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International Concrete Abstracts Portal

Showing 1-5 of 33 Abstracts search results

Document: 

SP229-19

Date: 

September 1, 2005

Author(s):

C. Alonso, C. Andrade, E. Menendez, and E. Gayo

Publication:

Symposium Papers

Volume:

229

Abstract:

A concrete exposed to environments of high temperature or directly to fire undergoes microstructural changes that result in loss of mechanical properties. The present paper deals with the study of high-performance concretes (HPC) and ultra high-performance concretes (UHPC) resistance to high temperatures. Microstructural changes are followed up to temperatures of 700°C. Changes on residual permeability and porosity, together with weight losses, due to moisture, binding water, aggregates and fibre transformations, are considered. The study, performed on a wide variety of concretes, indicates that UHPC seem to be less resistant at high temperatures than HPC, but the addition of fibres improves the fire resistance of UHPC.

DOI:

10.14359/14743


Document: 

SP229-18

Date: 

September 1, 2005

Author(s):

H.C. Lima, Jr. and J.S. Giongo

Publication:

Symposium Papers

Volume:

229

Abstract:

A theoretical model for steel-fiber-reinforced high strength concrete was developed and calibrated against the test results from 86 high-strength concrete columns tested under axial load. The effects of steel-fibers, the concrete compressive strength, and the transverse and longitudinal reinforcement ratio were accounted for in the proposed stress-strain model. The current model is based on the model developed by Cusson and Paultre, in which the effect of steel-fibers on the concrete ductility was incorporated using the reinforcement index of the volumetric ratio of the steel-fiber addition. The agreement between the model responses and test results was satisfactory.

DOI:

10.14359/14742


Document: 

SP229-14

Date: 

September 1, 2005

Author(s):

P. Castro-Borges, C. Andrade, C. Alonso, and E. Pazini Figueiredo

Publication:

Symposium Papers

Volume:

229

Abstract:

It has been demonstrated that the galvanic current is given by a macrocell which is formed during the curing of the repairs to a concrete member. After this time, the macrocell effect disappears giving place to a microcell behavior that lasts with time in spite of changes to the exposure conditions. This has been demonstrated for concrete containing 0.7% of chloride ion that was repaired, and where the reinforcement was primed with systems that provide protection by repassivation, inhibition, barrier or cathodic protection. However, not enough papers have been published about the electrochemical behavior of the juxtaposed regions (those in non-repaired zones but face to face to the repaired ones) after the repairs. This paper shows that repair approach, as presented here, has no adverse effects in the short and at medium term exposures to different environmental conditions.

DOI:

10.14359/14738


Document: 

SP229-28

Date: 

September 1, 2005

Author(s):

M.A.M. Coelho, M.G. da Silva, F.L. dos Santos Souza, R. Sarmento, R.P. de Moraes Frasson, S.M. de Moraes Pinheiro, E. Zandonade and T. Morimoto

Publication:

Symposium Papers

Volume:

229

Abstract:

This paper reports the results of an investigation on concrete containing alkali-activated slag (AAS). The activators used were liquid sodium silicate (3%, 4% or 5% Na2O, mass of binder) + lime (5%, mass of binder); clinker (10%, mass of binder) + lime (10%, mass of binder); lime (2%, mass of binder) + gypsum (6%, mass of binder) and clinker (16%, mass of binder). The activator of liquid sodium silicate (4% Na2O, mass of binder) + lime (5%, mass of binder) showed better compressive strength when compared to normal portland cement concrete. Other properties were studied such as elastic modulus, flexural strength, absorption of water by capillary forces, drying shrinkage and sulfate attack and the results are discussed in this paper.

DOI:

10.14359/14752


Document: 

SP229

Date: 

September 1, 2005

Author(s):

Editor: V.M. Malhotra

Publication:

Symposium Papers

Volume:

229

Abstract:

SP229 This special publication contains the papers presented at the Fourth International ACI/CANMET Conference held in Olinda, Pernambuco, Brazil, on September 6-7, 2005. It contains 32 papers on recent advances in concrete materials and testing on topics of chemical admixtures; deformations, creep, and cracking control; durability; fiber concrete; fire resistance; nondestructive tests; quality control; strengthening of structures; structural behavior; supplementary cementing materials; and sustainability. Specific papers include: Self Consolidating Concrete, High-Performance and Normal Concrete Affected by Creep at Different Age, Curing, Load Level, Strength, and Water-Cement Ratio with some Interrelated Properties; Properties of Concrete with Recycled Concrete Coarse Aggregates; Application of Different Curing Procedures in High-Performance Concrete; and many more.

DOI:

10.14359/15165


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