bluuebunny/crossref_metadata_2025 huggingface dataset:
Life Cycle Assessment of Circular Bio-Based Construction
Authors: Cascione Valeria , Roberts Matt , Allen Stephen , Dams Barrie , Maskell Daniel , Shea Andrew
Published: January 2022

The construction sector is a large consumer of non-renewable resources and it is responsible of 44% of global energy related CO2 emissions. Circular economy is an emerging strategy that has potential to make significant improvements in the construction industry, by taking efficient and sustainable actions against climate change. The principles of circular economy are to minimise the waste of resources, by maximizing materials' performances, whilst in use, and recycle and regenerate them at the end of their service life. Natural materials can potentially be suitable in this strategy, due to the use of renewable resources, carbon sequestration potential, and high suitability for reuse and recycling. The development of bio-based wall panel is a first step into the integration of a circular economy approach in the construction sector. In this study, vapour responsive bio-based panel prototypes with low thermal transmittance (U<0.20 W/m2K) are being designed, taking into consideration the burdens and benefits of natural materials over their entire life cycle. The challenge is to assess the environmental impact of the panels during their design and production, maximise performance and life span, when in use, and regenerate and recycle panel components at the end of the service life. In this paper, a life cycle assessment of a prototype bio-based panel designed with circular economy principles is investigated. The environmental impact of the panel is analysed to investigate limitation in assessing emissions and use of resources in a circular prospective. The objective of the research is to integrate environmental impact analysis during the early stage of panel design. This will put the basis for the development of a sustainable and circular building industry and for identifying area of improvements for the development of sustainable circular panels with expected hygrothermal benefits conferred using bio-based materials.
Water Sensitivity of Hemp-Foam Concrete
Authors: Mohamad Abdelrahman , Khadraoui Fouzia , Sebaibi Nassim , Boutouil Mohamed , Chateigner Daniel
Published: January 2022

The necessity to build energy-efficient and low environmental impact buildings favors the development of biobased light-weight materials as hemp-foam concretes. In this context, experimental protocols were developed to study the effects of hemp shiv and the production methods on the water sensitivity of bio-based foamed concrete (BBFC). Foam concrete incorporates several materials and compounds: cement, protein-based foaming agent, ground granulated blast–furnace slag, metakaolin as a binder, and hemp shiv as bio-based aggregates. The study investigated first the effect of the incorporation of hemp shiv (from 0 to 15 vol%) and then the elaboration method, comparing direct method versus preformed method on the resulting physical properties, the isotherms sorption-desorption and the capillary water absorption of hemp-foam concretes. We observe an increasing porosity of the concrete with hemp shives content. Additionally, hemp shives increase the adsorption and the capillary absorption of water. Moreover, the preformed method produces concretes more sensitive to water than the direct methods since it increases its porosities.
Experimental Investigation of the Compatibility of Lime Coating with Insulation Straw Biocomposite
Authors: Bahou Oumayma , Belayachi Naima , Ismail Brahim
Published: January 2022

The use of bio-based composite as building materials is one of the innovative solutions for dealing with environmental disorders caused by the construction sector. Among these materials we find biocomposites based on vegetable aggregates, which have proven their effectiveness as insulating materials in numerous studies. Despite the growing interest in these materials and the recognition of their performance, their use remains hampered by the lack of implementation rules specific to these materials to move towards a control of their use and their durability affected by the climate and use conditions to which they will be exposed at the level of a building. The objective of this work is to study the compatibility of a protective coating with a block substrate of biocomposites based on cereal straw. It is in fact a mixture of vegetable aggregates (straw), a binder composed of lime and additives also obtained from a renewable source (Ismail et al., 2020). These additives (air-entraining agent, casein protein and a biopolymer) have been added to improve both the fibre-binder interface and the porosity of the binder. The use of these bio-based materials for external or internal thermal insulation of the building requires the application of a coating to protect them against climatic aggressions and to give them an aesthetic appearance. The lime-based coatings, air-entraining agent and casein protein selected for this study have been the subject of an experimental investigation (Brahim Ismail, 2020). In order to assess the compatibility of these coatings with the straw-based insulating material, we were interested in studying the adhesion between the biocomposite and the coating after aging cycles in accordance with the EN 1015-21 standard. The samples (biocomposite + coating) were subjected to two types of aging, one using water and the other using a saline solution of sodium sulphates (Na2SO4). The results of the bond tests after aging showed that the cohesive fracture (at the level of the substrate) is a pattern observed in all the studied systems. In Addition, It has been found that the coating to which a percentage of fine fibers has been added undergoes considerable degradation after aging with salt solution, demonstrating the need of an additional layer of outer coating without fibers in order to ensure the sustainability of the system.
Comparative Study of Metakaolin and Zeolite Tuff Influence on Properties of High-Strength Concrete
Authors: Dvorkin Leonid I. , Zhitkovsky Vadim , Lushnikova Nataliya , Sonebi Mohammed
Published: January 2022

