Modified Fill-Box Test System for Self-Compacting Concrete (SCC)

Abstract

A system for testing the filling and flow capacity of self-compacting concrete (SCC), consisting of: a filling box with a volume of approximately 5.3 liters; Steel bars arranged horizontally and vertically inside the filling box to simulate reinforcement obstacles; a settling cone arranged in an inverted position for introducing SCC into the filling box; a horizontal closure configured for the controlled release of SCC; the time SCC needs to fill the box is measured as an indicator of its filling and throughput capacity.

Description

AREA OF INVENTION

[0001] The present invention relates to a system for evaluating the flow properties and workability of self-compacting concrete (SCC). In particular, the invention provides a modified filling box test for measuring the filling and flowability of SCC in its fresh state. This system is intended to provide more accurate and reliable results, especially when steel bars are used as obstacles in multiple directions during the test. BACKGROUND OF THE INVENTION

[0002] The most important requirements for self-compacting concrete are tested in its fresh state. The most important requirements are: 1) Filling capacity 2) Fit 3) Segregation resistance

[0003] The filling capacity of SCC is evaluated using the slump flow test, the T50cm slump flow test, and the Orimet and V-funnel tests. The flowability of SCC is evaluated using the L-box test, the J-ring test, the U-box test, and the fill-box test. The segregation resistance of SCC is evaluated using the V-funnel test at T5 minutes and the GTM sieve stability test. Of all the tests, the fill-box test can be selected to measure both the filling capacity and the flowability of SCC. The remaining tests assess either flowability or filling capacity. Therefore, more than two additional tests are required to predict the performance of fresh SCC. The fill-box test is the only acceptable method for evaluating both the flowability and filling capacity of SCC. However, the main disadvantage of the fill-box test is that 42 liters of SCC must be prepared for the test.The fill percentage is measured at the end of the test, after the SCC has been passed through 35 obstacles made of 20 mm PVC pipes within 8 seconds. All rods used to create the obstacles in the box point in only one direction. Variations in the results can be observed during this time.

[0004] To avoid these drawbacks, a modified filling box test with a capacity of 5.3 liters (corresponding to the volume of the setting cone) was developed, incorporating steel rods of varying diameters depending on the practical application. The restrictive steel rods are positioned in both directions to determine the precise flow and permeability of the SCC. The transparent cylindrical box has an opening at the top and a horizontal closure. A setting cone is placed upside down and fills the fresh SCC within one minute. After opening the closure, the fresh concrete can fill the cylindrical box. The time required to completely fill the modified box with the 5.3 liters of concrete serves as the benchmark for evaluating the filling and permeability of fresh SCC.

[0005] Self-compacting concrete (SCC) is a highly flowable, non-segregating concrete that can spread under its own weight and fill formwork without mechanical vibration. The increasing use of SCC in construction projects, particularly in complex structural elements with dense reinforcement, requires precise and reliable testing methods to evaluate the fresh-state properties of SCC, including filling capacity, permeability, and segregation resistance.

[0006] To assess these properties, various conventional tests have been used, including the slump flow test, the T50cm slump flow test, the Orimet test, the V-funnel test, the L-box test, and others. Among these, the fill-box test is frequently used to evaluate both the filling and flow capabilities of SCC. However, the conventional fill-box test has significant drawbacks, such as the need for large quantities of concrete (42 liters) and the tendency to produce inconsistent results. In the conventional fill-box method, SCC is passed through obstacles consisting of steel bars arranged in one direction, which may not accurately reflect real-world conditions. This is particularly true in areas with dense reinforcement, such as beam-column connections.

[0007] Furthermore, the test is time-consuming and inefficient, and the results can be inconsistent due to the design of the obstacles, which only consider one reinforcement direction. In practice, these limitations lead to inaccurate predictions of SCC performance.

[0008] To solve these problems, the present invention proposes a modified filler box test with a smaller capacity (5.3 liters) and additional horizontally and vertically arranged steel bars. This design more accurately simulates real-world conditions with reinforcement in multiple directions and provides more reliable results for evaluating the fill and permeability of SCC. The modified test eliminates many of the disadvantages associated with the conventional method and offers a faster, more efficient, and more precise testing method for SCC performance in construction. Summary of the invention

[0009] Self-compacting concrete (SCC) is a highly flowable, non-segregating concrete that can spread under its own weight and fill formwork without mechanical vibration. However, to assess its workability in the fresh state, certain critical properties such as fillability, permeability, and segregation resistance must be evaluated.

[0010] Traditional tests such as the slump flow test and the fill box test provide insights into SCC performance, but the fill box test has certain limitations. For example, the conventional fill box test requires 42 liters of SCC, and the results can be inaccurate if the obstructions are arranged in only one direction. The novel method of this invention overcomes these problems by using a modified fill box test with a capacity of 5.3 liters. This test incorporates horizontally and vertically arranged steel bars to simulate more realistic scenarios, particularly with dense reinforcement. This modified test enables a more accurate measurement of the flow and permeability of SCC, reduces errors, and ensures more reliable data. DETAILED DESCRIPTION OF THE INVENTION

[0011] The invention relates to a system for testing the fillability and flowability of self-compacting concrete (SCC). The system consists of a modified filling box with a volume of approximately 5.3 liters, which corresponds to the capacity of a standard setting cone. The reduced volume allows testing with smaller quantities of SCC while still delivering reliable results. The box is preferably made of transparent material so that the concrete flow can be clearly observed during the test.

[0012] Inside the filling box, steel bars are arranged horizontally and vertically to simulate typical reinforcement obstructions in concrete structures, such as beam-column connections. The bars can have different diameters and their positions can be adjusted to represent various reinforcement conditions. This arrangement allows for a more accurate reproduction of real-world conditions compared to conventional filling boxes where the bars run in only one direction.

[0013] The system also includes an inverted setting cone at the top of the box for filling with fresh SCC. A horizontal flap is located below the setting cone to control the concrete flow into the box. After the setting cone is filled with SCC, the flap is opened, and the SCC flows through the reinforcement mesh formed by the bars into the box. The time required to completely fill the box is measured and serves as an indicator of the SCC's filling and flow capacity.

[0014] In one embodiment, the system is equipped with sensors to measure flow time and a computer or control system to record and analyze the results. This ensures greater accuracy and reduces operator error. Alternatively, the fill level and flow behavior can be observed visually and recorded manually. The system is designed for easy cleaning and reuse for multiple tests, ensuring its practicality for laboratory and construction site applications.

[0015] The invention thus offers a compact, efficient, and precise testing system for SCC. It significantly reduces the required amount of SCC compared to conventional methods while simultaneously providing improved reliability in simulating reinforcement conditions. This ensures that the results obtained better reflect real-world construction scenarios with reinforcement in multiple directions.

Claims

[1] A system for testing the filling and flow capacity of self-compacting concrete (SCC), consisting of: a filling box with a volume of approximately 5.3 liters; Steel bars arranged horizontally and vertically inside the filling box to simulate reinforcement obstacles; a settling cone arranged in an inverted position for introducing SCC into the filling box; a horizontal closure configured for the controlled release of SCC; the time SCC needs to fill the box is measured as an indicator of its filling and throughput capacity. [2] System according to claim 1, wherein the filling box is made of a transparent material to allow visual observation of the SCC flow. [3] System according to claim 1, wherein the steel bars are adjustable in position and diameter to simulate different reinforcement conditions. [4] System according to claim 1, further comprising sensors for recording the filling time and a computer system for recording and analyzing the results. [5] System according to claim 1, wherein the system is configured for easy cleaning and reuse after each test.