L Box Test Overview
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. It simulates real life situations like pouring concrete around rebar, so it’s an essential tool to check the suitability of SCC mixes for complex consolidating needs. Originated from a Japanese design for underwater concrete, the L Box Test is described in the European standard BS EN 12350-10. With this test you can be sure your SCC mixes will perform in different challenging environments and give you reliable and reproducible results.
L Box for Self Compacting Concrete (SCC)
The L Box for Self Consolidating Concrete (SCC) is an alternative to determine flow and passability of self compacting concrete (SCC) mixes within bars representing reinforcing steel. This is used in Europe and some DOT’s in the US have adopted the procedure or are looking into it.
The 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 12x1.25in (305x32mm) Steel Straightedge is an optional accessory to strike off the concrete surface.
Dimensions: 8x24x32.5in. (203x610x26mm), WxDxH.
Meets Test Methods: ASTM C 1611 ASTMC 1621
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 an essential tool to check the quality and performance of self consolidating concrete (SCC) in different construction applications. 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.
Results
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.
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 complex 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.
Test Procedure and Equipment
The L Box Test Apparatus is a rectangular section box shaped like an ‘L’ with a vertical and horizontal section separated by a sliding gate. The vertical section has vertical reinforcing steel bars representing rebar and this section is open. Pour freshly mixed self consolidating concrete (SCC) into the 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.
Passing Ability and Results
The L Box Test results will give you information about the flowability and passability of 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 this section. A minimum acceptable value of 0.8 is used to determine if the self consolidating concrete (SCC) meets the requirements. This is a reliable and accurate way to test self-consolidating concrete mixes so you can optimize the self consolidating concrete (SCC) composition for specific applications to get the best possible results.