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International Concrete Abstracts Portal

Showing 1-5 of 51 Abstracts search results

Document: 

22-226

Date: 

May 1, 2023

Author(s):

Savitha Sagari Srinivasan and Raissa Douglas Ferron

Publication:

Materials Journal

Volume:

120

Issue:

3

Abstract:

Most concrete service life models are designed for uncrackedconditions, and the effect of microcracks on such models has not been as well researched. A service life model for concrete structures that takes into account microcracking is presented. A unique feature of this model is that its input parameters can be determined using only nondestructive methods, thus allowing it to be used when samples for laboratory tests cannot be extracted— for example, in in-service or critical infrastructure. The model was developed for low water-cementitious materials ratio (w/cm) concrete mixtures and validated on full-scale prestressed concrete girders. The results showed that the presence of a large number of microcracks could cause a loss in the remaining service life of concrete structures, even if individual microcracks did not cause asignificant impact.

DOI:

10.14359/51738686


Document: 

21-280

Date: 

September 1, 2022

Author(s):

Mohammad A. Khawaja, Kwangsuk Suh, Venkat Bhethanabotla, and Rajan Sen

Publication:

Materials Journal

Volume:

119

Issue:

5

Abstract:

This paper presents results from a comprehensive, cradle-to-grave study in which electrochemical measurements (corrosion potential and corrosion rate), crack progression, and gravimetric metal loss were recorded for one-third-scale Class V prestressed specimens exposed for over 3 years to a simulated outdoor marine environment. These data were used to isolate the effect of cracking on the corrosion rate and determine the appropriate oxygen permeation coefficient values that were used to quantify the differences in corrosion propagation between the cracked and uncracked states. The permeation coefficient in cracked sections was found to be more than 20 times larger than that in uncracked ones. It was also higher than that for reinforced concrete specimens under comparable wetting-and-drying saltwater exposure. The findings predict that comparable (Class V) full-size prestressed pile specimens will crack within 3 years of the destruction of the passive layer (depassivation).

DOI:

10.14359/51735950


Document: 

21-213

Date: 

May 1, 2022

Author(s):

Chaomei Meng, Liangcai Cai, Jianming Ling, Guanhu Wang, Yong Shen, and Hui Ye

Publication:

Materials Journal

Volume:

119

Issue:

3

Abstract:

Cross-tensioned prestressed concrete pavement (CTPCP) has good integration and anti-crack performance with a high bearing capacity. An approximate model considering the effects of the sliding layer is developed to predict the longitudinal prestress of CTPCP, in which a bilinear model is used to describe the performance of the sliding layer. Additionally, a numerical simulation model is also developed to verify and modify the analytical model. Furthermore, the influence on longitudinal prestress has been analyzed according to the modified analytical model. The results show that the performance of the sliding layer has significant influence on longitudinal stress. In the ending area, the longitudinal prestress increases gradually with the increase of prestressed strands. In other areas, the longitudinal stress remains unchanged when the frictional coefficient of the sliding layer is ignored, while it decreases gradually and exists at a minimal value at the pavement midpoint when the friction effect of the sliding layer is taken into consideration. The angle and spacing of cross-tensioned prestressed strands also have significant influence on longitudinal prestress. Decreasing the angle and spacing can effectively improve the longitudinal prestress.

DOI:

10.14359/51734611


Document: 

20-466

Date: 

September 1, 2021

Author(s):

R. Girardi, D. C. Dal Molin, F. A. P. Recena, and F. Tiecher

Publication:

Materials Journal

Volume:

118

Issue:

5

Abstract:

To dimension the structural systems of reinforced or prestressed concrete, it is necessary to know at least the elastic modulus and the compressive strength of the concrete. This is because several factors directly influence these two properties, from the dosage to the procedure adopted for curing the concrete. Therefore, this study aims to present the influence of two different types of curing (humid and thermal steam) over the elastic modulus of the concrete. The results demonstrate that a significant reduction occurs on the modulus when the concrete is submitted to thermal steam curing. Additionally, the increase in the volume of the paste in the mixture reduces the stiffness of the compound.

DOI:

10.14359/51732936


Document: 

19-404

Date: 

September 1, 2020

Author(s):

Chaomei Meng, Liangcai Cai, Guanhu Wang, Xingang Shi, and Jianming Ling

Publication:

Materials Journal

Volume:

117

Issue:

5

Abstract:

Cross-tensioned prestressed concrete pavement (CTPCP) has superior mechanical and durable performance over ordinary concrete pavement. An approximate model to predict stresses and displacement of CTPCP under temperature loading is developed. Elasticplastic model is adopted to describe the performance of sliding layer between CTPCP and subgrade. The stresses in concrete are divided into friction introduced, curling, and prestressed components. Friction introduced component is obtained with the equivalent equation of CTPCP and curling component is obtained with Westergaard solution for concrete pavement with infinite length but finite width. Furthermore, influences of parameters, including length and thickness of slab, elastic modulus of concrete, frictional coefficient, space, angle and position of prestressed strands and reaction modulus of subgrade, on stresses and displacements are discussed. Results show that decreasing length and thickness of pavement, frictional coefficient, and elastic modulus of concrete are effective ways to reduce stress under temperature loading. Furthermore, decreasing space but increasing diameter of prestressed strands is another way to prevent too large tensile stress in CTPCP. Additionally, it seems to be more concise that the perfect plastic model is adopted to predict friction introduced stress in engineering application after comparative analysis of difference between to bilinear model and plastic model.

DOI:

10.14359/51725979


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