Design of durable concrete in hot and humid environment (Persian Gulf region)
The Persian Gulf region is known to be one of the most aggressive environments for reinforced concrete constructions. Chloride-induced corrosion is believed to be the main reason for premature deterioration, and sometimes failure, of reinforced concrete structures constructed in this region. The harsh climate of the Persian Gulf region can be described as having high temperatures, high evaporation rates and consequently high salinity of water, which increases the chloride induced reinforcement corrosion rates. Typical extreme temperatures range from about 50°C down to 3°C and the relative humidity may be as high as 95% or as low as 5%.
The quality of concrete, mainly the permeability, nature and intensity of cracks, and the cover thickness, have a great bearing upon the initiation and sustenance of reinforcement corrosion. Poor quality of concrete combined with aggressive environmental conditions has exposed inadequacies in design: some structures have had alarming degrees of degradation within less than a decade. (with reference)
Design of self consolidating concrete (SCC)
Design of fiber reinforced concretes (with steel, synthetic, and glass fibers)
Design of roller compacted concrete (RCC)
Design of lightweight aggregate concrete
Design of decorative concrete
Assessment and repair of damaged concrete structures
Life-span evaluation of reinforced concrete structures under severe conditions
A large number of concrete structures are deteriorating, often prematurely, and need remedial measures to reinstate their safety and/or serviceability. Consequently, the need for repair and protection has grown considerably in recent years. While costs associated with repair of deteriorating concrete structures can be substantial, costs resulting from poorly designed or executed repairs may be even higher. The technical and economical success of repair projects depends on a range of factors, including a proper condition assessment of the structure, design and execution of remedial measures, and design and implementation of maintenance strategies.
For reinforced concrete structures, the main durability problem is corrosion of the reinforcement, resulting from the ingress of chloride ions or carbon dioxide and the subsequent depassivation of the steel. At the beginning of any repair project, a systematic condition assessment of the structure needs to be carried out to identify the cause(s) of deterioration and the extent of damage. Repair methods need to be designed with consideration for the anticipated or desired remaining service life of the structure. A distinction must be made between repairs intended to stop deterioration fully and those merely aimed at slowing down deterioration processes for a limited period of time. Furthermore, CMI has been designed a software which named Durap Gulf for predicting durability of concrete structures in Persian Gulf Region.
Thermal analysis of mass concrete structures
At a construction site of a dam or a large-scale concrete structure like an electric power plant, concrete would be placed in large quantities. Because the cement-water reaction is exothermic by nature, the temperature rise within a large concrete mass, where the heat is not quickly dissipated, can be quite high. Significant tensile stresses and subsequent cracks may result from the restrained volume change associated with a decline in temperature as heat of hydration is dissipated. Thermal cracks may cause loss of structural integrity and shortening of the service life of the concrete structure.
To find the optimal construction method for preventing the thermal cracks, numerical simulations by FEM can be carried out and checked for cracking. In this simulation, a parametric study is conducted to determine the effects of various factors including type of cement, concrete mix design, placement schedule, and cooling system, etc. Using these parameters, it can be understood how to generate and distribute the thermal stresses in concrete considering the effect of each parameter. In general, thermal stress analysis of the concrete structures consists of two phases, transient heat transfer analysis and thermal stress analysis using the results of the foregoing phase.
Assessment of concrete structure associated with sewage treatment plant environment
One of the most severe exposure conditions for concrete structures is a sewage environment where various kinds of chemical and biological aggressive ions exist. These substances react with concrete through different mechanisms and lead to the deterioration of concrete and corrosion of the reinforcement.