ing concrete surface. The top portion of the fractured aggregate particle separates from the concrete surface ... The aggregate particle does not often fracture and split as is the case of popouts from physical action. However, the ASR phenomenon can result in ...
the mould for slump test is a frustum of a cone, (300 mm) high. The mould placed on a smooth surface with the smaller opening at the top. The procedure to fill the cone with concrete in three layers, each layer is tamped 25 times with a standard (16 mm
· ASTM''s "Manual of Aggregate and Concrete Testing," included in Vol. 04.02 of Annual Book of ASTM Standards, states that the conical fracture is typical. In cases where the compressive strength is lower than anticipated, the manual suggests that fracture type may help in determining the cause.
The Discrete Element Method, DEM, is increasingly used in fracture studies of non-homogeneous continuous media, such as rock and concrete. A 2D circular rigid DEM formulation, developed to model concrete, has been adopted. A procedure developed to generate aggregate particles with a given aspect ratio and shape is presented. The aggregate particles are modelled with […]
The fracture energy varied from 38 to 55 J.m-2. A comparison of the number of aggregates that separated from the two concrete matrices with the highest fracture energies indicated that the concrete containing pebbles crumbled more easily and was
Fracture in Concrete and Reiriforced Concrete 261 concrete is very wide or not, two elementary justifications may be offered for the blunt crack band model. One of them is the heterogeneity of the material. We treat the material as a smoothed, homogeneous
Bažant, Z. P. and Kazemi, M. T., ''Determination of fracture energy, process zone length and brittleness number from size effect, with application to rock and concrete'',Int. J. Fract. 44 (1990) 111–131. Article Google Scholar Download references
The properties of aggregate have great effect on the fracture behavior of high performance concrete. In this paper, the effect of aggregate size distributions and the volume fraction of aggregate on the fracture parameters of high performance concretes with strength 50-80 MPa were investigated under three-point bending test.
· The paper reviews the size effect accompanying blunt fracture in brittle heterogeneous materials such as concrete and its applications to structural analysis and design. Various refinements of Baiant''s size effect 1 aware sunnari zed, and recent results of fracture tests of Bazant and. Pfe1 ffer whi ch estab 1 i sh measurements of concrete fracture energy on the basis of size effect are given.
· Consequently, concrete cone failure is a fracture mechanics problem, best described through tensile strength and fracture energy and, thus, it is also subject to size effect. If the fracture process zone is small compared to the structure size then, with good approximation, a stress singularity can be assumed and linear elastic fracture mechanics (LEFM) applies (see [ 33 ]).
· RE: Concrete cylinders testing and fracture type. concretemasonry (Structural) 10 Apr 10 09:55. If you see non-symetrical shears instead of conical, that would be an indication of poor sample preparation (non-parallel surfaces), improper placement of the samples (off-center) or some testing machine problem. We had historically had photos of all ...
The fracture energy of high strength concrete decreases with an increase in aggregate size, while the fracture energy of normal-strength concrete increases with an increase in aggregate size. High-strength concrete containing basalt and normalstrength concrete containing limestone yield higher fracture energies with higher coarse aggregate content than with lower coarse aggregate contents.
low-permeable rock with fine fractures only, sealing with clay is suitable, whereas concrete seals are proposed for those parts of the holes that intersect permeable fracture zones , cf. Figures 1 and 2. The average number of clay and concrete seals in 500 to
Concrete cone is one of the failure modes of anchors in concrete, loaded by a tensile force.The failure is governed by crack growth in concrete, which forms a typical cone shape having the anchor''s axis as revolution axis Mechanical models ACI 349-85 Under ...
However, aggregate characteristics other than strength, such as the size, shape, surface texture, grading and mineralogy are known to affect concrete strength in varying degrees. Size: The maximum size of a well-graded coarse aggregate of a given mineralogy can have two opposing effects on the strength of normal concrete.
Concrete cone is one of the failure modes of anchors in concrete, loaded by a tensile force. The failure is governed by crack growth in concrete, which forms a typical cone shape having the …
· However, using a recycled aggregate of more than 65% can impact the mix''s durability significantly, reducing its physical properties tenfold. The optimum amount blended in with the concrete should be 35%. Some experiments have shown that the recycled aggregate is durable, no doubt, but not as sturdy as natural coarse aggregate.
