JP5177963B2 - Method for imparting expansibility to hardened cement concrete - Google Patents

Description

  The present invention relates to a hardened cement concrete used mainly in the field of civil engineering and architecture, a cement composition thereof, and a method for producing a hardened cement concrete.

In chemical factories that manufacture or handle chemicals, sewerage facilities that handle various chemicals and pollutants, advanced water treatment plants, etc., construct structures using concrete that is highly resistant to chemical degradation. It is demanded.
In addition, for repair and reinforcement of concrete structures that are placed in a chemically harsh environment, protective materials are installed to cover the deteriorated parts, and protective materials are installed on the surface after repair. As a protective material used for such repair and reinforcement, it is necessary to apply a paint or cement with high chemical resistance to protect the surface or to perform regular repairs.

Alumina cement is known as a cement having high resistance to chemical degradation (see Patent Document 1).
Moreover, the manufacturing method of the high intensity | strength mortar hardening body etc. which age the cement mortar composition containing an alumina cement and a slag composition at the temperature of 30 degreeC or more are also known (refer patent document 2).
However, alumina cement has a property that initial strength development is quicker than portland cement, but long-term strength decreases due to hydrate conversion.

JP 2003-261372 A JP 2006-062946 A

  Even if the chemical deterioration resistance is high, if cracks occur in concrete, salt, sulfate, etc. may enter the concrete and deteriorate the reinforcing bars and the frame. For this reason, the improvement of crack resistance was calculated | required.

The present invention, binder is alumina cement, and also contains the aggregate, and water, the water / binder ratio of the cement composition is from 22 to 60%, kneading, before 8 hours between standing time, the temperature It is a method of imparting expansibility to a cement concrete hardened body, characterized by curing by heating at 35 to 90 ° C at a temperature rate of 5 to 30 ° C / hr, and the binder is alumina cement, Furthermore, it contains CaO-Al ₂ O ₃ —SiO ₂ compound and / or limestone powder, and 40 parts of alumina cement are included in 100 parts in total of alumina cement, CaO—Al ₂ O ₃ —SiO ₂ compound and limestone powder. It is a method of imparting expansibility to the cement concrete hardened body that is at least part, CaO-Al ₂ O ₃ —SiO ₂ compound, CaO 40-55 parts, Al ₂ O ₃ 15-30 parts, and SiO Is a method for imparting expansibility to the cement concrete hardened body containing ₂₀ to 35 parts of CaO-Al ₂ O This is a method of imparting expansibility to the cement concrete hardened body in which the vitrification rate of the _3- SiO ₂ compound is 50% or more.

  By curing the concrete under predetermined conditions, it is possible to impart expansibility, and in addition to conventional chemical degradation resistance, it is also possible to impart crack resistance.

The parts and% used in the present invention are based on mass unless otherwise specified.
Moreover, the cement concrete said by this invention is a general term for cement paste, mortar, and concrete.

  The alumina cement used in the present invention is not particularly limited. For example, commercially available products are trade names “Alumina Cement No. 1”, “Alumina Cement No. 2”, and “High Alumina Cement” manufactured by Denki Kagaku Kogyo Co., Ltd. The product names “SECAR 71” and “SECAR 80” manufactured by Lafarge can be used.

The CaO—Al ₂ O ₃ —SiO ₂ compound (hereinafter referred to as CAS) used in the present invention is mainly composed of CaO, Al ₂ O ₃ and SiO ₂ as chemical components.
CaO raw materials include quick lime (CaO), slaked lime (Ca (OH) ₂ ), and limestone (CaCO ₃ ), and Al ₂ O ₃ raw materials include alumina, bauxite, diaspore, feldspar, and clay, and Examples of the SiO ₂ raw material include quartzite, quartz sand, quartz, and diatomaceous earth.
CAS is manufactured by blending these raw materials at a predetermined ratio, then melting them in a rotary kiln, an electric furnace, and a high-frequency furnace, and rapidly cooling to vitrify.
From the economical aspect, it is possible to adjust and manufacture components such as blast furnace granulated slag, blast furnace slow-cooled slag, and secondary refining slag that are by-produced during metal refining.
The mixing ratio of each component, CaO is 40-55 parts Al ₂ O ₃ is 15 to 30 parts, and it is preferably SiO ₂ is 20 to 35 parts. Outside this range, a sufficient amount of expansion and strength may not be obtained.
Further, the raw materials contain impurities such as MgO, Fe ₂ O ₃ , TiO ₂ , and ZrO ₂ , but they may be contained as long as the effects of the present invention are not impaired. However, it is preferable that the content of K ₂ O, Na ₂ O, and MgO is small.
The vitrification rate of CAS is preferably 50% or more. If the vitrification rate is less than 50%, a sufficient expansion amount may not be obtained.
The vitrification ratio was measured by the X-ray diffraction Rietveld method shown below. That is, a predetermined amount of an internal standard substance such as aluminum oxide or magnesium oxide is added to the pulverized sample, and after sufficient mixing in an agate mortar, powder X-ray diffraction measurement is performed. Analyze the measurement results with quantitative software to determine the vitrification rate. As the quantitative software, for example, “SIROQUANT” manufactured by Sietronics can be used.

