JP6557708B2 - CO2 emission reduction method in the production of ready-mixed concrete - Google Patents

Description

The present invention relates to a method for reducing CO ₂ emissions in the production of ready-mixed concrete.

In the construction sector, accounting for many of the CO ₂ emissions among the buildings of the life cycle "production and procurement of materials associated with the construction, industrial waste treatment, construction machinery and operational aspects at the time of construction," the reduction of CO ₂ emissions Efforts have been mainly made.

Among the materials that make up buildings, concrete is heavy, along with iron, has a large environmental impact, and has a large CO ₂ emission.

As an example of obtaining general CO ₂ emissions in the construction of a structure using concrete (RC structure), it is per 1 m ³ of general concrete with a design standard strength of 24 to 36 N / mm ² using ordinary Portland cement. There is a report that the CO ₂ emission amount is 309.7 to 352.3 kg-CO ₂ / m ³ (the following Non-Patent Document 1), and about 90% or more is occupied by the cement emission amount. In addition to using a large amount of fossil fuel to obtain the combustion energy of the furnace in the production process of cement clinker, which is a raw material for cement, a large amount of CO ₂ due to limestone decarboxylation (CaCO ₃ → CaO + CO ₂ ). Due to the occurrence of
“LCA Tool for Buildings Ver. 4.05”, Architectural Institute of Japan, published on December 8, 2005 (revised on November 1, 2006)

In the following patent document, in order to improve the CO ₂ reduction effect in a cement-based material (mortar or concrete), it is extremely effective to apply a cement-based material with a small amount of cement used. In concrete reduced to m ³ or less, CO ₂ emissions per m ^{3 of} concrete are proposed to be dramatically reduced to about 100 kg-CO ₂ / m ³ or less.
JP 2010-265166 A

  This patent document 1 contains cement and an admixture as powder components, has a water powder ratio W / B of 20 to 46%, and has a mass ratio (substitution rate) of the admixture in the powder of 80. An environmental load-reducing mortar or concrete kneaded material that is excellent in the residual suppression of the unhydrated cement component after curing, which is ˜95%. As said admixture, what has 1 or more types of blast furnace slag and fly ash as a component is applicable.

Thus, in recent years, ordinary Portland cement in cement varieties among cement, aggregate, water, and admixtures, which are raw materials for ready-mixed concrete (hereinafter referred to as ready-mixed), has been used to reduce the carbon of concrete due to the suppression of greenhouse gases. (Hereinafter referred to as ordinary cement) The carbon dioxide emission associated with the production is 0.764 kg-CO ₂ / t, which is significantly larger than other raw materials. Instead of fly ash and steel slag, which are by-products of the plant, it is called low-carbon concrete, and it is recommended to use low-carbon concrete.

  Cement manufacturers produce and distribute mixed cement that uses blast furnace slag and fly ash generated from steelworks and power plants. However, Patent Document 1 and the like do not use these, but reduce the unit amount of cement as a low-carbon compounding of concrete, and use it as a low-carbon concrete with a high compounding amount using blast furnace slag and fly ash as an admixture. To do.

  There are some ready-to-use factories that cannot handle this technology with the existing equipment, and there are some factories that are difficult to handle because of quality control and replacement of storage bins.

  In addition, as mentioned above, there is a ready-mixed concrete factory that is difficult to handle with the current equipment as mentioned above, as well as low carbon concrete that mixes blast furnace slag and fly ash locally. There is a problem that a lot of labor is required.

  By the way, as for the ready-mixed concrete, the ready-mixed concrete for construction work is generally produced at the ready-made factory and transported to the construction site and delivered to the construction site.

  At the construction site, in consideration of safety with respect to the amount of raw concrete to be placed, a slightly larger amount of raw concrete is ordered, so surplus raw concrete is generated, and these are treated as unnecessary raw concrete. Therefore, the larger the placement amount, the larger the amount of raw concrete ordered. In addition, since the raw kon for construction of JIS must be used within 90 minutes after production, the raw kon that cannot be used in the middle of transportation and the raw kon canceled after production must be treated as surplus kon.

  Since such surplus kon is not yet solidified, it is fluidized, so when solid-liquid separation is performed in the treatment method, it is performed after diluting with water. Moreover, when crushing and processing after hardening, it is necessary to secure a place suitable for the processing amount. In either case, the amount recycled in the ready-mix factory is small, and most of it is processed waste. The amount of surplus kon produced varies depending on the region and factory scale, but about 4% of the production is generated in urban areas.

  Processing and disposal associated with the generation of surplus waste is a problem, and the amount that is discarded increases because the amount that is recycled is small. In the case of solid-liquid separation water treatment, a large amount of water is required. Not only costs, but also labor and carbon dioxide emissions associated with processing.

