A microstructural insight into the hygro-mechanical behaviour of a stabilised hypercompacted earth

Bruno, Agostino Walter; Perlot, Céline; Mendes, João; Gallipoli, Domenico

doi:10.1617/s11527-018-1160-9

Cited by 27 publications

(11 citation statements)

References 43 publications

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“…the ratio between plasticity index and clay fraction) is equal to 0.79, which corresponds to a normally active soil [35]. This is also consistent with the mineralogical composition observed by Bruno et al [36] via X-Ray diffraction tests, which indicated a predominant illitic clayey fraction with a presence of montmorillonite for the same Nagen soil.…”

Section: Methodssupporting

confidence: 87%

Recyclability, durability and water vapour adsorption of unstabilised and stabilised compressed earth bricks

Bruno¹,

Scott²,

D’Offay-Mancienne³

et al. 2020

Mater Struct

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This paper investigates the recyclability, liquid water durability and water vapour adsorption of both unstabilised and stabilised compressed earth bricks. Stabilised bricks were manufactured by adding either cement or the biopolymer guar gum to the base earth. Unconfined compressive strength tests were then performed on both unstabilised and stabilised earth bricks manufactured with recycled material (i.e. material taken from the failed compressed earth bricks after the compressive strength tests). These tests enabled to assess the influence of recycling on the stiffness, strength and strain energy of all compressed earth bricks. Immersion and drip tests were subsequently performed to investigate the effect of cement and biopolymer stabilisation on the durability of the compressed earth bricks against the weathering action of water. An additional set of laboratory experiments was finally conducted by means of a Dynamic Vapour Sorption (DVS) system to study the effect of earth stabilisation on the capacity of adsorbing/releasing water vapour as the ambient humidity changes. Outcomes from this experimental campaign showed that both unstabilised and biopolymer stabilised earth bricks maintained a similar mechanical performance after recycling, while cement stabilised bricks showed a remarkable reduction of both stiffness and strength. Finally, both cement and biopolymer stabilised bricks improved the liquid water durability while reducing the water vapour adsorption compared with the unstabilised earth bricks. Results from this experimental work will be useful for life cycle assessments, especially for modelling the end-of-life of the material as well as its potential reuse.

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Section: Methodssupporting

confidence: 87%

Recyclability, durability and water vapour adsorption of unstabilised and stabilised compressed earth bricks

Bruno¹,

Scott²,

D’Offay-Mancienne³

et al. 2020

Mater Struct

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“…Inspection of Figure 2 also indicates that the moisture adsorption capacity drastically reduces, for all manufacturing methods, as firing temperature increases. This is due to both the progressive vitrification of the brick surface, which reduces the permeability to vapour, and the progressive disappearance of the finest pore fraction (Bruno et al, 2018). Finally, Figure 2 also shows that, at the highest temperature of 1000 °C, the moisture adsorption capacity of the material becomes almost negligible.…”

Section: Moisture Buffering Capacity Test Resultsmentioning

confidence: 90%

Effect of quick firing on the hygro-mechanical behaviour of earth bricks

Perlot¹,

Gallipoli²,

Bruno³

2019

Sustainable Construction Materials and Technologies (SCMT)

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This paper presents the effect of quick firing on the compressive strength and moisture adsorption capacity of earth bricks manufactured according to three different methods, i.e. extrusion, standard Proctorcompaction and hypercompaction to 100 MPa. All bricks were fired inside an electrical furnace by rising the temperature at a quick rate of about 9 °C per minute to 280, 455, 640, 825 and 1000 °C, after which the furnace was turned off and left to cool to the atmosphere with the brick inside it. Results show that quick firing of hypercompacted bricks at moderate temperatures, between 455 and 640 °C, is enough to attain very high levels of compressive strength, between 29 and 34 MPa, and a good moisture adsorption capacity. The strength of hypercompacted bricks further increases to 53 MPa, a value similar to that of high-strength concrete, after quick firing at 825 °C. Hence, the combination of hypercompaction and quick firing improves material performance while enabling a significant reduction of firing temperatures and times compared to current bricks production methods.

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“…Bruno et al [26] measured the moisture dependent thermal conductivity of earth samples composed by 0.4% of gravel, 40.4% of sand, 42.9% of silt and 16.3% of illitic clay hypercompacted at a pressure of 100 MPa at the optimum water content of 5.2%. More details on the hypercompaction procedure can be found in Bruno et al [29] and Bruno et al [30]. After compaction, three different sets of hypercompacted earth samples were left to equalise inside a climatic chamber at a constant temperature of 25 °C and at the three levels of the relative humidity of 25, 62 and 95%.…”

Section: Model Validationmentioning

confidence: 99%

A Simple Thermal Conductivity Model for Unsaturated Geomaterials Accounting for Degree of Saturation and Dry Density

Bruno

Alamoudi

2020

Int. J. of Geosynth. and Ground Eng.

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This paper proposes a simple thermal conductivity model for geomaterials accounting for the combined effect of both degrees of saturation and dry density. The model only requires the determination of the thermal conductivity under dry conditions (i.e., at a degree of saturation equal to zero) and as little as two additional measurements of thermal conductivity performed at different levels of degree of saturation and dry density. The model is a function of only two fitting parameters, namely the moisture factor $${m}_{f}$$ m f and the density factor $${m}_{d}$$ m d . Despite its simplicity, the model can correctly predict the thermal conductivity of geomaterials and this has been validated against five sets of experimental data obtained on a very broad range of materials ranging from fine (e.g., bentonite) to coarser soils (e.g., a mix of gravel, coarse sand and silt) tested at different levels of degree of saturation and dry density. The paper also shows that the model can be applied to different engineering contexts such as (a) the thermal behaviour of earth materials used for building construction, (b) the thermal performance of bentonites employed for the storage of nuclear waste and (c) the estimation of the heat exchange in shallow geothermal reservoirs. Finally, the proposed model can be easily implemented in a finite element code to perform numerical simulations to study the heat transfer in unsaturated geomaterials.

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A microstructural insight into the hygro-mechanical behaviour of a stabilised hypercompacted earth

Cited by 27 publications

References 43 publications

Recyclability, durability and water vapour adsorption of unstabilised and stabilised compressed earth bricks

Recyclability, durability and water vapour adsorption of unstabilised and stabilised compressed earth bricks

Effect of quick firing on the hygro-mechanical behaviour of earth bricks

A Simple Thermal Conductivity Model for Unsaturated Geomaterials Accounting for Degree of Saturation and Dry Density

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