343 Modelling of concrete fracture at aggregate level using DEM based on x-ray µCT images of internal structure IV International Conference on Particle-based Methods – Fundamentals and Applications PARTICLES 2015 E. Oñate, M. Bischoff, D.R.J. Owen, P
The shape of slump cone of concrete with recycled aggregate is generally similar to conventional aggregate. The failure pattern of cubes / fracture mechanism is also similar to conventional cubes as shown in figure 6. If properties of sample recycled aggregate are
concrete to aggregate type, w/cm, and age is even more inconclusive, especially when correlated with strength properties. Aggregate type plays a role in determining the strength and fracture energy of concrete. Petersson (1980) studied fracture energy as a
· Order 4500 psi concrete with a maximum water-cement ratio of 0.45 to reduce surface porosity and increase the strength of the concrete. 3. Use air-entrained concrete and pozzolanic admixtures such as fly ash. 4. Place the lowest-slump concrete possible to minimize the floating of lightweight particles to the surface. 5.
The intention of this contribution is the numerical description of the rarely investigated phenomenon of mixed mode fracture in plain concrete. Since cracks in concrete are typically subjected to both normal and shear displacements, a new material model called ...
strength concrete (HSC) up to grade 100 no longer presents any major difficulties (Kwan et al. 1995a; MacArthur et al. 1996). In fact, since further increase in concrete strength would be limited by the strength of the rock aggregate used and could et al 1995b), it
softening. The failure of concrete is generally preceded by propagation of cracks, characterized by a large microcracking zone (fracture process zone or FPZ) which is proportional to the maximum aggregate size (d max). This fracture process is
Fracture properties of high strength lightweight aggregate concrete. / LO, T Y; Cui, H Z. 2007. Research output: Conference Papers (RGC: 31A, 31B, 32, 33) › 32_Refereed conference paper (no ISBN/ISSN) › peer-review
HKUST SPD contains HKUST Research Outputs in all forms and hosts the HKUST Scholar Profiles. Similar Items Fracture of concrete materials and structures …
The venue was Houston, Texas on June 17-19, 1987 and cooperation was provided by ACI 446, Fracture Mechanics and RILEM 90-FHA Fracture Mechanics of Concrete; Applications. The conference co-chai rmen were Professor S.P. Shah, Northwestern Uni versity and Professor S.E. Swartz, Kansas State University with the able assistance of Professor K.P. Chong, University of Wyoming.
Abstract：Fracture toughening exhibited in quasi-brittle materials such as concrete is often mainly related to the action of aggregate bridging, which leads to the presence of a fracture process zone ahead of stress-free cracks in such materials this investigation ...
FRACTURE BEHAVIOR OF LIGHTWEIGHT AGGREGATE CONCRETE UNDER MULTIAXIAL COMPRESSIVE STRESS Peter GrUb1 DYWIDAG, Erdinger LandstraBe 1, D-8000 MOnchen, Federal Republic of Germany ABSTRACT Lightweight
Factors Affecting Cylinder Results The "Manual of A gggg g gregate and Concrete Testin g," included as related material in Volume 4.02 of the 2003 Annual Book of ASTM Standa rds, states that the type of fracture may be of assistance in determining the cause for
Three concrete batches were cast utilising three different aggregate types. For two concrete ages (28 and 70 days), anchor tensile capacity and concrete properties were obtained. Concrete compressive strength, fracture energy and elastic modulus are used to normalize and compare the undercut anchor concrete tensile capacity employing some of the most widely used prediction models.
M. H. Mohammed et al. 220 cement and Merit 5000 low-pH cement, the latter for sealing rock containing boreholes with interacting seals of concrete and clay . Long -lasting grouts require chemical integrity, which is provided by selecting quartzite as aggregate.
This value accounts for 35% cement use by ready-mix producers (of total national consumption), average densities of 1870 and 2400 kg/m 3 for the aggregates and hardened concrete, respectively, and an average of 20% recycled concrete aggregate usage in new concrete fabrication.
Figure 1. Types of fracture: (a). Cone, (b) Cone and split, (c) Cone and shear, (d) Shear, (e) Columnar A cone failure happens when friction at the platens of the testing machine restraint lateral expansion of the concrete when the vertical compressive force is
This study presents a design methodology for concrete fracture properties, linking the average aggregate size d av to the tensile strength f t and fracture toughness K IC for a given cement grade and water/cement (W/C) ratio. Two different concrete mixes with d …