JP2005283363A - Method to measure the amount of water except for water absorption of aggregate of ready-mixed concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To establish a method to measure the amount of water except for water absorption of ready-mixed concrete until the concrete is used for construction. <P>SOLUTION: By correcting the loadings of coarse aggregate and fine aggregate in a recipe for surface moisture, or completely drying the coarse aggregate and fine aggregate, the amount of air included in ready-mixed concrete is measured. Then, the composite density of the coarse aggregate (G), the fine aggregate (S), and the cement (C) is measured and calculated. The unit quantity of water of the ready-mixed concrete is calculated by measuring the amount of the air included in the ready-mixed concrete whose recipe is corrected using the calculated composite density to control the unit quantity of water. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for measuring the amount of water excluding the amount of water absorption of the aggregate of ready-mixed concrete until the kneaded ready-mixed concrete is used for manufacturing and construction.

  Slumps of kneaded ready mixed concrete must be guaranteed at the construction site. Correction of slump fluctuation at the construction site to be delivered and slight changes in slump required from the site are adjusted at the time of manufacture. In general, the method of adjusting this is often carried out by adjusting the surface water correction value of the fine aggregate, but this changes the unit water amount. There is no quick way to know this unit water volume. At present, apparatuses for measuring by a microwave oven method, a reduced pressure heating method, a capacitance method, a radioisotope method, an air meter method and the like have been commercialized but are not in a satisfactory state. This is because the microwave oven method, the reduced pressure heating method, the capacitance method, and the radioisotope method are affected by the water absorption rate of the aggregate, and the air meter method is affected by the surface dry density of the aggregate.

  Test methods for the surface dry density and water absorption rate of the aggregate are defined in JIS A 1109 and JIS A 1110. On the other hand, water absorption is defined in JIS A 0203, number 3106, and surface dry density is defined in number 3108, but the test results do not match the definitions. Depending on the case, different results are measured, the test time is long, and the number of test samples is small, so the reliability of the measured value is low.

  For these reasons, the tests of JIS A 1109 and JIS A 1110 are rarely conducted, and the formulation is designed using data used in the past. The density used in the recipe is used to know the kneading volume and corrects the volume at the on-site recipe.

  As a manufacturing process control, the surface water content of the aggregate is tested according to JIS A 1111 and JIS A 1125. The measurement of surface dry density and water absorption can be known from the average value and standard deviation of surface dry density, but it takes about 30 hours to test, and the number of data sufficient to know the standard deviation cannot be obtained. A company's internal standards measure the surface water percentage of aggregates several times a day. However, the surface water ratio H11 measured by JIS A 1111 using the surface dry density and the surface water ratio H25 measured by JIS A 1125 using the water absorption rate result in H11 ≠ H25, and the difference is Since it is too large, there is no factory that does this, and it is in a situation where it is impossible to know the surface water rate of fine aggregate correctly.

Regarding the surface dry density, water absorption rate, and surface water rate of the aggregate, a measurement method is disclosed in Patent Document 1, and the contents of JIS that define the surface dry density and water absorption rate of the aggregate are described in detail in Patent Document 2. Has been. Recently, the orderer of ready-mixed concrete has been actively inspecting the “unit water volume”, and the demand for measuring the “unit water volume” quickly with high accuracy is increasing.
Japanese Patent No. 3398863 JP 2003-57231 A

Aggregates used in ready-mixed concrete are wet fine aggregates when the maximum aggregate size is 5 mm or less and contain water, and absolutely dry fine aggregates when water evaporates and is in a dry state, larger than 5 mm. A state containing water and moisture is called wet coarse aggregate, and a case where water is evaporated and dried is called absolutely dry coarse aggregate. When preparing ready-mixed concrete, a recipe is required, and there are “indication mix” and “on-site mix”. The indication blending is instructed by the specifications, and the “onsite blending” is a blending determined according to the material condition and the measuring method at the spot so that the “indication blending” concrete can be obtained.
“Unit amount” is the amount of each material used when making 1 m3 of concrete, and includes unit cement amount, unit water amount, unit coarse aggregate amount, unit fine aggregate amount, and unit admixture. The test blending is carried out according to [JIS A 1138] using “indication blending”. The material using this is specified in the material preparation. This material is different from the material used for manufacturing, and this different part is corrected by "in-situ blending", but this method is technically problematic.