  The total amount of delivered raw concrete is used, and naturally the fuel economy worsens and the amount of warming effect gas increases when surplus raw concrete is installed and returned, rather than the fuel economy of the raw concrete car that returns to the raw concrete factory in an empty state.

  There are several methods for processing surplus food waste. Although there are cases where recycled roadbed materials (hereinafter referred to as RC), which are cured and crushed as they are, are processed into industrial waste as concrete glass, and recycled concrete that is crushed and classified with a predetermined particle size (hereinafter referred to as RC), are recycled. In recent years, road construction and the like have also decreased, and since the balance with the quantity used for RC cannot be maintained, the quantity used for this has decreased, and the quantity that becomes waste has increased.

  Next, when surplus kon is processed as it is, since it must be processed as sludge in industrial waste in the state before curing, there is a method of entrusting the processing to an acceptable intermediate processor. In other words, if surplus raw concrete cannot be hardened and crushed in the raw concrete factory, or if solid-liquid separation treatment cannot be performed, it becomes sludge treated material that is disposed of outside the factory, increasing the burden of processing costs including transportation costs. .

  Solid-liquid separation processing is performed at large-scale ready-mix factories and factories that are environmentally friendly to some extent. In other words, after diluting surplus kon with water, it is classified into coarse particles that cannot retain moisture and particles other than sand that contain a lot of moisture, and fine particles less than sand that also contain cement are dehydrated. Reduce the volume to cake. However, what has been hardened by cement hydration after being pressed into a cake may not be classified as sludge depending on its strength.

  Solid-liquid separation is a technique of reducing the volume of surplus raw waste and processing it outside the factory, but a large amount of diluted water is also required. Inevitably, drainage must be performed at a quality below the environmental standard, so it is necessary to install these treatment facilities and manage factory wastewater.

  In terms of the number of live-con vehicles that are arranged by the raw-con factory, if the number of surplus-container-equipped vehicles increases, it will be a detrimental factor in vehicle management for rationally operating a limited number of live-con vehicles.

The object of the present invention is to eliminate the inconveniences of the above-mentioned conventional examples. The purpose is to provide a method for reducing CO ₂ emissions in the production of ready-mixed foods that will be improved all at once, including effective utilization.

In order to achieve the above-mentioned object, the present invention according to claim 1, when producing ready-mixed kon, as a substitute for aggregate, which is a natural resource supplied to the ready-made kon factory from the production area, surplus uncooked kon in an unsolidified state is assembled. The aggregated processed material that has been granulated is crushed and used as an aggregate. After the aggregate is processed, the amount of moisture that becomes saturated is calculated from the volume and mass of the aggregate that has been submerged. Thus , the gist is to determine the blending amount of the aggregate after the agglomeration treatment with respect to the unit volume of the raw concrete .

  According to the present invention, surplus raw kon is originally raw corn mixed with balanced coarse and fine aggregates, and can be modified to a measurable state by crushing after the aggregate treatment As long as it is not special (special) concrete specification, aggregate preparation becomes unnecessary and can be used as recycled aggregate, so it does not require much energy (compared to carbon dioxide emissions when manufacturing recycled aggregate) It can be aggregated (with much smaller energy), and it can reduce carbon dioxide emissions at the time of raw material procurement (transport stage), which accounts for about 80% of the mass of concrete.

  As for ready-mixed concrete, the current Building Standards Act and concrete JIS rules are only for the quality of materials and how to handle them, and the quality is guaranteed so as to guarantee the prescribed performance of the concrete after curing. Not. In other words, in JIS, the aggregate in raw material raw materials is basically defined by the quality of natural new aggregate. The waste concrete used as a raw material even if it is made into JIS as a recycled aggregate is regulated up to the age after hardening. Aggregates collected from concrete that has not yet solidified are only those that have undergone a solid-liquid separation and classification process called recovered aggregates.Concrete using these recycled aggregates meets the required strength. However, from the design specifications, the range of use is limited depending on the importance of the structure.

  In other words, under the current regulations, the ready-mixed concrete manufacturing method of the present invention cannot be used for concrete structures that are specified by JIS or concrete certified by the Minister of Land, Infrastructure, Transport and Tourism. It is not used for any purpose. The quality of concrete for these markets can be adequately dealt with, at least not only contributing to the reduction of carbon dioxide emissions in the production of ready-mixed concrete in this market, but also reducing the cost of reducing industrial waste and processing waste. Can also contribute.

  In the case of processing surplus corn, fluidity is lost by agglomeration, so loading with an excavator such as a back-for, transportation by a dump truck, and transfer of a belt conveyor can be performed immediately.

