Quick mineralogical quantification of blended cement

Aeris Cement edition Introduction One of the key elements of reducing CO 2 emissions during cement production is to reduce the clinker-to-cement ratio by replacing clinker with supplementary cementitious materials (SCMs). The amount of SCMs in cement can go up to several tens of percent. This drastically reduces the carbon footprint per kilogram and also reduces fuel consumption. What is more, many of these blended cements have better properties than Ordinary Portland Cement (OPC).

Essential for the production of these cements is the careful blending of the SCMs into the cement mix. As SCMs have many elements in common with the clinker, direct mineralogical probing by X-ray diffraction is the only way to obtain the necessary information for controlling and guaranteeing good SCM feed. This information can also be used to benchmark against cement classification norms like EN-197, ASTM C150, ASTM C595 and ASTM C1157.

The Cement edition of Aeris is the first benchtop X-ray diffractometer designed for process control and quality assurance in a cement plant. In this data sheet we show typical results from a phase quantification of blended cements along with the repeatability of these results.

Experimental In order to show the capabilities of the Cement edition of Aeris two types of blended cements were analyzed:

1) a blended cement containing both fly ash and slag;

2) a pozzolan cement.

The measurement time was 10 minutes, followed by automatic phase quantification. Each sample was measured 15 times in order to judge the repeatability of the analysis chain.

Summary When producing blended cements, direct mineralogical probing with X-ray diffraction is essential for correct and accurate control of the SCM feed into the cement mix. The Cement edition of Aeris is an easy-to-use benchtop X-ray diffractometer and the first that is automatable and fully suited for process control.

In this data sheet we show that quantification results of the phases in blended cements are both accurate and precise, showing that the Cement edition of Aeris is a perfect quality assurance tool for these innovative cements.

Result and discussion Figures 1 and 2 show the quantitative results of the fly ash/ slag cement and the pozzolan, respectively. The usual cement phases are quantified along with SCMs. Note that slag, fly ash and pozzolan themselves contain many phases, but are quantified as a whole [1].

The results of the phase concentrations of both cements are also presented in Table 1. The standard deviations of the repeatability of all phases are well below 1 wt%, making the analyses with Aeris well-suited for process control.

[1] N. Scarlett and I. Madsen, “Quantification of phases with partial or no known crystal structure,” Powder Diffr., vol. 21, pp. 278-284, 2006.

Figure 1. Phase concentrations of cement containing both slag and fly ash

Figure 2. Phase concentrations of a pozzolan cement

Table 1 Repeatability at 1σ of the fly-ash/slag and pozzolan cement. Values are in wt-%.

Conclusions The presented results show the Cement edition of Aeris to be a fast and precise analysis tool for full mineralogical phase analysis. It is the first benchtop XRD instrument designed for demanding industrial process control requirements. The Cement edition of Aeris is perfectly suited for quality assurance of blended cements.

Quick mineralogical quantification of blended cement

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