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Abstract: Although the unsustainability of the human civilization has been recognized long ago, little has ever been done to change it. During the last century, materials use increased 8-fold and as a result Humanity currently uses almost 60 billion tons (Gt) of materials per year. The construction industry alone consumes more raw materials than any other economic activity. However, research on construction materials still is excessively focused on their mechanical properties with minor concerns regarding environmental considerations. In September of 2000 189 UN member states signed the Millennium Development Goals (MDGs), in which the seventh goal is related to environmental sustainability. This is a cornerstone event of paramount significance. However, research in the field of the built environment especially on the field of construction materials still seems unable to recognize its importance. This paper provides some insights on future construction materials research priorities in the context of the seventh MDG. It reviews publication patterns on the field of construction materials highlighting investigations gaps and misdirected research lines. It addresses the importance of nano and biotech hot areas and briefly analyzes the gap between research and market use. [Copyright &y& Elsevier]

Abstract: An estimated 1000 million tyres reach the end of their useful lives every year and 5000 millions more are expected to be discarded in a regular basis by the year 2030. Up to now a small part is recycled and millions of tyres are just stockpiled, landfilled or buried. This paper presents results about the properties and the durability of HPC with partial replacement of sand by tyre rubber wastes. Fly ash and metakaolin are used as partial cement replacement. The durability performance was assessed by means of capillary water absorption and resistance to sulphuric acid attack. The results show the existence of a synergetic effect between fly ash and metakaolin that minimizes the strength loss associated to the use of rubber waste. Results also show that is possible to use rubber waste up to 15% and still maintain a high resistance to acid attack. The mixes with 45% fly ash and 15% metakaolin show a much higher resistance to sulphuric acid attack than the reference mix independently of the rubber waste content. [Copyright &y& Elsevier]

Abstract: The volume of polymeric wastes like tyre rubber and polyethylene terephthalate bottles (PET) is increasing at a fast rate. An estimated 1000 million tyres reach the end of their useful lives every year and 5000 millions more are expected to be discarded in a regular basis by the year 2030. Up to now a small part is recycled and millions of tyres are just stockpiled, landfilled or buried. As for PET bottles annual consumption represent more than 300,000 million units. The majority is just landfilled. This paper reviews research published on the performance of concrete containing tyre rubber and PET wastes. Furthermore it discusses the effect of waste treatments, the size of waste particles and the waste replacement volume on the fresh and hardened properties of concrete. [Copyright &y& Elsevier]

Abstract: The alkali activation of alumino-silicate materials is a complex chemical process evolving dissolution of raw materials, transportation or orientation and polycondensation of the reaction products. Publications on the field of alkali-activated binders, state that this new material is likely to have high potential to become an alternative to Portland cement. While some authors state that the durability of these materials constitutes the most important advantage over Portland cement others argue that it’s an unproven issue. This paper presents a review of the literature about the durability of alkali-activated binders. The subjects of this paper are resistance to acid attack, alkali–silica reaction, corrosion of steel reinforcement, resistance to high temperatures and to fire, resistance to freeze–thaw. Special attention is given to the case of efflorescences, an aspect that was received very little concern although it is a very important one. [Copyright &y& Elsevier]

Abstract: This study has investigated the joint effect of several factors on the workability and mechanical strength of alkali-activated metakaolin based mortars. The factors analysed through a laboratory experiment of 432 specimens, pertaining to 48 different mortar mixes were, sodium hydroxide concentration (10M, 12M, 14M, 16M), the superplasticizer content (1%, 2%, 3%) and the percentage substitution of metakaolin by calcium hydroxide in the mixture (5%, 10%). The results show that the workability decreases with the concentration of sodium hydroxide and increases with the amount of calcium hydroxide and superplasticizer. The results also show that the use of 3% of superplasticizer, combined with a calcium hydroxide content of 10%, allows improving the mortar flow from less than 50% to over 90%, while maintaining a high compressive and flexural strength. [Copyright &y& Elsevier]

Highlights: [•] Fibres are added for improving the weak bond capacity between GFRP rebar and concrete. [•] The various fibres show positive hybrid effect on the bond effect between GFRP and concrete. [•] The bond capacity of GFRP in concrete with fibres is better than that of steel rebar in concrete. [•] The hybrid use of different macro fibres provides also cost benefit. [Copyright &y& Elsevier]

Abstract: The nano-carbon black (NCB) and carbon fiber (CF) as electric conductive materials were added into the concrete. The effect of the NCB and CF on the mechanical properties and on the fractional change in resistance (FCR) of concrete was investigated. The relationships among the FCR, the strain of initial geometrical neutral axis (IGNA) and the beam damage degree were developed. The results showed that the relationship between the FCR and IGNA strain can be described by the First Order Exponential Decay function, and the internal damage of concrete beam was reflected by the relationship between damage degree and resistance. [Copyright &y& Elsevier]