  In addition, by applying the agglomeration technology of agglomerating the surplus raw concrete that is not solidified, it can be used in the production of ready-mixed concrete, thereby reducing the amount of slurry and reducing the amount of water treatment and dehydration equipment. Can be realized.

  By taking the method of crushing, classifying and collecting aggregates after the surplus concrete is hardened and made concrete, it is possible to reduce the amount of energy to break, simplify the crushing work and Miniaturization becomes possible. Furthermore, it is possible to classify immediately without waiting for the time until it hardens. Thereby, a crushing operation process is omitted.

  In addition, without calculating the amount of surface dry water considered in the mixing of ordinary concrete, the amount of water to be saturated can be calculated by calculating the amount of water that becomes saturated from the volume and mass of the aggregate after submerged aggregate. The amount of aggregate after aggregate formation treatment per unit volume of is determined. As a result, it is possible to set a concrete mixture that does not change in volume even after addition of water and cement in the ready-mixed mixture. The blending strength for the required performance of concrete can be set by determining the amount of unit cement from the correlation with compressive strength using the water-cement ratio, which is the ratio of water to cement, in the same manner as conventional ordinary concrete. .

  The present invention according to claim 2 is used as an aggregated aggregate within 10 days after the treatment of surplus raw concrete, and utilizes the hardening function of cement hydrate in the aggregate after aggregated process. The gist is to manufacture.

  According to the second aspect of the present invention, the cement hydrate is rehydrated by water replenishment according to the elapsed time (material age) from the agglomeration treatment. By performing the blending utilizing this rehydration, it becomes possible to suppress the unit cement amount of the aggregate after the agglomeration treatment. The material age using this effect is preferably within 10 days after the agglomeration treatment.

As described above, the method for reducing CO ₂ emissions in the production of ready-mixed foods according to the present invention solves the problem of surplus raw cooked foods in consideration of everything from ready-mixed food manufacturing to distribution and industrial waste treatment, and realizes reduction of environmental load. It can be done.

A fresh concrete formulation set flow diagram illustrating an embodiment of the fresh concrete to reduce CO ₂ emissions process in the manufacture of the present invention. It is explanatory drawing which shows a mass ratio by the outline | summary of a raw-corn mixture. It is explanatory drawing which shows the comparison with the raw kon produced by this invention by the outline | summary of raw kon mixing | blending. It is explanatory drawing which shows the phase distribution of a raw kon raw material. It is a graph which shows a particle size distribution. It is a density test conceptual diagram of a water immersion state. It is a graph which shows the comparison of the normal raw concrete and the raw concrete of this invention in compressive strength. It is explanatory drawing regarding the carbon dioxide emission calculation of raw concrete.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For the ready-mixed concrete for construction, the time from the production of the ready-mixed to the placement is determined by JIS, and those exceeding the time limit are not used. In the present invention, surplus raw food containers other than these raw food containers are raw food containers that are not used due to the difference between the order quantity and the placement amount, and raw food containers that have been canceled after ordering.

  In the case of producing ready-mixed concrete, the present invention provides an alternative to aggregate, which is a natural resource supplied from the production area to the ready-mixed factory, and is used to solve the aggregated processed product obtained by aggregating the surplus ready-mixed raw material that has not been hardened. The content is to be crushed and used as an aggregate.

First, an explanation will be given of the method for aggregating surplus kon used in the present invention. After the surplus kon fluidized in the agitator mounted on the unction car is discharged from the agitator, the rotation of the agitator An anionic polyacrylamide system having a weight average molecular weight of 10 to 25 million and an anionic monomer of 25 to 100 mol%, which was previously emulsified by applying a continuous stirring apparatus having a number of 100 min ⁻¹ or more. A polymer aggregating agent containing (A-PAM) as a main component is added, and the amount of air gap is increased by the stirring device.

Anionic polyacrylamide (A-PAM) polymer group grain agent mainly composed of the range of the unit amount of 0.5kg / m ³ ~5kg / m ³ to be added to the volume 1 m ³ per excess raw Con And

  In the present invention, the agglomerated material is used as an aggregate (Japanese Patent No. 6166801 does not clearly indicate the use of such raw concrete as an aggregate). The formulation setting is shown.

  In blending settings, when normal natural aggregate is used, the moisture between the aggregate particles is calculated in advance by a predetermined test method (test method for natural aggregate), and this is the surface dry saturated condition The amount of water (surface dry water) is determined, and this amount of water is regarded as having no effect on cement hydration, and is selected from a concrete blending index called a water-cement ratio without counting the blended water.