  In general, the produced aggregate is freed of mud and adjusted in particle size. Even if the slump that appears in this state is as designed, the slump does not appear normally in the aggregate used for manufacturing. For this reason, the ratio setting change of fine aggregates and coarse aggregates, volume correction, oversized grains, oversized grains, etc. are corrected to make “on-site blending”. It has been confirmed in the field by slump measurement that it can not be guaranteed if technically satisfactory products can be manufactured. In order to satisfy this, the surface water ratio of the aggregate is adjusted. This is because the slump is adjusted by the amount of water, so the "unit water amount" is different.

  When the amount of unit water of the concrete increases, drying shrinkage, bleeding, settling after driving, etc. increase, resulting in increased undesirable properties such as drying shrinkage, cracking and subsidence cracking in the structural concrete. As a method for estimating the unit water amount, a unit water amount estimating method by an air meter method is known. However, since most of the mass of concrete is occupied by aggregates, if the density of the aggregates is not accurately grasped, the estimation accuracy of the unit water amount is lowered. It is an object of the present invention to accurately grasp the average density of aggregate and cement and measure the water amount excluding the water absorption amount of ready-mixed concrete.

  The inventions of the present application described in claims 1 and 2 measure and calculate the composite density of coarse aggregate (G), fine aggregate (S), and cement (C) during test mixing according to the recipe. On how to do. The invention of the present application described in claim 3 and claim 4 is a unit of ready-mixed concrete using the composite density of coarse aggregate, fine aggregate and cement obtained by the invention described in claims 1 and 2. It is a method for measuring and managing the amount of water.

That is, the invention of claim 1 measures the amount shown in the combination table of coarse aggregate and fine aggregate, cement, water, and admixture close to the surface dry state, and kneads them to prepare ready mixed concrete. The sample collected from the ready-mixed concrete is packed in a container having an internal volume V used for measuring the air amount, and after measuring the sample weight t, the air amount A% is measured, and the coarse aggregate G, The total weight of fine aggregate S, cement C, water W, admixture AE is T, the volume of sample weight t that does not include air is L, and the composite density of coarse aggregate G, fine aggregate S, and cement C is ρ. _GSC , where μ is the density of water and R is the condensation amount, R = t / T, and the volume of the ready-mixed concrete with the total weight T not including the amount of air is:
L / R = (G + S + C) / ρ _GSC + (W + AE) / μ
So
ρ _GSC = (G + S + C) × R × μ / {L × μ− (W + AE) × R}
The composite density ρ _GSC of the coarse aggregate G, the fine aggregate S, and the cement C is obtained by the following formula to produce ready-mixed concrete.

In the invention of claim 2, the fine aggregate is obtained by measuring the absolute dry weight D, the absolute volume S, the water absorption q, the surface water volume h, and obtaining the surface water ratio H = 100 h / (D + q),
Corrected fine aggregate weight = S (1 + H / 100)
Correction water amount = W−S × H / 100
The corrected fine aggregate weight, corrected water amount, coarse aggregate, cement, and admixture are adjusted and weighed to match the materials in the blending table so as to fit the mixer, and the total weight T of each material is kneaded. The sample collected from the ready-mixed concrete was packed in a container having an internal volume V used for measuring the air amount, and after measuring the sample weight t, the air amount A% was measured, the coarse aggregate G, The total weight of fine aggregate S, cement C, water W, admixture AE is T, the volume of sample weight t that does not include air is L, and the composite density of coarse aggregate G, fine aggregate S, and cement C is ρ. _GSC , where μ is the density of water and R is the condensation amount, R = t / T, and the volume of the ready-mixed concrete with the total weight T not including the amount of air is:
L / R = (G + S + C) / ρ _GSC + (W + AE) / μ
So
ρ _GSC = (G + S + C) × R × μ / {L × μ− (W + AE) × R}
The composite density ρ _GSC of the coarse aggregate G, the fine aggregate S, and the cement C is obtained by the following equation, and the invention is a method for producing ready-mixed concrete.

