A NEW GENERATION of superplasticizers is impacting concrete performance and giving producers more flexibility than ever before.

More than a decade ago, admixture supplier BASF, of Beachwood, Ohio, added polycarboxylate superplasticizers to its portfolio, as part of an effort to improve the performance of dispersant chemistries and pass the benefits along to producers. Since then, it has continued to refine this technology to supply concrete producers with a broad range of superplasticizers with various performance characteristics.

Prairie Material, a ready-mix producer based in Bridgeview, Ill., has used superplasticizers for more than 25 years. In the 1980s, Prairie used high-range water reducers made with melamine and napthaline that were added at the jobsite due to their limited working time. Now, the producer adds polycarboxylate superplasticizers to its mixes during batching, to ensure success on such high-profile projects as Chicago's Trump International Hotel & Tower and Aqua Tower.

Polycarboxylate superplasticizers are ideal for low water/cement ratio mixes, self-consolidating concrete (SCC), and applications that require a very workable mix, such as heavily reinforced slabs with tight rebar spacing. Superplasticizers also can improve finishing characteristics, achieve highearly strength (ideal for highway repair projects, where roads can open to traffi c within three to six hours), and help control the rate of hardening, workability retention, finishability, and pumpability.

The admixtures are also helping producers meet demands for green construction and sustainability by overcoming performance deficiencies associated with supplementary cementitious materials.

Prairie routinely produces live trial batches in the field to confirm results they achieve with superplasticizers in the lab.Especially with new mix designs, test runs to jobsites help the technical services staff become familiar with the products and how they will behave on a job. The producer also works closely with BASF and relies on the supplier's product experts for support and assistance.

Not all superplasticizers are the same; they can have different impacts on concrete's performance as a whole. By identifying which performance characteristics are most important, producers can operate more efficiently and most importantly, determine how these products can best meet customers' needs.

Following is a selection of superplasticizers that can improve concrete's performance in a variety of applications.

Admixtures provide ecological and cost benefits

Green Sense Concrete, containing Glenium superplasticizers, attains desired setting characteristics, strength, durability, and if needed, higher slump at a reduced cost to the producer. The Green Sense Concrete mixture proportioning service uses supplementary cementitious materials, non-cementitious fillers, or both, with Master Builders brand high-range water reducers and/or RheoTEC Z-60 workabilityretaining admixture to meet or exceed performance targets. BASF. 800-628-9990.www.basf-admixtures.com

Powdered admixture in jobsite-friendly packaging

Supercizer PCE polycarboxylate ether superplasticizer has been added to the company's line of high-range water reducers containing lignons, napthalenes, melamines, and ketones. It is available as a powder, in easy to use, water-soluble packaging for onsite corrections of PCE mixes. The company offers free samples of the new product. Fritz-Pak Corporation. 888-746-4116.www.fritzpak.com

Produce high-slump, flowing concrete

ADVA superplasticizers improve workability characteristics and promote good segregation for highslump, flowing concrete. The admixtures can also produce concrete with very low water/cement ratios at low or normal slumps. For ready-mix and precast producers, ADVA products extend slump life and offer faster placement than conventional superplasticizers, while providing a shorter set time with quick and easy finishing. Grace Construction Products. 877-423-6491. www.graceconstruction.com

Reduce water, control air

Powerful Superflo multirange, waterreducing polymers enhance concrete's workability and finishability while extending slump and improving the overall properties of the mix. Defoamer additives maintain consistent air content throughout the entire dosage range. Superflo polymers keep producers at the forefront of concrete technology. RussTech Inc. 502-267-7700. www.russtechnet.com

Improve strength and workability

Casecrete superplasticizer offers flexible water/cement ratios that increase compression and tensile strengths and improve workability. The all-natural casein protein is a zero-VOC polymer that improves flow and heal in cementitious applications and pourability in concrete. Casecrete allows access to historically inaccessible areas with higher, more favorable water/cement ratios and leveling results. American Casein Co. 609-387- 3130. www.americancasein.com

Admixtures for specific applications

Two high-performance admixtures offer plasticizing action, high-range water reduction, and densification. Krete Super Kast is designed for wet cast concrete, and Krete SuperPlast 700 is formulated for self-consolidating concrete products. Contact the company to request samples for evaluation. Krete Industries Inc. 800-777-9562. www.krete.com

Related articles: "Designed for Success," TCP April/May 2011