Concrete containing supplementary cementitious materials (SCMs) as partial replacement of ordinary Portland cement is regarded as green and durable concrete, with several advantages such as improved strength gain mechanism, resistance to degradation and extended service life of structure. Water absorption or porosity of concrete is directly related to the durability of concrete. In this present study, five concrete mixes involving three different SCMs are investigated for water absorption and rapid chloride penetration rating. A comparison between porosity values obtained using four standard testing methods, i.e., BS 1881-122, RILEM CPC 11.1, RILEM CPC 11.3, and ASTM C642 are presented for three different concrete mixes containing varied compositions and proportions of two SCMs. The testing method by RILEM CPC 11.3 includes distinctive sample preparation and is regarded as a stringent method to represent the degree of concrete porosity. Two additional concrete mixes with three SCMs are further investigated for their water absorption and immersion following the testing method by RILEM CPC 11.3. The impact of SCMs on concrete porosity is discussed. A linear correlation between porosity and rapid chloride penetration (RCP) ratings obtained as per ASTM C1202-19 on specimens of all investigated concrete mixes is proposed as a rapid approach to assess chloride penetration of concrete specimens containing SCMs.

In the last few decades, the United Arab Emirates (UAE) witnessed rapid development in the construction industry. It was recently emphasized to adopt sustainability practice in all aspects related to construction. The recent sustainable practice that was enforced by Dubai Municipality in construction field is “greening the concrete” by solely replacing the Portland Cement with supplementary cementitious materials (SCMs), such as grand granulated blast furnace slag (GGBS) and fly ash. On the other hand, the use of recycled aggregates can also contribute to the greening of concrete and to the reduction of carbon foot print from the construction industry in the UAE. Consequently, it is significant to study the suitability of local available recycled aggregate and their effect on concrete fresh and hardened properties, in order to expand the current practice. The recycled aggregates, used in this investigation, are obtained from a local recycled aggregates plant in Abu Dhabi using concrete from demolished buildings in Abu Dhabi. The natural aggregates in concrete mixtures were replaced by recycled aggregates with the following percentages: 20%, 40%, 60% and 100%. The concrete parameters investigated are mainly the slump retention, rheology and compressive strength. The results are analyzed to arrive to pertinent conclusions for the utilization of concrete with recycled aggregates in different types of construction projects.

The rheological properties of fresh concrete incorporating recycled aggregate and various supplementary cementitious materials (SCMs) were investigated as a function of recycled aggregate replacement percentage, SCM content, and time. The recycled aggregates were obtained from a local recycled aggregates plant in Abu Dhabi that extracts the aggregates from demolished buildings in Abu Dhabi. Two supplementary cementitious materials were used in binary and ternary blends—namely, ground-granulated blast-furnace slag and fly ash. The rheological testing was performed using a concrete rheometer. The test results indicate that the rheological properties (static yield stress, dynamic yield stress, and plastic viscosity) of concrete are significantly affected by changes in amount of recycled aggregate, mixing time, and SCM dosage. The relationship between yield stress and plastic viscosity is used to establish workability control charts for sustainable concrete proportioned with recycled aggregates. These charts are expected to serve as a rational means for assessing the workability of concrete with recycled aggregates using local materials in the United Arab Emirates. The results of this study are of practical significance in providing realistic recommendations for sustainable concrete with recycled aggregates.

Understanding the thermal properties of a construction material is necessarily to evaluate its heat transfer resistance that has a major contribution to the energy-efficiency required to achieve sustainable structure. Thermal properties are evaluated through three main parameters namely: thermal conductivity, thermal resistivity and thermal transmittance. The aforementioned parameters are commonly referred as K-value, R-value, and U-value respectively. Recent regulations by Dubai municipality enforced to use sustainable concrete in construction. This is by replacing cement with supplementary cementitious materials (SCMs), such as grand granulated blast furnace slag (GGBS) and fly ash. The use of grand granulated blast furnace slag (GGBS) at relatively high percentage replacement became a typical practice in ready-mixed concrete industry in Dubai. As such, it is essential to characterize the thermal properties of this sustainable concrete. The current paper investigates the thermal properties of sustainable concrete mixtures incorporating supplementary cementitious materials, air entrainment additives, polypropylene and hybrid synthetic fiber. K-value, R-value and U-value are evaluated in accordance with ASTM C518. Additionally, hardened density of all investigated mixtures are measured. The results show that the foamed concrete has better heat transfer resistance than that for the non-air entrained mixture.