The technique of replacing the cement with other alternative materials focus on the production of materials with similar performance and reduced environmental impacts relative to traditional cement. The main aim of this study is to investigate the effect of replacing the cement content with high volume of GGBS and PFA on the mechanical performance of cement mortar. Three mixtures were prepared with different percentages of GGBS and PFA (40%, 60% and 80%) as replacement of cement along with other mixture that made with 100% cement as a control mixture. In order to evaluate the performance of the cement mortars, compressive strength test after 7, 14 and 28 days of curing was used. The results indicated that after 7 days of curing, the increase of GGBS and PFA contents caused a reduction in the compressive strength in comparison with the control mixture. After 28 days of curing, the results indicated that the mixture incorporated 80% GGBS and PFA has higher compressive strength relative to the control mixture. Such findings will significantly contribute in reducing the cost of the produced mortar by reducing the amount of used cement and this consequently reduce the cement demands/manufacturing. Less production of cement will reduce the CO2 emissions of the cement industry.

The quality of asphalt pavement maintenance depends on several important factors, including the selection of patching materials and choice of repair technique. Conventional hot mix plants operate to support large paving projects, and economy favors high-volume output. When repairs and maintenance are needed it can be challenging to maintain small quantities of hot bituminous mixtures at a sufficient temperature, especially in the case of winter maintenance and consequently the repair materials cannot be compacted to the desired level in some occasions. The temperature sensitivity plays a significant factor to understand the asphalt pavement failures and indicates how quickly asphalt properties change over time in terms of indices such as penetration index. Therefore, this research aims to develop a polymer-modified binder with reduced temperature sensitivity, and it can be used for hand-laid application in small quantities for emergency winter repair and maintenance. The results showed that the highest penetration index has been achieved by modifying bitumen with 20% rubber and 2% wax, which is reduced the temperature sensitivity by 168%. Additionally, the Fourier Transform Infrared Spectroscopy (FTIR) test and X-Ray Diffraction (XRD) test were conducted to monitor the changes in the chemical composition and identify crystalline phases of polymer modified binder from the aspect of functional groups. It is indicated that the bitumen, rubber, and wax react chemically to build 3D networks that have an interlaced form in the bitumen matrix resulting in reduced temperature sensitivity of the polymer modified binder.

Conventional hot mix plants operate to support large paving projects, making production more economic with high volume output. When repairs and maintenance are needed, it can be challenging to maintain small quantities of hot bituminous mixtures at a sufficient temperature, especially in the case of winter maintenance. Consequently, the repair materials cannot be compacted to the desired level on some occasions. This research aimed to develop a polymer modified asphalt binder with reduced temperature sensitivity for hand-laid and low-volume applications. The results showed that the highest penetration index has been achieved by modifying bitumen with 20% rubber and 2% wax. The FTIR and XRD analysis indicated that the bitumen, rubber and wax that react chemically to build 3D networks have an interlocked structure in the bitumen matrix resulting in reduced temperature sensitivity of the polymer modified asphalt binder. Furthermore, indirect tensile stiffness, permanent deformation, creep test and fatigue life test, water sensitivity and freeze-thaw cycle demonstrated an improvement in the asphalt mixture properties in terms of mechanical and durability perspectives. Overall, based on this investigation, modifying asphalt binder with 20% rubber and 2% wax resulted in stronger and durable asphalt mixture in comparison to traditional hot mix asphalt.

Hot mix asphalt has various benefits such as good workability and durability. It is one of the most general materials used as asphalt mixtures in road pavements. Asphalt mixtures and binders can be improved by modifying them with various additives. Gilsonite is a natural asphalt hydrocarbon which may be used as an additive to hot mix asphalt. It is used as an asphalt binder modifier (wet process) and an asphalt mixture modifier (dry process) to improve the properties of the mix. It provides the option of improved rheological properties, stability, strength rutting resistance and moisture sensitivity. This paper examines the current research relating to the use of gilsonite to improve the asphalt properties (binder and mixture). The rheological properties of the modified asphalt binders and mechanical properties of the modified asphalt mixtures will be reviewed. The influence of adding gilsonite individually or combined with other additives will be discussed. Furthermore, assessment of the environmental and economic perspectives of the studied asphalt along with some suggestions to improve the asphalt binders and mixtures will be explored.