Caltrans (2016) — Fly Ash: Current and Future Supply

Citation

Caltrans Concrete Task Group. (2016). Fly Ash: Current and Future Supply. California Department of Transportation (Caltrans), Division of Engineering Services, Office of Structural Materials, Sacramento, CA.

DOI: needs_check (Government Agency Technical Report / Caltrans METS)
Atlas layer: context / supply-chain
Related Victor Li book chapter: Chapter 9: Green ECC (Supplementary Cementitious Materials, Supply Chain Realities & Alternative Pozzolans)
Source PDF: caltrans-2016-fly-ash-current-and-future.pdf
Extracted text: full_text/caltrans-2016-fly-ash-current-and-future_full_text.md
Source note: source_notes/caltrans-2016-fly-ash-current-and-future_source_note.md

Why this paper matters

Provides essential industry and governmental insight into the declining supply of coal fly ash due to thermal power plant closures and environmental regulations. Serves as a vital strategic reference for why the ECC Research Atlas must diversify from conventional high-volume fly ash systems toward alternative pozzolans (slag, calcined clay/LC3, natural pozzolans, recycled glass).

Main contribution

Analyzes the structural drivers of fly ash shortages across California and North America: coal plant decommissionings, natural gas switching, seasonal electricity demand shifts, and EPA coal combustion residual (CCR) rules.
Documents the historical dependency of high-durability infrastructure concrete on Class F fly ash for alkali-silica reaction (ASR) mitigation, heat of hydration reduction, and permeability suppression.
Evaluates technical mitigation strategies to address fly ash supply deficits: 1. Harvesting/reclaiming landfilled and ponded fly ash. 2. Utilizing Class C fly ash. 3. Expanding the use of alternative SCMs: blast furnace slag, silica fume, metakaolin, rice hull ash, natural pozzolans (volcanic ash/pumice), and ground recycled glass. 4. Transitioning to Portland-Limestone Cements (Type IL) and multi-component blended SCMs.

Evidence summary

Supply Trends: Accelerating retirement of coal-fired generation (over 40 GW retired between 2010–2015 in the US) creates structural regional deficits of specification-grade Class F fly ash (Section 2 & 3).
Alternative SCM Viability:
Natural Pozzolans / Calcined Clays: Abundant mineral reserves with pozzolanic reactivity matching or exceeding Class F fly ash (Section 4.7).
Slag Cement (GGBFS): Readily available alternative providing comparable durability and sulfate resistance, though sensitive to curing temperatures (Section 4.4).
Ground Recycled Glass: Emerging pozzolan passing ASTM C618 requirements, effectively controlling ASR (Section 4.8).
Portland-Limestone Cement (PLC): Up to 15 % interground limestone reduces clinker carbon footprint by ~10 % without sacrificing early strength (Section 4.10).

Linked Atlas nodes

04_material_systems/green_ecc.md
04_material_systems/low_carbon_binders.md
02_concepts/supplementary_cementitious_materials.md

Relationship to Victor Li book

Primary book anchor: Victor Li (2019) Chapter 9 (Green ECC).
While Victor Li's foundational Green ECC mix designs heavily utilize high-volume fly ash (FA/C ratios up to 2.8 to 4.0), this Caltrans report provides empirical supply-chain evidence explaining why the field must transition to broader SCM portfolios (calcined clay, slag, limestone, natural pozzolans) to ensure scalable deployment.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`02_concepts/supplementary_cementitious_materials.md`	Coal-fired power plant retirements create structural shortages of specification Class F fly ash, necessitating alternative SCM adoption	Caltrans supply analysis documents widespread regional fly ash deficits driven by coal plant closures and EPA regulations	Section 2 & 3, Fig. 1-3	verified_from_pdf
`04_material_systems/low_carbon_binders.md`	Natural pozzolans, slag, and ground recycled glass provide viable substitutes for fly ash in low-carbon cementitious composites	Technical evaluation demonstrates comparable pozzolanic reactivity and ASR suppression for natural pozzolans and glass pozzolans	Section 4, Section 4.7-4.8	verified_from_pdf

Verification status

PDF preserved: yes (caltrans-2016-fly-ash-current-and-future.pdf)
Text extracted: yes (full_text/caltrans-2016-fly-ash-current-and-future_full_text.md)
DOI verified: N/A (State Agency Technical Report)
Metadata verified: yes (Caltrans METS Concrete Task Group, 2016)
Claim-evidence matrix ready: yes

Cautions

This is a state transportation department policy and supply-chain technical report, not an experimental mechanics paper on fiber-reinforced composites.
Provides macro-level supply context justification for developing non-fly-ash Green ECC systems.