The classification of the aggregates according to their potential segregation is rather simple. The method has been applied to various aggregate crushed quartz porphyry, crushed muschelkalk, gravel, fluvial sand. Powder additives and chemical admixtures play an important role for structural behavior and potential abilities of this type of concrete. These properties are obtained with three different coaxial cylinder rheometers configurations. Focus is placed on the study of the influence of the polycarboxylate ether molecule type as well as different viscositymodifying agents on the temperature robustness. Due to its flowable nature, reinforcing bars can become an obstacle, mixture components may float or segregate and the casting technique determines the orientation of fibers, if any. The computational time is additionally increased when simulating casting of reinforced sections, where each single reinforcement bar has to be modeled.
Flowable concrete offers an extended range of engineering properties and the potential for product innovation. Design, production and placement of self-consolidating concrete. The results illustrate the importance of understanding the inter-particle interactions in concrete if rheological properties, workability and segregation resistance are to be controlled. Approximately 130 papers were presented at the general sessions in addition to other papers discussed during the poster session. In the second step systematic investigations were conducted to determine the effect of the rheological properties on the fresh concrete pressure on the formwork of constructional elements walls.
The study consisted of three parts: firstly, the rheological characteristics thixotropy, yield value and plastic viscosity of the fresh grout were determined, secondly, a parameter-study was carried out on the filling behavior of the grout with a scaled Plexiglas version maximum length: 5. In the course of the wider use of concretes with pourable consistency more and more practice-relevant and economic questions arise. One of the most challenging problems that can confront a repair engineer is that the completed structure is a monolithic mass that is free from cracks, especially with regard to the plastic shrinkage cracking in concrete flatwork. The effect of slump flow consistency on performance was also investigated. It should be noted that packing density for the paste was measured in accordance with reference Khayat and Feys, 2010 procedure and with respect to references British Standards Institution, 1995;Okamura and Ozawa, 1995;Puntke, 2002 recommendations. But the description of the segregation resistance of the mortar is much more difficult.
Rheological investigations with mortar compositions of similar flowability reveal that different Portland cements of similar fineness affect static yield stress and thixotropy differently. . The flow conditions near solid surfaces no-slip, slip, lubrication were investigated using the results of gravimetric flow tests, full scale instrumented pump tests and rheological measurements on matrix, mortar and self-compacting concrete. Thanks to the suitably adapted rheology of the concrete matrix, it is possible to achieve a uniform dispersion of fibers, which is of the foremost importance for a reliable performance of structural elements. The difference in rheological properties between the different configurations increases with increasing aggregate content and increasing yield stress-to-plastic viscosity ratio, which is related to plug flow.
The durability of environment-friendly concrete containing two types of waste material is investigated. The effect of yield stress on the orientation process is specially studied. In the literature very contradictory statements are depicted partially to the pressure of concrete on formwork when using concretes with pourable consistency. This information is important for researchers and professionals working in this area. Self-compacting concrete is the new generation composites, characterized with high filling and passing ability, as well as high resistance to segregation.
In an effort to realize shorter construction times and develop new concrete process technologies, and in view of ever-increasing degrees of component loading, international research has been going on for approximately 30 years for materials that have led, among other things, to the development of high-performance concrete. Design codes usually confront this bond reduction by applying a correction factor. Hereby, the production process can be optimized. Balanced viscosity of concrete may also be helpful to drive the fibers along the concrete flow direction. Monitoring fiber dispersion related issues through suitable non destructive methods would also be crucial for reliable, time and cost-effective quality control.
A material model for fresh concrete pressure, if designed on a physically sound basis, enables the calculation of the formwork pressure of different kinds of concrete, depending on their rheological properties. We would like to acknowledge the input of the International Scientific Committee for providing critical input to guarantee high quality of these peer-reviewed proceedings. At higher surface coverage the effective layer thickness increases and causes a reduction in the maximum attraction between the particles. By several examples it is demonstrated how little changes in the powder composition can cause major changes in concrete properties and how such influences can be determined effectively. A test vessel has been designed which enables the determination of the void ratio of the aggregate and the necessary paste volume. A proposal for the design of formwork, based on the experimental tests and the semi-probabilistic safety concept was developed. All beams were tested up to failure by four point bending regime with the shear span vary from 550 to 950 mm.
Both series of conferences enjoyed great success with a steadily increasing number of papers, participants, and interest from across globe. The successful application of self-compacting concrete depends more and more on the exact knowledge of the rheological properties during mixing, handling and placement. Its workability, hydration heat evolution, chloride penetration resistance, and mechanical properties were analyzed. Physical and mechanical properties as compressive strength; spreading and fluidity were measured. During the testing the maximum applied load was recorded and the crack and failure mechanism were observed.
It is not possible to evaluate a mortar solely based on the rheological properties. The specimens were loaded at constant rate and during testing the slip of the bars and the applied load were recorded. This transition occurs at a critical fiber volume fraction between a regime in which hydrodynamic effects govern the rheological behavior and a regime in which direct mechanical contacts between fibers are predominant. The results showed, however, that the drying shrinkage was not significantly affected by the cement type. Thus, it is now possible to pump high performance concrete and self-compacting concrete up to 600 m without any problem of bleeding, segregation or risk of blocking the pump line.
Experimental results show that microsilica and glass powder do not contribute to concrete corrosion reduction and the most important variable would be superplasticizer content. The minimum mass-loss was related to 15. The bond stress increases with increasing bar diameter. To achieve this goal, state-of-the-art concrete plants need to meet certain minimum requirements. The aim is to create a solid body without voids that can withstand ground settlements. The results show that, while the rates of evaporation and bleeding affect shrinkage, it is over shadowed by other factors, such as fiber type, binder type and use of latex. We invite you to explore a wealth of information in the electronic proceedings.