  For the ready-mixed mix, the quality of the concrete according to the application is required in advance. In general, priority is given to strength in required performance. It is known that there is a certain relationship between the compressive strength of concrete and the water cement ratio W / C on the blend, and in particular, the cement water ratio C / W, which is the reciprocal of the water cement ratio, is approximated by a linear function. In the ready-mix factory, the mass ratio of water and cement in the blend is determined based on the correlation between the cement water ratio and strength.

In the Architectural Institute of Japan “Standard Building Construction Specification / Explanation JASS5 Reinforced Concrete Work”, there are calculation formulas for each type of cement, which are also used. That is, the mass ratio of cement and water is determined at the beginning of the blending procedure. Next, the mass and water content of each aggregate are determined from this water cement ratio from the mixing ratio of the coarse aggregate and fine aggregate used in the ready-mix factory and the water cement ratio. As described above, in the handling of moisture in the aggregate in the blended water amount of ready-mixed rice, the set water amount in blending does not include the moisture content in the surface dry state as shown in Table 1 below.

On the other hand, since it is difficult to determine the moisture content of the aggregate in the dry state after aggregate processing, the water cement ratio including the moisture in the dry state is included in the water cement ratio of general concrete. When it is calculated as W ′ / C and applied to the concrete using aggregate after the agglomeration treatment, it is as shown in Table 2.

  The surplus raw kon in the aggregated processed product of the present invention (hereinafter referred to as aggregate after aggregated processing) is set with the same composition as the normal raw kon, The blending ratio of the coarse aggregate is in a balanced state in the concrete blending.

  As for the compounding strength, it is possible to grasp the blending details of surplus raw mix by grasping the factory shipping state. In addition, except for surplus concrete containing special concrete such as road pavement concrete, it is possible to grasp the amount of fine aggregate, coarse aggregate and unit cement in the surplus concrete using average blending strength. Therefore, the mixing ratio of the fine aggregate and the coarse aggregate in the aggregated processed product can also be calculated by this average mixing ratio.

  However, the amount of cement hydrate mixed in is the hydrate produced during the cement hydration process, but it is aggregated during the curing process (during hydration), so water will evaporate or drain excess water. It is conceivable that the water required for the sum is insufficient. In terms of engineering, the water that hardens when the cement reacts with water is divided into three types: bound water, water that is not drained from the hardened concrete is bound water, and drained water is free water. Are discussed.

  It is assumed that this free water is drained (evaporated) during the agglomeration process. The difference between the moisture content of raw kon before aggregation and the moisture content after aggregation is about 5%, although it differs depending on the composition and weather compared to the state before aggregation.

  The required performance of quality is mainly required for nominal strength and fluidity, as with general concrete. Since the fluidity can be adjusted by the type of admixture and the amount added, the blending can satisfy a value (preparation strength) which is larger than the design strength and is called nominal strength. In addition, the amount of admixture added in the blending is not considered, as in general concrete.

(1) With reference to a general concrete blend using natural aggregate that satisfies the required strength of concrete, a blend that can satisfy the blend management strength and compressive strength is targeted.
(2) Already here, the physical property value of the aggregate after the agglomeration treatment and the moisture W in the cement water ratio (C / W) which is the reciprocal of the water-cement ratio are as follows. It is assumed that the value calculated from the moisture content is set as W ′, and the relationship between C / W ′ of the test composition and the compressive strength is statistically determined. Even in general concrete blends, the aggregates used by factories differ, so the relationship between C / W and strength is compiled in a database. In addition, it is assumed that the particle size test results are also made into a database.
(3) The moisture content of the aggregate after the agglomeration treatment in the wet state at the time of use is determined.
(4) While putting the aggregated aggregate in a wet state into a predetermined container, it is hydrated and packed into a predetermined capacity. Water is added to the surface so that water floats, and the mass and amount of water in the water immersion state are measured, and the wet density is measured.
(5) Based on the data obtained from (4), the presence or absence of a saturated state is confirmed, and the amount of water that becomes saturated is calculated. The aggregate amount in this state is a state in which the volume does not change, and the dry mass is calculated and used as a reference for the unit aggregate amount.
(6) The water content necessary for the hydrate in the aggregate after aggregation to be hardened is not included in the blended water, but the blended water is set as W ′, which is necessary from the relationship between the data in (2) and the nominal strength. Calculate the amount of cement and water. At that time, the blending strength is determined so that the compressive strength becomes larger than the nominal strength.
(7) Combining these, create a blend using the aggregate after the aggregated treatment in the dry state, considering the moisture content in the wet state of the aggregate after the aggregated treatment that is actually used Create

  The compressive strength of concrete and the cement water ratio C / W are approximated by a linear function. In the present invention, normal concrete W corrected by adding surface dry water to W 'is used.

