Recommendations on the Use of Various Chemical Water Reducing Agents with Ultra High Strength Concretes

Recommendations on the Use of Various Chemical Water Reducing Agents with Ultra High Strength Concretes

Ultra-High Strength Concrete (UHSC) is a high-strength concrete that has been designed to provide compressive strengths greater than 130 MPa. In order to make the material workable for positioning, handling and consolidation, UHSC materials usually have a very low water-to – cement (w / c) which requires the use of a chemical admixture. For this function, superplasticizers are widely used. A superplasticizer is a type of chemical mixture used to modify fresh concrete ‘s workability (viscosity). When the w / c is low and a specific workability is needed, the workability of fresh concrete is also of special importance. Superplasticizers are made from various formulations, with Polynaphthalene Sulfonate (PNS), Polymelamine Sulfonate (PMS) and Polycarboxylate Ether (PCE) being the most popular. The effect of multiple superplasticizers on the compressive strength and rheological efficiency of two UHSC mixtures was investigated in this research. In this analysis, a total of 12 distinct forms of superplasticizers were used. Six superplasticizers based on PNS; three different compositional strengths (high , medium, normal range) from the local supplier; and three different compositional strengths (high , medium, normal) from the lead supplier. In addition, six different PCE base superplasticizers with the same compositional strengths were also used, three from a brand name supplier and three from a local supplier. Relevant properties measured were the viscosity of superplasticizers, concrete workability via the mortar-spread test, concrete rheology, and compressive strengths of UHSC 7, 14, and 28 days. Two mixtures of 2 w / cm (0.20 and 0.15) were made, which would then increase the amount of superplasticizer required from 34.7L / m3 to 44.5L / m3. The results show that the PCE-based superplasticizer of the high-range brand composition provided the overall highest distribution, lowest viscosity, and highest compressive strength at all tested ages. In all other compositional ranges, there were mixed results between both the locally supplied admixtures and the PNS versus PCE. In addition, the rheology test also showed that the high-range PNS name brand and UHSC produced with the high-range PNS name brand had lower viscosity at all angular velocities than the others measured.

Author(s) Details

Dr. Anthony Torres
Texas State University, San Marcos, TX, 78666, USA.

Dr. Federico Aguayo

Texas State University, San Marcos, TX, 78666, USA.

Dr. Srinivas Allena
Cleveland State University, Cleveland, 44415, USA.

Michael Ellis

Texas State University, San Marcos, TX, 78666, USA.

View Book :- https://bp.bookpi.org/index.php/bpi/catalog/book/318

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