The extensive studies devoted so far to normal-strength light-weight aggregate concrete (LWAC orLWC) have exhaustively clarified its behaviour in ordinary conditions. However, the introduction of high-performance light-weight aggregate concrete (HPLWAC or HPLWC), containing such pozzolanic components as microsilica and fly ash, raises some concerns, for instance about the behaviour at high temperature and after cooling. To investigate the temperature-induced mechanical damage, both in compression and tension, of silicafume HPLWCs, a systematic research program was carried out at the Politecnico di Milano on materials residual behaviour (testing after cooling down to room temperature). Three concrete mixes (Normal-Strength Concrete =NSC, fc20 = 30MPa; Light-Weight Concrete =LWC, fc20 40MPa; and High-Performance Light-Weight Concrete =HPLWC, fc20 60MPa), five temperature levels (20, 105, 250, 500 and 750 C, no loads applied during heating), one thermal state (after cooling), three nominally-equal tests for each case (for repeatability) were planned, bringing the total number of specimens to 120 (45 tested in compression, 45 in direct tension and 30 in indirect tension by splitting). At the same time, the thermal diffusivity of the materials was evaluated up to 750 C (4 specimens). The results show that HPLWC is somewhat more temperature-sensitive than both NSC andLWC, but this extra sensitivity is counterbalanced by HPLWC’s lower diffusivity. Its better insulation properties are advantageous for the concrete in axially-loadedmembers and for the tension bars in the beams, as demonstrated by the thermo-mechanical analyses of three typical R/C sections (rectangular, T and slab sections) carried out in the second part of the paper

Self-compacting/consolidating concrete (SCC) is certainly one the most innovative material used today by the construction industry, because of its astonishing workability and low permeability, both properties being ensured by the large amounts of fine aggregates, the special additives and the fillers, that characterize SCC’s mix compared to traditionally-vibrated concrete (VC). Since many of the structures where SCC is used (like tunnel linings, off-shore structures, containment shells, bridge decks, slabs on grade) are often required to face severe environmental conditions, such as fire, information on SCC’s behavior at high temperature is badly required, because SCC’s more dense or compact microstructure, with smaller and less connected pores, may in principle make this material more heat-sensitive than VC, as occurs in high-performance/high-strength concrete. While the thermal effects on VC have been extensively investigated in the last 20 years and several studies have been devoted to SCCs spalling in fire, only in the last few years due attention has been paid to the mechanical properties of SCCs at high temperature (“hot” properties) and/or after cooling (“residual” properties). The few of papers on this subject, however, give limited information on the stress–strain curves in compression and on the tensile behavior, that are the first objective of this project, with reference to three self-compacting “limestone” concretes (target strength f c = 50, 80 and 95 MPa). The second objective is to synthesize the test results available in the literature and to make systematic comparisons, something that is not as simple as one may expect, because of the different heating rates, specimen types, and procedures in data treatment and presentation. The agreement, however, is more than satisfactory and confirms what has been more or less overtly indicated in previous studies, that the thermal and mechanical behavior of SCC at high temperature is hardly different from that of VC, at least in quasi-static thermal conditions and uniaxial loading

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