Purpose The aim of this paper is to make lightweight high-performance concrete (LWHPC) with high economic performance from existing materials on the Algerian market. Concrete with high values with regard to following properties: mechanical, physical, rheological and durability. Because of the implementation of some basic scientific principles on the technology of LWHPC, this study is part of the valuation of local materials to manufacture LWHPC with several enhanced features such as mechanical, physical chemical, rheological and durability in the first place and with regard to the economic aspect in the second place. Design/methodology/approach The experimental study focused on the compatibility of cement/superplasticizer, the effect of water/cement ratio (W/C 0.22, 0.25, 0.30), the effect of replacing a part of cement by silica fume (8 per cent), the effect of combined replacement of a part of cement by silica fume (8 per cent) and natural pozzolan (10 per cent, 15 per cent, 25 per cent) and the effect of fraction of aggregate on properties of fresh and hardened concrete using the mix design method of the University of Sherbrooke, which is easy to realize and gives good results. Findings The results obtained allow to conclude that it is possible to manufacture LWHPC with good mechanical and physical properties in the authors’ town with available materials on the Algerian market. The mix design and manufacture of concrete with a compressive strength at 28 days reaching 56 MPa or more than 72 MPa is now possible in Biskra (Algeria), and it must no longer be used only in the experimental field. The addition of silica fume in concrete showed good strength development between the ages of 7 and 28 days depending on the mix design; concrete containing 8 per cent silica fume with a W/B (water/binder) of 0.25 has a compressive strength higher than other concretes, and concrete with silica fume is stronger than concrete without silica fume, so we can have concrete with a compressive strength of 62 MPa for W/C of 0.25 without silica fume. Then, one can avoid the use of silica fume to a resistance of concrete to the compressive strength of 62 MPa and a slump of 21 cm, as silica fume is the most expensive ingredient in the composition of the concrete and is very important economically. A main factor in producing high-strength concrete above 72 MPa is to use less reactive natural pozzolan (such as silica fume) in combination with silica fume and a W/B low of 0.25 and 0.30. The combination of silica fume and natural pozzolan in mixtures resulted in a very dense microstructure and low porosity and produced an enhanced permeability of concrete of high strength, as with resistance to the penetration of aggressive agents; thus, an economical concrete was obtained using this combination. Research limitations/implications The study of the influence of cementitious materials on concrete strength gain was carried out. Other features of LWHPC such as creep, cracking, shrinkage, resistance to sulphate attack, corrosion resistance, fire resistance and durability should be also studied, because there are cases where another feature is most important for the designer or owner than the compressive strength at 28 days. Further studies should include a range of variables to change mixtures significantly and determine defined applications of LWHPC to produce more efficient and economical concretes. It is important to gather information on LWHPC to push forward the formulation of characteristics for pozzolan concrete for the building industry. Practical implications The LWHPC can be used to obtain high modules of elasticity and high durability in special structures such as marine structures, superstructures, parking, areas for aircraft/airplane runways, bridges, tunnels and industrial buildings (nuclear power stations). Originality/value The novel finding of the paper is the use of crystallized slag aggregates and natural pozzolan aggregates to obtain LWHPC.
Purpose The purpose of this paper is to make a contribution to understanding the influence of factors such as the water/cement (W/C) ratio and the granular class on the mechanical and physical properties of high-strength concretes (HSCs). In the formulations of HSC, aggregates by their high mass and volume proportion play an important role. When selecting aggregates, it is necessary to know their intrinsic properties. These properties influence the performance of concrete, in particular the quality of the granulate cimentary adhesion. Design/methodology/approach This experimental study focused on the effect of W/C ratio (0.25, 0.30, 0.35), the effect of replacing a part of cement by silica fume (SF) (8%), the effect of fraction of aggregate on properties of fresh and hardened concrete, the effect of different environment conversation like drinking water and sea water on compressive strength and the study of absorption of water and softening using the mix design method of the University of Sherbrooke combined with the Dreux-Gorisse method which gives good results. Findings At the end of our work, the examination of the results obtained made it possible to establish the correlations between the formulations studied and the physicomechanical characteristics of the concrete compositions (HSC25, HSC16, HSC8). The results of this study show that the use of three granular classifications (DMAX8, DMAX16 and DMAX25) and three report W/C (0.25, 0.30 and 0.35) in two different conservation environment (drinking water and sea water) give HSCs, HSC25 with an W/C = 0.25 ratio has reached the largest mechanical strength of 90 MPa for different environments of conservation. For selecting aggregates, it is necessary to know their intrinsic properties, these properties influence the strength of concrete. In general, there is a slight decrease in the compressive resistance of the specimens stored in seawater, it can be said that the conservation life has not had effect on the resistance (28 days). The effect of aggressive environment can appear in the long term. Research limitations/implications Mixed design and concrete fabrication with a 28-day compressive strength of up to 68 MPa or more of 90 MPa can now be possible used in Jiel (Algeria), and it should no longer be considered to be used only in an experimental domain. Addition of SF in concrete showed good development of strength between 7 and 28 days, depending on the design of the mix. Practical implications Concrete containing 8% SF with W/B of 0.25 has higher compressive strength than the other concretes, and concretes with SF are more resistant than concretes without SF, so it is possible to have concrete with a compressive strength of 82 MPa for W/C 0.25 without SF. Like as a result, we can avoid the use of SF to affect the strength of concrete at compressive strength of 68 MPa, and a slump of 21 cm, because the SF is the most expensive ingredient used in the composition of concrete and is therefore very important economically. One of the main factors of production of HSC above 90 MPa is use of aggregate DMAX25, which is stronger with W/B of 0.25 and 0.30. Social implications This mixtures leads to a very dense microstructure and low porosity and produces increased permeability of HSC and is able to resist the penetration of aggressive agents. This combination has a positive effect on the economy of concrete. Originality/value The combination of the Dreux-Gorisse method with the Sherbrook method is very beneficial for determining the percentage of aggregates used, and the use of coarse aggregates of Jijel to obtain HSC with 90 MPa and 16 cm of workability.
High performance concrete (HPC) is an innovative concrete that finds its place in modern buildings. The new high-performance concrete formulation and conception techniques have improved sustainability and acquiring remarkable mechanical properties compared to conventional concretes. The objective of this work is to make a contribution to understanding the influence of factors such as the W/ C ratio and the granular class on the mechanical and physical properties of high performance concretes. In the formulations of HPC aggregates by their high mass and volume proportion, play an important role, the Sherbrook and Dreux-Gorisse method has been used. When selecting aggregates it is necessary to know their intrinsic properties. These properties influence the performance of concrete in particular the quality of the granulate cimentary adhesion. At the end of our work, the examination of the results obtained made it possible to establish the correlations between the formulations studied and the physico-mechanical characteristics of the concrete compositions (HPC 25, HPC 16, HPC 8). The results of this study show that the use of three granular classifications (DMAX8, DMAX16 and DMAX25) and three Report W / C (0.25, 0.30, and 0.35) in two different conservation environment (EP drinking water and sea water ), clearly proves that the composition of high performance concrete is HPC25 concrete with an W/ C = 0.25 ratio has reached the largest mechanical strength of 80 MPa for different environments of conservation. When selecting aggregates it is necessary to know their intrinsic properties, these properties influence the performance of concrete. In general, there is a slight decrease in the compressive resistance of the specimens stored in seawater, it can be said that the conservation life has not had effect on the resistance (28 days). The effect of aggressive environment can appear in the long term.
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