建築材料優れた味を追求する為の粒子径と形状の解析

Building materials are required for a wide range of construction work including carpentry, roofing, structural reinforcement, insulation, and plumbing. The particle size and particle shape of the raw materials influence quality and performance of the end product, and therefore require quality control by particle characterization. Microtrac analyzers are successfully used to determine the size and shape of various building materials.

Building materials range from naturally occurring substances such as rock, clay, sand, and wood to synthetic polymers and multiple combinations of both (composites). Concrete or mortar are for example mixtures of cement and aggregates like sand or gravel.

Why are particle properties so important for building materials?

The particle size and particle shape of raw materials are important for many reasons. The particle size distribution has various effects on the processing of building materials, for example:

Powder flow: a wide distribution or too many fines reduce flowability
Segregation: a wide distribution will lead to size segregation
Suspension rheology: fines or irregularly shaped particles increase viscosity

Problematic effects due to oversized particles

Poor quality of the final product (grains sticking out of the plaster, rough surfaces of tiles, inhomogeneous materials may break)
Changes in the “look and feel” of the final product
Changes in the flow behavior and other process parameters of the final product
Blockage of production sieves
Removal of material from the production process, and recycling (additional costs and effort)

Problematic effects due to undersized particles

Change of the “look and feel” of the final product
Dust (pollution) in the work place
Filter blockage
Changes in the flow behaviour and other process parameters of the final product

Microtracでは、レーザ回折、DLS、画像解析など多様な粒子径測定技術を用いた製品を提供しています。

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テスト結果粒子径分布・粒子形状分析装置 CAMSIZER X2

より速く、より鮮明に、より多くの粒子を短時間で解析

CAMSIZER X2+ は、動的画像解析法（Dynamic Image Analysis：ISO 13322-2）に基づき、0.9 μm～8 mm の非常に広い測定範囲を測定する粒子径・粒子形状解析装置です。

超高輝度LEDストロボ光源を2台の500万画素のカメラと組み合わせることで、レンズ等の切り替え無しに粉体・顆粒・懸濁液中の粒子を高精度に測定します。また、毎秒420フレーム以上の撮像速度有し、各フレームに数百個の粒子が含まれるため、わずか3分程で数百万の粒子データを得ることができます。短時間で多くのデータが得られるため統計的な信頼性が高く、再現性の高い測定を実現しています。

研究開発（R&D）用途から日常的な品質管理（QC）業務まで、幅広い用途に活躍する分析装置です。

粒子径分布・粒子形状分析装置 CAMSIZER X2

例 1 Sieve correlation with sand samples

In most cases the particle size distribution of sand used in building materials is analyzed by sieve analysis. Microtrac's CAMSIZER series can replace this time-consuming and error-prone technique with a quicker, more reliable method that provides a higher resolution of particle size results as well as additional particle shape information.

Two types of sand taken from different locations, measured with the CAMSIZER X2. This sand is used as a layer in glass-reinforced plastic pipes to increase the stiffness. The reported size parameter is xc min (=particle width). The red curve is slightly bimodal. Sand with a wide size distribution can be more closely packed in the core of the pipe which gives the finished product a higher stability.

One sand sample that was measured by sieving (black) and by the CAMSIZER X2 using two different dispersion modules: the X-Fall module (green) and the X-Jet module (red). The results compare extremely well, proving that CAMSIZER X2 can match existing sieve analysis results. Hence, product specifications based on sieve analysis can remain unchanged when transitioning to a CAMSIZER system.

例 2 Particle size & shape analysis of limestone

Limestone (calcium carbonate) is a raw material used in many products.

The particle size distribution as measured with the CAMSIZER X2 for a range of limestone grades.

The particle shape distribution results for the same collection of limestone samples. The reported shape parameter is sphericity, defined as: sphericity = 4 p A/ P2 where "A = Area of the particle projection" and "P = Perimeter length of the particle projection". The least round sample is Nr 6 (red), while the most round sample is Nr 4 (light blue).

例 3 Effective dispersion of plaster samples

Typical result from a particle size analysis of a plaster sample. The size range is fairly wide, ranging from 2 microns to about 1 mm. The graph shows the result of the CAMSIZER X2 in X-Jet mode, measured with a dispersion pressure of 150 kPa (red curve).

The plaster particles are agglomerating and “sticky”, thus the results of a conventional sieve analysis shows much coarser data (black curve), especially for the fine particles. However, if the particles are dispersed properly with an air jet sieve (AS 200 jet, blue curve), the results agree perfectly with the CAMSIZER X2.

例 4 Detection of oversize in tile coatings

Save and reliable detection of oversized particles are among the most important objectives of particle size analyis. For this purpose, Dynamic Image Analysis with the CAMSIZER X2 is the most powerful technique with unmatched accuracy.

Figure 6 shows a silicate sample that was analyzed with the CAMSIZER X2 using the X-Fall module. First, the original sample was measured and the size distribution was found to range from 5 μm to 100 μm (red curve). Then, 0.1 % of oversized (> 100 μm) particles were added and the sample was analyzed again (green curve). Finally, the experiment was repeated with 1 % oversize added (blue curve).

This silicate is used as raw material for the coating of tiles and oversized particles will result in a rough and uneven surface of the finished tile. The CAMSIZER X2 reliably detects the correct amount of oversize. Note that below 100 μm, where all samples are identical, the reproducibility is excellent!