GB/T 750-2024 Test method for autoclave expansion of cement
Warning: This test is dangerous. The autoclave shall be used safely during the test. Pay attention to the position of exhaust port to avoid being scalded by steam
1 Scope
This document gives the method and principle of autoclave expansion of cement, and specifies apparatus, materials, test conditions, forming and curing of specimens, measurement of specimen length, autoclave of specimens, and the calculation and evaluation of results.
This document is applicable to the measurement of autoclave expansion of hardened cement stone. Among them, the test method for 25mm×25mm×280mm specimen is the reference method, and the test method for the 25mm×25mm×146mm specimen is the substitute method.
2 Normative references
The following normative documents contain provisions 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 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 603 Standard test method for drying shrinkage of mortar
JC/T 681 Mixer for mixing mortars
JC/T 723 Cement mortar vibrating table
JC/T 729 Mixer for cement paste
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
autoclave
a treatment process in which the specimen is kept in a closed environment with saturated steam at 215.7℃ and a corresponding pressure of 2.0MPa for a certain period of time
4 Method principle
Under saturated steam conditions, the temperature and pressure are increased to enable the majority of minerals such as magnesite and free calcium oxide in cement to hydrate within a relatively short period of time. The volume stability of cement is judged by the linear expansion rate of the specimen.
5 Apparatus
Contents
Foreword II
1 Scope
2 Normative references
3 Terms and definitions
4 Method principle
5 Apparatus
6 Materials
7 Test conditions
8 Forming and curing of specimen
9 Measurement of specimen length
10 Autoclaving of specimen
11 Result calculation and assessment
Annex A (Normative) Test method for 25mm×25mm×146mm specimen
Annex B (Normative) Safety precautions
