Preparing Cement and Concrete Materials for Analysis

No. Different measurements depend on different sample properties. Confirm what the analysis must measure and what preparation is allowed to change.

The cement and concrete industry is one of the key pillars of the global construction sector. Without cement, there would be no stable buildings, roads, or bridges: it is the binding agent of modern infrastructure. Every year, billions of tons of cement are pro‑ duced worldwide to meet the growing demand for housing, transportation networks, and industrial facilities. The industry is characterized by stringent quality require‑ ments, complex chemical processes, and continuous development toward more sus‑ tainable and energy‑efficient material technologies.

For laboratories, this means precise analyses, reproducible testing methods, and reliable sample preparation to ensure the performance, safety, and compliance of concrete prod‑ ucts with applicable standards. At the same time, the industry is at the center of the climate debate. Approximately 7–8 % of global CO₂ emissions originate from cement production, a challenge that demands both innovation and responsibility.

A significant portion of emissions arises unavoidably from the calcination of limestone:

CaCO₃ → CaO + CO₂

Around 50 % of CO₂ emissions are process‑related, while additional shares result from the use of fossil fuels and electrical energy for grinding and conveying processes. Even with a complete transition to renewable energy, this chemically inherent CO₂ release remains unavoidable.

Key strategies for emission reduction therefore include:

Reduction of clinker content Use of alternative materials (SCMs) Utilization of recycled materials Use of secondary fuels Innovative activation methods such as mechanochemistry

Research laboratories play a key role by developing new formulations, evaluating material properties, and validating industrial processes.

In the conventional production process, limestone, clay, sand, and iron ore are crushed and ground into raw meal. This material is burned in a rotary kiln at approximately 1450 °C, for‑ ming clinker. The clinker is then ground together with gypsum and other additives such as granulated blast‑furnace slag or fly ash to produce cement. All raw materials, intermediate products, and final products must be continuously tested. Reproducible sample preparation using jaw crushers, laboratory mills, sieve shakers, and presses, for example from RETSCH, is indispensable for this purpose.

Limestone and Clay Limestone and clay are the primary constituents of cement. For quality control, these materials must be homogenized. Depending on the process, jaw crushers such as the compact BB 50 or high‑performance models up to the BB 600 are used for pre‑crushing. Alternatively, hammer or impact mills such as the HM 200 are suitable.

Fine grinding down to < 40 µm is typically performed in ball mills. Depending on sample volume and target particle size, solutions range from RETSCH mixer mills such as the MM 400 to planetary ball mills like the PM 100, PM 300, or PM 400, and drum mills such as the TM 300 for larger sample quantities.

Clinker, Cement, and Concrete Clinker is significantly harder and more abrasive. After pre‑crushing in a jaw crusher, robust mill types such as cross‑beater or vibratory disc mills like the RS 200 or RS 300 are used. These combine high throughput with very short grinding times and achieve final finenesses below 100 µm within minutes. For even finer particle sizes, ball mills such as the PM 400 are suitable.

Gypsum – soft but challenging Gypsum is soft but tends to agglomerate. Proven solutions include combinations of jaw crushers, rotor mills such as the SK 300 or ZM 300, and upstream drying using the TG 200 drying unit. Cyclone modules significantly improve sample discharge and reduce dust generation.

Proper sample preparation does not end with grinding:

Drying prevents agglomeration and improves reproducibility Cyclones ensure low‑dust discharge and higher sample recovery Presses are essential for reliable X‑ray fluorescence (XRF) analys

Programmable presses such as the PP 40 ensure constant pressing forces and holding times, crucial for reproducible analytical results.

Secondary fuels derived from waste or biomass streams increasingly replace fossil energy sources. These materials are often inhomogeneous and bulky, making representative sampling, sample division (e.g., PT 200), and size reduction – often using cutting mills such as the SM 300 – essential. For plastics or fibrous materials, targeted sample preparation using cyclones, embrittlement, or staged size‑reduction concepts is critical.

Supplementary cementitious materials (SCMs) such as slags, fly ash, pozzolans, or incinera‑ ted plant residues replace clinker and significantly reduce emissions. Their preparation requi‑ res flexible grinding concepts:

Slags: jaw crusher → SK 300 or ball mills Pozzolans & volcanic rocks: rotor mills (SR 300, ZM 300) Biogenic ashes: cutting mills, ZM 300, or ball mills depending on analytical

Activated clays are among the most promising SCMs. Instead of energy‑intensive calcination, mechanochemical activation uses targeted energy input in ball mills to alter crystal structu‑ res and increase reactivity. Planetary ball mills such as the PM 100 or PM 300 allow precise adjustment of rotational speed, grinding time, and ball‑to‑powder ratio. Studies show that reactivity increases significantly with rising energy input until an optimum is reached. A key tool is the GrindControl system, which monitors temperature and pressure inside the grinding jar in real time. It prevents overheating, enables process control, and provides valuable insights into material composition, for example, through CO₂ release from dolo‑ mite‑containing clays.

Particle size distribution has a major influence on reactivity, strength, and workability of cement. RETSCH sieve shakers enable fast, reproducible analyses. For fine powders in par‑ ticular, air jet sieving machines such as the AS 200 jet and AS 200 jet pro are highly effecti‑ ve, enabling dry sieving below 50 µm within minutes.

The cement and concrete industry is undergoing profound transformation. Sustainable for‑ mulations, alternative raw materials, and innovative processes such as mechanochemistry open new pathways to CO₂ reduction. A prerequisite for this progress is powerful and repro‑ ducible sample preparation. With a comprehensive portfolio ‑ ranging from jaw crushers, rotor mills, and ball mills to dryers, cyclones, presses, sieve shakers, and digital process mon‑ itoring with GrindControl ‑ RETSCH supports laboratories in ensuring quality, accelerating development processes, and actively shaping the transition toward sustainable cements.

Plan the configuration for your material.

Define the process material and the analytical question before selecting crushing, fine grinding, sieving or pressing. A preparation appropriate for elemental analysis may not preserve the same information needed for phase analysis. Connect the equipment sequence to the test rather than the broad cement application alone.

How should the application examples be used?

The results describe the materials and configurations discussed here. Confirm equipment options, contact materials and operating conditions for your own sample before adopting a method. A demonstrated endpoint does not guarantee the same outcome for a different material.

Discuss material testing with Glen Mills or request further information or a quote.

Explore the equipment discussed

• RETSCH ZM 300 Ultra Centrifugal Mill
• RETSCH PM 100 Planetary Ball Mill
• RETSCH PM 300 Planetary Ball Mill
• RETSCH PM 400 Planetary Ball Mill

Related technical articles

• Ball Milling Clay for Green Cement Development
• Mechanochemical Activation of Clay
• Ceramic Production: Preparing Raw and Process Samples