Contribution to Research

 

I have been actively engaged in two research areas, namely Glass Fiber Reinforced Plastic (GFRP) bars and concrete durability.

I have conducted several studies on GFRP bars. This topic was of special interest to me as my Ph.D. dissertation work was also related to this subject. Since corrosion of reinforcing steel and the resulting reduction in the design-life of structures in the Arabian Gulf, are of concern to the local construction industry, there has been a concerted effort to develop non-corrosive reinforcement. I was an active member of the group at KFUPM that initiated studies on the GFRP reinforcement. As part of these studies, different types of commercially available GFRP bars were exposed to accelerated exposure conditions. These included: alkaline solution, alkaline plus seawater, alkaline plus sabkha solution, acidic solution, thermal variations, outdoor exposure, and fire exposure. The changes in the properties of GFRP bars, due to aforesaid exposures, were assessed by measuring tensile strength, compressive strength, bond strength, and weight loss. The chemical and microstructural changes in the GFRP bars were assessed by scanning electron microscopy (SEM). Another group of specimens were tested for bond strength. Concrete specimens with GFRP reinforcement were exposed to conditions simulating the local aggressive environmental conditions including potable water, seawater, sabkha solution and outdoor exposure for a duration of 24 months, in addition to fire exposure. They were tested for bond strength and bending behavior plus tensile strength.

Field exposure and testing was also initiated to obtain information on the long time performance of GFRP reinforcing steel bars under the local exposure conditions. The ultimate objective is to identify areas of application of GFRP reinforcement in the local environment. In this study, pull-out and beam concrete specimens with GFRP bars were cast and exposed to the tidal zone, below ground zone, and above ground zone in Khaleej Mardomah field station. The specimens would be retrieved after predetermined periods of exposure and bond strength, and tensile strength of retrieved GFRP bars would be evaluated. Moreover, all the exposed specimens will be monitored visually for any sign of damage or deterioration throughout the duration of the study. The microstructural changes of limited number of retrieved GFRP bars will be examined using scanning electron microscopy (SEM).

The findings of the laboratory work as well as the ongoing field investigations in this area will be of great interest to the researchers since they address unique exposure conditions such as sabkha. The results of laboratory studies on GFRP bars have already been used in formulating the Guide for Design and Construction of Concrete Reinforced with FRP Bars by ACI Committee 440.

 

My second area of research activity has been in the area of concrete durability. Since the environmental conditions of the Arabian Gulf significantly accelerate concrete deterioration, there has been a concerted effort since the early eighties of the past century to evaluate the causes of concrete deterioration and formulate remedial measures. Due to the importance of the problem, both nationally and internationally, I have been involved in the research on this aspect.

I was the Task Leader of a study through which a field exposure study was established five years ago along the shoreline of Al-Jubail Industrial City. Concrete specimens with varying mixture design composition, reinforcing steel, inhibitors were prepared and placed at the exposure site. The exposure would continue up to 20 years.

I was also involved in studies that were conducted to inhibit reinforcing steel corrosion under atmospheric condition, effect of dust in aggregates and the chloride concentration in soil on concrete durability, effectiveness of concrete patch repairs using formed and non-formed cementitious repair materials, effect of rebar cleanliness on the effectiveness of repairs, comparative study of the performance of water quenched steel bars with air-cooled bars, and specification for silica fume to produce durable concrete.

I was the Project Manager of a study on the usefulness of corrosion inhibitors in inhibiting corrosion of fusion bonded epoxy coated bars with holidays and surface damage. I was the principal investigator of two studies funded by KFUPM. These included: protection through chemical inhibitors in reinforced concrete structures with fusion bonded epoxy coated bars, and protection through chemical inhibitors in blended cement concrete structures reinforced with surface damaged FBEC bars.

 

My research activities in concrete durability have been concentrated on the following topics:

 

        Plastic shrinkage cracking of concrete under hot weather conditions

        Structural performance of concrete structures with corroded reinforcement

        Effectiveness of penetrating sealers in preventing concrete deterioration

        Cathodic protection under hot weather conditions

        Performance evaluation of concrete surface coatings

        Protection of concrete utilizing corrosion inhibitors

        Durability of high performance concrete

        Effect of sulfate concentration and ionic concentration on the performance of plain and blended cements

In general, the data developed in the completed and ongoing projects are very useful to the clients and the local construction industry. The clients have updated their specifications. In some cases, the outcome of the projects has helped the clients in their marketing activities. Since the projects relate to assessing the performance of conventional and advanced materials under local conditions, the outcome is highly applicable to the local construction industries. This information could also be adopted in other hot and semi-arid regions.

 

I was a member of M.S. theses committees in the Department of Civil Engineering at KFUPM.