The inventions of claim 3 and claim 4 are respectively prepared by using the mixed density ρ _GSC of coarse aggregate G, fine aggregate S, and cement C obtained by claim 1 or claim 2, respectively. It is an invention of a method for measuring and managing the unit water amount of concrete.
That is, ready mixed concrete is manufactured by blending each material using the composite density ρ _GSC of coarse aggregate G, fine aggregate S, and cement C, and the sample weight t and the amount of air A% are measured to obtain coarse aggregate. G, fine aggregate S, cement C, total weight of water W is T, the volume is M, the volume not including air is L, the density of water is μ, and R = t / T, aggregate and cement The solid content weight K is:
K = (t−L × μ) × ρ _GSC / (ρ _GSC −μ)
The amount of water contained in ready-mixed concrete W _X = T−K / R
Since the kneading volume M of T is V / R, the unit water amount M _MIX = W _X / M
This is a method of measuring and managing the unit water amount of the ready-mixed concrete produced by obtaining the unit water amount.

  According to the present invention, the composite density of coarse aggregate, fine aggregate, and cement is measured at the time of test kneading, and the ready-mixed concrete produced is collected and packed in an air amount measurement container to determine the sample weight and air amount. The unit water amount can be managed by measuring and calculating the unit water amount using the synthetic density of the coarse aggregate, fine aggregate and cement. This makes it possible to judge whether or not the ready-mixed concrete being produced is maintained in the state of the test kneading, making it possible to keep the quality of the ready-mixed concrete uniform, such as drying shrinkage, bleeding, It is possible to obtain an excellent ready-mixed concrete that does not cause sedimentation after driving and does not induce drying shrinkage, cracking, and settlement cracking in the structural concrete.

Ready-mixed concrete is produced by kneading surface dry aggregate, cement, water, and admixture with a mixer for a certain period of time. Ready-mixed concrete consists of a mixture of (surface dry aggregate + cement) solids, (water + admixture) liquid and bubbles. Knowing the density of solids and the density of liquids, the amount of liquid can be known by putting ready-mixed concrete into a quantitative container, measuring the weight of the concrete, and measuring the amount of bubbles. The liquid is a mixture of water and an admixture, and the admixture is about 1.5% of the weight of water, so the liquid is treated as water.
In the preparation of ready-mixed concrete, the weights of coarse aggregate, fine aggregate, cement, water, and admixture are measured and kneaded for a certain period of time. Since coarse water and fine aggregate contain surface water, they are corrected. The air volume, slump, and concrete temperature of the ready-mixed concrete made in this way are inspected before shipment and confirmed at the delivery site.

The production of ready-mixed concrete is indicated in the recipe, and the test kneading is thereby carried out. For the material to be subjected to the test kneading, prepare the surface dry material for the aggregate or correct the surface water content to correct the surface dry weight. The amounts listed in the recipe may not be compatible with the mixer for the test mix. In such a case, each material is multiplied by 1 / r and weighed with a mixer for a certain period of time so as to obtain concrete in the composition table. The sample weight t is measured, and the air amount A% is measured. If the total weight of each material indicated in the recipe is T, the volume without air volume L = V / (1 + A / 100)
From this, the volume of T that does not include air volume M = L × T / t

The surface dry weight G of the coarse aggregate, the surface dry weight S of the fine aggregate, the weight C of the cement, and the weight W of the water.
T = G + S + C + W
If the density of water is μ, the aggregate density of coarse aggregate, fine aggregate, and cement is ρ _GSC ,
M = (G + S + C) / ρ _GSC + W / μ
Therefore,
ρ _GSC = (G + S + C) μ / (M × μ−W)
This ρ _GSC is defined as “composite density of coarse aggregate, fine aggregate and cement” and used as basic data.

Next, a process actually performed will be described.
First, materials used for manufacturing are prepared. Coarse aggregate is easy to put in a surface dry state. That is, spread thinly on the waterproof sheet, gently send warm air to scatter the surface water, visually confirm that there is no surface water, and cover with the waterproof sheet. Do not remove mud etc. Prepare cement for use on site.
Next, the surface water ratio of the fine aggregate is measured. Fine aggregate used for production is collected as is. This is mixed uniformly and mixed evenly as shown in FIG. 1 (a). About 1 kg is extracted from several locations from the fine aggregate of (a) (b), and this is evenly mixed (c) to collect equal amounts of samples X and Y of about 500 g (Eg) (d).

