Akademik Veri Yönetim Sistemi
First International Workshop onDurability and Sustainability ofConcrete Structures, Bologna, İtalya, 1 - 03 Ekim 2015, ss.43
Concrete durability-related properties are known to be
negatively affected due to expansion and cracking that result from factors such as
freezing and thawing actions, alkali-aggregate reactions, sulfate attack, corrosion
of the reinforcement, shrinkage, and other similar factors. Durability, and,
therefore, sustainability of properly designed and constructed concrete
structures depends primarily upon the quality of the materials of construction
and other simple, but critical, steps. Concrete construction can last 100 years
or more if five simple "steps" are followed: (1) materials selection;
(2) structure design; (3) construction; (4) quality management; and, (5) timely
evaluation, maintenance, and repairs. This is a holistic approach. Most
mistakes are made in not satisfactorily following Steps 4 and 5. Conventional
mixture proportioning technique used for production of high-strength concrete
does not guarantee long-term durability of concrete. Concrete mixtures must be
proportioned to attain desired workability, high-dimensional stability,
high-strength, and high-durability related properties; i.e., high-quality
concrete (HQC). However, mixture proportioning requirements for HQC must be
varied according to the type and expected use of the concrete construction. HQC
mixtures must have high-quality constituent materials: durable aggregates, low
heat of hydration cement, mineral additives, and chemical admixtures. Furthermore,
the mixing water must be minimized (i.e. a low water to cementitious materials
ration, W/Cm). A strict quality control is also needed in various aspects of
the production of HQC. Research activities conducted at the UWM Center for
By-Products Utilization (UWM-CBU), CANMET, and elsewhere, have demonstrated
that HQC mixtures can be proportioned to obtain strength in excess of 100 MPa
(14,000 psi) and service life of 100 plus years.