Composite admixtures which include active pozzolanic components and high-range water reducers, allows to obtain high-strength, particularly dense and durable concrete to achieve a reduction in resources and energy consumption of manufacturing.Zeolite, containing a significant amount of active silica, can serve as one of the alternative substances to resources and energy consuming mineral admixtures like metakaolin and silica fume. The deposits of zeolites are developed in Transcarpathia (Ukraine), USA, Japan, New Zealand, Iceland and other countries. It is known that zeolite tuffs exhibit pozzolanic properties and are capable to substitution reactions with calcium hydroxide.However, the high dispersion of zeolite rocks leads to a significant increase in the water consumption of concrete. Simultaneous introduction of zeolite tuffs with superplasticizers, which significantly reduce the water content, creates the preconditions for their effective use in high-strength concrete.Along with dehydrated (calcined) zeolite, natural (non-calcined) zeolite expresses itself as an effective mineral admixture of concrete. When using non-calcined zeolite, the effect of increasing in compressive strength at the age of 3 and 7 days is close to the effect obtained when using dehydrated zeolite: 8-10% and 10- 12%, respectively, and 28 days the strength growth is 13-22%. The use of non-calcined zeolite has a significant economic feasibility, so it certainly deserves attention. There were compared the effect of zeolite to metakaolinThe results of the research indicate that the use of composite admixtures, consisted of calcined (non-calcined) zeolite tuff of high dispersity and superplasticizer of naphthalene formaldehyde type, allows to obtain concretes classes C50…C65.
Experimental and Numerical Study of Hygrothermal Behaviour of a Washing Fines Hemp Test Wall
Authors: Boumediene Naima , Collet Florence , Prétot Sylvie , Ayed Lazhar , Elaoud Sami
Published: January 2022

Bio-based materials are a promising tracks that offer thermal and environmental performances in order to reduce the consumption of energy and of non-renewable resources. For this purpose, in a previous study, the LGCGM worked on the development of Washing Fines Hemp composites (WFH) and characterized them on multiphysical points of view. Such materials show low thermal conductivity and high moisture buffer ability. In order to characterize their hygrothermal behavior at wall scale, a test wall is set up in an air-conditioned bi-climatic test room to simulate indoor and outdoor climates. This paper investigates the characterization of hygrothermal behavior of Washing Fines Hemp wall under typical Tunisian summer climate. It consists in an experimental study, supplemented by numerical simulation performed with WUFI Pro V6.5 software. The experimental hygrothermal response of the wall to such solicitations is analyzed from the temperature and relative humidity kinetics at several positions in the wall and from temperature and vapor pressure profiles. It shows that for daily cycles the two thirds of the thickness of the wall on the exterior side are active, as well regarding heat and moisture phenomena. More sorption-desorption phenomena are highlighted. The numerical results are consistent with experimental data for temperature and underestimate vapor pressure in the inner part of the wall.
Erosion Behaviour of Bio-Stabilised Earthen Materials
Authors: Audren Mathieu , Guihéneuf Simon , Rangeard Damien , Perrot Arnaud
Published: January 2022

Development of earthen building materials is one of the answers that the construction sector can provide to tackle the accelerated climate change issue. However, these materials present a wide variability, even at the local scale, and their water durability can be difficult to ensure. In order to improve their durability regarding water and avoid its prejudicial effect on earthen material’s properties, the stabilisation with bio-polymers is an increasingly studied solution. In this paper a ten-minute erosion drip test is developed and performed for various combinations of Breton earths and bio-based additions or surface treatments (linseed oil, xanthan gum, casein, alginate, vegetal varnish and tannins). The final pitting depths and eroded volumes are compared and the evolution of erosion during the test is monitored. These results are also linked to previously obtained water capillary absorption coefficients. The obtained results enable to highlight the impact of bio-based additions on erodibility of earthen materials: linseed oil and xanthan gum help to protect the earth-based samples from erosion. Other original parameters characterizing the erosion of the samples during the drip test are suggested. Limitations of this type of erosion tests are also brought out.
An Experimental Investigation on Suitability of Using Sisal Fibers in Reinforced Concrete Composites
Authors: Makunza John K. , Kumaran G. Senthil
Published: January 2022

