Hossam F. Hassan

Effect of organic fibers on open-graded friction course mixture properties

Open-graded friction course (OGFC) or porous asphalt mixtures are special mixes used for improving the surface friction, increasing surface permeability, and reducing pavement noise. The mix consists mostly of coarse size aggregate with little fines. This study was conducted to evaluate the effect of two types of organic fibers: date-palm fibers and textile fibers, in combination with styrene butadiene rubber (SBR) polymer on the properties of OGFC mixes. A total of six different mixes were evaluated. Mix designs were performed according to the design procedure proposed by the National Center of Asphalt Technology (NCAT) for a range of 4.5–6.5% asphalt content. One-way ANOVA using the Tukey method of multiple comparisons was used to test the effect of the modifier and/or stabilizer on abrasion as an indication of raveling potential as well as draindown. The results indicated that the asphalt mix containing date-palm fibers and SBR polymer at 5.0% and the asphalt mix containing textile fibers and SBR polymer at 6.5% asphalt content satisfied the mix design criteria. The asphalt mixes at optimum asphalt content were evaluated for moisture susceptibility using the indirect tensile strength.

Stabilization of oil‐contaminated soils using cement and cement by‐pass dust

Purpose – To investigate the effect of cement and cement by‐pass dust (CBPD) as a stabilizer on the geotechnical properties of oil‐contaminated soils resulting from leaking underground storage tanks, or soils surrounding petroleum refineries and crude oil wells.Design/methodology/approach – Oil‐contaminated soil (untreated soil) and a soil treated by bio‐remediation (treated soil) as well as a natural soil were obtained from Northern Oman. These soils were stabilized with cement and cement by‐pass dust at 0, 5, 10, 15 and 20 percent, by dry weight of the soil, and cured for seven, 14 and 28 days. Compaction, compressive strength, direct shear, permeability and leaching tests were carried out on the stabilized soils.Findings – The results indicate that cement and cement by‐pass dust improve the properties of oil‐contaminated soils. Traces of arsenic, barium, cadmium, chromium and lead were found in the oil soils, but none of them exceeded the EPA limits.Practical implications – Reuse in construction applic...

The use of brackish and oil-contaminated water in road construction

This paper discusses the use of non-freshwater, including brackish groundwater and oily production water, in road construction. Non-freshwater was obtained from four major oil production fields in Oman. First, chemical analyses were carried out on nine non-freshwater types, including tap water, obtained from the four sites. These water types were then used with well-graded sand (WGS), high-plasticity silt (HPS), and a road base material to evaluate water effect on material properties. Atterberg limits, compaction, California Bearing Ratio (CBR), swell percentage, swell pressure, and direct shear tests were performed. Results show that there is a slight decrease in the liquid limit when non-freshwater is used. Non-freshwater resulted in a slight decrease in optimum moisture content and a slight increase in maximum dry density in WGS, whereas with HPS it caused slight decreases in optimum moisture content and maximum dry density values. There was an increase in CBR when non-freshwater was used with WGS and HPS soils. However, the use of production water caused a decrease in CBR values for WGS. For the road base material, the use of non-freshwater generally caused a decrease in CBR. The swell pressure tends to increase when non-freshwater is used with HPS. For the road base material, there is a decrease in cohesion and an increase in friction angle when non-freshwater is used in lieu of tap water. Promising laboratory results indicate the potential use of brackish and oily water types in road construction.

Characterisation of asphalt mixes containing MSW ash using the dynamic modulus |E*| test

Municipal solid waste incinerator ash was used to replace fine aggregate in hot-mix asphalt concrete with up to 40% by aggregate weight in the mix. Mix design was performed according to the Marshall mix design method to find the optimum asphalt content for different mixes. The dynamic modulus |E*| test was conducted on all mixes. |E*| master curves were developed. The curves were compared with Witczaks predictive model. Shift factor equations were developed and compared with the proposed equation in the Mechanistic–Empirical Pavement Design Guide (M-E PDG). |E*|/sin δ was used as an indicator for the rutting potential of the mixes. The results indicated good agreement between the developed master curves and the predictive model for the control mix (conventional mix), while significant difference was noticed for the ash mixes. The M-E PDG shift factors were found to lie in the middle of the developed factors. The increase in ash content in the asphalt layer is expected to result in higher rutting.