  In setting the strength, it is preferable to perform management by creating a comparison of the compressive strength of the raw kon using the aggregate after the aggregation process shown in FIG. This figure also shows the relationship with the nominal strength of ordinary raw corn as a reference value.

  FIG. 2 shows the approximate mass ratio of the mixture in the mixture of raw foods excluding the admixture.

  Moreover, when natural aggregate is used as the main raw material composition of normal raw concrete and when aggregated processed products obtained by agglomerating surplus raw concrete that is not solidified as in the present invention are used as aggregate FIG. 3 shows the case of the mass ratio of the outline of the raw kon.

  Since the agglomerated product is in a state where the amount of voids is large, it is in an environment in which water in the surplus kon is easily evaporated. Since this aggregated product contains cement hydrate and free water in the hydration process (during curing by cement hydration), it is solidified by the hydration reaction of the cement if left as it is.

  However, since the aggregated state is a state in which the gap between the aggregate and the hydrate is large, the adhesion between the aggregate and the cement hydrate due to hardening is reduced, and the aggregate is compared with the hardening strength of normal concrete. Since the solidification strength of the compound is small, it can be easily crushed when used as an aggregate.

  When using the aggregated material after pulverization, the hydrate in the cement hydration process varies depending on the age used as the aggregate, but re-hardens by supplying water. Therefore, when the aggregated product is used as an aggregate, the cement hydrate in the hardening process can be used, so that a concrete blend with a reduced unit cement amount can be realized.

  In blending settings, when normal natural aggregate is used, the moisture between the aggregate particles is calculated in advance by a predetermined test method (test method for natural aggregate), and this is the surface dry saturated condition The amount of water (surface dry water) (hereinafter referred to as “surface dry state”) is obtained, and this water amount is regarded as having no effect on cement hydration. The selection of blending is performed from

  On the other hand, the aggregated processed material (hereinafter referred to as aggregate after aggregated processing) as in the present invention (hereinafter referred to as aggregate after aggregated processing) is a hydration process, and thus (surface dry water) cannot be measured. . The surplus raw concrete is set with the same composition as normal raw concrete, and the blending ratio of fine aggregate and coarse aggregate is in a balanced state in the concrete composition.

  The concrete composition using the aggregate after the agglomeration treatment as in the present invention is as follows.

  As for cement hydrate, it is assumed that the state of hydrate varies depending on the material age (although it is known that the hydration process and reaction of cement has not been clarified scientifically), in the present invention, Since it is necessary to grasp the physical properties of the aggregate after the aggregate treatment by the age of a given aggregated product as a phenomenon, the amount of cement hydrate mixed for each given age is statistically determined from the grain size test. At the same time, it is necessary to measure the unit volume mass in the dried state so that proper blending can be carried out.

  This allows us to calculate the amount of water that becomes saturated from the volume and mass of the aggregate that has been submerged in aggregate, without having to calculate the amount of surface dry water that is taken into account when blending ordinary concrete. The blending amount of aggregate after agglomeration treatment per unit volume of ready-mixed concrete is determined. Since the mass per unit volume of the aggregate after the agglomeration treatment is an optimum blending amount that does not change in volume, a blending plan as concrete can be performed by adding cement and moisture.

  The strength of the required performance of the concrete can be set from the correlation with the compressive strength using the water-cement ratio, which is the ratio of water to cement, as in the case of conventional ordinary concrete.

Formulation of the concrete is set in a unit mass of the raw materials used in the fresh concrete 1 m ³ per. The water cement ratio (W / C) is set and the unit water amount (W) and the unit cement amount (C) are determined so that the required strength, workability and other conditions can be met. The unit water amount is included in the aggregate. It is necessary to consider the moisture that is.

  The mass of the aggregate to be considered in the ready mixed concrete composition of JIS A5308 is in a surface dry state, and the gap inside the aggregate is filled with water, but the surface is not in the state of water adhering. .

In general ordinary concrete blending, the unit mass of each material per 1 m ^{3 of} ready-mixed concrete is set. The water cement ratio (W / C) is set and the unit water amount (W) and the unit cement amount (C) are determined so that the required strength, workability and other conditions can be met. The unit water amount is included in the aggregate. It is necessary to consider the moisture that is.

  The amount of water in the aggregate considered in the preparation of the ready mixed concrete of JIS A5308 does not include the amount of water considered to adhere to the aggregate in the dry state and do not affect the unit water amount and the mixed water.

  However, since aggregates are mixed with hydrates in the middle of hydration after being aggregated, they cannot be applied to a test for examining this state. Therefore, in the present invention, the density (unit volume mass) in the dry state of the aggregate after the agglomeration treatment is obtained, and the relation between the water cement ratio and the strength of the aggregate of the ordinary concrete is also examined under the same conditions to obtain the required performance. Set the filling formula.

