Performance of Self-Consolidating Concrete made with Diutan Gum


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Title: Performance of Self-Consolidating Concrete made with Diutan Gum

Author(s): K.H. Khayat, A. Mechaymech, and B. Skaggs

Publication: Special Publication

Volume: 239


Appears on pages(s): 545-566

Keywords: admixture compatibility; frost durability; rheology; self-consolidating concrete; stability; superplasticizer; viscosity-modifying admixture

Date: 10/1/2006

Dynamic and static stability of self-consolidating concrete (SCC) affect the production, transport, and overall performance of the concrete. Viscosity- modifying admixtures (VMAs) are often incorporated to enhance the stability of SCC, especially in the case of cast-in place concrete. The influence of a new type of polysaccharide, diutan gum, on key characteristics of SCC targeted for the construction and repair of concrete infrastructure is examined. The investigation compares the performance of SCC made with diutan gum and different types of high-range water reducing admixtures (HRWRAs), including polynaphtalene sulphonate (PNS)-based and two polycarboxylate polymer (PCP)-based HRWRAs. The effect of admixture combination on workability, rheology, stability, and setting time was investigated. The robustness of optimized VMAHRWRA system and key durability parameters of the concrete were also determined. Test results indicate that the use of diutan gum increases the plastic viscosity and yield stress of SCC. Regardless of the VMA and HRWRA combination, the use of diutan gum can significantly decrease segregation and bleeding, and lead to greater homogeneity of the concrete during the dormant period of cement hydration. The performance of SCC made with diutan gum depends on the type of PCP in use. Out of two PCP-based HRWRA, one system resulted in lower HRWRA demand, increase in viscosity with the increase in VMA content, and greater stability. The use of PCP and diutan gum is shown to lead to adequate robustness where the SCC can tolerate small changes in sand moisture content without significant effect on SCC properties. SCC made with medium dosage of diutan gum and PCP is shown to develop adequate air-void system and excellent frost durability and resistance to de-icing salt scaling.