Issam Minkarah

Optimum mark-up for bidding: a preference-uncertainty trade off approach

Abstract This paper outlines a procedure for selecting the mark-up in competitive bidding situations. The procedure is developed on the basis of multidimensional utility theory. Mark-up is split into different segments representing different contexts. The contexts that have been considered are loss, general overhead, and profit. These segments are assigned separate utility functions, which represent the underlying reference structure of the bidder. The individual utility functions are then combined into one additive function. This function is transformed into an expected utility curve by successive consideration of sources of uncertainty. The mark-up corresponding to the maximum expected utility is considered to be the optimum mark-up.

Long-Term Performance of Broken and Seated Pavements

A study was developed to evaluate the effectiveness of breaking and seating (B/S) as a rehabilitation strategy for retarding reflective cracking in asphalt concrete (AC) overlays on jointed reinforced concrete pavements (JRCP). Several test sections were constructed by milling the original AC layer, breaking and seating the concrete slabs, and constructing new AC overlays. Control sections were constructed adjacent to the B/S sections in the same way, but without breaking the underlying concrete slabs. Two types of pavement breakers were used in this study: guillotine and pile hammer. The majority of the concrete slabs were broken into 0.46-m (18-in.) segments. Performance of the test sections was monitored for a total period of 9 years. Breaking the concrete slabs into smaller pieces resulted in a reduction in the flexural strength, an increase in the surface deflection (50% to 100%), and a decrease in area and spreadability (20% to 30%). Within 2 to 4 years, reflection cracks developed over more than 80% of the joints in all the control sections. The B/S sections were relatively free of cracks after 9 years. This result clearly indicates that breaking and seating has been extremely effective in minimizing and delaying reflection cracking. Based on the results of this study, it was concluded that breaking and seating is an effective technique for the rehabilitation of composite pavements (AC over JRCP). It provides an effective solution for the maintenance and rehabilitation of in-service composite pavements.

Performance evaluation of asphalt overlays on broken and seated concrete pavements

Evaluating the effectiveness of breaking and seating concrete pavements prior to asphalt overlay is a subject of great importance for pavement rehabilitation. A number of studies reported that breaking and seating delayed reflection cracking, but some indicated that, after 4 to 5 years, the cracking of the asphalt overlays on broken and seated sections increased and was about the same as in the other sections. Structural analysis of these pavements confirmed a significant loss of structural support. A controlled experimental project in Ohio investigated the effectiveness of breaking and seating jointed reinforced concrete pavements before asphalt overlay. Four miles of in-service composite pavements carrying heavy traffic were rehabilitated by milling the original asphalt layer, breaking and seating the concrete slabs, and constructing new asphalt overlays. Four more miles of the same sections were constructed in the same way except for breaking and seating. After 2 1/2 years of study, the results confirm the previous findings regarding the effectiveness of breaking and seating in delaying reflection cracks and reduction in structural capacity, increase in surface deflection, and loss of flexural strength. This study indicates that the type of breaking equipment used and the extent of breaking are the most significant factors affecting the performance of these pavements.

Joint Sealant and Structural Performance at the Ohio Route 50 Test Pavement

The performance of joint sealants and the structural condition of the pavement at the Ohio Route 50 test site after 3 years in service are reported. The project involved 10 different sealant compounds (4 silicone, 2 hot-applied, and 4 compression seals) and 4 unsealed sections. A total of 15 different sealant-joint configuration combinations are examined. Compression seals generally outperformed the other sealants, and sealants in the westbound lanes were more effective than those in the east-bound lanes. These observations suggest that crew experience in sealant installation is a critical factor. Nonetheless, structural performance and surface profile smoothness appeared to be unrelated to sealant condition. Many of the sealant sections with high effectiveness values also exhibited high percentages of structural distresses and decreases in pavement surface smoothness. Flooding after intense rainfall may have softened the subgrade and caused transverse cracking and corner breaks. Implementing a drainage outlet maintenance program that includes cleaning silt and debris from the outlets annually is recommended. Unraveling the complex interactions of all these factors calls for long-term monitoring of both sealant and structural performance.

TO SEAL OR NOT TO SEAL? A FIELD EXPERIMENT TO RESOLVE AN AGE-OLD DILEMMA

Construction and evaluation to date of a joint sealant project in the Wet-Freeze climatic zone near Athens, Ohio, are described. Fifteen different combinations of materials and joint configurations have been used. The new pavement consists of a 250-mm (10-in.) portland cement concrete slab, placed over a 100-mm (4-in.) free-draining base layer, constructed over a 150-mm (6-in.) crushed aggregate subbase, resting over the predominantly silty clay local subgrade. The highway has a 20-year design period and a design traffic level of 11 million single-axle loads. The eastbound lanes were constructed first and have been open to traffic since the spring of 1998, and the westbound lanes have been serving traffic only since the spring of 1999. Evaluations to date indicate that with one exception, preformed compression seals have performed significantly better than liquid sealants. Unsealed sections also are performing very well, exhibiting no visible signs of distress at the joints or in the pavement slabs at this time. In contrast, after only 1 year of service, silicone and hot-pour sealants in the eastbound lanes are in fair to poor condition. The worst sections are those with narrow [3-mm (1/8-in.)] joints. Oversight and inspection provided were ineffective in averting the use of equipment and procedures that were obviously inadequate. The most significant shortcomings appear to have been the omission of sandblasting during placement and inadequate sealant recess.

Call for Papers on Engineering Management during the Global Recession and Recovery

The global financial crisis has had a significant impact on the world’s most powerful economies and is contributing to an international crisis of confidence. Considering the significant role that the construction industry plays in a country’s economy, it is imperative and important to identify the effects and challenges of the global financial crisis on that industry, to evaluate and examine existing engineering management theories and practices during the global recession and recovery, and to explore innovative research directions. The Journal of Management in Engineering is seeking original contributions on this subject with a particular interest in innovative engineering management theories, best practices, and lessons learned from different geographic areas while tackling the global recession. It is expected that the special issue or section will showcase the economic impact and importance of the construction industry from a global perspective and stimulate debate over recovery policies and critical strategies and tactics that engineering and construction firms can use to survive current economic turbulence.

AN INTERACTIVE ALGORITHM TO EVALUATE PROJECT COST ESCALATION

Abstract The existing methods of cost control do not assist management in forecasting the attributes which might be responsible for generating potential cost escalation in line items (or cost centers) in a project. The urgent need for a method which is capable of predicting the probable project cost escalation and identifying the attributes which might be responsible for the escalation is evident from the large number of projects finishing over budget. The model presented in this paper not only assists management in predicting the probable project cose escalation, but it also identifies the risk attributes and their associated cost influence.