The Cement Heat of Hydration Tester by Heat of Solution Method is used to determine the heat released during cement hydration, which is an important indicator for evaluating cement performance and thermal characteristics. The heat of hydration is particularly relevant to the temperature development of concrete and the risk of thermal cracking in mass concrete structures. This operating procedure provides practical guidance on test preparation, instrument operation, calorimeter calibration, sample testing, result calculation, and equipment maintenance. The procedure is based primarily on GB/T 12959-2024 and may also be referenced against EN 196-8:2010, Methods of Testing Cement — Heat of Hydration — Solution Method, where applicable.

I. Test Preparation

1. Carefully review GB/T 12959-2024, Test Methods for Heat of Hydration of Cement, and develop a detailed test plan according to the solution calorimetry method. For international applications, EN 196-8:2010, Methods of Testing Cement — Heat of Hydration — Solution Method, may be used as a relevant reference standard.

2. Read the equipment operating manual carefully and familiarize yourself with the performance, test setup, operating procedures, and safety requirements of the cement heat of hydration tester.

II. Operating Procedure

1. Fill the test water tank of the Cement Heat of Hydration Tester with drinking water until the water level is approximately 3 cm below the bottom of the internal partition. Connect the power supply and switch on the instrument for preheating. Open the drain valve at the rear of the unit. As soon as water begins to flow out, close the valve immediately. This step is intended to remove air from the circulating water lines.

2. Instrument Operation During the Test

2.1 Open the chamber cover and install the vacuum bottle, acid-resistant liner, and acid solution stirring rod.

2.2 Close the chamber cover securely and tighten the wing nuts to ensure a proper seal.

2.3 Connect the power supply, check that the grounding connection is secure, and then switch on the power of the control unit.

2.4 Adjust the crossbeam so that the main shaft is aligned with the acid solution stirring rod.

2.5 Loosen the chuck, raise and install the stirring rod, adjust it to the proper height, and tighten the chuck securely.

2.6 Ensure that the Beckmann differential thermometer and charging funnel are correctly installed. Perform the operation in accordance with the applicable test standard.

2.7 Stop all operating functions in sequence, switch off the main power supply, and unplug the power cord.

2.8 Remove and clean the Beckmann differential thermometer, charging funnel, acid solution stirring rod, and acid-resistant liner in sequence. Store them properly for future use.

2.9 Close the test inner cylinder, place it under the cylinder holder, and cover the water bath with the movable cover.

Note: The test can be started only after the equipment has maintained a constant temperature for 24 hours.

3. Calibrate and calculate the calorimeter heat capacity in accordance with Section 7.4.1, “Calibration of Calorimeter Heat Capacity,” of the applicable test standard. The calorimeter heat capacity shall be calibrated in duplicate, and the average of the two calibration values shall be used as the final result. If the difference between the two calibration values exceeds 5.0 J/°C, the calibration shall be repeated.

4. Follow the procedures specified in the applicable test standard to determine the heat of solution of unhydrated cement and the heat of solution of partially hydrated cement. Calculate the test results and complete the test report accordingly.

5. After completing the test, thoroughly clean the equipment and all test components, and return them to their designated storage positions.

III. Precautions

1. Arrange all instruments, equipment, and accessories in a proper and orderly manner to facilitate operation, observation, and data recording.

2. Before switching on the equipment, ensure that the power supply voltage matches the specified input voltage of the instrument. Equipment equipped with a three-pin power plug must be connected to a power outlet with protective grounding to ensure safe operation.

3. The chemical reagents used in the test may be hazardous to human health. Wear appropriate personal protective equipment (PPE) throughout the test. After the test, properly seal the reagents and store them in a secure, locked location.