No abstract

10In this paper, influence of moisture content on the mechanical characteristics of rammed-earth has 11 been studied. Samples from different soils (sandy, clayey, stabilized) were manufactured and tested 12 in unconfined compression at several moisture contents. Compressive strength, elastic modulus and 13Poison's ratio were determined. A simplified method to measure the suction within rammed earth 14 samples has been developed and validated. The variation of mechanical characteristics related to 15 moisture content and suction are presented. This paper shows that a slight increase in the moisture 16 content of dry rammed-earth is not followed by sudden drop in wall strength. Qualitative 17 explanations at the nano-scale are presented. 18

No abstract

11Nowadays, rammed earth construction is attracting renewed interest throughout the world thanks to its 12 "green" characteristics in the context of sustainable development. Firstly, using a local material (soil on site 13 or near the site), rammed earth constructions have very low embodied energy. Secondly, rammed earth 14 houses have an attractive appearance and present advantageous living comfort due to substantial thermal 15 inertia and the "natural regulator of moisture" of rammed earth walls. This is why several research studies 16 have been carried out recently to study the mechanical and thermal characteristics of rammed earth. 17However, to our knowledge, there are not yet sufficient studies on the tensile strength and the shear strength 18 of rammed earth. The tensile strength of rammed earth is neglected in general due to its very low value, but 19 in extreme conditions (e.g., seismic conditions), knowing the tensile strength is necessary for structural 20 design. Moreover, the shear strength is required in many cases to check the local failure of rammed earth 21 quickly, which has been observed in old structures (especially those submitted to concentrated loads). 22This paper presents experimental results on tensile strengths and the Poisson ratio of rammed earth 23 specimens. Local failure tests were also conducted on 1 m × 1 m × 0.3 m wallettes manufactured in the 24 laboratory. The shear strength was then identified using a simple method based on compressive strength, 25 tensile strength and Mohr's circle theory. The approach proposed was validated by tests on the wallettes. 26Finite Element (FE) modeling was also carried out to confirm the results. Last, the method presented was 27 validated for stabilized rammed earth lintels presented in the literature. 28

This paper presents an experimental investigation on the mechanical properties and microstructure of geopolymer concrete mixed using class F fly ash (FA), ground granulated blastfurnace slag (GGBS) and high-magnesium nickel slag (HMNS). An optimal combination of FA, GGBS and HMNS was determined using the compressive strength tests of geopolymer (GP) pastes mixed with various different replacements of FA with GGBS and/or HMNS. It was found that the replacement of FA with 20% of GGBS and 10% of HMNS in GP concrete increases the 28-day compressive strength by 100% and the 28-day splitting tensile strength by 58%. The microstructure analysis of the GP concrete using SEM, XRD, and FTIR showed the formation of aluminosilicate amorphous phase in a three-dimensional network. The SEM images revealed a fully compact and cohesive geopolymer matrix, which explains the reason why the mechanical properties of the FA based GP concrete with both GGBS and HMNS are improved.

No abstract

No abstract

No abstract