Hamad I. Al-Abdul Wahhab

The use of an analytical hierarchy process in pavement maintenance priority ranking

This paper describes the use of an analytical hierarchy process (AHP) in determining the rational weights of importance of pavement maintenance priority ranking factors. These weights were obtained by capturing the local people’s perception towards this vital part of the pavement management system (PMS). In this regard, different groups of individuals were asked to estimate the weight of importance in pavement maintenance of different factors for ranking pavement sections. These factors were road class, pavement condition, operating traffic, riding quality, safety condition, maintenance cost, and the overall importance of the road section to the community. The AHP method of pair‐wise comparison was employed to get the factor weights, which were compared with the weights obtained from the direct assignment method. It was concluded that the two methods were statistically similar which confirms that the results of the direct assignment method can be used safely with a sound reliability and consistency. This conclusion comes from the fact that the AHP method has a high reputation and applications, and it uses a high‐precision technique for obtaining the weights (priorities) of alternatives or items. Priority factor weights were used in developing a pavement maintenance priority ranking procedure for a road network. This procedure was validated by real case studies, and found to be logically and efficiently able to handle the ranking of a huge number of pavement sections for maintenance and repair.

PERFORMANCE OF A STABILIZED MARL BASE: A CASE STUDY

Abstract The formation of depressions and settlement in roads shortly after being constructed is one of the major challenges facing the road authorities in the Arabian Gulf States. Such problems have been closely related to the nature of pavement materials and loading conditions as well as to the proximity of groundwater tables to the surface. A major road in eastern Saudi Arabia was reported for frequent deterioration even when the construction was properly carried out. A preliminary investigation was conducted to quantify the properties of the base course material (i.e. marl soil) and the cause of failure. The laboratory investigation indicated that the marl used in the construction, similar to other marls, has acute water sensitivity and loss of strength whenever the soil is inundated. A precautionary and immediate solution was proposed to stabilize the soil with cement. Consequently, a comprehensive laboratory program was carried out to assess the performance of cement-stabilized marl mixtures under different exposure conditions. Based on the laboratory results and the traffic data for the road under investigation, four sections were constructed, two of them being without any additive while in the other two the base course being treated with 4% cement. Continuous monitoring and evaluation of the four sections for 4 years indicated that the cement-treated road sections have exhibited superior performance over the untreated ones. Unlike the untreated sections, which have experienced various forms of deterioration within a few months after construction, the stabilized sections are still in an excellent condition.

Temperature variation of flexible and rigid pavements in Eastern Saudi Arabia

Abstract Temperature is one of the most important factors affecting the design and performance of both rigid and flexible pavements. This importance calls for special attention and interest in research to develop procedures for design and analysis that account for temperature considerations. Two field experiments were carried out for the monitoring of temperature variations of asphalt concrete and Portland cement concrete pavements at King Fahd University of Petroleum and Minerals (KFUPM) in Dhahran, Eastern Province of Saudi Arabia. A temperature data base was developed and used to generate regression models for predicting temperatures in flexible pavements, and temperature differentials in rigid pavements, from measured air temperatures. These models are essential for pavement design and analysis.

Stabilisation of soils with emulsified sulphur asphalt for road applications

This paper presents the study carried out to assess and compare the performance of marginal soils, namely marl, sabkha and dune sand stabilised with emulsified sulphur asphalt (ESA) with the mixtures of the same soils stabilised with conventional emulsified asphalt (EA) to be used as a base layer for road layers. The mixtures of ESA and EA for the three marginal soils were designed utilising 2% Portland cement and were optimised to meet dry and wet Marshall stability requirements. Designed mixtures were assessed for dry indirect tensile strength (ITS), static triaxial (shear strength) and dynamic resilient modulus at 22°C. Results indicate that ESA decreased the stability and shear strength of the treated soils compared to the conventional EA. On the other hand, there was an improvement in ITS, especially for marl and sabkha soils, and an increase in the resilient modulus of soils–ESA mixtures compared with standard soils–EA mixtures. ESA can be used successfully to construct base layers for roads from available marginal soils since it fulfilled the specification requirements.