Fiber reinforcement is widely used in construction engineering to improve the mechanical properties of concrete such as compressive and tensile strengths. Concrete is strong in compression but weak in tension and is a brittle material. In the construction industry, strength, durability and cost are among the major factors for selecting the suitable construction materials. During this investigation, the mechanical properties of sisal fibers reinforced concrete (SFRC) were assessed namely, flexural strength, tensile strength ad interfacial bond strength. The said properties were assessed in two types of reinforcement namely, randomly oriented sisal fibers and parallel oriented sisal fibers reinforcement. In both cases the sisal fibers were varied in volume fractions so as to establish the optimum value.
The mechanical properties of flexural and tensile strengths were found to increase considerably with increasing fiber volume fractions until an optimum volume fraction is reached, thereafter, the strengths were found to decrease continuously. The prominent increment of 32.4% in flexural strength at fiber volume fraction of 2.0% parallel reinforced fiber concrete composite was observed. There was very small increment on both flexural and tensile strength for randomly oriented chopped sisal fibers reinforced concrete (SFRC). The Interfacial bond strength was found to be 0.12 N/mm2 and was observed to be prominent for chopped sisal fibers reinforced concrete specimens tested for flexural strength. During failure, fiber pull-out was observed and the composite was observed to behave in a ductile manner whereby the fibers were able to carry more load while full fracture had occurred on the specimen. The water absorption capacity of the SFRC was found to increase with increasing sisal fiber volume fraction.
Bio-Stabilised Earthen Blocks: A Critical Study on Compression Tests of Immersed Samples
Authors: Guihéneuf Simon , Perrot Arnaud , Rangeard Damien , Cocheteux Mathilde
Published: January 2022

Currently, much consideration is given to earthen building materials regarding their highly sustainable properties. Numerous studies have highlighted their structural ability but their water sensitivity is still limiting a potentially more spread use. To limit this sensitivity several studies have recently brought out the positive effects of bio-stabilisers such as linseed oil or xanthan gum. These recent developments allow bio-stabilized earthen materials to be resistant to immersion in water. Also, a French experimental standard (XP P 13-901) for compressed earth blocks already asks for a minimal compressive strength after a two-hour immersion that is overly severe and is difficult to satisfy without the addition of high contents of hydraulic binders. In this paper, a critical study of this compressive test after immersion is conducted on bio-stabilized (linseed oil and xanthan gum) samples of different Breton earths. Some testing adjustments are suggested and the water-diffusion in the samples is followed and linked to previously obtained capillary absorption coefficients. It is shown that the effect of immersion on the mechanical strength depends on the sample size and that an equivalence between size and immersion time can be made based on an equivalent penetration depth. Linseed oil and xanthan gum help to significantly increase the compressive strength of the earthen materials after immersion and allow to avoid the addition of hydraulic binders in earthen blocks to obtained a strong water resistance. The water diffusion in the sample during the immersion can be linked to capillary absorption behaviour, thus a water content and a compressive strength after a given time of immersion could be easily predicted.
Earth-Based Mortars: Mix Design, Mechanical Characterization and Environmental Performance Assessment
Authors: Paiva Rayane de Lima Moura , Martins Adriana Paiva Souza , Caldas Lucas Rosse , Reales Oscar A.M. , Toledo Filho Romildo Dias
Published: January 2022

The incorporation of sustainable materials in the civil construction sector has grown in recent years to minimize environmental impacts. Among these materials, the use of earth, a local raw material that does not require much energy for its processing, appears as an advantageous and promising alternative. Earth mortars stabilized with natural binders, when compared to conventional mortars, can have technological, economic and environmental advantages. The objective of this work was to develop an earth-based mortar stabilized with mineral binders using a 1:3 binder to aggregate mass proportion, and to evaluate its fresh and hardened state properties, as well as its environmental impacts using Life Cycle Assessment (LCA) with a cradle to gate scope. The selected materials were divided in four groups: (i) cement, hydrated lime, fly ash and metakaolinite (binders), (ii) natural sand and coarse fraction of the earth (aggregates), (iii) calcium chloride and superplasticizer (additives) and (iv) water. In the matrix formulation the clay fraction from earth constituted the majority of the binder. The selection of supplementary cementitious materials as additional binders provided improvements in workability and mechanical properties of the mortar. A mix design was carried out using different cement (5; 7.5 and 10%) and fly ash (11; 13.5 and 16%) mass percentages. The water/binder material ratio, superplasticizer content and calcium chloride content were 0.65; 2% and 1%, respectively. The results showed that an increase in fly ash content combined with a decrease in cement content provided an increase in workability and a decrease in mechanical properties of mortars. Nevertheless, the mechanical performance of the mortars remained above the minimum values prescribed in Brazilian construction codes. From the results analysis it was concluded that partial replacement of cement by fly ash provided greater workability in the fresh state and reduced the environmental impacts of the earth-based mortar.
How can a Climate-Neutral Building Look Like?
Authors: Carcassi Olga Beatrice , Habert Guillaume , Malighetti Laura Elisabetta , Pittau Francesco
Published: January 2022

