This Week's Featured Presentation
Sustainable and Low-Cementitious-Materials-Content Self-Consolidating Concrete (ACI Fall 2018 Convention, Las Vegas, NV) The study proposes an appropriate design approach for producing SCC of low carbon footprint (Eco-SCC). The maximum powder content for an Eco-SCC mixture is typically set to 315 kg/m3. The design method is based on optimization of the volumetric proportions of sand and coarse aggregate according to an ideal particle gradation curve. The water content is adjusted to provide the necessary minimum paste volume to obtain self-consolidating properties. The cement, supplemental cementitious materials, and fillers are determined according to rheological optimization of paste to reduce the water demand while satisfying mechanical properties, durability aspects, and environmental considerations. Mixtures with total powder content ranging from 280 to 310 kg/m3 are shown to exhibit satisfactory workability characteristics and 28-day compressive strengths in the range of 25 to 30 MPa. The durability and drying shrinkage of the investigated mixtures are found to be adequate. The eco-efficiency of Eco-SCC mixtures is assessed and shown to be within the optimum area.
May 25 - 31
Sustainable Self-Consolidating Concrete: Utilization of Limestone Powders
by Natalia Cardelino, Mercer University; Kimberly Kurtis, Georgia Institute of Technology; and Russell Gentry, Georgia Institute of Technology
Sustainable and Low-Cementitious-Materials-Content Self-Consolidating Concrete (ACI Fall 2018 Convention, Las Vegas, NV) Blending limestone powder with Type III cement is becoming more common in precast applications and can contribute to sustainability by reducing clinker fraction. The greater availability of limestone powder compared to fly ash coupled with its potential to improve mix cohesion makes limestone powder a viable alternative in sustainable SCC. Concrete mixes made with limestone powders of varying particle size (3µm to 40µm) and varying limestone quantities (up to 25% cement replacement) will be evaluated. Results show improved workability with mixes containing coarsely ground limestone powders and finer ground limestone powders at cement replacement values above 15%. Early age compressive strengths of mixes with finely ground limestone powder were comparable to ordinary Portland cement (OPC) mixes and slightly lower at 25% replacement values. Drying shrinkage results exhibit comparable rates for air-cured mixes made with limestone powder. Preliminary creep results show that mixes with limestone powder experience slightly higher creep rates.