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Blended cements, where Portland cement clinker is partially replaced by supplementary cementitious materials (SCMs), provide the most feasible route for reducing carbon dioxide emissions associated with concrete production. However, lowering the clinker content can lead to an increasing risk of neutralisation of the concrete pore solution and potential reinforcement corrosion due to carbonation. carbonation of concrete with SCMs differs from carbonation of concrete solely based on Portland cement (PC). This is a consequence of the differences in the hydrate phase assemblage and pore solution chemistry, as well as the pore structure and transport properties, when varying the binder composition, age and curing conditions of the concretes. The carbonation mechanism and kinetics also depend on the saturation degree of the concrete and CO2 partial pressure which in turn depends on exposure conditions (e.g. relative humidity, volume, and duration of water in contact with the concrete surface and temperature conditions). This in turn influence the microstructural changes identified upon carbonation. This literature review, prepared by members of RILEM technical committee 281-CCC carbonation of concrete with supplementary cementitious materials, working groups 1 and 2, elucidates the effect of numerous SCM characteristics, exposure environments and curing conditions on the carbonation mechanism, kinetics and structural alterations in cementitious systems containing SCMs.

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This paper presents a comparative environmental assessment of several different green concrete mixes for structural use. Four green concrete mixes were compared with a conventional concrete mix: recycled aggregate concrete with a cement binder, high-volume fly ash concrete with natural and recycled aggregates, and alkali activated fly ash concrete with natural aggregates. All five concrete mixes were designed and experimentally verified to have equal compressive strength and workability. An attributional life cycle assessment, based on the scenario which included construction practice, transport distances, and materials available in Serbia, was performed. When treating fly ash impacts, three allocation procedures were compared: 'no allocation', economic, and mass allocation, with mass allocation giving unreasonably high impacts of fly ash. Normalization and aggregation of indicators was performed and the impact of each concrete mix was expressed through a global sustainability indicator. A sensitivity analysis was also performed to evaluate the

An experimental study of the shear behavior of recycled aggregate concrete (RAC) beams with and without shear reinforcement is presented. Nine full-scale simply supported beams were loaded in fourpoint bending tests until failure. Three different replacement ratios of coarse natural with coarse recycled concrete aggregate (0%, 50%, and 100 %), and three different shear reinforcement ratios (0%, 0.14%, and 0.19 %) were the main parameters. All natural aggregate concretes (NAC) and recycled aggregate concretes (RAC) were designed and experimentally verified to have similar compressive strength and workability. It was found that the shear behavior and the shear strength of the beams with 50% and 100% of recycled concrete aggregate was very similar to that of the corresponding natural aggregate concrete beams. The applicability of different code provisions for the shear strength predictions of the RAC beams with and without shear reinforcement was tested by comparison to test results obtained on 85 beams, 58 RAC and 27 corresponding NAC beams. The shear strength of RAC50 and RAC100 beams with and without shear reinforcement was conservatively predicted by the analyzed codes with similar reliability as for the corresponding NAC beams shear strength. At this state-of-knowledge, the application of the analyzed codes' provisions for NAC beams shear strength can be recommended both for the RAC50 and the RAC100 beams. Highlights Nine full-scale NAC and RAC beams were tested until shear failure.  Similar shear behavior and strength of RAC and NAC beams.  Codes' provisions for the NAC beams shear strength can be also used for RAC beams.Abstract 1 An experimental study of the shear behaviour of recycled aggregate concrete (RAC) beams with and 2 without shear reinforcement is presented. Nine full-scale simply supported beams were loaded in four-3 point bending tests until failure. Three different replacement ratios of coarse natural with coarse 4 recycled concrete aggregate (0%, 50% and 100 %), and three different shear reinforcement ratios (0%, 5 0.14% and 0.19 %) were the main parameters. All natural aggregate concretes (NAC) and recycled 6 aggregate concretes (RAC) were designed and experimentally verified to have similar compressive 7 strength and workability. It was found that the shear behaviour and the shear strength of the beams 8 with 50% and 100% of recycled concrete aggregate were very similar to that of the corresponding 9 natural aggregate concrete beams. The applicability of different code provisions for shear strength 10 predictions of the RAC beams with and without shear reinforcement was tested by comparison with 11 test results obtained on 85 beams, 58 RAC and 27 corresponding NAC beams. The shear strength of 12 RAC50 and RAC100 beams with and without shear reinforcement was conservatively predicted by the 13 analyzed codes with similar reliability as for the corresponding NAC beams shear strength. At this 14 state-of-knowledge, the application of the analyzed codes' provisions for NAC beams shear strength...

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A two-phase experimental study on the effect of simultaneous partial replacement of cement and fine aggregate with fly ash on the mechanical and time-dependent properties of high-volume fly ash concrete (HVFAC) is presented. The results of the first phase of the study show that it is possible to make structural grade HVFAC with 50% of cement and an additional 30% of fine aggregate replacement that has a similar compressive strength to that of the control cement concrete and with adequate workability. In the second phase of the study the mechanical and time-dependent properties of HVFAC with a mass of fly ash of 50–70% of the total mass of cementitious materials were tested. The results show that with the increase in fly ash content the compressive strength of HVFAC increased by 22% on average at all ages tested. With the exception of the early-age compressive strength, it was found that the European standard EN 1992-1-1:2004 provisions for ordinary cement concrete underestimate the mechanical properties and significantly overestimate the shrinkage and creep of HVFAC. Better correlation with experimental results was obtained using different coefficients developed for HVFAC.