In the construction industry, a push in the name of sustainability, has accelerated in recent years, with Type IL Portland Limestone Cement (PLC)—often referred to as Type 1L or L1 cement—emerging as a key player. This blended cement, which incorporates up to 15% finely ground limestone as a replacement for traditional clinker, was introduced into U.S. specifications in 2012 but saw widespread adoption starting in 2021. Designed to reduce the carbon footprint of concrete by approximately 10%, Type IL cement is being praised as having environmental benefits, however, its integration into concrete mixes has not been without challenges, including reports of performance issues and potential failures such as cracking and reduced durability. This article examines adoption statistics and available data on failures since 2021, drawing from industry reports, surveys, and user experiences.

L1 Market Penetration Since 2021

Transition to Type IL cement was mostly implemented in 2021 as cement manufacturers responded to the push by green advocates for lower-carbon products. According to a report from the Precast/Prestressed Concrete Institute (PCI), many U.S. cement plants either switched from producing ASTM C150 Type I/II cement OPC to ASTM C595 Type IL cement PLC or announced plans to do so starting in 2021. This shift was driven by green agenda outcrys, with PLC offering an 8-10% reduction in CO2 emissions compared to ordinary Portland cement it was quickly adopted industry-wide.  (pci.org)

By mid-2023, shipments of Type IL cement surpassed those of traditional Portland cement in the U.S., pushing it as the dominant type for general concrete construction. In 2022, the U.S. Geological Survey (USGS) estimated that 70-75% of produced cement sales went to ready-mixed concrete producers. 

Regional Type IL cement adoption varied: for instance, markets like Dallas/Fort Worth saw significant use, while Houston lagged behind. By May 2022, 44 state Departments of Transportation had approved Type IL for infrastructure projects after performance testing.

In Canada, where PLC has been in use since 2008, a 2021 technical report by the Cement Association of Canada highlighted its broad application, including in pavements and bridges, major widespread failures were not reported, and CAC emphasized the need for mix adjustments. Globally, over 4.4 billion tons of Portland-based cement were produced in 2023, with blended variants like Type IL mainly used in ready-mixed concrete plants nationwide. 

Performance Challenges and Failure Modes

While Type IL cement is marketed as a one-to-one replacement for OPC, real-world applications since 2021 have revealed nuances in performance. The finer particle size of limestone increases surface area, which can lead to higher water demand, reduced workability, and altered set times. If not used in conjunction with specific curing or admixtures, these factors contribute to failures such as cracking and surface weaknesses. Many of today’s available admix products are not compatible.

https://www.1lcementproblems.com/

Common issues with use of Type IL cement include:

Cracking: Plastic shrinkage cracks, thermal cracks, and shrinkage cracking in hot weather have been widely reported.

Stress Failures: In tilt-up construction, increased curling stresses have prompted design changes like reduced dowel spacing in slabs-on-grade.

Strength Development: Slower early-age strength gain can delay operations, such as panel erection in precast work. Some Type IL cement mixes achieve only 3,000 psi at 28 days compared to 3,500 psi with OPC. Ultimate strength may require up to 50 days in some cases.

Durability Concerns: Reduced resistance to freeze-thaw cycles, deicer salt scaling, and surface wear has been noted, potentially leading to weak, dusty surfaces and blistering. 

pci.org

Set Time Variations: Set times can be faster in hot weather or slower in cold, affecting placement and finishing.

These statistics and reported failures depended on mix design, environmental conditions, and the limestone content (up to 15%).

Statistics on Failures and Issues

Quantitative data on Type IL concrete failures remains limited, as widespread tracking began only recently. However, surveys and anecdotal reports provide insights:

ASCC Survey (2024): Over half of respondents (concrete contractors) reported experiencing problems more frequently with Type IL cement than with OPC, including bonding issues in thinset and hydraulic cement, and a 2% difference in low-strength breaks. The other half reported no issues, highlighting variability.

In a discussion among concrete professionals, multiple users noted low breaks (failed strength tests), with strength development taking up to 50 days. One described Type IL concrete as more prone to shrinkage cracking and tearing, attributing it to higher limestone content stretching the true cement strength (4-13% observed in tests). With added water demand increased, and finishing times were extended.

PCI Report (2025): In precast/prestressed applications, some plants reported lower strengths with Type IL, but no specific failure rates were quantified. Durability properties (e.g., resistance to chloride ingress, sulfate attack) were comparable to OPC, with adjustments needed.

pci.org

Tilt-Up Association Findings (2024): In central Texas, curling stresses increased, but failure statistics were not provided. One project showed a 14% reduction in 28-day compressive strength.

Broader Industry Data: No large-scale failure databases specific to Type IL exist, but general concrete failure stats (e.g., from NIST or OSHA) indicate cracking and durability issues in 20-30% of investigated cases. A 2023 study noted up to 9.3% higher flowability in some Type IL mixes but warned of potential durability risks without adjustments.

Mitigation and Future Outlook

To address the challenges attributed to the use of Type IL cement, experts recommend trial batches, admixture adjustments, and enhanced curing practices. For instance, using supplementary cementitious materials (SCMs) like fly ash can improve performance while maintaining low-carbon benefits. 

https://www.1lcementproblems.com/

As projected use of Type IL cement is slated to reach 80-90% market share by 2030—better data collection on failures will emerge. For now, Type IL is has replaced OPC, vigilance in mix design is essential to minimize the risk of its use.