ABSTRACT
Abstract A measuring method of an autogenous length change by using laser sensors equipped with a digital computer system was proposed. This method is excellent in accuracy and reproducibility, and moreover measurement can be done automatically and continuously by applying it. Simultaneously laser sensors and thermocouples in this method are used, the correction of a change in length for temperature can be carried out simply and easily. This method is effective for quality control, and on top of that, it is suitable especially for measuring an autogenous length change of special cement such as expansive cement and rapid hardening cements. Keywords: Autogenous length change, Quality control, Laser sensor, Digital computer system, Non-contact way
1 Introduction
The real circumstances at present are that an autogenous length change of special cement or cement additives and so forth is not yet made clear. Expansive cement presents autogenous expansion at early age along with hydration [1][2]. Rapid hardening cement generates a large quantity of hydration heat from initial setting [3]. Therefore, in order to discuss an autogenous length change of these special cements, that measurement of expansion can be carried out, and moreover correction of heat are able to be executed, are required. A dial gauge methods as a measuring method of an autogenous length change [4]. However, because this method was in need of skill, it turned frequently out a failure especially in a period of 24hours from initial setting. It reasons was that this method was a contact type, and in addition measurement was performed by manual work.
