Portland cement hydration is related to mechanical properties, durability and sustainability of cement concretes, and also to the service level of building and structures. This paper will report an initial understanding of Portland cement hydration under low temperatures based on several laboratorial investigations (e.g. thermal gravity analysis /derivative thermogravimetry and X-ray diffraction). Mechanical behaviours and phase evolution are discussed in this report. Calculation based on Powers’ model in cement hydration was also utilised to analyse the Portland cement hydration process under low temperatures. Research shows that low temperature slows the hydration reaction rate and delays the initial setting time, as a result the mechanical behaviours are also influenced. The mechanical behaviours evolution was in great agreement with the calcium silicate hydrate fraction calculated by Powers' model.

Styrene-butadiene-styrene (SBS) modified asphalt used in road engineering is a complicated mixture of various compositions. The present study was undertaken to evaluate the influence of different raw materials and their content on the moisture stability of SBS copolymer modified asphalt mixture. A total of 18 different combinations of base asphalt, SBS, furfural extract oil (FEO), and stabilizer were considered to prepare different SBS modified asphalt samples, and the contact angle test was carried out to determine the work of adhesion and the work of debonding of SBS modified asphalt with aggregate. Moreover, a multi-factor Analysis of Variance (ANOVA) was conducted to investigate the statistical effects of the material composition factors. The results show that the bond strength between SBS modified asphalt and aggregate is significantly affected by the source of base asphalt, but it is insensitive to the change of SBS type under dry and wet conditions. Besides, the moisture damage resistance of SBS modified asphalt improves firstly and then reduces with the rising storage of SBS, FEO, and stabilizer. Furthermore, linear regression analysis suggests that the work of adhesion under dry condition has excellent correlation with the work of debonding under wet condition.

To investigate the effects of nanoparticle content, storage time, and storage temperature on the storage stability of asphalt binders modified by nanoparticles, hot tube storage tests, softening point tests, and dynamic-shearing rheometer (DSR) tests were adopted to evaluate the properties of two kinds of nanotitanium dioxide (TiO₂) modified asphalt binders. A statistical one-way analysis of variance (ANOVA) test was employed to analyze the effects of those variations on the storage stability of the nano-TiO₂ modified asphalt binders. The results indicated that the softening point, the failure temperature, the dynamic-shear viscosity, and G⁎/sinδ of the binders increased with nanoparticle content. The storage stability of the binders decreased with nanoparticle content. The impact of storage time on the storage stability of the binders was remarkable when the storage time was more than 48 h. Moreover, the storage stability of the binders at low temperatures was better than that at high temperatures. Based on the one-way ANOVA, the size of nanoparticle had little influence on the storage stability of the nano-TiO₂ modified asphalt binders in this study. Reducing the nanoparticle size cannot effectively enhance the storage stability of the nanoparticle modified asphalt binder due to the agglomeration of nanoparticle.