Use of Tank Bottom Sludge to Construct and Upgrade Unpaved Roads

Tank bottoms are the liquids and residue, such as heavy hydrocarbons, solids, sands, and emulsions, that collect at the bottom of the treating vessel or that remain at the bottom of storage tanks after a period of service. Sludge composition is 50% to 65% crude oil, 20% to 35% water, and 5% to 20% solids. Disposal of tank sludge is a significant item of tank maintenance costs. Results are presented on the use of tank bottoms as a binder to construct and upgrade unpaved roads. Various sludge samples were initially characterized for chemical and physical composition, then three mixtures were prepared by using blends of aggregates and tank bottoms. No bitumen was used in the mixes. The mixtures include hot mix (aggregate and sludge were both heated), heated sludge and cold aggregate mix, and cold mix (no heat was applied). The Marshall mix design (ASTM D1559) was followed in the preparation and testing of the specimens. Results indicate that tank bottoms act as a binder to the aggregate and can provide significant strength. Heating both the sludge and the aggregate resulted in the highest stability value of 11.9 kN. An optimum sludge content of 6.5% by total weight of the mixture satisfied the requirements for low (3.3 kN) or medium (5.3 kN) trafficked surfaces or base layers according to Asphalt Institute specifications. Other mix properties, such as flow, air voids, voids in mineral aggregate, and voids filled with asphalt, were acceptable.

Binder Contribution to Cracking of a Lightly Trafficked Asphalt Pavement Made with Clear Binder

This paper reports the findings of a technical investigation on the role of clear asphalt binder in the development of extensive block cracking in a lightly trafficked colored pavement. Visual inspection of the pavement surface was carried out together with detailed laboratory investigation on the rheological characteristics of the binder. The results showed that the tested clear binder is extremely viscous and harder than any bitumen grade specified by ASTM standards. Furthermore, the clear binder has much lower ductility compared to the conventional asphalt bitumen. The clear binder is almost 11 times more viscous than the conventional bitumen at the tested temperatures.

ABET Accreditation: An Engineering Experience from Sultan Qaboos University, Oman

The Accreditation Board for Engineering and Technology (ABET) accredits college and university programs in engineering under the Engineering Accreditation Commission (EAC). The process follows Engineering Criteria (EC) 2000, which focuses on outcomes (what is learned) rather than what is taught. This paper presents an overview of the processes developed by the civil engineering (CE) program at Sultan Qaboos University to satisfy ABET Criteria 2, 3, and 4. The program had a successful accreditation visit in November 2013. Program educational objectives (PEOs) were developed. A review and revision process for PEOs was also developed. ABET student outcomes (SOs) were adopted by the CE program. SOs were broken to outcome elements. Key performance indicators were developed for each outcome element, according to the six levels of Bloom’s taxonomy for cognitive domain. The process used direct indicators from student work as well indirect survey instruments. The program has developed a detailed and systematic approach for assessment of SOs with feedback and follow-up on implementation of actions for continuous improvement. Planning for the next accreditation cycle of SO assessment proved valuable, as the new accreditation committee started executing an already laid out work plan.

Potential Use of Petroleum-Contaminated Soil in Hot Mix Asphalt Concrete

Petroleum-Contaminated Soil (PCS) results from leaking underground storage tanks, oil spills on clean soils, or soils surrounding petroleum refineries and crude oil wells. In Oman, Petroleum Development Oman (PDO) generates more than 50,000 tons/year of petroleum-contaminated soil (PCS) and faces a real challenge to safely dispose of these quantities. PDO is currently practicing the bioremediation process with high cost and limited results. This paper presents the results of using PCS as an fine aggregate substitute in Hot Mix Asphalt concrete (HMA) with percentages up to 40 percent by total aggregate weight. Environmental assessment was performed by analyzing the raw contaminated soil for heavy metals, and hydrocarbons. The Marshall mix design method was used to prepare and test the mixes. The results indicated a reduction in optimum asphalt content from 4.1 percent in the control mix to 3.5 percent in the PCS mixes. The increase in PCS content up to 40 percent resulted in a reduction in stability from 24.3 to 4.7 kN and increase in air voids from 3.5 to 9.4 percent. The flow was within the limits of specifications. Leaching of heavy metals using the Toxicity Characteristic Leaching Procedure (TCLP) was also performed on selected mixes. The results indicated concentrations well below the TCLP regulatory limits except for Zn for the 40 percent PCS mixes. The results indicated potential use of up to 15 percernt PCS in surface mixes, while higher percentages (up to 40 percent can however be used for medium or light traffic surface or base course layers.