A pycnometer 2 with a stopper 1 shown in FIG. 2 (internal volume V when stoppered) is prepared. Prepare a pan 4 with a plug 3 as an accessory (a), set it in the pycnometer 2, add sample X to the pan 4 and add water 5 (b), pull out the water plug 3 of the pan 4 and Pour water 5 (c). Further, it is filled with water and left for about 10 seconds to allow bubbles in the water to float up, filled with water and plugged (d), and the weight T1 of the internal volume is measured. The internal volume of the pycnometer when plugged is V, the amount of water w, the density of water is μ, the absolute dry weight D, the absolute dry volume S of the sample X, and the water absorption q.
T1 = D + q + w
V = S + w / μ
q = T1−D− (V−S) μ (1)

The sample Y is completely dried, and the hot sand weight D is measured. As shown in Fig. 3, the sample Y was controlled at a temperature of 100 to 110 ° C and occasionally dried with stirring with a jar, and this was confirmed by covering the container with a glass plate for about 10 seconds and clouding with water vapor. Make sure that it does not occur and make it completely dry. The hot sand weight D is measured. E is the weight of the sample Y.
E = D + q + h ……………………………………………… (2)

As shown in FIG. 3, this is put in the metal cooling container 6 (a) and floated and cooled in the cooling water 7 (b). Cooling water 8 that covers the cooling sample Y is put into the pycnometer 2 (c) The moisture in the tray with the stopper is removed, the entire amount of the cooling sample Y is put in, and the stopper is gently lifted and poured into the pycnometer 2 (d). Add water to the saucer with a stopper, fill the pycnometer and measure the weight T2 of the internal volume (e). At this time, the pycnometer is stimulated so as not to perform the defoaming operation.
T2 = D + w ……………………………………………………… (3)
V = S + w / μ …………………………………………………… (4)
From formulas (3) and (4): S = V- (T2-D) / [mu] …………………………………… (5)
(1) q is obtained from the equation (5).

q = T1−D− (V−S) μ
h = E- (D + q)
S = V− (T2−D) / μ
In this way, the vector component, absolute dry weight (D), absolute dry volume (S), water absorption q, and surface water h of sample X or sample Y are determined.
From this vector component, surface water ratio H = 100 × h / (D + q) (6)

Since the fine aggregate when subjected to the test kneading is the absolute dry weight (D), the absolute dry volume (S), the water absorption q, and the surface water h, from this vector component, the surface water content, water content, water absorption rate, The surface dry density ρ _W and the absolute dry density are obtained as follows.
Surface water ratio H = 100 × h / (D + q)
Water content Z = 100 (q + h) / D
Water absorption Q = 100 × q / D
Table dry density ρ _W = (D + Q) / S
Absolutely dry density ρO = D / S
When these values are calculated and stored and ready-mixed concrete is manufactured, measurement is performed several times a day as a manufacturing process control, and whether the fine aggregate used for manufacturing is the same as when testing. Please make sure that the surface water correction is done correctly in the laboratory.

  Another method is to spread the fine aggregate collected on the waterproof sheet thinly and flatly and send warm air to near dryness, or close to dryness in the sun, and the amount of water equivalent to the amount of water absorbed. Is sprayed, mixed with a mixer, and covered with a waterproof sheet for 24 hours to make a fine dry aggregate. This sample is handled with the surface water ratio = 0%.

[Table 1] is a recipe. In order to test this, a coarse aggregate is prepared in a surface dry state, and the surface water percentage H% is measured for the fine aggregate.
These materials are coarse aggregate = G, fine aggregate corrected with surface dryness = S (1 + H / 100), cement = C, water corrected with water amount corrected for surface dryness = (W−S × H / 100), Admixture = AE
Test kneading is performed so that the concrete of the blending table can be obtained. Each material is multiplied by 1 / r so as to adapt to the test kneading mixer, and these are weighed and kneaded for a certain period of time to prepare ready-mixed concrete.