The climate crisis is urging us to act fast. Buildings are a key leverage point to reduce greenhouse gas (GHG) emissions, but the embodied emissions related with their construction remain often the hidden challenge of any ambitious policy. Considering that a complete material substitution is not possible, we explore in this paper a material GHG compensation where fast-growing bio-based insulation materials are used to compensate building elements that necessarily release GHG. Looking for analogies with other human activities, different material diets as well as different building typologies are modelled to assess the consequences in term of bio-based insulation requirement to reach climate-neutrality. The material diets are defined according to the gradual use of herbaceous materials, from the insulation up to the structural level: omnivorous, vegetarian and vegan. Our results show the relationship in terms of volume between the climate intensive materials and the climate-negative ones needed to neutralize the overall building GHG emissions. Moreover, they suggest how climate-neutral building can look like and that it is possible to have climate-neutral buildings with wall thickness within the range of current construction practices.
Effect of Mix Proportions on Fresh and Rheological Properties of Cementitious Mixture Containing Natural Fibre: Modelling Using Factorial Design
Authors: Kaushik Sandipan , Sonebi Mohammed , Amato Giuseppina , Perrot Arnaud , Das Utpal Kumar
Published: January 2022

This paper aims to discuss the influence of mix composition of cement mortar on fresh and rheological properties of cement mortar. Two different natural fibres, basalt (BA) and sisal (SL) are selected based on fresh and rheological behaviour for its usability in a cementitious mixture. The workability and rheological behaviour are evaluated by flow table test, cone penetrometer and slump test of the mixture. A full factorial design method was used to investigate the effects of four mix components: dosage of cement content (B), percentage of fly-ash (FA) by mass of cement, dosage of basalt fibre (BA) and dosage of superplasticizer (SP) along with a water/binder ratio of 0.41. A mathematical model which predicts the main effect and interactions of these components for each of the measured properties are derived using the factorial design. The proposed mixtures consist of two levels of binder content as 550 kg/m3 and 650 kg/m3, FA as 5% and 20% by mass of cement, BA as 1 kg/m3 to 3 kg/m3 and SP as 2 kg/m3 to 4 kg/m3. By reducing the number of test batches needed, the mathematical models produced with this method can expedite optimizing the mixture proportions of cement mortar to achieve desired fresh and rheological properties.
Experimental Investigation on the Fracture Energy and Mechanical Behaviour of Hemp and Flax Fibre FRC Compared to Polypropylene FRC
Authors: Da Costa Santos Ana Caroline , Archbold Paul
Published: January 2022

Natural fibre reinforced concrete is been studied for many years as a more sustainable option to current reinforced concrete used in industry. The most common fibre materials currently adopted are steel, glass and synthetic fibres. Apart from the high oxidation and cost, their environmental impact is a serious issue as they are petroleum-based materials. This study assesses the feasibility of replacing polypropylene fibre with hemp and flax fibres. According to the inventory of carbon and energy (ICE) the embodied energy of polypropylene (PP) is 95.4MJ/kg and the embodied carbon is 4.98kgCO2/kg during its lifetime. It represents approximately 3 times more than the estimated values for vegetable fibres. For this, Different concrete mixtures reinforced by 0.5% to 1.0% of hemp, flax and polypropylene fibres were tested, and their post-crack flexural tensile strength, elastic’s modulus, compressive strength and fracture energy were evaluated. The mixtures containing hemp fibres presented properties equivalent to those containing polypropylene under the same proportion. Although both compressive and tensile strength were reduced for the mixes containing flax fibres, the Young’s modulus was 49% smaller and could be an interesting approach for applications that require better elasticity from the concrete, such as industrial floors and structures that may be submitted to impact.
Experimental Out-of-Plane Behaviour of a Rammed Earth Sub-Assemblage Subjected to Seismic Inputs
Authors: Romanazzi Antonio , Oliveira Daniel V. , Silva Rui A. , Candeias Paulo X. , Costa A. Campos , Carvalho Alexandra
Published: January 2022

Rammed earth technique is spread worldwide, representing the local identity of many cultures for which they must be preserved. Yet, rammed earth heritage is also well known for its high seismic vulnerability and despite the increasing concern for this aspect, few investigations were conducted on dynamic response of such structures. In this framework, an experimental program was undertaken on a rammed earth mock-up by means of shake table tests carried out at the National Laboratory of Civil Engineering (LNEC) in Lisbon. To investigate the out-of-plane behaviour of rammed earth walls, a mock-up was built in real scale with a U-shape and then subjected to a series of increasing seismic inputs. The results are here discussed in terms of damage, displacements and base shear coefficient. In conclusion, the model behaved as a rigid block to earthquake excitations.
Tackling Variability of Clay to Provide a Robust Binder
Authors: Ardant Daria , Brumaud Coralie , Habert Guillaume
Published: January 2022

