6.6
圧縮係数試験
圧縮係数試験は、コンクリートの作業性を評価するために使用される方法です。この試験は、最大 3.81 cm の大きさの骨材を含むコンクリート混合物に特に適しています。この試験には、摩擦を最小限に抑えるために内面が研磨された 2 つの円錐台形のホッパーと 1 つのシリンダーで構成される特殊な装置が使用さ…
締固め係数試験は、骨材サイズが最大1.5インチまでのコンクリートの施工性を決定します。
試験装置は、底部にヒンジ付きドアを備えた2つの円錐形ホッパーとシリンダーで構成されており、すべて順番に積み重ねられ、内部表面は摩擦を減らすために研磨されています。
コンクリートは圧縮されずに上部ホッパーに配置され、下部のドアが開かれ、コンクリートが下部ホッパーに流れ込みます。
次に、下部ホッパーの下部ドアが開き、コンクリートが下のシリンダーに落ち、余分なコンクリートが打ち落とされます。
スチールロッドを使用して、テスト中に一方または両方のホッパーに詰まったコンクリートを優しく突き刺して取り除きます。
シリンダーの設定体積内のコンクリートの最終的な重量が決定され、この部分的に圧縮された密度が計算されます。
完全に圧縮された密度は、シリンダーを4つの層にコンクリートで満たし、各層を突き固めることによって決定されます。
最後に、締固め係数は、部分的に締固められたコンクリートの密度と完全に締固められたコンクリートの密度の比として計算され、これは混合物の作業性を示します。
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Q1: What is the compacting factor test used for in concrete testing?
The compacting factor test assesses the workability of concrete, indicating how easily concrete flows and compacts. It measures the ratio of partially compacted concrete density to fully compacted density, providing a numerical value that reflects the concrete's ability to be placed and consolidated in molds during construction projects.
Q2: What equipment is needed to perform a compacting factor test?
The test requires two truncated cone-shaped hoppers with hinged bottom doors, a cylinder for collection, and a steel rod. All equipment has polished interior surfaces to minimize friction and allow concrete to flow freely between components during the test procedure.
Q3: How is the compacting factor value calculated?
The compacting factor is calculated as the ratio of the density of partially compacted concrete to the density of fully compacted concrete. Partially compacted density is obtained from concrete falling through hoppers into a cylinder, while fully compacted density is determined by filling the cylinder in four layers and tamping each layer thoroughly.
Q4: What concrete aggregate sizes are suitable for the compacting factor test?
The compacting factor test is suitable for concrete mixes containing aggregates with a maximum size of one and a half inches. This size limitation ensures the concrete flows properly through the hopper system and provides reliable workability measurements for the specified aggregate range.
Q5: What steps are involved in performing the compacting factor test procedure?
Concrete is placed in the upper hopper without compaction. The bottom door opens, allowing concrete to flow into the lower hopper. The lower hopper door then opens, letting concrete fall into the cylinder below. Excess concrete is struck off, and a steel rod dislodges any stuck material. The cylinder weight is recorded to calculate partially compacted density.
Q6: Why are polished interior surfaces important in compacting factor test equipment?
Polished interior surfaces reduce friction between the concrete and equipment, allowing the concrete to flow freely and naturally through the hoppers and into the cylinder. This minimizes artificial resistance and ensures the test accurately reflects the concrete's true workability characteristics without equipment interference.
Q7: How does the compacting factor test differ from determining fully compacted concrete density?
The compacting factor test measures partially compacted density by allowing concrete to fall freely through hoppers, simulating natural placement conditions. Fully compacted density is determined separately by deliberately filling the cylinder in four layers and tamping each layer to achieve maximum compaction, providing a baseline for comparison.