UNIVERSITY OF SIEGEN

Investigation of the influence of ­crystal ­morphology on the strength development of ­various a-hemihydrates by use of an in-situ ­ultrasonic technique and complementary methods

1 Temporal change in ultrasonic energy and velocity of a-hemihydrate (1) [W/aHH-ratio: 0.33, Temperature: 23 °C]
1 Temporal change in ultrasonic energy and velocity of a-hemihydrate (1) [W/aHH-ratio: 0.33, Temperature: 23 °C]
2 Temporal change in ultrasonic frequency of a‑hemihydrate (1) [W/aHH-ratio: 0.33, Temperature: 23°C]
2 Temporal change in ultrasonic frequency of a‑hemihydrate (1) [W/aHH-ratio: 0.33, Temperature: 23°C]
3 Results of in-situ optical microscopy on hydration of a-hemihydrate (1) [W/aHH-ratio: 0.8, Temperature: 23°C]
3 Results of in-situ optical microscopy on hydration of a-hemihydrate (1) [W/aHH-ratio: 0.8, Temperature: 23°C]
4 Temporal change in ultrasonic energy and velocity of a-hemihydrate (2) [W/aHH-ratio: 0.33, Temperature: 23°C]
4 Temporal change in ultrasonic energy and velocity of a-hemihydrate (2) [W/aHH-ratio: 0.33, Temperature: 23°C]
5 Temporal change in ultrasonic frequency of a‑hemihydrate (2) [W/aHH-ratio: 0.33, Temperature: 23°C]
5 Temporal change in ultrasonic frequency of a‑hemihydrate (2) [W/aHH-ratio: 0.33, Temperature: 23°C]
6 Results of in-situ optical microscopy of hydration of a-hemihydrate (2) [W/aHH-ratio: 0.8, Temperature: 23 C]
6 Results of in-situ optical microscopy of hydration of a-hemihydrate (2) [W/aHH-ratio: 0.8, Temperature: 23 C]
7 Temporal change in ultrasonic energy and velocity of a-hemihydrate (3) [W/aHH-ratio: 0.33, Temperature: 23°C]
7 Temporal change in ultrasonic energy and velocity of a-hemihydrate (3) [W/aHH-ratio: 0.33, Temperature: 23°C]
8 Temporal change in ultrasonic frequency of a‑hemihydrate (3) [W/aHH-ratio: 0.33, Temperature: 23°C]
8 Temporal change in ultrasonic frequency of a‑hemihydrate (3) [W/aHH-ratio: 0.33, Temperature: 23°C]
9 Results of in-situ optical microscopy on hydration of a-hemihydtrate (3) [W/aHH-ratio: 0.8, Temperature: 23 C]
9 Results of in-situ optical microscopy on hydration of a-hemihydtrate (3) [W/aHH-ratio: 0.8, Temperature: 23 C]
10 Temporal change in ultrasonic energy and velocity of a-hemihydrate (4) [W/aHH-ratio: 0.33, Temperature: 23°C]
10 Temporal change in ultrasonic energy and velocity of a-hemihydrate (4) [W/aHH-ratio: 0.33, Temperature: 23°C]
11 Temporal change in ultrasonic frequency of a‑hemihydrate (4) [W/aHH-ratio: 0.33, Temperature: 23 C]
11 Temporal change in ultrasonic frequency of a‑hemihydrate (4) [W/aHH-ratio: 0.33, Temperature: 23 C]
12 Results of in-situ optical microscopy on hydration of a-Hemihydrate (4) [W/aHH-ratio: 0.8, Temperature: 23 C]
12 Results of in-situ optical microscopy on hydration of a-Hemihydrate (4) [W/aHH-ratio: 0.8, Temperature: 23 C]
13 SEM-micrographs of a-hemihydrates
13 SEM-micrographs of a-hemihydrates
14 Average flexural and compressive strength values of a-hemihydrates after one day of hydration
14 Average flexural and compressive strength values of a-hemihydrates after one day of hydration
All authors
All authors

An efficient method to measure definite properties is the in-situ ultra-sonic wave measurement to characterize the hydration process of inorganic binding materials. A direct characterization of the chemical reactions taking place during the hydration process and the creation of the structure of the hydration product during the hydration is now possible because of the new interpretation technique of ultra-sonic results. In addition to the in-situ ultra-sonic wave measurements different other methods were used to verify the results of the ultra-sonic measurements.

The hydration of calcium sulphate hemihydrate is a dynamic process composed of various chemical reaction steps that take place in parallel. These reaction steps influence the utility properties of the gypsum stone created by the hydration of hemihydrate. The determination of technically relevant properties of modern, inorganic materials, e.g., workability, initial set, hydration progress and mechanical properties, involves the use of various time-consuming, conventional methods requiring substantial human-resource inputs. One efficient method of obtaining information on many such parameters...

Find out more in

ZKG 6/2016

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ZKG 6/2016

Ressort:  Process
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TEXT Dr. Yilmaz Sakalli, Dr. Christian Pritzel, Prof. Dr. Reinhard Trettin,
Institute for Buildings and Materials Chemistry, University of Siegen, Siegen/Germany

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