L Box Test Limit for Self Compacting Concrete (SCC)

L Box Test Limit for Self Compacting Concrete (SCC)

Introduction

The L Box Test is a widely used method to test the flowability and passing ability of self-compacting concrete (SCC) through tight spaces and around obstacles. This test is essential in construction applications where complex shapes and forms need to be filled without vibration. From a Japanese design for underwater concrete, the L Box Test is described in the European standard BS EN 12350-10. The test checks the ability of self-compacting concrete to flow without segregation or blocking, so it’s a must have tool to check the suitability of SCC mixes for various construction projects.

Properties of Self Compacting Concrete

Self-compacting concrete is a type of concrete that can flow under its own weight, high flowability and passing ability through tight obstructions. Low segregation and blocking tendency, ideal for filling complex shapes and forms without vibration. Properties of self-compacting concrete are high workability, ability to fill small interstices of formwork, limited amount and size of coarse aggregate. Using self-compacting concrete can improve the quality and durability of construction projects, reduce the need for extra labor and equipment.

Dimensions: 8x24x32.5in. (203x610x26mm), WxDxH.

Meets Test Methods: ASTM C 1611, ASTM C143, ASTMC 1621. Learn more about the Steel Concrete Slump Cone used in these tests.

What is the L Box Test?

The L Box Test is a standard test to measure the flowability and passability of self compacting concrete (SCC) through tight spaces and around obstacles such as bars representing reinforcing steel. It simulates real life situations like pouring concrete around rebar, so it’s a must have tool to check the quality and performance of self consolidating concrete (SCC) in different construction applications. The extent of the L-box test's applicability includes measuring both the filling and passing ability of highly flowable concrete. A figure of the L-box apparatus is crucial for understanding the configuration and dimensions required for measuring flowability and segregation resistance of concrete. The L Box Test originated from a Japanese design for underwater concrete and is described in the European standard BS EN 12350-10. By seeing how the concrete flows through the confined spaces the test will tell you if SCC mixes are suitable for complex consolidating needs.

Equipment and Procedure

The L Box Test Apparatus is an L shaped box with a vertical and horizontal section separated by a sliding gate. The vertical section has vertical steel bars representing rebar and the horizontal section is open. Pour freshly mixed SCC into the vertical section until it reaches a certain level. Lift the gate and the concrete will flow into the horizontal section. Measure the distance the concrete flows in the horizontal section and the time it takes to reach certain points. The L Box Test Apparatus is made of durable stainless steel to withstand multiple testing. Measuring slump flow diameters of self-compacting concrete mixtures that incorporate plastic waste is also essential in this context. T20 and T40 results from the L-box test provide an indication of the ease of flow of the mixtures. For more information on concrete testing, check out this step-by-step procedure.

The L Box Test results will give you information about the flowability and passability of the SCC. Flowability is measured by the distance the concrete flows in the horizontal section, the more the better. Unfilled areas behind the steel bars is blocking which can be quantified by calculating the blocking ratio. The blocking ratio is the ratio of the concrete height in the horizontal section to the height in the vertical section. A minimum value of 0.8 is used to determine if the self consolidating concrete (SCC) meets the requirements. This ratio will tell you if the concrete mix can flow past obstacles without segregation. Certain parameters, such as plastic waste content, influenced the slump flow time and V-funnel flow time of self-compacting concrete mixtures. The procedure involves the preparation of concrete samples and indicates that these samples are cured in the laboratory environment before undergoing compressive strength testing.

Benefits and Applications

The L Box Test has many benefits and applications in construction. It’s easy and fast to do so it’s a useful tool for quality control. The results will give you information about the SCC’s flowability and passability so you can pour concrete in shapes and around rebar. This test is useful to check the effectiveness of SCC mixes in different construction applications like high rise building, bridges and other infrastructure projects. You can also use the L Box Test to test different SCC mixes and optimize their composition for specific applications to get the best possible results in terms of strength and durability in terms of strength and durability. The different aggregates and supplementary cementitious materials used in their self-compacting concrete mixtures play a critical role in workability, strength and overall properties of the concrete. The maximum aggregate size is crucial for determining the spacing of reinforcing bars for concrete mixtures.

Test Procedure and Equipment

The L Box Test Apparatus is a vertical hopper with a sliding gate at the bottom. There are three bars representing rebar and a horizontal trough in front of the gate. Fresh concrete is poured into the vertical hopper without consolidating. A concrete sample is required to fill the vertical section of the apparatus before testing the concrete sample and its performance in the flow test. Pour the concrete into the vertical section of the apparatus and then lift the slide gate and the concrete will flow past the bars into the horizontal trough. Measure the final depth of the concrete at the gate and at the end of the trough and the proportional difference is the blocking ratio. Some versions of this procedure require timing the flow with a stopwatch. The passing ability of SCCs is determined through measurements like the L-box height ratio. The 12x1.25in (305x32mm) Steel Straightedge is an optional accessory to strike off the concrete surface.

The L Box Test Apparatus is an L shaped box with a vertical and horizontal section separated by a sliding gate. The vertical section has vertical steel bars representing rebar and the horizontal section is open. Pour freshly mixed SCC into the vertical section until it reaches a certain level. Lift the gate and the concrete will flow into the horizontal section. Measure the distance the concrete flows in the section and the time it takes to reach certain points. The L Box Test Apparatus is made of durable stainless steel to withstand multiple testing.

Measuring slump flow diameters of self-compacting concrete mixtures that incorporate plastic waste is also essential in this context. The arrangement of rebar in the L-box test for concrete is critical and should be spaced accordingly.