Aging of hemp shiv used for concrete

Delannoy, Guillaume; Marceau, Sandrine; Glé, Philippe; Gourlay, Étienne; Guéguen-Minerbe, Marielle; Diafi, Dinarzed; Nour, Issam; Amziane, Sofiane; Farcas, Fabienne

doi:10.1016/j.matdes.2018.10.016

Cited by 35 publications

(30 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These micro-organisms damage the plant structure, resulting in a loss of mechanical properties and an increase of water sorption capacity of hemp concretes [14,15]. A study on the aging of bulk shiv also highlighted the variation of its hydric properties as well as the loss of acoustic properties when it is subjected to cycles of relative humidity (98% for 5 days and 40% for 2 days) or to outdoor conditions [16]. However, a high relative humidity, greater than 90%, is necessary for the proliferation of microorganisms.…”

mentioning

confidence: 99%

Durability of hemp concretes exposed to accelerated environmental aging

Delannoy

Marceau

Glé

et al. 2020

Construction and Building Materials

Self Cite

View full text Add to dashboard Cite

This study examines the evolution of the functional properties of two hemp concretes formulated with two different binders over 2 years in different environmental conditions. Stable environmental conditions (50% RH -20°C) have been applied to hemp concretes to obtain the reference aging A REF .An accelerated aging process A WD is chosen, consisting of cycles of wetting and drying. In relation to the reference aging, no significant variation of the chemical, microstructural and functional properties is observed, whether in terms of the thermal, acoustic, hydric or mechanical behavior. During accelerated aging, variations of properties are observed: an increase of thermal conductivity, and water vapor sorption capacity for both binders and a decrease of acoustic performance for the limebased binder. No variation of mechanical properties is observed. These results are linked to alterations of the chemical and microstructural properties: hydration and carbonation of the binder, mineralization, swelling and shrinkage and consumption of vegetal walls by micro-organisms. By comparing these results with measurements carried out under real conditions, this work shows that the performance of hemp concretes should remain stable for several years. *Revised Manuscript Click here to view linked ReferencesA range of disorders have been observed in early hemp concrete constructions, such as binder powdering in the core of the material, development of micro-organisms, cracking of the renders applied on its surface, or delamination of renders [5]. These issues stem from an unsuitable implementation of materials, which causes high water content in the hemp concrete, due, for example, to insufficient drying, capillary rise or water infiltration. The validation of construction rules made it possible to greatly reduce the occurrence of these construction defects [6]. Today, with a view to increasing the use of these materials, the question of the evolution of their long-term performance arises. Indeed, the durability of hemp concretes is not yet known, and it is not possible to guarantee that a minimum level of thermal, hygrothermal and acoustic performances will be preserved for a given time. In this context, some reservations still remain that limit the use of these biobased insulating materials.The evolution of the properties of hemp concretes depends on the conditions of their use and the environment to which they are exposed. Parameters such as relative humidity, temperature, liquid water and UV radiation cause changes in chemical and microstructural properties, altering the functional properties. Previous studies have shown that water has many impacts on the properties of hemp concrete. As a matter of fact, as hemp shiv is hydrophilic, the presence of water leads to a swelling of the aggregates which increases the stresses at the interface between the vegetal particles and the binder [7], and can lessen the mechanical properties of hemp concrete. In addition, the presence of water and mineral binder causes a high pH within the m...

show abstract

mentioning

confidence: 99%

Durability of hemp concretes exposed to accelerated environmental aging

Delannoy

Marceau

Glé

et al. 2020

Construction and Building Materials

Self Cite

View full text Add to dashboard Cite

show abstract

“…The standard NF EN ISO 1270 [148] governs the SSS technique. Briefly, plant aggregates samples are dried at 40 °C [24,32,69,114] in an oven until mass stabilization (change in mass less than 0.1% between two weighings in 24 h). Following this, at least 10 g of the material to be tested is put in a container that is not sensitive to humidity variation (glass cups, for example) and then kept in a ventilated sealed desiccator or box at 23 °C in which the RH is controlled by saturated salt solutions.…”

Section: Figure 12mentioning

confidence: 99%

“…In the DVS method, few particles between 10 and 100 mg are put on a microbalance kept inside a sealed thermostatically controlled chamber at a constant temperature of 20 °C [28], 23 °C [7,32,43,114], or 25 °C [45,69]). Each study followed its way of programming the DVS, but the idea is to regulate the RH inside the controlled chamber in a step-wise manner from zero to more than 95% in the case of sorption and the reverse path for desorption.…”

