International Concrete Abstracts Portal

Showing 1-5 of 15 Abstracts search results

Document: 

SP224

Date: 

December 1, 2004

Author(s):

Editor: Ashish Dubey / Sponsored by: ACI Committee 549

Publication:

Symposium Papers

Volume:

224

Abstract:

"This publication contains the papers originally presented in a symposium on the topic of thin reinforced cementitious products organized by ACI Committee 549, Thin Reinforced Cementitious Products and Ferrocement, during the ACI 2003 Spring Convention held in Vancouver, British Columbia, Canada. The symposium explored current state-of-the-art and recent advances in material science, manufacturing methods, and practical applications of thin reinforced cementitious products. The topics covered in this publication include material science of textile reinforced concrete, use of textile reinforced concrete for integrated formwork and exterior cladding panels, prestressed thin-sheet concrete products, ultra-high-performance thin precast concrete products, production of concrete tubes by centrifugation method, freezing-and-thawing durability of commercial fiber-reinforced cement boards, structural evaluation of cement-skin sandwich building systems, microwave accelerated curing method for producing precast cementitious products, history of glass fiber-reinforced concrete (GFRC) products, and modeling of cement-based laminate composites." Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP224

DOI:

10.14359/14031


Document: 

SP224-13

Date: 

December 1, 2004

Author(s):

B. Mobasher

Publication:

Symposium Papers

Volume:

224

Abstract:

Techniques for modeling the mechanical response of thin section cement-based composites intended for structural based applications are presented using a micromechanical approach. A layer model is used and the property of each layer is specified based on the fiber and matrix constituents in addition to the orientation and the stacking sequence in each lamina. The overall axial and bending stiffness matrix is obtained using an incremental approach which updates the material parameters. The simulation is conducted by imposing an incremental strain distribution, and calculating the stresses. A stress based failure criterion is used for the three failure modes of initiation of cracking, ultimate strength of matrix, and ultimate strength of lamina. As the cracking saturates the specimen, it results in a gradual degradation of stiffness. A continuum damage model based on a scalar damage function is applied to account for the distributed cracking. The model predicts the response of unidirectional, cross ply and angle ply laminae under tensile loading in longitudinal and transverse directions. The load-deformation responses under tension and flexure are studied. It is shown that by proper selection of modeling approach, parameter measurement, and theoretical modeling, a wide range of analysis tools and design guidelines for structural applications of FRC materials are attainable.

DOI:

10.14359/13416


Document: 

SP224-14

Date: 

December 1, 2004

Author(s):

Momahed Boulfiza and Nemkumar Banthia

Publication:

Symposium Papers

Volume:

224

Abstract:

Cement-based composites, reinforced with randomly distributed short fibers exhibit a nonlinear behavior, called damage, which could be described in terms of microcrack initiation, growth and coalescence leading to the creation of macrocracks. A micromechanics-based continuum damage mechanics, MBCDM, model is proposed for the prediction of the effect of initial microcrack configuration and propagation on the macroscopic Young’s modulus and thermodynamic force associated with the chosen damage variable. Parametric studies for a number of periodic crack distributions in a two-dimensional case have been carried out. Both unreinforced (brittle) and pitch-based carbon fiber reinforced thin sheet cementitious materials have been considered. It is shown that despite the relative simplicity of the damage measure used, the model was able to capture the main effects of cracking patterns on the overall behavior of the composite. Simulation results also reveal that, whereas the evolution of the normalized stiffness is practically the same for all configurations over the entire range of damage variation, the damage thermodynamic force is different for each case. The results predicted by the proposed approach, appear to be consistent with experimental observations regarding the tensile behavior of CFRC composites.

DOI:

10.14359/13417


Document: 

SP224-10

Date: 

December 1, 2004

Author(s):

K C G Ong, C P Teo, C H Shum, L H J Wong, S T Tan and C T Tam

Publication:

Symposium Papers

Volume:

224

Abstract:

The use of microwave technology to speed up the production of precast ferrocement secondary roofing slabs is explored in this paper. In particular, the use of discrete on-off microwave curing regimes and the effects of such regimes on the strength and durability of the ferrocement slabs are investigated. By a regime of on-off microwave application to maintain the temperature of the slab within a specified range during microwave curing, overheating of the slabs can be avoided. High early age strengths were attained in slabs cured using such regimes, with no strength loss at 28 days. In addition, the durability of such slabs need not be compromised. The use of an appropriate reduced power level during the later stage of the curing process was found to result in a marginal improvement in the near surface quality without any reduction in early age strength.

DOI:

10.14359/13413


Document: 

SP224-11

Date: 

December 1, 2004

Author(s):

Katherine G. Kuder and Professor Surendra P. Shah

Publication:

Symposium Papers

Volume:

224

Abstract:

Fiber-reinforced cement board (FRCB) is increasing in consumer popularity because it is more durable than conventional wood products. However, concerns exist about the freeze-thaw durability of the material due to its laminated structure and high porosity. To overcome these weaknesses, some manufacturers have begun to press the material after it is formed. The objective of this work is to evaluate the effects of this new processing on the durability of the FRCB. Three commercially-available FRCB products – two that had been pressed and one that had not – were subjected to accelerated freeze-thaw cycling according to a modified version of ASTM Standard C1185. The flexural strength, interlaminar bond (ILB) strength and porosity were measured. The results indicate that pressure might improve the ILB and flexural strength of the FRCB after freeze-thaw testing. However, porosity is not affected by pressure after freeze-thaw.

DOI:

10.14359/13414


123

Results Per Page 





ABOUT THE 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.