ADMIXTURES FOR ULTRA-HIGH STRENGTH (UHS) SELF-CONSOLIDATING CONCRETE (SCC)

While the early development of polycarboxylate ethers (PCE) was driven by a general need for higher concrete strength, the latest admixture technology has pushed the limits for ultra high strength concrete (UHSC) to new heights. Triggered by very high land prices in big cities, architects strive to maximize usable space, reducing concrete column diameters and enlarging concrete beam spans to create spacious interiors. Such desire requires highly workable, ultra high strength concrete. Recent applications reach compressive strengths of up to 150 MPa and more. Apart from the very low water/binder ratio of such concrete and the resulting need for extremely strong water reducing performance, admixtures specialized for this application need to address additional problems of UHSC when made as SCC, such as pump ability, concrete thixotropy, and shrinkage. This paper will discuss the performance of new admixtures developed to address these problems encountered when producing and placing UHS-SCC.