Safwan Khedr

Rutting parameters for asphalt concrete for different aggregate structures

Pavements are subjected to many distresses during their service lives. One of the main distresses that a pavement is subjected to is rutting. This paper focuses on the effect of using a fine or coarse gradation, as related to the restricted zone, on the rutting behaviour of asphalt concrete in flexible pavements. The restricted zone was one of the Superpave gradation selection criteria. This was done through traffic-simulated dynamic testing programme of asphalt concrete made of Egyptian materials. The Ohio state model as one of the models that could be used in predicting rutting was employed in this research. The model relates rutting to the resilient and residual properties of the pavement. The experimental results were analysed according to that model. It was found that fine gradations, passing above the restricted zone, were more susceptible to rutting especially for higher deviator stress.

Investigating a Natural Plant-Based Bio Binder and Cement Dust Mix as a Bitumen Substitute in Flexible Pavements

Bitumen use in flexible pavements is energy intensive and is associated with many environmental concerns. A natural organic binder, Agmin, which is both renewable and cheap, was investigated in combination with cement dust as a substitute for bitumen. This paper highlights the preliminary results of this investigation. An experimental program was set up that included Marshall and Superpave testing procedures. Marshall stability and flow, rutting susceptibility, and resilient modulus were among the parameters measured for Agmin–cement dust mixes. Samples were subjected to heat cycles as part of their durability assessment. The results of this investigation indicate that Agmin–cement dust road mix displays greater stability than unmodified asphalt mixes and is less susceptible to rutting. It is also relatively unaffected by temperature changes.

Using Polyacrylamide Grouts for Permeability Control in Sand

Chemical grouting of permeable soils with highly concentrated low-molecular-weight polymeric solutions greatly reduces the permeability. However, a toxicity problem arose from these chemicals. A new process of treating soil with low-concentration cationic and anionic polyacrylamides with cross-linking aluminum citrate in a cyclic way with particular sequencing is introduced. The new process provides effective control of permeability and eliminates the risk of toxicity. A total of 25 one-dimensional flow laboratory tests were carried out on sand. The effect of three anionic-type polyacrylamides having different molecular weights on the number of cycles required to attain a significant reduction in permeability was investigated. Controlled volumes of chemical flood solutions having four levels of concentration were injected to inspect the impact of concentration on the gel distribution. The effects of water flow and time factor on gel stability were studied. The results of these runs demonstrate the effecti...

Solution Model for Infrastructure Planning and Design for Urban Slums: Egyptian Case Study

Urban Slums represent a chronic problem to Egypt. According to official statistics, there are 1,221 urban slum inhabited by 17 million people in Egypt. These urban slums suffer from deterioration in infrastructure; this includes lack of access to proper sanitation, inadequate water distribution networks and congested street networks. These issues in infrastructure systems are reflected on the social aspect and the quality of life in these areas with problems such as high crime rates, health problems and spread of epidemics.

Preliminary evaluation of the materials in Egypt for Superpave implementation

The Egyptian code of practice for the design of asphalt mixtures is based on Marshall mix design methodology. There is a significant shift to Superpave mix design worldwide and Egypt is one of the countries that is expected to follow this shift. For the transition to be smooth and easy for practitioners, an analysis was done to evaluate the compliance of the gradation bands available in the current Egyptian code of practice to Superpave requirements. This showed that only a few of the gradation bands could still be used with Superpave mix design, and these only with some considerations. Four gradations were developed from two of the gradation bands, and these mixes were designed using both Superpave and Marshall mix design methods. The Superpave mix design samples were tested for stability and flow. A comparison was made between both designs. The results showed that Superpave mix design yielded lower optimum binder content and that its samples had higher values of stability and flow.