  It is very difficult to measure the amount of water while accurately adjusting this state. In other words, the surface dry state is theoretical only, and its judgment is also human, strictly speaking, it is an instantaneous state in the measurement process, and if it is out of timing it will dry out, so the uncertainty of measurement Questions arise. However, the current concrete mix is based on moisture that is not physically stable.

  In the present invention, we propose a blending method that is reasonable in handling the amount of moisture referred to as surface dry water, and obtain the density (unit volume mass) of the aggregated aggregate after drying, For the aggregate of ordinary concrete, the relationship between water cement ratio and strength compared under the same conditions is examined, and the composition that satisfies the required performance is set.

  Specific water content adjustment is as follows. In concrete blending, the unit water volume (W) and unit cement mass (C) are set in advance from the water cement ratio (W / C) that exceeds the target strength, and the aggregate (fine aggregate and coarse aggregate) ) Is determined. At that time, the amount of water adhering to the aggregate is set as the amount of kneaded water as the amount of water subtracted from the unit water amount calculated in the saturated state (zero air amount state).

  In general handling of moisture in aggregates, it is regarded as aggregates of particles, not aggregate particles, and the moisture in the dry state of the aggregate surface is determined by the amount of water in the water cement ratio. Is subtracted, it becomes like a general concrete conceptual diagram shown on the left side of FIG.

  On the other hand, when it is used as an aggregate after agglomeration treatment as in the present invention, a cement hydrate has already been generated, and the crystal includes a state where water is not drained as an aggregate component. ing. Moreover, there is a possibility that air is not completely removed from such an aggregate composition.

  That is, the moisture of surplus kon after granulation can be divided into those that have become crystal water, those that have already evaporated in the air, and those that have adhered without being drained.

  Furthermore, since the amount of water varies depending on the period (curing period) used as an aggregate, it is difficult to measure the aggregate volume after aggregation in a fully saturated state. The amount of mixture and unit water volume are calculated from the state. A conceptual diagram of this is shown on the right side of FIG. It is possible to calculate the adjusted amount of water at the time of production by obtaining the wet amount of water in this figure, performing correction, and calculating the saturated amount of water. In the figure, the interstitial air in the aggregate is the amount of air taken in during the process of agglomeration, which has already been discharged and is not included in the volume of the raw concrete.

  In addition, the particle size test is performed with the aggregate dried and the aggregate is dried, and the particle size test results of the natural aggregate on the ready-mixed mixture are compared. At the same time, the density (specific gravity) of the sample in the dry state is measured and used to calculate the unit aggregate amount at the time of blending. FIG. 5 shows an example of the particle size test result.

  According to this, the slope of the aggregate of 2.5 mm particle size or more of aggregate after aggregation is almost the same as that of natural aggregate, but the slope of 0.5 mm or less is gentle, and the cement water It can be seen that the amount of Japanese products is increasing.

  From each particle size / mass ratio of the test results, the amount of cement hydrate obtained by removing the natural aggregate from the aggregate after aggregation was about 19.5%. The ratio varies depending on the amount of unit cement of surplus kon, but the aggregate after the agglomeration treatment is used after being crushed and mixed, so the variation due to this is small.

  Also, the cement hydrate is rehydrated by water replenishment according to the elapsed time (age) from the aggregation process. By blending using this hydration, the amount of unit cement can be suppressed. The material age using this effect is preferably within 10 days after the agglomeration treatment.

  When surplus kon after aggregate is used as an aggregate, cement hydrate is also regarded as a part of the aggregate, the amount of water remaining without being drained is measured, and the amount of residual water is adjusted as the amount of residual water There is a need to. That is, in the measurement method called surface water amount, which is frequently used as a test for adjusting the amount of water in general aggregates, an error due to the amount of fine particles occurs. It is not suitable because there is a possibility that moisture from the voids cannot be completely removed.

  Since aggregate hydrate is mixed in the aggregate after the aggregate treatment, it is assumed that the entire amount of mixed air cannot be discharged. However, in the case of concrete, it is considered that this gap is filled with hydrate hardening or crystal water. Hydrate and crystal water in the aggregate after the aggregation process are treated as a part of the aggregate as a solidified product.

  Assuming that the aggregate after the agglomeration treatment of the water-immersed specimen is regarded as not changing in volume, the mixture can be mixed by replacing the pore water with cement slurry. In other words, knowing the unit volume mass of the aggregate after the aggregate treatment is zero, the moisture content in the wet state can be calculated from the moisture content in the water immersion state. .

