AHP-Based Evaluation Model for Optimal Selection Process of Patching Materials for Concrete Repair: Focused on Quantitative Requirements
Jeong-Yun Do
Doo-Kie Kim
The process of selecting a repair material is a typical one of multi-criteria decision-making (MCDM) problems. In this study Analytical Hierarch Process was applied to solve this MCDM problem. Many factors affecting a process to select an optimal repair material can be classified into quantitative and qualitative requirements and this study handled only quantitative items. Quantitative requirements in the optimal selection model for repair material were divided into two parts, namely, the required chemical performance and the required physical performance. The former is composed of alkali-resistance, chloride permeability and electrical resistivity. The latter is composed of compressive strength, tensile strength, adhesive strength, drying shrinkage, elasticity and thermal expansion. The result of the study shows that this method is the useful and rational engineering approach in the problem concerning the selection of one out of many candidate repair materials even if this study was limited to repair material only for chloride-deteriorated concrete.
1. Introduction
Recently, many repair materials which have long been
used in concrete repair work have their own characteristics,
applications, advantages, and limitations. When selecting
materials for engineering designs, we must have a clear
understanding of the functional requirements for each
individual component. In selecting materials for an application,
technological considerations of material characteristics are
important. The economic aspects of materials and cost of
manufacturing are equally important. Basically, the more
service life of concrete repaired with some material can
obtain some accompanying benefit like cost and resource
savings etc. (Beushausen and Alexander 2007; Chawalwala
1999; Chen 1994; Mailvaganam 2001).
Long service life of concrete repairs, to a large degree,
depends on correct choice and use of repair materials. In
recent a large number of different proprietary brands of
repair materials have been introduced. They include
cementitious, polymer-based and polymer-modified
cementitious materials. As explained in Fig. 1, the precise
formulation of the materials varies from one supplier to another,
and even properties may vary significantly within one family
group. Generally, repair materials similar to the concrete
substrate or easily available repair materials or the material
with which the user is familiar have been applied to the
repair work with being wrongly regarded to be the optimal
materials. Additionally, just a few materials are
misunderstood into being better materials among various concrete
repair materials available. This can cause a problem in the
repair work in terms of the qualitative performance as well
as the quantitative performance (Cusson and Mailvaganam
1996; Do 2009; Emmons et al. 2000; Emmons 1995;
ICRINo.320.2R 2009; Keoleian et al. 2005; Kosednar and
Mailvaganam 2005; Nabhan 2007; Singh 2005; Vaysburd
et al. 2000; Vaysburd 2000).
Namely when selecting materials for repair design, a clear
understanding of the functional requirements for each repair
application is required and various important criteria or
attributes need to be considered. Repair material selection
Repair like with like
Familiar or easy to get
Misunderstanding only few materials
as almighty materials
Selecting according to a simple knowledge
or criteria
Dissatisfaction of an orderors
requirements
Not successful repair work
Hindering the active application of
innovative materials and technology
Fig. 1 Current state of repair work and its anticipated effect.
Fig. 2 The scope of this study and hierarchy structure of performance criteria affecting repair materials selection problem.
attribute is defined as an attribute that influences the
selection of a repair material for a given application. These
criteria include: physical properties, electrical properties,
mechanical properties, chemical properties, manufacturing
properties, material cost, material impact on environment,
aesthetics, recycling, etc. (Do 2009; Vaysburd et al. 2000;
Vaysburd et al. 2000; ACI546.3R-06 2006; ACI546R-04
2004; Al-Zahrani et al. 2003; Rizzo and Sobelman 1989).
The selection of an optimal material for repair application
from among two or more alternative materials on the basis of
two or more criteria is a multiple criteria decision making
(MCDM) problem. Various approaches to this problem had
been proposed in the past to help address the issue of
material selection and the detailed explanations about this
are in the following chapter 2. Liao (1996) presented a fuzzy
multi-criteria decision making method for material selection.
However, the method is complicated and requires much
more computation. Ashby (2000, 2005; Ashby and Johnson
2002) proposed multi-objective optimization in materials
design and selection using utility functions. Even though
the method is simple but it is not efficient only to be useful
for initial screening (...truncated)