stirrer, and stirring for 90 seconds.

Comparative example 1

A graphene oxide modified recycled concrete and a preparation method thereof are disclosed:

(1) pouring 0.9 part of polycarboxylic acid water reducing agent, 3.8 parts of hydrogen peroxide, 0.3 part of sodium hydroxide and 80 parts of water into a stirrer, uniformly mixing, adding 1190 part of recycled aggregate, and stirring for 20 seconds;

(2) uniformly stirring 30 parts of graphene oxide, 18 parts of vinyl triethoxysilane and 65 parts of water, adding the mixture into a stirrer, stirring for 20 seconds, adding 210 parts of portland cement, and stirring for 40 seconds;

(3) and (3) uniformly stirring 2 parts of polycarboxylic acid water reducing agent and 70 parts of water, adding into the stirrer, and stirring for 90 seconds.

Comparative example 2

A graphene oxide modified recycled concrete and a preparation method thereof are disclosed: (1) weighing 1000 parts of graphene oxide, carrying out ultrasonic treatment for 2 hours, then placing the graphene oxide in a reaction kettle for stirring, and heating the graphene oxide to 70 ℃ in a water bath; and weighing 4 parts of vinyltriethoxysilane (10 ml of absolute ethyl alcohol is added to assist dissolution if necessary) and reacting for 2 hours to obtain the coupling agent grafted graphene oxide.

(2) Weighing 360 parts of HPEG allyl polyoxyethylene ether and 2.2 parts of hydrogen peroxide according to the mass ratio, and 210 parts of the coupling agent grafted graphene oxide obtained in the step (1), sequentially adding the weighed materials into a four-neck flask, controlling the reaction temperature to be 60 ℃, and stirring for 2 hours at the rotating speed of 300 r/min;

(3) then adding 21 parts of AA acrylic acid and 52 parts of HEA hydroxyethyl acrylate which are weighed according to the mass ratio, and controlling the dripping time within 2.2 h; continuously dropwise adding 1.8 parts of VC ascorbic acid, 2.2 parts of TGA thioglycollic acid and 100 parts of water which are weighed according to the mass ratio, wherein the dropwise adding time is controlled within 2.8 h;

(4) 5mol/L sodium hydroxide solution was added dropwise, and 210 parts of the moisturizing water was neutralized. And adjusting the pH value to 7.0, and uniformly mixing to obtain the graphene oxide modified polycarboxylic acid water reducer.

(5) Pouring 0.9 part of graphene oxide modified polycarboxylic acid water reducing agent, 0.3 part of sodium hydroxide and 80 parts of water into a stirrer, uniformly mixing, adding 1190 part of recycled aggregate, and stirring for 20 seconds;

(6) uniformly stirring 30 parts of graphene oxide, 18 parts of vinyl triethoxysilane and 65 parts of water, adding the mixture into a stirrer, stirring for 20 seconds, adding 210 parts of portland cement, and stirring for 40 seconds;

(7) and (3) uniformly stirring 2 parts of graphene oxide modified polycarboxylic acid water reducing agent and 70 parts of water, adding into the stirrer, and stirring for 90 seconds.

Comparative example 3

A graphene oxide modified recycled concrete and a preparation method thereof are disclosed: (1) weighing 1000 parts of graphene oxide, carrying out ultrasonic treatment for 2 hours, then placing the graphene oxide in a reaction kettle for stirring, and heating the graphene oxide to 70 ℃ in a water bath; and weighing 4 parts of vinyltriethoxysilane (10 ml of absolute ethyl alcohol is added to assist dissolution if necessary) and reacting for 2 hours to obtain the coupling agent grafted graphene oxide.

(2) Weighing 360 parts of HPEG allyl polyoxyethylene ether and 2.2 parts of hydrogen peroxide according to the mass ratio, and 210 parts of the coupling agent grafted graphene oxide obtained in the step (1), sequentially adding the weighed materials into a four-neck flask, controlling the reaction temperature to be 60 ℃, and stirring for 2 hours at the rotating speed of 300 r/min;

(3) then adding 21 parts of AA acrylic acid and 52 parts of HEA hydroxyethyl acrylate which are weighed according to the mass ratio, and controlling the dripping time within 2.2 h; continuously dropwise adding 1.8 parts of VC ascorbic acid, 2.2 parts of TGA thioglycollic acid and 100 parts of water which are weighed according to the mass ratio, wherein the dropwise adding time is controlled within 2.8 h;

(4) 5mol/L sodium hydroxide solution was added dropwise, and 210 parts of the moisturizing water was neutralized. And adjusting the pH value to 7.0, and uniformly mixing to obtain the graphene oxide modified polycarboxylic acid water reducer.

(5) Pouring 0.9 part of graphene oxide modified polycarboxylic acid water reducing agent, 3.8 parts of hydrogen peroxide, 0.3 part of sodium hydroxide and 80 parts of water into a stirrer for uniformly mixing, and then adding 1190 part of recycled aggregate and stirring for 20 seconds;

(6) uniformly stirring 30 parts of graphene oxide and 65 parts of water, adding the mixture into a stirrer, stirring for 20 seconds, adding 210 parts of portland cement, and stirring for 40 seconds;

(7) and (3) uniformly stirring 2 parts of graphene oxide modified polycarboxylic acid water reducing agent and 70 parts of water, adding into the stirrer, and stirring for 90 seconds. And (3) measuring the compressive strength and the slump of the concrete according to GB50164-2011 concrete quality control standard.

TABLE 1 concrete Properties

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.