Section: Figure 12mentioning

confidence: 99%

See 1 more Smart Citation

A Review of the Multi-Physical Characteristics of Plant Aggregates and Their Effects on the Properties of Plant-Based Concrete

Ratsimbazafy¹,

Laborel-Préneron²,

Magniont³

et al. 2021

RPM

View full text Add to dashboard Cite

The use of plant aggregates obtained from agricultural co-products mixed with mineral binders to form eco-friendly insulating building materials has been initiated for a few years to bring environmentally friendly solutions to the construction sector. Several studies on different agro-resources have already been carried out, providing various information about the properties of plant aggregates and plant-based concrete. However, the characteristics of the agricultural co-product, which allow it to qualify as a plant aggregate for plant-based concrete, are not yet very clear despite the multitude of data, especially on hemp concrete. Therefore, it is important to gather numerous but very disparate pieces of information available in the literature concerning the properties of plant aggregates and their correlations with composites. This review is based on the results of 120 articles and aims to identify the characterization methods and the multi-physical properties of plant aggregates affecting those of plant-based concrete and to propose additional factors that could influence the properties of the composites. A total of 18 plant aggregates of different origins used for plant-based concrete have been listed in the literature. In France, hemp shiv is the most studied one, but its quantity is quite low unlike cereal or oilseed straws and wood transformation residues. With the existence of several characterization methods, properties like microstructure, particle size distribution, bulk density, water absorption capacity, and chemical composition of aggregates are easily and frequently determined. In contrast, data on the apparent density of particles, the skeleton density, and the hygro-thermal properties of aggregates are rare. The particle size, density, and porosity have been identified as important parameters influencing the properties of the composites. Other parameters related to the behavior of the aggregates under wet compaction and compression of their stacking can also predict the physical and mechanical properties of the obtained plant-based concrete. Dosages of the constituents should be preferred as formulation parameters for future studies assessing the impact of the aggregate properties on the composites.

show abstract

“…When insulating based on cellulosic fibers are used, particular attention must be devoted to degradation due to microbial contamination. Delannoy et al [11] investigated the long thermal behavior of hemp shiv, comparing a natural aging with accelerated aging conditions based on humidification and drying cycle. They found that fungal attacks alter the microstructure of the hemp shiv, and therefore its functional properties.…”

Section: Introductionmentioning

confidence: 99%

Influence of Carding and Pressing on Hygrothermal Properties and Fire Reaction of Hemp Fiber Nonwoven Mats

Donatelli¹,

Aversa²,

Terzi³

et al. 2019

Adv. Sci. Eng.

View full text Add to dashboard Cite

This article depicts the effect of carding and pressing on hygrothermal properties of hemp fibers nonwoven mats, trying to understand if their implementation can improve their behavior when employed as insulation materials in buildings. Hemp fibers belonging to Cannabis Sativa species and coming from local area (Apulia - Italy) were examined, then samples of carded and pressed hemp fibers nonwoven mats were prepared. According to European standards, the thermal conductivity, the vapor permeability and the fire reaction of hemp fibers samples were measured. Results were compared to each other and with those of a commercial nonwoven mat made with hemp (90 wt. %) and synthetic fibers (10 wt. %), used as reference. We observed that carded and pressed hemp fibers were characterized by a lower thermal conductivity when compared to unprocessed hemp fibers, likely because the removing of wood elements. On the other hand, not processed hemp fibers show higher breathability when compared to carded and pressed ones, as well as with respect to the commercial nonwoven mat. Moreover, it was proved that the absence of synthetic commingled fibers in hemp fibers allows a better behavior in fire reaction. At last, the improvement in terms of insulation properties of a hollow brick when filled with hemp fibers was verified, by comparing the thermal conductivities of an empty and a filled hollow brick; as expected, the filled hollow brick shows a lower thermal conductivity, underlining the effectiveness of hemp fibers as insulation material.

show abstract

Aging of hemp shiv used for concrete

Cited by 35 publications

References 31 publications

Durability of hemp concretes exposed to accelerated environmental aging

Durability of hemp concretes exposed to accelerated environmental aging

A Review of the Multi-Physical Characteristics of Plant Aggregates and Their Effects on the Properties of Plant-Based Concrete

Influence of Carding and Pressing on Hygrothermal Properties and Fire Reaction of Hemp Fiber Nonwoven Mats

Contact Info

Product

Resources

About