GB/T 12959-2024 Test methods for heat of hydration of cement
1 Scope
This document describes the test conditions, materials, isothermal conduction calorimetry, solution calorimetry, direct method, result processing and precision of test methods for heat of hydration of cement.
This document is applicable to the measurement of heat of hydration of cement. Among them, the isothermal conduction calorimetry is used as the reference method, and the solution calorimetry and the direct method are used as substitute methods.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 176 Methods for chemical analysis of cement
GB/T 1346 Test methods for water requirement of normal consistency, setting time and soundness of the portland cement
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB/T 17671 Test method of cement mortar strength (ISO method)
JC/T 681 Mixer for mixing mortars
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
baseline output
output signal of the isothermal conduction calorimeter changing with time when the test cell and reference cell are filled with test water and reference water of the same heat capacity
3.2
baseline drift
slope of the linear regression of baseline output with measurement time during the measurement period
3.3
baseline noise
standard deviation of the baseline output over time during the measurement period
3.4
thermal power
heat release rate of the test cement during the measurement period
3.5
calibration
operation to establish a linear relationship between the automatic acquisition voltage of a data collector and the output thermal power of an isothermal calorimeter using a heat source with known thermal power
3.6
calibration coefficient
ratio between the output thermal power of an isothermal calorimeter and the automatic acquisition voltage of a data collector
3.7
sensitivity
minimum thermal power output of an isothermal calorimeter
4 Test conditions
4.1 Laboratory
The temperature of laboratory shall be kept at (20±1)℃, and the relative humidity shall not be lower than 50%. When measuring the heat of hydration by isothermal conduction calorimetry, the voltage fluctuation of the power supply shall not be greater than ±10V, and the laboratory shall be equipped with an uninterrupted regulated power supply to ensure that the isothermal calorimeter continues to run after 8h of power failure. When measuring the heat of hydration by solution calorimetry, the laboratory shall be equipped with ventilation equipment.
4.2 Medium temperature
During the measurement period, the air temperature inside the thermostatic control chamber of the isothermal calorimeter shall be kept at (20.0±0.1)℃, and the water temperature in the thermostatic water tank and thermostatic water tank by direct method of the solution calorimeter shall be kept at (20.0±0.1)℃.
4.3 Temperature of materials and appliances
The temperature of materials and appliances shall be the same as that of the laboratory.
Contents
1 Scope
2 Normative references
3 Terms and definitions
4 Test conditions
5 Materials
6 Isothermal conduction calorimetry (reference method)
7 Solution calorimetry (substitute method)
8 Direct method (substitute method)
9 Result processing
10 Precision
Annex A (Normative) Calibration of isothermal calorimeter
Annex B (Normative) Standardization of isothermal calorimeter