The limestone powder used in the present invention is not particularly limited, and is mainly composed of calcium carbonate (CaCO ₃ ), and it is usually used by pulverizing what is used as an aggregate for concrete. Is possible.

Fineness of alumina cement, CAS, and limestone powder used in the present invention, Blaine specific surface area value (hereinafter, referred to as Blaine value) is preferably ^{1,000~6,000cm 2 / g, 2,000~5,000cm 2 /} g Gayori preferable. If it is less than 1,000 cm ² / g, the hydration activity may be insufficient and the strength and expansion may be insufficient, and if it exceeds 6,000 cm ² / g, it may be uneconomical due to excessive grinding power.

  In the present invention, when alumina cement and CAS and / or limestone powder are used in combination, the alumina cement is preferably 20 parts or more, more preferably 40 parts or more, in 100 parts of the binder composed of alumina cement and CAS or limestone powder. If the blending amount of alumina cement is less than 20 parts, sufficient expansion amount and compressive strength may not be obtained.

The aggregate used in the present invention is not particularly limited, and materials usually used for concrete production such as crushed sand, river sand, sea sand, quartz sand, lime sand, crushed stone, and limestone can be used.
The amount of aggregate used is not particularly limited, but is preferably 50 to 1,000 parts with respect to 100 parts of the binder. If it is less than 50 parts, the amount of the binder may increase and it may be uneconomical. If it exceeds 1,000 parts, fluidity and expandability may not be obtained.

In the present invention, for example, expansion can be imparted by heating and curing at 35 to 80 ° C. within 8 hours after mixing.
The method of heating curing is not particularly limited, and both steam curing and autoclave curing are possible.
The curing temperature is preferably 35 to 80 ° C, more preferably 50 to 65 ° C. If the curing temperature is outside the above range, the expansion amount may be small.
The holding time of the curing temperature is not particularly limited, but is usually preferably about 3 to 6 hours. If the holding time is less than 3 hours, the amount of expansion may be small, and even if it is cured beyond 6 hours, further increase in the amount of expansion cannot be expected.

  In the present invention, the pre-treatment time from mixing the concrete to heating and curing is particularly important, preferably within 8 hours, and more preferably within 4 hours. If the preposition time is outside this range, the amount of expansion may be small.

  The rate of temperature rise is also particularly a demand, preferably 10 ° C./hr or more, more preferably 15 ° C./hr or more, and further preferably 20 ° C./hr or more. If the rate of temperature rise is slow, the amount of expansion may be small.

  The amount of water used in the present invention is not particularly limited, but the water / binder ratio is preferably 22 to 60%, more preferably 30 to 50%. If it is less than 22%, it may be difficult to ensure the predetermined fluidity, and if it exceeds 60%, sufficient expansion amount and strength may not be obtained.

  In the present invention, in addition to the cement composition, a water reducing agent, a high performance water reducing agent, an AE water reducing agent, a fluidizing agent, an antifoaming agent, a thickening agent, a rust preventive agent, a defrosting agent, a polymer, a shrinkage reducing agent, a setting agent. A range in which one or more kinds of modifiers, clay minerals such as bentonite, anion exchangers such as hydrotalcite, and fibrous materials such as vinylon fibers, acrylic fibers, and carbon fibers are not impaired. Can be used.

  The mixing method of each material in this invention is not specifically limited, Each material may be mixed at the time of construction, and a part or all of them may be mixed beforehand.

  Any existing apparatus can be used as the mixing apparatus, and examples thereof include a tilting cylinder mixer, an omni mixer, a Henschel mixer, a V-type mixer, and a Nauter mixer.

  Hereinafter, the present invention will be further described based on experimental examples of the present invention.

Experimental example 1
Alumina cement is used as the binder, and mortar is prepared with the combination of water / binder ratio and binder / sand ratio shown in Table 1, filled into the mold in an environment of 20 ° C., with a pre-set time of 0 hours, The temperature was raised at a rate of 15 ° C./hr, and curing was performed at the temperature shown in Table 1 for 5 hours to form a specimen. After demolding at 1 day of material age, the compressive strength and the amount of expansion were measured. The results are also shown in Table 1.
When the water / binder ratio was small and mixing was difficult, a water reducing agent was added to such an extent that mold filling was possible.

<Materials used>
Alumina cement: Denka alumina cement No. 1, density 3.00g / cm ³ , brane value 5,000cm ² / g
Sand: JIS standard sandwater: Tap water reducing agent: Polycarboxylic acid-based high-performance water reducing agent, commercial product

<Measurement method>
Compressive strength: Conforms to JIS R 5201 Expansion amount: Conforms to JIS R 6202

Experimental example 2
The test was performed in the same manner as in Experimental Example 1 except that 60 parts of alumina cement and 40 parts of CAS were used as the binder. The results are shown in Table 2.

