Sessions & Events

Workability Challenges and Solutions for Low-Carbon Concrete Mixtures

Monday, October 27, 2025  4:00 PM - 6:00 PM, H - Holiday 3

Low-carbon concrete mixtures typically have low cementitious materials and/or high content of supplementary materials. Also, Type 1L cement contains inter-ground limestone of up to 15%. Concrete mixture with Type 1L cement and/or high content of supplementary materials usually require relatively low water-to-cementitious ratios (w/cm) to achieve satisfactory strengths and other properties such as drying shrinkage, modulus of elasticity, etc. Low water amount, low w/cm and/or low cementitious materials lead to low past volume, which can cause poor workability, poor workability retention and other related challenges.

Learning Objectives:
(1) Discuss issues/challenges of workability and related properties of low-carbon concrete mixtures if they are not properly designed, produced and constructed;
(2) Describe rheological properties of low-carbon concrete mixtures containing supplementary materials;
(3) Investigate optimization of low-carbon concrete mixtures and their applications in pilot and real structures;
(4) Report on admixture technologies for low-carbon concrete mixtures.

This session has been approved by AIA and ICC for 2 PDHs (0.2 CEUs). Please note: You must attend the live session for the entire duration to receive credit. On-demand sessions do not qualify for PDH/CEU credit.

Rheological and Thixotropic Properties of Low-Carbon Concrete Blended with Limestone Filler and Traditional Supplementary Cementitious Materials

Presented By: Jingjie Wei
Affiliation: Missouri University of Science & Technology
Description: The future availability of traditional supplementary cementitious materials (SCMs) is declining due to the phase-out of coal power plants and shifts in steel production processes. Limestone filler (LF) might be a promising material as LF is globally available and consistent quality. ASTM C595 only allows up to 15% LF in cement production, while EN197-1 has increased to 35% LF based on performance specification. Further increasing of LF content in concrete could offer promising ecological benefits in the U.S. and meeting the target performance specification. This study investigates the rheological and thixotropic properties of low carbon concrete (LCC), replacing 80% of cement content with a combination of 50% LF and 30% SCMs. The findings contribute to a better understanding of the fresh behavior of LCC incorporating high LF and SCMs.

The Construct-ability Challenges with Concrete Today: The Innovative Solution Contractors Want

Presented By: Joseph Daczko
Affiliation: Master Builders Solutions
Description: The construction industry is experiencing rapid changes, from alternative concrete constituents to stricter specifications, making it increasingly challenging to work with fresh concrete. Contractors desperately need a solution for their pump-ability, place-ability, and finish-ability problems. Master Builders Solutions has introduced a novel admixture technology, MasterEase®, a water-reducing and conditioning admixture that provides superior handling characteristics by improving the overall rheology of concrete.

Low-Carbon Concrete Optimization in Mass Concrete Structures

Presented By: Matthew D'Ambrosia
Affiliation: MJ2 Consulting, PLLC
Description: Mass concrete thermal control requirements often necessitate optimization of concrete mixtures for reduction of Portland cement, thus making low heat performance concrete (LHPC) mixtures among the lowest carbon concrete used to date in the construction industry, ranging from 15-50% clinker. When placement conditions necessitate flowable or self-consolidating behavior to accommodate dense reinforcing steel configurations or inaccessible locations, optimization becomes more critical. To address these challenges, we will discuss project experience and case studies where mass concrete has been optimized for both flowability and low clinker content.

Does Low Carbon Mean Low Workability?

Presented By: Karthik Pattaje
Affiliation: Wiss, Janney, Elstner Associates, Inc.
Description: In a recent laboratory and field pilot study, four low carbon concrete mixes for interior slab-on-grade datacenter application were placed. The study included concrete made with blends of Type IL cement, slag cement, and a propriety performance-based (ASTM C1157) cement. The low water to cementitious materials ratio of the ASTM C1157 cement mixes, along with its unique rheological properties, posed challenges to placing and finishing the concrete to the requirements of a datacenter slab. This talk will share experiences and lessons learnt from successfully placing these mixes.

Improving Rheology and Workability of Low-Carbon Concrete with Effective Use of Strength-Enhancing Admixtures

Presented By: Van Bui
Affiliation: Master Builders Solutions US LLC
Description: Low-carbon concrete mixtures typically contain low content of cementitious materials and low water-to-cement ratio. These can lead to too low paste volume, unsuitable rheology and poor workability if concrete mixtures are not property designed. One of the solutions for improving the rheology and workability of low-carbon concrete mixtures is proper use of strength-enhancing admixtures. The presentation will present test results and discuss how to use effectively the strength-enhancing admixtures, Master X-Seed to overcome the challenges of workability of low-carbon concrete mixtures.