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International Concrete Abstracts Portal

Showing 1-5 of 123 Abstracts search results

Document: 

18-353

Date: 

May 1, 2020

Author(s):

Nabeel A. Farhan, M. Neaz Sheikh, and Muhammad N. S. Hadi

Publication:

Materials Journal

Volume:

117

Issue:

3

Abstract:

The effects of aspect ratio and volume fraction of steel fibers on the engineering properties of ambient-cured geopolymer concrete (GPC) were investigated. Straight macro steel fibers with an aspect ratio of 65 and straight micro steel fibers with an aspect ratio of 30 were added into the GPC mixtures. The test results showed that the engineering properties of GPC significantly improved with the addition of 2% macro steel fibers and 2% micro steel fibers by volume. The stress-strain behavior of GPC changed from brittle to ductile with significant improvement in the post-peak behavior by the addition of steel fibers. The compressive strength of GPC increased significantly with the addition of low-aspect-ratio steel fibers and the indirect tensile strength, flexural strength, direct tensile strength, and double punch tensile strength of GPC increased significantly with the addition of high-aspect-ratio steel fibers.

DOI:

10.14359/51724591


Document: 

18-553

Date: 

January 1, 2020

Author(s):

Manuel A. G. Silva and Miguel Estêvão

Publication:

Materials Journal

Volume:

117

Issue:

1

Abstract:

Glass fiber-reinforced polymer rods, both bare and embedded in concrete or lime mortar, were immersed in an alkaline solution at 20°C for up to 6 months and tested to find the influence of the protective covers on the degradation of the rods. Diffusion and porosimetry studies were used to interpret the results. Reduction of the proportion of larger pores in the mortar cylinders altered the transport of contaminant to the reinforcing bars. Accelerated effects due to immersion in solution at 60°C caused marked degradation of the rods. SEM images revealed damage to the matrix and the interface fiber-resin, mostly noticeable on the resin matrix and in the peripheral region of the rods. Severe loss of capacity of energy absorption was found in low-velocity impact tests after exposure to solution at 20°C for more than 5000 hours. Globally, results showed that the embedment delayed the initiation of damage but did not shield the rods against the maximum intensity of degradation by the alkaline contaminant.

DOI:

10.14359/51719071


Document: 

18-507

Date: 

November 1, 2019

Author(s):

Saranya P, Praveen Nagarajan, and A. P. Shashikala

Publication:

Materials Journal

Volume:

116

Issue:

6

Abstract:

Development of geopolymer concrete (GPC) with industrial by-products is a solution to the disposal of the industrial wastes, thus making the concreting process sustainable. This paper focuses on the development of GPC using ground-granulated blast-furnace slag (GGBS) and dolomite (by-product from rock crushing plant) as source materials. Strength properties of slag-based GPC are studied with different proportions of dolomite. It is observed that the addition of dolomite into slag-based GPC reduces the setting time, enhances workability, and rapidly improves the early-age strength. Addition of dolomite into slag GPC also improves the durability properties, such as high resistance towards water absorption, sorptivity, marine attack, and chemical attack.

DOI:

10.14359/51716981


Document: 

18-456

Date: 

November 1, 2019

Author(s):

Joseph J. Assaad, Najib Gerges, Kamal H. Khayat, Najib Lattouf, and Jimmy Mansour

Publication:

Materials Journal

Volume:

116

Issue:

6

Abstract:

A comprehensive research project was undertaken to evaluate the effect of styrene butadiene rubber (SBR) latex admixture on washout loss and bond strength of underwater concrete (UWC) designated for repair applications. Three UWC series possessing low to high stability levels that incorporate 5 to 15% SBR, by binder mass, were tested. A 1.5 m (4.93 ft) long specially designed channel was developed to enable the UWC to free fall from the outlet of a V-funnel apparatus, flow along an inclined surface submerged in water, then spread onto a horizontal concrete surface. Results show that underwater casting leads to reduced pulloff strengths caused by washout loss and aggregate segregation that weaken in-place properties. The incorporation of SBR was particularly efficient to reduce washout loss and improve adhesion between the repair overlay and substrate. Regression models enabling the prediction of residual bond strengths from the UWC rheological properties, washout loss, and polymer content are established.

DOI:

10.14359/51716982


Document: 

17-433

Date: 

November 1, 2019

Author(s):

Er-yu Zhu and Ze-wen Zhu

Publication:

Materials Journal

Volume:

116

Issue:

6

Abstract:

A total of 16 pullout specimens were tested to investigate the effect of curing conditions on bond behavior of near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP) strengthening concrete under curing temperatures from 35 to 65°C (95 to 149°F) and curing times from 6 to 12 hours. It was compared to that of specimens in ambient conditions (16°C [60.8°F]). On these bases, a nonlinear local bond-slip model was proposed. Two key parameters—A and B—are employed in the proposed bond-slip model, the specific expressions of which were mainly related to ultimate pullout load and peak shear stress of the specimen. The results show that the bond behavior of CFRP strip represents a negative quadratic curve with curing temperature and positive inverse tangent curves with curing time, respectively. The nonlinear local bond-slip model, considering the curing temperature-time, is deduced and validated.

DOI:

10.14359/51719148


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