Locally available and with infinite recycling possibilities, the use of earth as building material leads to one of the lowest environmental impacts in the construction sector. Recent advances in the earth materials field have been made based on concrete and ceramics technologies to facilitate its uses in dense areas. It is possible to modify clay particle interactions and the material's whole behavior by adding inorganic dispersants and flocculants into clay paste. Earth becomes easy to cast and unmold into formworks, and by removing cement in its composition, poured earth can reach a low CO2 emission rate. Even if this technology is promising, further work has to be performed, as it cannot be implemented on earth from excavation sites with high variability. Tackling the clay nature variability is now the main issue to push this product on the market with robust properties. This research investigates the robustness of the poured earth binder. In this way, several clays (three montmorillonites, two kaolinites, and binary mixes at different proportions) were investigated. Their compacity (C) was determined following the water demand protocol with Vicat apparatus and compared to their consistency properties (liquidity and plasticity limits), and a correlation between these values is established. Different clay pastes prepared at different solid volume fractions were tested to define the influence of the clay nature on the paste consistency evolution. The results showed that clay nature for paste at high solid volume fraction does not influence constituency's evolution when their respectivecompacity is taking into account. It can be suggested that for a clay binder with a consistency close to C, which might be mandatory for poured earth application, only the swelling capacity might influence the mix design.
Effect of Plant Fibres on the Variability of Cob Materials
Authors: Tchiotsop Junior , Issaadi Nabil , Poullain Philippe , Bonnet Stéphanie
Published: January 2022

Earthen materials have different nature components and present a high variability comparing to conventional materials; researchers try to settle it down for a future normalization as environmentally efficient material. But there is a need in energy to do it, either directly (compaction, organic matter extraction, particle screening to get the best particle size distribution ...) or indirectly by including inefficient materials from an environmental perspective (cement, limestone ...). The aim of this study is to follow the variability problematic of cob materials by comparing and understanding variation level of the hygrothermal characteristics due to fibres nature and fibres content. We found that plant fibres (hemp, flax and hay) act as a stabilizer for dry bulk density; at 1% fibres substitute, hemp fibre composites show the highest coefficient of variation on the thermal properties (6.1% on thermal conductivity, 18.74% on specific heat capacity) but flax fibres show the highest mean values. Increasing hay stalk content induces the spread of the hygrothermal properties inside their range of variaation.
Construction Field Monitoring of a COB Prototype Building
Authors: Azil Athmane , Le Guern Malo , Touati Karim , Gomina Moussa , Sebaibi Nassim , Boutouil Mohamed , Streiff François , Goodhew Steve , Louahlia Hasna
Published: January 2022

Cob is an earthen building material made by soil, fibres and water used for millennia. However, cob construction disappeared out during the nineteenth century. These last years, it is experiencing a renaissance in Northwestern France and Southern England. Due to a limited technical knowledge, the investigation of engineering properties is important for modern design practice and code requirements. Moreover, to ensure building properties, it is necessary to have same quality mix along the building phases. The aim of this study is to determine material variation during the monitoring of a cob prototype building in Normandy (France). This study investigated structural cob mix composition, water content, density, mechanical properties and thermal conductivity. Specimens shape used were cylindrical 110 x H220 mm and prismatic 300 x 300 x 70 mm. Results indicated a variation in cob mix (water content, materials proportions) between three different lifts. These variations lead to different densities and, consequently, to variables compressive strengths: 0.99 to 1.38 MPa and thermal conductivities from 0.610 - 0.816 W.m-1∙K-1.
Effect of Viscosity Modifying Agent on the Performance of Hybrid Bio-Based Concrete
Authors: Sonebi Mohammed , Thiele P. , Abdalqader A. , Dvorkin Leonid I. , Lushnikova Nataliya , Khatib J.
Published: January 2022

An experimental investigation was conducted in order to study the water absorption, mechanical performance, thermal properties and durability of hybrid hemp-rapeseed composite materials. The hybrid composite material is made with 50% hemp shives and 50% rapeseed fibres. The purpose of this study is to investigate the influence of the incorporation of viscosity modifying agent (VMA) on hybrid concrete. Four mixes were made for: shuttered walls and roof insulation with and without VMA. The water absorption of the hybrid composite fibres was, first, measured. The compressive strengths of these mixes at 7 and 28 d were then determined in order to compare the mechanical behaviour of the hybrid composite materials made with VMA. In addition, the capillary absorption and coefficient of thermal conductivity were also measured. The results revealed that VMA improved the performance of the hybrid concrete.
Overcoming the Perceptual Gap: Worldwide Perceived Comfort Survey of Earthen Building Experts and Homeowners
Authors: Ben-Alon Lola , Loftness Vivian , Harries Kent A. , Cochran Hameen Erica
Published: January 2022