As shown in FIG. 4, an instrument for measuring the amount of air is prepared.
A container having an internal volume V is filled with ready-mixed concrete according to the procedure of JIS A1128, the internal volume weight t is measured, and the air amount A% is further measured. The volume L of the internal volume weight t excluding the air amount is
L = V / (1 + A / 100)
The weight T of ready-mixed concrete is
T = G + S + C + W + AE ……………………………………………… (7)
If the ready-mixed concrete condensation ratio is R,
R = t / T
The volume of the ready mixed concrete T that does not include the air volume ML = L / R
L / R = (G + S + C) / ρ _GSC + (W + AE) / μ
ρ _GSC = (G + S + C) × R × μ / {L × μ− (W + AE) × R} (8)

The sample t with no air amount in the container includes the solid content weight K and the water amount w of the aggregate and cement.
t = K + w ………………………………………………………………… (9)
L = K / ρ _GSC + W / μ ……………………………………………… (10)
(9) From equation (10) K = (t−L × μ) ρ _GSC / (ρ _GSC −μ) (11)

Water amount W _X contained in ready-mixed concrete
W _X = TK / R = w / R ………………………………………………… (12)
Mixing volume M of ready-mixed concrete T _MIX = V / R
Unit water volume W _MIX = W _X / M _MIX
In this way, the unit water amount of ready-mixed concrete can be known.

The coarse aggregate is used in the surface dry state, but if hG surface water remains, the unit water amount M _X = (W _X + h _G ) / M. Since the surface area of the coarse aggregate is smaller than the surface area of the fine aggregate, there is no problem. The method of managing whether the ready-mixed concrete produced is the same as when testing is to at least manage the wet fine aggregate vector [DSqh].

[Table 2] is a recipe that was implemented, and [Table 3] is an on-site recipe that was implemented by multiplying the weight of Table 2 by 1.015.

[Measures [DSqh] of wet fine aggregate]
Wet fine aggregate used for test kneading is uniformly mixed, samples of about 1 kg or more are collected from five locations, and this is mixed uniformly, and two sets of sample A, sample B, and weight E = 500 g are taken out. .

Sample X (see Fig. 2)
Prepare a pycnometer with a stopper with an internal volume V = 752 cc and a stopper with a stopper.
Combine these, put E = 500g in the saucer, fill up the water, and gently pull up the stopper.
E = 500 g is placed in a pycnometer with water. (Water temperature 20 ° C)
E = 500 g settles on the bottom, and bubbles formed by surface water separate into water.
Check that there are no air bubbles after a while.
After confirmation, add a water stopper until the pycnometer is full. Internal volume weight T1 = 1052g

Sample Y (see FIG. 3)
The sample B is put in a heating container, and water is scattered while being stirred and stirred so as not to exceed about 110 ° C. Confirm the absolutely dry condition by covering the glass plate with a heating vessel for about 5 to 10 seconds and checking that there is no clouding by water vapor. Place the cooling container on the weighing instrument and measure the hot sand sample weight. D = 480.5g
The sample in the cooling vessel is flattened, covered with an acrylic plate having a thickness of 3 mm, and floated in cooling water having a water temperature of 20 ° C. until the temperature of the sample reaches 20 ° C.
Put enough cooling water to cover the cooled sample into the pycnometer to remove the water from the stoppered tray, add the entire amount of the cooled sample, and gently pull up the stopper. Add water to the stoppered tray, fill the pycnometer and measure the weight T2 of the internal volume. T2 = 1045.5g

Summary of measured values V _P = 752cc
E = 500g
T1 = 1052g
D = 480.5g
T2 = 1045.5g
S = V- (T2-D) / [mu] = 186.0 ... From equation (5) q = (SV) [mu] + (T1-D) = 6.5 From equation (1) h = Eq-D = 13 ……………………………………………………… (2) From the formula Table dry density = (D + q) /S=2.618
Absolutely dry density = D / S = 2.583
Surface water ratio H = 100 h / (D + q) = 2.7
Water absorption rate = 100q / D = 1.35
Moisture content = 100 (h + q) /D=4.1

Each value in Table 2 is shown in Table 4 after surface water correction of the fine aggregate as follows.
Fine aggregate = 767 (1 + 2.7 / 100) = 788.0
Water = 163−767 × 2.7 / 100 = 142
Each material is weighed and kneaded with a mixer. Weight of ready-mixed concrete completed T = 2310.0 kg, temperature 21 ° C.