  The amount of moisture in the surface dry state of general aggregates is determined by the JIS test method, but even if the surface water content is corrected in real time, it has not led to accurate lightweight concrete production. Based on the background of the proposal of a method for producing concrete that is difficult to determine the surface dry condition and is not affected by surface water, in the present invention, in order to grasp the volume when surplus kon after aggregated processing is used for aggregate Since it is difficult to completely eliminate the amount of air, the dry mass and aggregated aggregates in the cylinder shown in FIG. Since the water content ωwet is obtained from the change in the water content and the wet density ρwet before the production of the ready-mixed corn based on the volume and mass in the state immersed in water, the kneading water amount is adjusted accordingly.

  The basic unit of raw concrete raw material and carbon dioxide emission in general ready-mixed concrete will be explained. The raw material of ready-mixed food is composed of cement, water, aggregate, and admixture, and the admixture is a polymer material and the amount added is extremely small.

  In general, the aggregate accounts for about 75% to 85% in volume ratio on the blend, and about 80% in mass ratio, although it varies depending on the concrete blend. This aggregate is divided into fine aggregate and coarse aggregate. The former is sand of natural resources, the latter is gravel and crushed stone, and recently lime crushed stone is used.

  As for fine aggregates, mountain sand in mountainous areas is often used, but it is said that it is difficult to secure mountain sand due to problems such as depletion of forests, and limestone crushed sand has been attracting attention in recent years. .

  Limestone, which is also used in coarse aggregates, is the main raw material for cement. Cement factories are often located near Limeyama. Depending on the production area, the cement factory is often procured in the Kanto region. Cement is also imported from overseas.

  As described above, limestone mine, which is frequently used as coarse aggregate, is often a mining site in the same area as limestone that is used as a raw material for cement. For example, some of the domestic cements distributed in the Kanto region are produced in the Chichibu and Tochigi regions. Many.

  For fine aggregate sand, inland mountain sand is used in the Kanto region. Mass transport by ship including transportation merit is more efficient, but in sandy mountains, the scale of excavation is smaller and the production areas are dispersed compared to limestone, so in most cases sand and crushed stones in other production areas A blend with sand is used. The blending place is either a ready-mix factory or a mixing place with dedicated mixing equipment. Fine aggregates are also being procured from remote areas in the Kanto area due to restrictions on mining for environmental protection.

  CO2 emissions from coarse aggregates are often calculated by producers, and representative basic units are also disclosed in academic association research materials. On the other hand, there are few cases where producers have calculated themselves because of the small mine size of fine aggregates, but they are published in papers and reports on low carbon concrete.

Well water, industrial water, and tap water are used as kneading water for raw concrete raw materials. The amount of carbon dioxide emitted from tap water and industrial water varies depending on the water facilities and scale in the area. By the way, in 2009, the basic unit of carbon dioxide emission of tap water reported by the Tokyo Metropolitan Government's Environmental Bureau is 200 g / m ³ . Carbon dioxide emissions from the use of well water can be determined from the amount of electric power from the pump, but there are also land subsidence problems in well water, and there are some areas where the amount of use is restricted.

  Carbon dioxide emissions during the production of cement are listed in public materials of the Japan Cement Association.

  The composition of ordinary concrete is mainly composed of cement, fine aggregate, coarse aggregate and water. In addition, chemical admixtures are used. About 1% of the cement mass is used as the admixture, and the type of admixture varies depending on the producer, but it is also calculated from the basic unit published in the materials calculated by the producer and academic papers and reports. it can.

  As described above, since the basic unit of the amount of carbon dioxide in various raw materials is available, the amount of carbon dioxide during production can be easily calculated. In the procurement of raw materials, it is possible to use a predetermined calculation method according to the geographical conditions of the factory and the supplier. However, in production calculations at the ready-mix factory, the carbon dioxide emissions per unit production may vary greatly depending on the equipment scale and shipment quantity.

As shown in Fig. 8, the carbon dioxide emissions related to the ready-mix factory are as follows: (1) Raw material production process-> (2) Raw material transport process-> (3) Raw-con manufacture-(4) Product transport-> (5) Surplus On-site processing of ready-mixed food → (6) Can be divided into off-site disposal factories. Table 3 below shows the differences between the general raw food containers and the raw food containers of the present invention.

Regarding the mix of concrete using aggregate after aggregated with normal concrete, carbon dioxide emissions during raw material production, raw material transportation, product transportation, factory production and processing of industrial waste per 1 m ³ of raw concrete were calculated. Those are shown in Table 4 below.

  Regarding the carbon dioxide emission during the production of raw material products, the carbon dioxide emission of concrete using aggregate after aggregated processing equivalent to the concrete quality of general blending has been reduced by about 13.5%. As apparent from the relationship between C / W ′ and compressive strength shown in FIG. 7, the compressive strength at the same C / W ′ is superior to the concrete using aggregate after the agglomeration treatment, so the unit cement amount becomes small, Inevitably, the amount of cement used with a large unit of carbon dioxide emissions can be reduced.