Earthen building materials are a critical future for sustainable construction because they are locally available, minimally processed, and waste-free. However, despite their advantages, earthen materials still face challenges for comprehensive implementation. First, their technical data vary significantly, making it challenging to quantify their true performance for different climates and environmental contexts. Second, people mistakenly perceive these materials as low-tech and poor in their performance. Lastly, building codes and standards do not comprehensively represent these materials worldwide. This work identifies perceptual barriers that hold back the broader implementation of earthen materials in order to ascertain possible solutions and assess the performance of earthen buildings and perceived comfort among primary resources such as practicing professionals and people who live in earthen houses. The results of an online survey of 126 earthen building experts and homeowners are presented, providing important insights regarding a range of barriers to, and motivating factors for, the implementation of earthen materials, as well as design and thermal performance aspects of existing earthen homes. The results of the surveys show that, of the various earthen building techniques, light straw clay requires the lowest maintenance, and construction of adobe and/or clay plaster encountered the least barriers to implementation. The energy performance of existing earthen homes show that all types of earthen materials reduce the need for cooling, in all climate zones. Insulation over earthen walls was shown to increase occupants’ perceived comfort levels, but only slightly. Additional results provide significant recommendations for future research on thermal performance and comfort guidelines for earthen structures. This study contributes to the development of environmental and policy measures that could be used by policymakers by synthesizing technical and environmental data and by identifying means of improving the perception of natural building.
Biological Stabilisers in Earthen Construction: A Mechanistic Understanding of their Response to Water-Ingress
Authors: Kulshreshtha Yask , Vardon Philip J. , Du Yi , Habert Guillaume , Vissac Aurélie , Morel Jean-Claude , Rao Sudhakar M. , van Paassen Leon , van Loosdrecht Mark C.M. , Mota Nelson J.A. , Jonkers Henk M.
Published: January 2022

Earthen construction is re-gaining popularity as an ecological and economical alternative to contemporary building materials. While building with earth offers several benefits, its performance due to water ingress is a concern for its widespread application. This limitation is often solved by adding chemical stabilisers such as Portland cement and hydraulic lime. Chemical stabilisers are a subject of widespread debate as they increase the cost and embodied energy of the structure, and reduce the desirable characteristics of raw or unstabilised earth. This along with perceived environmental performance, renewability, and proven effectiveness in traditional earthen construction has led to a growing interest in biological or organic stabilisers. Although the strengthening mechanism of biological stabilisers is widely covered in scientific studies, discussion regarding the water-resistance is limited. This review aggregates the research from the field of earthen construction and geotechnical engineering and extends it to explain the possible mechanism responsible for the water-resistance behaviour of biologically stabilised earthen materials. This study includes a wide range of traditional and industrial biological stabilisers derived from animals (cow-dung, casein, chitosan), plants (starch, guar gum, cactus mucilage, lignin, tannin) seaweeds (alginate, agar, carrageen) and microbes (xanthan gum, gellan gum). A conceptual model of water-ingress in unstabilised earthen blocks is proposed and the response of biological stabiliser to water ingress and related physico-chemical and physical factors is discussed using the model at microscale (stabiliser interaction with clay, sand) and macroscale (hydraulic conductivity of block). Properties of stabilisers such as hydrophobicity, stability under wet conditions or interaction with cations have a dominant effect on the overall response to water ingress. Key gaps have been identified in the existing knowledge that are necessary to investigate in order to understand the water-resistance behaviour comprehensively. The study concludes with a brief assessment of biological stabilisers based on their performance and feasibility to use in contemporary earthen construction.
Influence of the Variability of Limestone and Fly Ash on the Setting and Mechanical Properties of a Moroccan Composite Cement
Authors: El Fami Nisrine , Agourrame Hind , Khachani Nacer , Boukhari Ali , Diouri Adeljebbar
Published: January 2022

The Moroccan cement industry is looking for new processes to effectively minimize the high energy costs associated to cement manufacturing. This work presents the effect of three types of limestone with different chemical compositions and different CaCO3 contents on the physical and mechanical properties of resulting composite cements by the addition of fly ash in the proportions by weight of: 5 % and 10 %. The samples are studied in order to evaluate the interaction between different types of limestone and fly ash. Ternary cements based on fly ash-limestone-clinker induce a significant prolongation of the setting time compared to binary cements based on limestone-clinker. The substitution of clinker by limestone induces an improvement in mechanical strength compared to ternary cements in the first days; at 28 days, cements prepared with fly ashes reach significant strength due to their pozzolanic reaction.
Risk for Mould Growth on Hemp-Lime at Different Relative Humidity
Authors: Johansson Sanne , Balksten Kristin , Strandberg-de Bruijn Paulien Brigitte
Published: January 2022

Microbial growth often thrives in humid conditions, at high relative humidity. Moulds are complex organisms; many types of mould are able to survive strong variations in humidity and temperature, such as those on building façades. For some building materials a critical relative humidity is determined, which functions as a theoretical threshold; at this (or lower) relative humidity microbial growth will likely not occur. Hemp-lime is a building material that consists of hemp shiv (the woody core parts of the hemp stem) and building lime. It is a material that can be used for walls, and even though it has been used for more than 20 years, thusfar little is known about its critical moisture levels for microbial growth. The aim of this research was therefore to determine at what relative humidity microbial growth occurs on carbonated hemp-lime material, and to study if there is a protective influence of a carbonated lime binder on the hemp shiv. The objective was to study microbial growth on hemp shiv, hemp-lime and on hemp with a thin layer of lime at three relative humidity (75 %, 85 % and 95 %) and at two different temperatures (15°C and 23°C); conditions that could occur naturally in a hemp-lime façade exposed to high rain loads in a northern European climate. Hemp shiv seems to have a relatively low resistance to microbial growth, similar to that of wood. However, because the hemp is protected by lime it can withstand much higher relative humidity without microbial growth occurring on the material. The critical moisture level for hemp-lime seemed to occur between 75 and 85 % RH, while the material was completely without microbial growth at 75 % RH. The lime had a protective effect on the hemp and acted as a mould inhibitor, both over time and with varying temperature and humidity.
Plant Biomass Used for Green Concrete: A Review of Treatment Methods
Authors: Chaussy Mariann , Chabannes Morgan , Day Arnaud , Bulteel David , Becquart Frederic , Laidoudi Boubker
Published: January 2022

