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Comparison of Cold Mix Asphalt (CMA) technology to traditional Hot Mix Asphalt (HMA) technology, reveals that the first has several advantages in terms of economic, eco-friendly, safety and sustainability. A promising development of CMA technology is Cold Bituminous Emulsion Mixtures (CBEMs). Unfortunately, some characteristics of this technology are still in development need; namely high porosity, long curing time and low early strength. Half Warm Bitumen Emulsion Mixture (HWBEM) was introduced in previous attempt, as a treated CBEMs with optimum heating temperature being less than 100 °C. This work focuses on treating the CBEMs with low heat energy technique (i.e., microwave heating), plus two types of admixtures; Ordinary Portland Cement (OPC) and acrylic (AR) polymer. The effect of low energy heating (i.e., microwave heating) on developed CBEMs characteristics is tested. Acrylic (AR) polymer was utilized in percentages of 1.25, 2.5, 3.75 and 5% of the residual bitumen. The developed mixtures of HWBEM is tested statically by Marshall and dynamically by Wheel track parameters. The results reveal that the HWBEM with OPC and 1.25% AR, showed better deformation resistance roundly 81 times with vital development in its mechanical and volumetric properties comparable to traditional HMA. Therefore, low energy heating and polymer treatment sustain the new promising paving technology called HWBEM.

A previous study conducted by the authors proved that the inferiority of the mechanical properties of Cold Bituminous Emulsion Mixtures (CBEMs) could be overcome by incorporating a waste or by-product material, namely Paper Sludge Ash (PSA). The new CBEMs have demonstrated comparative mechanical and durability properties compared to conventional Hot Mix Asphalt (HMA). Furthermore, the new CBEMs have less impact on the economy, environment, and safety. However, the air void content of the new CBEMs is still high – to a stage unacceptable by pavement engineers. Thus, this study introduces a treatment method to reduce the air void without affecting the improvement achieved in mechanical properties and other environmental and economic issues. This study presents microwave energy treatment as a unique post-mix treatment method to overcome high air void content in CBEMs. Test results showed that microwave energy improves the stiffness modulus and air void content. However, new post-mix microwave treatment CBEMs still have comparative mechanical, volumetric, economic, and environmental characteristics to HMA.

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Scientists have effectively demonstrated that the introduction of a waste product comprising cementitious chemical compositions can enhance the mechanical properties and durability of cold bitumen emulsion mixes (CBEMs). On the other hand, the high air void content of the CBEM mix remains a challenge that is considered unsatisfactory by paving engineers. As a result, this investigation highlights two major changes that were made. The first is the use of waste paper sludge ash (PSA) as a filler in CBEM instead of the conventional mineral filler (CMF). The second change was made to further improve the mixture by reducing the amount of CBEM air voids using microwave (MW) heating energy as a post-treatment method. When compared to typical hot mix asphalt (HMA), the new CBEMs showed great mechanical properties and durability. Moreover, the proposed method, using CBEMs, has lower environmental risks, is safer, and is more cost-effective than existing paving mix technologies. This study presents a method for controlling air voids within pavement specifications without affecting mechanical behaviour or generating additional environmental or economic considerations. When compared to typical mixtures, laboratory test results showed that MW-heating can enhance both the stiffness modulus and the air void content. Furthermore, these results revealed a minor reduction in creep stiffness and water sensitivity. Nevertheless, in terms of mechanical, volumetric, and economic properties, the suggested post-mix treatment was comparable to HMA. The findings point to the need to adopt CBEM post-heating approaches, particularly the MW treatment procedure.

Sustainability has recently gained a high profile in many fields. Construction, due to its huge demand to materials, is one of the important targets. More than 95% of roads are paved with hot mix asphalt (HMA). Production of HMA using virgin materials consumes a lot of energy and contributes to the emission of a considerably large volume of CO 2 . Therefore, the replacement of virgin materials with waste and extending material life is of considerable value. Half-warm bituminous emulsion mixture (HWBEM) is a cold bituminous emulsion mixture subjected to a moderate heating energy before the compaction process. This study aims to evaluate the extent of enhancement in HWBEM crack resistance using a low energy heating technique (i.e., microwave) where virgin fine aggregates within the mixture were replaced with waste crushed glass. In addition to the measurement of volumetric properties and mixture sensitivity to moisture damage, crack related tests of indirect tensile strength test (ITS), cracks resistance test (Ideal-CT test), fracture energy (G f ), cracking resistance index (CRI) and toughness index (TI) were conducted to evaluate mixtures tensile strength. Test results showed that the procedure followed to prepare HWBEM containing waste crushed glass worked out and prevented cracking failure. It was concluded that adopting ITS is not sufficient to reflect all mixture behavior phases when resistance to the tensile cracking is the concern, as it depends on the peak load only. Other indices, such as CT-index, depend on more than one parameter and reflect a reasonably more realistic evaluation.

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