The basic unit of carbon dioxide emissions used for this is as follows.
Cement: Summary of cement LCI data: Cement Association, 2015.24
Fine Aggregate and Coarse Aggregate: Referenced by the manufacturer's calculated value Admixture: Japan Concrete Industry Association: Researcher's Report on Minimizing Global Warming Substances and Waste in the Concrete Sector. P128 July 10, 2010 Use intermediate value of listed value Aggregating agent: Refer to manufacturer's calculated value

In this calculation, even if the cement used is replaced with blast furnace cement, the required strength is satisfied. Therefore, the calculation for the case where the cement is replaced with blast furnace cement is as shown in Table 5 below. This is a reduction of about 37.8% compared to the general formulation used. In addition, it is about 28.0% lower than aggregate concrete after agglomeration treatment using ordinary cement. Furthermore, it is reduced by 28% just by changing from ordinary cement to blast furnace cement, and a synergistic effect with the aggregate after aggregation is obtained.

  Transportation related to raw material procurement, product delivery, and industrial waste processing. Of these, the products used differ depending on each green factory, but the basic unit of carbon dioxide emissions of raw materials is almost the same unless there is a big difference in production processes and equipment. Moreover, the average value of each maker is used in the material published by the association etc. which the raw material maker joins.

  However, transportation differs depending on the raw material production location, the relay base, and the geographical conditions of the ready-mix factory, but if aggregate is used after aggregate processing, it will be produced in the ready-mix factory, so there is an advantage that the count is zero. . The calculation was based on the ton-kilometer method based on the procurement conditions implemented (inland shipping, land transport) and the transport distance. Regarding this, there is a guideline for a calculation method for CO2 emissions in the logistics field, which was created jointly by the Ministry of Economy, Trade and Industry and the Ministry of Land, Infrastructure, Transport and Tourism regarding the revised Energy Law that has been implemented since April 2006. The calculation in the present invention is also performed by this calculation method.

(3) Carbon dioxide emissions during factory production In this calculation, there is a practical use in which the production quantity is determined in advance. Although it depends on the scale of the ready-mix factory, the calculation assumes that 120,000 m ^{3 is} produced annually, and surplus cooked food is generated at 4% of the production volume. In addition, the power consumption of equipment at the time of production, the amount of water except for blending water, fuel use of heavy equipment, carbon dioxide emissions per 1 m ³ of the power consumption of the processing equipment of the excess raw Con determined. The basic unit used for the calculation was referred to the emission basic unit database (Ver.2.3) for the calculation of greenhouse gas emissions of the organization through the supply chain in March 2016.

As described above, per 1 m ^{3 of} raw material for the production stage of product raw materials, the procurement stage of product raw materials, various facilities at the production sites using these raw materials and carbon dioxide emissions generated during processing and those associated with transportation The total amount of carbon dioxide emissions was calculated, and the total amount was 34 kg-CO ₂ / m ³ for ordinary concrete and 271 kg-CO ₂ / m ³ for aggregates after aggregated treatment. Compared to, an aggregate reduction effect of 20.5% can be obtained by using the aggregate after the agglomeration treatment. In comparison at the time of production, since it is reduced by 13.5%, it can be seen that the aggregate after the agglomeration treatment can contribute to the compression of carbon dioxide emission comprehensively.

  Part of the amount of cement used as a raw material can be compounded by replacing one or more selected from blast furnace slag, fly ash and silica fume, which emits less carbon dioxide than raw cement. It is.

  In addition, aggregated aggregates are mixed with natural new aggregates, recycled aggregates made from waste concrete, and recovered aggregates generated from solid-liquid separation during the surplus concrete processing process. It can also be manufactured.

Claims (2)

When producing ready-mixed concrete, as an alternative to aggregate, which is a natural resource supplied to the ready-mixed factory from the production area, the aggregated processed product obtained by aggregating the surplus ready-mixed raw material that has not been hardened is disintegrated to produce bone Aggregated after aggregated treatment per unit volume of raw concrete by calculating the amount of water that becomes saturated from the volume and mass of the aggregated state after submerged aggregate. A method for reducing CO ₂ emissions in the production of ready- mixed foods , characterized in that the blending amount of the raw material is obtained. Use as aggregated aggregate within 10 days after surplus raw concrete treatment, and set the amount of raw concrete blended to be produced by utilizing the hardening function of cement hydrate in aggregate after aggregated treatment The method for reducing CO ₂ emissions in the production of ready-mixed kon according to claim 1.