Human activities require a growing need for raw materials. In order to contribute to sustainable development, many business sectors are focusing on biomass valorization. Whether from dedicated crops or first industrial processing, it generates materials with high potential that can be used in many fields. Non-food uses mainly concern the energy, chemical, and construction sectors. Whatever the intended application, a pre-treatment stage is essential to clean the material and/or to access a specific fraction. An additional modification may occur in order to endow the material with a new function thanks to a process known as functionalization. Uses of plant fractions (aggregates) in combination with cement offer advantages like low-density materials with attractive thermophysical properties for building. However, their development is limited by the compatibility of crop by-products with hydraulic binders such as Ordinary Portland Cement (OPC). This includes delays in setting time and hydrophilic character of vegetal components and their interaction with an alkaline environment. The aggregate/cement interfaces can therefore be strongly affected. In addition, the diversity of crop by-products and mineral binders increases the level of complexity. In order to overcome these drawbacks, the treatment of plant fractions before their use with mineral binders may result in significant benefits. In this way, various treatments have been tested, but the methods used at an industrial scale remain relatively under-researched. The purpose of this review is therefore to highlight the mechanisms involved in each specific process, thus justifying the operating conditions specific to each. This bibliography study aims to highlight potential treatments that could apply to biomass before their mixing with cementitious binders. According to the objective, a distinction can be made between extraction processes as hydrothermal or solvent treatments, assisted or not, and structural modification processes as surface treatments, impregnation, or grafting.
Synthesis of the Current Knowledge Concerning the Construction of French Traditional Cob Building for Giving Recommendations
Authors: Bonnet Stéphanie , Alzeort Darwish , Poullain Philippe
Published: January 2022

The museum of the “Bourrine du bois Juquaud” is a tourist site located in the town of Saint Hilaire de Riez in France. It presents the daily life of the inhabitants of the marsh in the early twentieth century and their traditional earthen houses called Bourrine. The Bourrine is a cob construction with reed roof. The earth used for walls is soil from marshlands added with dune sand and straw fibres but some part are without fibres like coating applied on walls. By now, the knowledge acquired on the implementation of these mixtures for the lifting of the walls are oral knowledge and it is necessary to ensure the preservation of this traditional heritage. Currently the done reparations present cracks due to shrinkage. This study aims at well defining the mixtures by a scientific approach. The earth and dune sand were analyzed by taking cores from different existing bourrines and also by extracting soil on site. Different mixtures were produced by varying the proportion of earth sand and water. The linear shrinkage were measured. Corrections were done to get the best mixture for manufacturing and repairing the Bourrines.
Hygrothermal Behaviour of Air Lime Coatings with Mussel Shell Sand
Authors: Martínez-García Carolina , González-Fonteboa Belén , Carro-López Diego , Martínez-Abella Fernando , Faria Paulina
Published: January 2022

Air lime coating mortars with mussel shells exhibit useful hygrothermal properties related to humidity and temperature regulation. Introducing mussel shell sand produces a significant increase in pore volume, changing mortar’s microstructure and reducing density. This is attributed to the flaky and irregular shape of the shell particles that present also traces of organic matter. In this work, the natural aggregate is replaced by mussel shell sand in increasing percentages of 25%, 50% and 75%. Additionally, a mortar with 0% of sand replacement is used as baseline of reference. These mortars are tested focusing in two main parameters, in first term, thermal conductivity. And also absorption and desorption cycles, at 80 and 50% relative humidity. The results are very positive for mussel shells specimens, it can be concluded that the use of mussel shell aggregates can improve the hygrothermal properties of air lime coating mortars. Another interesting result is a subjective property such as the aesthetic quality of the finishing, the results is pleasing and, combined with the promising hygrothermal properties opens a good opportunity for mussel shell mortars.
Evaluation of GHG Emissions from the Production of Cross-Laminated Timber (CLT): Analysis of Different Life Cycle Inventories
Authors: Caldas Lucas Rosse , Sierra-Pérez Jorge , Toledo Filho Romildo Dias , Silvoso Marcos
Published: January 2022