<Materials used CAS: granulated blast furnace slag, CaO 40.6%, Al ₂ O ₃ 14.8%, SiO ₂ 33.1%, MgO 6.7%, Fe ₂ O ₃ 1.0%, vitrification rate 95%, brane value 4,500 cm ² / g, density 2.91 g / cm ³

Experimental example 3
Using the binders shown in Table 3, prepare a mortar with a water / binder ratio of 50% and a binder / sand ratio of 1/3, a pretreatment time of 4 hours, a heating rate of 15 ° C / hr, and a curing temperature of 50 ° C. The test was performed in the same manner as in Experimental Example 1 except that the holding time was 5 hours. The results are also shown in Table 3.

<Materials used>
CAS A: CaO 48.0%, Al ₂ O ₃ 17.0%, SiO ₂ 32.0%, MgO 0%, Fe ₂ O ₃ 1.0%, vitrification rate 96%, brane value 5,000cm ² / g, density 2.98g / cm ³ , Limestone, bauxite, and quartzite melted at 1,650 ° C, quenched and synthesized CAS: CaO 46.4%, Al ₂ O ₃ 28.3%, SiO ₂ 22.4%, MgO 0%, Fe ₂ O ₃ 0.7%, glass Conversion rate 96%, Blaine value 2,000 cm ² / g, Density 2.93 g / cm ³ , Limestone, bauxite, and silica were melted at 1,650 ° C. and quenched to synthesize CAS: CaO 48.0%, Al ₂ O ₃ 17.0 %, SiO ₂ 32.0%, MgO 0%, Fe ₂ O ₃ 1.0%, Vitrification rate 50%, Blaine value 5,000cm ² / g, Density 3.00g / cm ³ , Limestone, bauxite and silica at 1,650 ° C Melted and cooled synthetic limestone powder: Limestone fine powder, crushed limestone from Aomi mine, brain value 6,000cm ² / g, density 2.71 g / cm ³
Silica: Fine silica powder, pulverized JIS standard sand, brain value 6,000cm ² / g, density 2.6g / cm ³

Experimental Example 4
Using the binder shown in Table 4, a mortar with a water / binder ratio of 50% and a binder / sand ratio of 1/3 was prepared, and the pretreatment time shown in Table 4, the heating rate of 15 ° C./hr, the curing temperature The experiment was performed in the same manner as in Experimental Example 1 except that the temperature was 50 ° C. and the holding time was 5 hours. The results are also shown in Table 4.

Experimental Example 5
Using the binder shown in Table 5, a mortar having a water / binder ratio of 50% and a binder / sand ratio of 1/3 was prepared, the pre-treatment time was 0 hours, the heating rate shown in Table 5, and the curing temperature was 50 ° C. The test was performed in the same manner as in Experimental Example 1 except that the holding time was 5 hours. The results are also shown in Table 5.

Experimental Example 6
Using the binders shown in Table 6, prepare a mortar with a water / binder ratio of 50% and a binder / sand ratio of 1/3, a pretreatment time of 4 hours, a heating rate of 15 ° C / hr, and a curing temperature of 50 ° C. The test was performed in the same manner as in Experimental Example 1 except that the holding time was 5 hours. The results are also shown in Table 6.

Experimental Example 7
Using the binders shown in Table 7, prepare a mortar with a water / binder ratio of 50% and a binder / sand ratio of 1/3, a pretreatment time of 0 hours, a heating rate of 15 ° C / hr, and a curing temperature of 50 ° C. , And the same holding time as shown in Table 7 was carried out in the same manner as in Experimental Example 1. The results are also shown in Table 7.

Claims (4)

A cement composition containing an alumina cement binder, aggregate, and water and having a water / binder ratio of 22 to 60% is kneaded, and the preheating time is within 8 hours, the heating rate is 5 to 5%. A method of imparting expansibility to a hardened cement concrete, characterized by curing by curing at 35 to 90 ° C at 30 ° C / hr. The binding material contains alumina cement, and further a CaO—Al ₂ O ₃ —SiO ₂ compound and / or limestone powder, and is a total of alumina cement, CaO—Al ₂ O ₃ —SiO ₂ compound, and limestone powder. The method for imparting expansibility to a hardened cement concrete according to claim 1, wherein the alumina cement is 40 parts or more in 100 parts. CaO-Al ₂ O ₃ -SiO ₂ compound, 40 to 55 parts of CaO, Al ₂ O ₃ 15 to 30 parts, and cement concrete curing according to claim 2, the SiO ₂ comprising 20 to 35 parts A method of imparting expansibility to the body. The method for imparting expansibility to the hardened cement concrete according to claim 2 or 3, wherein the vitrification ratio of the CaO-Al ₂ O ₃ -SiO ₂ compound is 50% or more.