Coarse aggregate is collected from the manufacturing site for the amount used for test kneading, thinly spread on a waterproof sheet, and warm air is gently sent to scatter surface water. Make sure that there is no surface water visually, and cover with a waterproof sheet. Do not remove mud etc. Prepare cement for on-site use. For fine aggregate, a surface water ratio of 2.7% is measured.
The mixer for the test kneading is for 0.5 m ³ . Since the recipe is designed at 1 m ³ , these materials are multiplied by 1 / r = 0.5.
Coarse aggregate = 767 (1 + 2.7 / 100) × 0.5 = 393.8
Cement = 330.0 × 0.5 = 165
Water = (163−767 × 2.7 / 100) × 0.5 = 71.2
AE = 0.099 × 0.5 = 0.05
Weigh and knead for a certain time to make ready-mixed concrete. The concrete had a temperature of 21 ° C.

The weight T of the ready-mixed concrete in the composition table = 2310.0 kg, and the internal volume V of the container for measuring the amount of air = 6.940 liters. The container was filled with ready-mixed concrete and the sample weight t was measured to be 16.110 kg. When the amount of air was measured, a value of A = 5.0% was obtained.
Sample volume L not including air volume
L = V / (1 + A / 100)
L = 6.640 / (1 + 5.0 / 100) = 6.60952
From [Table 2] T = G + S + C + W + AE = 2310.0
G + S + C = 2147.0
R = 16.110 / 2310.1 = 0.006974
μ = 0.99799

From equation (4) ρ _GSC = (G + S + C) × R × μ / {L × μ− (W + AE) × R}
ρ _GSC = 2.737
The density of solids contained in ready-mixed concrete produced in the recipe is ρ _GSC as basic data.
From equation (5) K = (t−L × μ) × ρ _GSC / (ρ _GSC −μ)
K = 14.973
K / R = 2147 = G + S + C

In the ready-mixed concrete made in [Table 2], since the aggregate used is in a dry state, there is no water other than the surface water amount = 0, that is, the design blended water (W + AE).
The amount of water contained in ready-mixed concrete is calculated from equation (6): W _X = 2310.0-2147.0 = 163
[Table 2] kneading volume M _X = V / 1000R
M _X = 6.940 × 2310.1 / 16110 = 0.9951
Volume M _MIX calculated using the density in [Table 2]
M _MIX = (1050.0 / 2.70 + 767.0 / 2.6 + 330.0 / 3.04 + 163 / 0.99799) × 1.05 / 1000 = 1.005
M _MIX -M _X = 1.005 -0.9951 = 0.0099
This error arises from the density error.
Unit water quantity MW = W _X / M _X = 163 / 0.9951 = 163.8

  As described above, according to the present invention, the composite density of coarse aggregate G, fine aggregate S, and cement C is measured and calculated at the time of test kneading, and the manufactured ready-mixed concrete is collected and used in an air amount measuring container. The unit water volume can be managed by packing and measuring the sample weight and air volume. In manufacturing process management, the dry weight D, the absolute dry volume S, the water supply q, and the surface water h are measured to calculate the surface water ratio from these components. Surface water correction can be managed.

It is explanatory drawing which shows the collection process of the fine aggregate sample currently used for manufacture from the field. It is explanatory drawing which shows the measuring method for calculating the surface water content, moisture content, water absorption, surface dry density, and absolute dry density of the extract | collected sample using a pycnometer. It is explanatory drawing which shows the measuring method for making a sample collected into a completely dry state using a pycnometer, and calculating a surface moisture content, a moisture content, a water absorption rate, a surface dry density, and a completely dry density. An air flow meter is shown.

