Title:
Effects of In-Transit Addition of Superplasticizer
Author(s):
Eric P. Koehler and Mark F. Roberts
Publication:
Symposium Paper
Volume:
288
Issue:
Appears on pages(s):
1-13
Keywords:
automation; process control; slump; superplasticizer, truck; variability.
DOI:
10.14359/51684226
Date:
9/14/2012
Abstract:
New automated slump control technology is available to manage the quality of concrete in a mixing truck. This technology measures the workability of concrete while in the mixing truck, and then adjusts the workability by adding water or superplasticizer during transit to the construction site. This paper describes this process control technology and the implications for polycarboxylate-based superplasticizer performance. Field data are presented showing the performance of superplasticizers when added in multiple doses during transit rather than all at once in the plant. The effect of varying superplasticizer dose on entrained air content is evaluated. The data confirm that the use of superplasticizer with process control technology can reduce variability in delivered slump. Recommendations are given for selecting admixtures and for programming process control systems to ensure optimal concrete performance.