CONTRIBUTIONS TO THE APPLICATION AND IMPLEMENTATION OF THE RAPID METHOD TO DETERMINE THE STANDARD STRENGTH OF CEMENT CEM I AND CEM II/A, B-S IN HEIDELBERGCEMENT GROUP'S PLANT LABORATORIES

摘要

The standard strength (28-day compressive strength) of cement is a property of major significance in the ultimate assessment of cement quality and essential in setting the trading destination for cement products. Rapid methods to predict it and provide information of prime utility in making optimal decisions are under constant interest both in Romania and abroad. The present method is based on laboratory experiments on similar cements. It involved three experimental and calculation steps: (ⅰ) determination of the 28-day compressive strength as per SR EN 196-1, (ⅱ) determination of the 1-day compressive strength on cement samples heat-cured as per the present rapid method, (ⅲ) establishing a linear correlation y = ax + b, where y is the 28-day compressive strength and x, the 1-day compressive strength, on samples cured at a temperature. The regression equations were conceived in the INC CEPROCIM testing laboratory. The equations were validated on similar cements from the same producer, and led to a rapid prediction (approx. 28 hrs) of the 28-day compressive strength with a precision of ±2.5 MPa. The paper reveals the results obtained in the INC CEPROCIM testing laboratory and the strengths obtained with the application and implementation of the rapid method at MOLDOCIM, Bicaz, and CASIAL, Deva.