Coal Clinker & Slag as Supplementary Cementitious Materials (SCMs) and Structural Lightweight Aggregates

Industrial Circular Economy in African Construction

As urbanization accelerates across Africa, the demand for affordable building materials, blended cements (CEM II, CEM IV), and structural lightweight concrete has surged. Concurrently, thermal power plants, metallurgical smelters, and industrial boilers generate significant volumes of bottom ash and fused coal clinker.

Transforming these combustion residuals into Supplementary Cementitious Materials (SCMs) and graded aggregates creates substantial economic value while cutting embodied carbon.

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Chemical & Physical Characteristics of Coal Clinker vs. Fly Ash

| Parameter | Fused Coal Clinker / Bottom Ash | Pulverized Fly Ash (Class F) | Granulated Blast Furnace Slag (GGBS) | | :--- | :--- | :--- | :--- | | Particle Form | Porous, angular, fused clinker nodules | Spherical micro-beads | Angular glassy particles | | Specific Gravity | 2.10 – 2.45 g/cm³ | 2.20 – 2.60 g/cm³ | 2.85 – 2.95 g/cm³ | | Silica ($ ext{SiO}_2$) | 45.0% – 58.0% | 48.0% – 60.0% | 32.0% – 38.0% | | Alumina ($ ext{Al}_2 ext{O}_3$) | 20.0% – 30.0% | 22.0% – 32.0% | 10.0% – 16.0% | | Calcium Oxide ($ ext{CaO}$) | 2.0% – 8.0% | 1.5% – 6.0% | 38.0% – 44.0% | | Reactivity Mechanism | Pozzolanic (requires fine grinding) | Pozzolanic | Latent Hydraulic |

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Structural Applications in Modern Civil Works

1. Lightweight Structural Concrete Blocks (Cinder Blocks)

- Graded coal clinker (2.36mm – 10mm) replaces conventional dense gravel aggregate. - Density Reduction: Concrete density decreases from $2,400\text{ kg/m}^3$ to $1,650\text{--}1,850\text{ kg/m}^3$. - Thermal Insulation: Thermal conductivity ($\lambda$) drops by over 35%, providing superior indoor temperature regulation in tropical climates.

2. Clinker-Pozzolan Blended Cement (CEM II/B-P & CEM IV)

- Inter-grinding 15% to 30% processed bottom ash or coal clinker with Portland clinker and gypsum meets EN 197-1 and KS EAS 18-1 standards for general construction cement.

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Why Clinker Coal Link Logistics Ltd is the Company of Choice for SCMs & Industrial Aggregates

Cement grinding mills and precast concrete manufacturers choose Clinker Coal Link Logistics Ltd for certified circular mineral raw materials:

- Consistent Granulometry & Processing: We deliver mechanically crushed and screened coal clinker and GGBS parcels with strict size gradations (0–5mm fines and 5–12mm aggregates), ensuring seamless integration into concrete batching plants. - Certified Pozzolanic Strength Activity: Every lot supplied by Clinker Coal Link Logistics Ltd is verified by third-party testing to exceed ASTM C618 28-day strength activity indices ($>78\%$). - Cost-Effective Bulk Sourcing: We source directly from major regional metallurgical smelters and utility plants, providing cement mills with a high-margin alternative to virgin pozzolana.