Explanation of symbols

1 Pycnometer plug 2 Pycnometer 3 Plug 4 Receptacle 5 Water 6 Dish 7 Cooling water X Sample Y Sample T1 Weight of internal volume T2 Weight of internal volume G Coarse aggregate S Fine aggregate C Cement AE Admixture A Air volume V measurement Inner volume L Sample volume not including the amount of air in the measuring instrument D Absolute dry weight of sample X S Absolute volume of sample X q Water absorption of sample X h Surface water volume of sample X t Sample weight H Surface water ratio W Water μ Water density ρ _GSC G · S · C composite density K Weight of solids composed of aggregate and cement T Total weight of ready-mixed concrete M Mixing volume of ready-mixed concrete W _X Amount of water contained in ready-mixed concrete M Unit water volume of _MIX ready-mixed concrete
Condensation amount of R ready mixed concrete

Claims (4)

Weigh each amount shown in the composition table of coarse and fine aggregates close to the surface dry, cement, water, and admixture, and knead them to produce ready-mixed concrete. From the ready-mixed concrete, The collected sample is packed in a container having an internal volume V used for measuring the air amount, and after measuring the sample weight t, the air amount A% is measured, and the coarse aggregate G, fine aggregate S, cement C, water W, the total weight of the admixture AE is T, the volume of the sample weight t that does not include the air volume is L, the composite density of coarse aggregate G, fine aggregate S, and cement C is ρ _GSC , and the density of water is μ, condensation When the amount is R, R = t / T, and the volume of the ready-mixed concrete with the total weight T not including the air amount is
L / R = (G + S + C) / ρ _GSC + (W + AE) / μ
So
ρ _GSC = (G + S + C) × R × μ / {L × μ− (W + AE) × R}
The composite density ρ _GSC of the coarse aggregate G, the fine aggregate S, and the cement C is obtained by the following formula to produce ready-mixed concrete. The fine aggregate is measured by measuring the absolute dry weight D, absolute volume S, water absorption q, surface water volume h, and determining the surface water ratio H = 100 h / (D + q).
Corrected fine aggregate weight = S (1 + H / 100)
Correction water amount = W−S × H / 100
The corrected fine aggregate weight, corrected water amount, coarse aggregate, cement, and admixture are adjusted and weighed to match the materials in the blending table so as to fit the mixer, and the total weight T of each material is kneaded. The sample collected from the ready-mixed concrete was packed in a container having an internal volume V used for measuring the air amount, and after measuring the sample weight t, the air amount A% was measured, the coarse aggregate G, The total weight of fine aggregate S, cement C, water W, admixture AE is T, the volume of sample weight t that does not include air is L, and the composite density of coarse aggregate G, fine aggregate S, and cement C is ρ. _GSC , where μ is the density of water and R is the condensation amount, R = t / T, and the volume of the ready-mixed concrete with the total weight T not including the amount of air is:
L / R = (G + S + C) / ρ _GSC + (W + AE) / μ
So
ρ _GSC = (G + S + C) × R × μ / {L × μ− (W + AE) × R}
The composite density ρ _GSC of the coarse aggregate G, the fine aggregate S, and the cement C is obtained by the following formula to produce ready-mixed concrete. Each material is mixed using the composite density ρ _GSC of the coarse aggregate G, fine aggregate S, and cement C obtained by the method according to claim 1 to produce ready-mixed concrete. A% is measured and the total weight of coarse aggregate G, fine aggregate S, cement C, water W, admixture AE is T, the volume is M, the volume not containing air is L, and the density of water is μ , R = t / T, solid content weight K composed of aggregate and cement is
K = (t−L × μ) × ρ _GSC / (ρ _GSC −μ)
The amount of water contained in ready-mixed concrete W _X = T−K / R
Since the kneading volume M of T is V / R, the unit water amount M _MIX = W _X / M
A method of measuring and managing the unit water volume of the ready-mixed concrete produced by obtaining the unit water volume by the above method. The mixed density ρ _GSC of the coarse aggregate G, the fine aggregate S, and the cement C obtained by the method according to claim 2 is used to produce a ready-mixed concrete, and the sample weight t, the amount of air A% is measured and the total weight of coarse aggregate G, fine aggregate S, cement C, water W, admixture AE is T, the volume is M, the volume not containing air is L, and the density of water is μ , R = t / T, solid content weight K composed of aggregate and cement is
K = (t−L × μ) × ρ _GSC / (ρ _GSC −μ)
The amount of water contained in ready-mixed concrete W _X = T−K / R
Since the kneading volume M of T is V / R, the unit water amount M _MIX = W _X / M
A method of measuring and managing the unit water volume of the ready-mixed concrete produced by obtaining the unit water volume by the above method.