6.8
フローテーブル試験
フローテーブル試験は、コンクリートの作業性を評価するために確立された方法であり、特に高流動性コンクリートの混合物の評価に役立ちます。この試験では、木製の板の上に鋼板を載せた、総重量約 15.87 kg の装置を使用します。板はヒンジを介して台座に接続されており、各辺の長さは 70.10 cm です。…
コンクリートの施工性を調べ、流動性の高いコンクリートを評価するために使用されるフローテーブル試験には、鋼板を上に乗せた木の板からなる装置が含まれ、総重量は35ポンドです。
ヒンジがボードをベースに接続し、ボードの各辺のサイズは27.6インチです。
上部ボードは1.6インチの高さまで持ち上げられるように設計されており、テーブルにはコンクリートを配置する場所をガイドする特定のマーキングがあります。
高さ8インチの円錐台、ベースの直径が8インチ、上部の直径が5インチの円錐台がコンクリートで満たされています。やさしく締固められ、余分なコンクリートが取り除かれ、30秒後にコーン型枠が丁寧に取り除かれます。
テーブルは15回揺れ、各揺れは4秒間隔で与えられ、コンクリートが広がります。
テーブルの2つのエッジに平行な広がりの範囲の平均は、衝撃後に測定され、コンクリートの作業性を示し、特定の値は中程度または高い作業性に対応します。
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Q1: What is the flow table test used for in concrete testing?
The flow table test assesses the workability of concrete, particularly for highly flowable mixes. It measures how easily concrete spreads and flows under controlled jolting, providing data on the concrete's ability to settle under its own weight. This information determines suitability for construction applications requiring high fluidity and even distribution.
Q2: What are the key components of a flow table apparatus?
The flow table apparatus consists of a wooden board topped with a steel plate, weighing 35 pounds total. The board measures 27.6 inches on each side and connects to a base via a hinge. The upper board lifts to 1.6 inches height during testing. A truncated cone mold, 8 inches high with an 8-inch base and 5-inch top diameter, holds the concrete sample.
Q3: How is concrete prepared and placed in the flow table test?
Concrete is placed in the truncated cone mold and gently compacted to ensure uniform density. Excess concrete is carefully cleared away from the top of the mold. After 30 seconds, the cone mold is carefully removed, leaving the concrete sample on the steel plate ready for jolting.
Q4: What happens during the jolting phase of the flow table test?
The table is jolted 15 times at 4-second intervals by lifting the upper board to 1.6 inches and releasing it. Each jolt causes the concrete to spread outward from its initial cone shape. The controlled jolting simulates the effects of vibration during concrete placement in construction applications.
Q5: How is concrete workability determined from flow table test results?
After jolting completes, the extent of concrete spread is measured parallel to the two edges of the table. The average of these two measurements indicates the concrete's workability. Specific spread values categorize the concrete as having medium or high workability, reflecting its flow characteristics.
Q6: Why is measuring concrete spread important for construction?
Measuring concrete spread reveals how well the material flows and distributes under its own weight. This data ensures the concrete meets project requirements for fluidity and even placement. Understanding spread behavior helps prevent segregation and ensures proper concrete consolidation in structural elements.
Q7: How does the flow table test differ from other concrete workability assessments?
The flow table test specifically evaluates highly flowable concrete through controlled jolting and spread measurement. Unlike other workability tests, it simulates vibration effects during placement. This method provides precise quantitative data on concrete flow behavior, making it ideal for self-consolidating and high-performance concrete mixes.