International Concrete Abstracts Portal

International Concrete Abstracts Portal

The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

Showing 1-5 of 22 Abstracts search results

Document: 

SP261-09

Date: 

October 1, 2009

Author(s):

P. Desnerck, G. De Schutter, and L. Taerwe

Publication:

Symposium Papers

Volume:

261

Abstract:

Aggregate interlock along inclined cracks is one of the basic mechanisms which contributes to the shear resistance of reinforced concrete members. In self-compacting-concrete (SCC) the amount of coarse aggregates is lower than in conventional vibrated concrete (CVC). This different grading could have an influence on the aggregate interlock. To study this effect, push-off tests are carried out. The shear plane of the specimen is crossed by steel bars resulting in reinforcement ratios ranging between 0.45 and 2.68%. It follows that the experimentally determined shear friction of self-compacting concrete is slightly higher than the shear friction of CVC. However, the vertical displacement corresponding with the ultimate shear strength is larger.

DOI:

10.14359/51663206


Document: 

SP261-10

Date: 

October 1, 2009

Author(s):

V. Corinaldesi and G. Moriconi

Publication:

Symposium Papers

Volume:

261

Abstract:

In this work, several self-compacting concretes were prepared by using three different types of fibers made of steel, poly-vinyl-alcohol (PVA), high toughness poly-propylene (PPHT), and two different types of mineral addition (limestone powder and powder from recycled concrete). The water-cement ratio (w/c) was in every case equal to 0.40. Fresh concrete behavior was evaluated by means of slump flow, V-funnel, and L-box tests while the hardened concrete behavior was evaluated by means of flexure and compression tests as well as free drying and restrained plastic shrinkage measurements. Excellent performances were generally detected, particularly for the selfcompacting concretes prepared with steel and PPHT fibers.

DOI:

10.14359/51663207


Document: 

SP261-05

Date: 

October 1, 2009

Author(s):

C.N. MacDonald

Publication:

Symposium Papers

Volume:

261

Abstract:

Synthetic fibers provide a type of three-dimensional reinforcement for concrete with several benefits, especially in slab-on-ground applications. Any design process, and specifically design of synthetic fiber-reinforced concrete, involves making some decisions based on performance-quality, schedule, and cost assumptions. Further, most designs can be analyzed for material substitution of conventional steel reinforcement bending moments with synthetic fiberreinforced concrete bending moments. The design process for slabs-on-ground and substitution with synthetic fiber-reinforced concrete is analyzed for consistency and compared with other design procedures, based on what is known and not known about the synthetic fiber-reinforced concrete material behavior from testing and field performance. Case histories are presented about how these dosages of synthetic fiber-reinforced concrete were used and constructed, and regarding their performance including what was and was not expected.

DOI:

10.14359/51663202


Document: 

SP261-06

Date: 

October 1, 2009

Author(s):

D. Feys, G. De Schutter, and R. Verhoeven

Publication:

Symposium Papers

Volume:

261

Abstract:

Self-compacting concrete (SCC) is a very flowable cementitious material, which does not need external vibration during casting. On the other hand, somewhat surprisingly, pumping of self-compacting concrete requires higher pumping pressures than traditional concrete. This paradox can be fundamentally explained by studying the rheological properties of self-compacting concrete and linking them to pumping operations. This paper describes full-scale pumping tests on self-compacting concrete. The first part deals with the influence of the rheological properties of the concrete on the pumping process, showing that viscosity and shear thickening have a major importance. The second part discusses the influence of pumping on the rheological properties of the concrete, clearly showing a decrease in viscosity due to pumping. Structural breakdown and air content change the rheological properties of the SCC. If structural breakdown dominates the effects of the air content, the yield stress and plastic viscosity will decrease, and the SCC will show a larger tendency to segregate. If the effects of the air content dominate, the yield stress of the SCC will increase, possibly leading to improper filling of the formwork.

DOI:

10.14359/51663203


Document: 

SP261-07

Date: 

October 1, 2009

Author(s):

D. Revuelta, M.C. Alonso, J.L. García, and A. Barona

Publication:

Symposium Papers

Volume:

261

Abstract:

Heavyweight concrete made of water, cement, and heavyweight aggregate is used for shielding in structures where radiation protection is required. Water reduction helps to achieve high density mixtures, since water is the component with the lowest specific gravity. Thus, the use of superplasticizers helps to obtain workable concrete with low water-cement ratio (w/c) and high density. This paper discusses properties for heavy-weight self-consolidating concrete (SCC) made with polycarboxilic-based superplasticizer and barite aggregate. Fresh concrete properties were characterized using the suitable test methods employed in SCC. Since segregation is a key issue in this type of concrete due to the large difference between the densities of the mortar and coarse aggregate, some specific tests were carried out in concrete columns to verify homogeneity of the concrete, including the measurement of the capillarity and water permeability.

DOI:

10.14359/51663204


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