The Cross-Laminated Timber (CLT) has been receiving special attention in recent research as an alternative for climate change mitigation since it is a renewable source and can remove and stock high amounts of CO2 from the atmosphere. Some countries, such as Brazil, still do not have mature and large CLT industry. However, the development of this industry in other countries is expected since the CLT is considered the main wood material to be used in high-rise mass timber buildings. It is particularly important to have environmental information, especially concerning the climate change impacts, in terms of life cycle greenhouse gas (GHG) emissions, for this product to increase its competitiveness in a new market. In this context, this research aimed to evaluate three different Life cycle inventories (LCIs) for CLT production of studies from Japan and the United States. Based on the first findings, we summarized the critical items in the LCI of CLT production and listed some actions for the reduction of GHG emissions that occur in this process. The LCIs are adapted considering the context of Brazil (a country with a cleaner electricity matrix) and China (a country with the highest share of fossil fuels). The main inconsistencies present in the LCIs are presented and discussed. The GHG emissions are concentrated in the following hotspots: (1) Roundwood production; (2) electricity consumption; and (3) adhesives production for CLT production. Therefore, the reduction of the consumption of these materials and activities should be encouraged for the decrease of GHG emissions. The data of Roundwood used in the modelling severely affects the final results. Their GHG emissions are related to the consumption of diesel in forestry activities. This research brings insights into the evaluation of the life cycle GHG emissions from the production of CLT.
Physical Properties and Hygrothermal Behavior of Mycelium-Based Composites as Foam-Like Wall Insulation Material
Authors: Gauvin Florent , Tsao Vesta , Vette Joost , Brouwers Henricus Jozef Hubertus
Published: January 2022

This research aims to study mycelium-based composites (MBC) by assessing their performance as foam-like wall insulation material. Various substrates have been selected to get optimized performance of the composite. Results showed that a prolonged growing period arose a denser mycelium outer layer in MBC, which rendered better water resistance due to the hydrophobicity of mycelium. Thermal conductivity and mechanical properties are highly dependent on substrate choices than other parameters of MBC, which coincided with the literature. Additionally, influences of accelerated aging test and moisture buffer capacity of MBC were first studied in this research. The results indicated that MBC not only maintained good functional performance after the accelerated aging test (i.e. drying and wetting cycles) but also constituted good moisture buffer capacity. This means that MBC has key material essences to apply as internal wall insulation material and become one of the layers in vapor-permeable building envelope systems to passively regulate indoor relative humidity and thermal comfort.
Stabilization of Dicalcium Silicate-Zn Composite Approaching Layered Double Hydroxide Structure for Bioactive Cement Applications
Authors: Agourrame Hind , Belafhaili Amine , El Fami Nisrine , Khachani Nacer , Alami Talbi Mohamed , Boukhari Ali , Diouri Adeljebbar
Published: January 2022

Layered Double Hydroxide (LDH) is ionic clay that is characterized by the union of metal cations and OH- hydroxides. LDH composites exhibit considerably high releasing and recharging capacity and have applications as bioactive cements. They can be prepared by direct co-precipitation of metal salts at controlled pH. The preparation is carried out from an acid solution of Zn (NO3)2.6H2O, Al (NO3)3.9H2O and a basic solution of Na2CO3 and NaOH, with a Zn/Al ratio = 3, the pH is stabilized between 9 and 9.5 at a constant temperature of 45°C. The objective of this study is to incorporate Zinc and Aluminum elements at different percentages in dicalcium silicate phase to produce C2S phase incorporating LDH composite. The characterizations of the developed phases by XRD and SEM indicate the formation of stoichiometric LDH phases Zn6Al2(OH)16CO3.4H2O and non-stoichiometric Zn0.61Al0.39 (OH)2(CO3)0.195.xH2O, the incorporation of Zn in the belitic C2S phase and not Al. The obtained micrographs by SEM(EDAX) analysis show new morphology of the stabilized composite.
Environmental Performance of Wood Bioconcretes with Different Wood Shavings Treatments
Authors: Aguiar Amanda Lorena Dantas , Bezerra Carolina Goulart , Caldas Lucas Rosse , Bernstad Anna S. , Toledo Filho Romildo Dias
Published: January 2022

The wood bio-concrete (WBC) production is a solution for the advancement of sustainable construction, since it has the potential to recycle waste in the form of shavings generated in wood processing and stock CO2, contributing for climate change reduction. However, the chemical incompatibility between plant biomass and cementitious matrix leads to the need for previous treatment of wood shavings to application in bio-concretes. In the present study, one heat treatment and two alkaline treatments with immersion in Ca (OH)2 solution were evaluated using Life Cycle Assessment (LCA) methodology. The environmental modeling was performed by SimaPro, using the Ecoinvent database, and primary data collected in the laboratory. The potential environmental impacts were related to the compressive strength of produced WBC (in MPa) as an ecoefficiency indicator. Considering the functional unit of mechanical performance, the alkaline treatment with two immersions was the one that generated less environmental impacts.