Recovering from Transition to Type 1L Cement in Concrete Production

Mallory A. Westbrook and Jon S. Belkowitz, PhD, PE

Abstract

The move to Type 1L, also known as Portland-Limestone Cement (PLC), introduces a specific array of challenges for concrete producers and construction professionals. The cement industry initially marketed Type 1L as a direct substitute for traditional ASTM C 150 (Type I, I/II, ...) cements, asserting that it would deliver comparable performance in both fresh and hardened states. However, this transition has revealed unforeseen complications, such as early-age cracking and diminished compressive strength. To effectively address these challenges and restore confidence in your cement supply and concrete quality, it is crucial to implement a series of methodical experimental and field-based strategies.

Key Recovery Steps

1. Understanding the Implications of Type 1L

Before proceeding, it is vital to comprehend the ramifications of utilizing Type 1L cement:

• Composition: Currently, Type 1L permits up to 15% interground limestone, compared to only 5% for Type 1. This significant difference can affect the hydration kinetics and final properties of the resulting concrete mix.
• Performance Challenges: Documented incidents of early-age cracking and reduced strength are often attributable to variations in cement composition, particularly its interaction with aggregates and mix water.

2. Modify Existing Specifications

The transition to Type 1L necessitates the modification of existing specifications.

• Review Current Specifications: Conduct a thorough analysis of existing contracts and specifications to determine necessary adjustments for integrating Type 1L.
• Update Standards: Ensure compliance with ASTM C595 standards for Type 1L instead of the conventional ASTM C150 cements.

3. Conduct Experimental Evaluations

Experimental processes are essential for identifying and mitigating potential issues associated with Type 1L cement:

• Compressive Strength Testing: Regularly perform compressive strength assessments on concrete mixtures incorporating Type 1L to validate their performance against established benchmarks.
• Shrinkage Testing: Implement tests to evaluate plastic shrinkage cracking under various environmental conditions.
• Workability Assessments: Continuously monitor the workability of freshly mixed concrete to ensure it aligns with project requirements.

4. Implement Field Trials

Field trials provide invaluable insights into the real-world performance of Type 1L in specific conditions:

• Pilot Projects: Initiate pilot projects using Type 1L to identify any significant challenges prior to broader implementation.
• Monitor Performance Metrics: Track the concrete's performance over time, focusing on key indicators such as compressive strength, durability, and incident rates of cracking.

5. Enhance Stakeholder Communication

Rebuilding trust with stakeholders is imperative during this transition:

• Educate Your Team: Organize training sessions for your team on the properties and handling of Type 1L cement.
• Engage Stakeholders: Foster open communication with engineers and construction firms by sharing findings from your experimental and field evaluations.
• Provide Regular Updates: Keep all stakeholders informed regarding the steps being taken to rectify any issues stemming from the transition.

6. Prioritize Quality Control

Robust quality control measures can significantly mitigate the likelihood of issues:

• Adjust Mixing Procedures: Reassess and potentially modify mixing procedures to accommodate the distinct characteristics of Type 1L cement.
• Establish Regular Testing Protocols: Implement a stringent schedule for testing cement quality to ensure all batches meet performance criteria.

7. Commit to Continuous Improvement

Recovery is a progressive endeavor:

• Create a Feedback Loop: Establish channels for construction teams to provide insights regarding the performance of Type 1L across various applications.
• Adapt Strategies Accordingly: Be willing to modify strategies based on the feedback and data collected through ongoing testing.

Conclusion

Transitioning to Type 1L cement offers a significant opportunity to enhance sustainability without compromising concrete quality. By diligently following these recovery steps, you can restore stakeholder confidence in your cement supply, ensuring that your concrete projects meet the highest industry standards. For further inquiries or guidance on transitioning to Type 1L, consider consulting with industry experts or specialists who can support you through this process. Together, we can not only overcome the challenges presented by this innovative material but also harness its potential benefits.

Learn more from Intelligent Concrete LLC:

+ Whitney Belkowitz, President and CEO: https://bit.ly/3uAWBKR

+ Jon Belkowitz, Chief Technical Officer: https://bit.ly/3eV79yJ

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