Abstract
One of the objectives of COIN's Focus Area 3.1 Crackfree concrete structures is to develop guidelines for recommended mix design for different types of structures subjected to restraint thermal and autogeneous dilation. FA 3.1 should develop further the theoretical and practical implications of crack control by stress calculation, aiming at full incorporation of the technology in the specification for civil engineering structures.
As part of this research, a test series of four different concretes, which has been named “COIN P3.1 series” has been carried out within the project. The intention was to investigate how replacing cement with an increasing amount of fly-ash would affect the development of the main mechanical characteristics for such concrete qualities.
The report gives a detailed description of the materials and the test methods used in the experimental programme, and presents the results from this mechanical test programme for the four concrete qualities in question.
The mechanical test programme covers fresh concrete properties; slump, density and air content, tested according to NS-EN 12350, Part 2, 6 and 7. Further, it covers testing of the following hardened concrete properties:
- Density and compressive strength, NS-EN 12390, Part 7 and 3
- Modulus of elasticity in compression (NS 3676), and tension
- Uniaxial tensile strength, SINTEF internal procedure 14-05-04-512
- Splitting tensile strength, NS-EN 12390-6
- Activation energy, NS 3656:1993
- Heat development, NS 3657
In general, it is shown that all the investigated properties; the final heat generated, the compressive strength, the tensile strength and the E-modulus decrease with increasing FA content approximately linearly.
The material models used for the heat development and the time dependence of the mechanical properties are described. Furthermore are the model parameters determined for all the investigated concretes. In general, the material models describe the test results very well. The model parameters are logically related to the FA content, and confirm previous experience. The calculated material model parameters are to be implemented for calculations in the data program Crack TeSt COIN.
The experimental programme is extended and the theoretical approach is further elaborated within COIN FA 3.1.