JPH07113623B2 - Equipment for measuring the amount of cement in cement mixtures - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for measuring the amount of cement in a cement mixture.

(Prior Art) Cement mixtures are used in various fields such as construction and civil engineering, and it is necessary to measure the amount of cement in the mixture to confirm the strength. Conventionally, as a method for measuring the amount of cement in a cement mixture, the cement mixture is dried in an absolutely dry state, the water content is measured, and then the powder is crushed and dissolved in hydrochloric acid, and then calcium oxide and silica, or insoluble residue is chemically analyzed. Has been used to estimate the amount of cement from that value.

However, this method is not suitable for construction management during on-site construction because it takes a long time for the test and it is necessary to bring the sample into the chemical analysis room. Further, when the aggregate or the soil contains a component that is dissolved by hydrochloric acid, there is a problem in terms of accuracy.

(Problems to be Solved by the Invention) The problem to be solved by the present invention is to facilitate the construction management by measuring the amount of cement in the cement mixture, so that the amount of cement can be easily measured in a short time on site. And to improve the measurement accuracy.

(Means for Solving the Problem) A sealed hollow coil, a device capable of sucking or discharging the cement mixture into the coil, and a device for measuring the inductance of the coil are provided. The amount of cement in a cement mixture containing cement in which ferromagnetic particles are mixed in a predetermined ratio with respect to cement is measured.

(Operation) When a magnetic material is placed in a hollow coil with impedance Z ₀ ,
The impedance of the coil changes depending on the magnetic permeability of the magnetic material. The impedance Z ₀ of the air-core coil is given by Z ₀ = R ₀ + jωL ₀ (1) where j is a pure imaginary number, L ₀ is an inductance, and R ₀ is a resistance. When a magnetic material with magnetic permeability μ * is placed in the coil, the impedance of the coil is S ₀ , the cross-sectional area of the coil, S ₁
Where Z ₁ = R ₀ + ωL ₀ (S ₁ / S ₀ ) μ ″ + jωL ₀ {(S ₀ −S ₁ ) + μ ′S ₁ } / S ₀ …………… (2) Where μ ′ is the real part of permeability μ *,
With μ ″ as an imaginary part, μ * = μ′jμ ″. Further, the impedance of the coil when a magnetic material is put is Z ₁ = R ₁ + jωL ₁ (3) where L ₁ is the inductance and R ₁ is the resistance. Therefore, R ₁ = R ₀ + ωL ₀ (S ₁ / S ₀ ) μ ″ L ₁ = L ₀ {(S ₀ −S ₁ ) + μ ′S ₁ } / S ₀ , and the real and imaginary parts of permeability are μ ′ = (S ₀ / S ₁ ), respectively. (L ₁ / L ₀ −1) +1 μ ″ = (S ₀ / S ₁ ) (R ₁ −R ₀ ) / ωL ₀ . From this, by measuring the inductance and resistance of the coil when the hollow and the magnetic substance are put, the magnetic permeability of the magnetic substance put in the coil can be measured. At this time, if a ferromagnetic material without magnetic loss up to high frequencies is used,
At the measurement frequency, μ ″ is 0 and only μ ′, and the magnetic permeability can be measured by measuring only the inductance change of the coil. Further, the magnetic permeability of the mixture in which the ferromagnetic particles are dispersed in the non-magnetic material is dispersed. It is proportional to the amount of ferromagnet.Therefore, the ferromagnet which can behave the same as that of the ferromagnet is blended, and the blending ratio of these two is kept constant, and it is mixed with other specific ferromagnet to be distinguished. In this state, the amount of cement in the cement mixture can be measured by measuring the magnetic permeability of the mixture from the change in the inductance of the coil.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. A coil 2 fixed to a hollow rod 3 and a sensor portion composed of a case for sealing, and a cement mixture 1 in the hollow rod.
It is composed of a pump 7 for sucking in or discharging, and an inductance measuring device 5 and a measuring unit including a calculation and display unit 6. The cement mixture 1 is sucked into the coil by a pump, and the inductance at that time is measured. The magnetic permeability is obtained from the difference with the inductance when the coil is hollow, which is measured in advance by the calculation unit, and the amount of cement is calculated from that value. Fig. 2 shows the dependence of permeability on the ferrite concentration in the cement milk (ferrite + cement): water = 1: 1 mixture of cement with a fixed ratio of ferrite with a magnetization of 85 emu / g and a specific gravity of 4.8. It is shown. The magnetic permeability (μ'-1) changes linearly with respect to the ferrite concentration. Next, various cement milks were produced with the ferrite concentration kept constant, the same mixture was measured, and the relationship between the magnetic permeability and the amount of cement in the cement mixture was obtained, as shown in FIG. Using this, the amount of cement in the cement mixture can be measured from the magnetic permeability. Table 1 is 5w
This is an example of the amount of cement obtained by measuring the amount of cement by measuring the cement mixture in which the amount of cement was adjusted to 20, 30, and 40 g using t% ferrite cement, water, and earth and sand, and using the apparatus of the example. Thus, it was possible to accurately measure the amount of cement.

(Effects of the Invention) As described above, according to the present invention, the amount of cement in the cement mixture is determined by mixing the ferromagnetic particles such as ferrite in the cement at a constant concentration and measuring the inductance change of the coil. It is possible to provide a measuring device that can perform simple measurement, does not require chemical treatment, and has few errors. In addition, the device of the present invention can be provided in a portable size and can be used for cement amount inspection while moving.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the device of the present invention, and FIG.
FIG. 3 is a diagram showing the ferrite concentration dependence of the magnetic permeability of the cement mixture, and FIG. 3 is a diagram showing the relationship between the cement concentration in the cement mixture and the magnetic permeability. In the figure, 1 ... Cement mixture, 2 ... Coil, 3 ... Rod, 4 ... Sealing case, 5 ... Inductance measuring section, 6 ... Computing section and display section, 7 ... For suction and discharge pump

Claims (1)

[Claims] 1. A method comprising: a sealed hollow coil; a device capable of sucking or discharging a cement mixture into the coil; and a device for measuring the inductance of the coil, wherein ferromagnetic particles are applied to the cement. An apparatus for measuring the amount of cement in a cement mixture, which comprises measuring the amount of cement in a cement mixture containing cement mixed in a predetermined ratio in advance.