Fabric Reinforced Cementitious Research Articles

3D Textile Reinforced Cement (TRC) composites with integrated synthetic microfibres: Evaluation of mechanical response and crack formation in bending

This study explores the integration of short synthetic microfibres into 3D Textile Reinforced Cement (3D TRC) composites to achieve enhanced flexural capacity and improved crack control. The homogeneous distribution of microfibres within 3D TRCs was a challenge unaddressed in the current state of the art. The influence of the added microfibres on the bending behaviour and crack formation of the 3D TRCs was evaluated, along with the effect of crucial parameters such as the microfibre type (PP/PVA), length (3 mm/6 mm/8 mm) and content (0.5 %/0.7 %/1.0 %). Microfibre-enhanced 3D TRCs demonstrated a higher ultimate load and post-cracking stiffness, as well as more and narrower cracks.

Confinement of masonry columns with FRCM: A new confined strength formulation and experimental validation

In this work, a wide experimental dataset about the axial behavior of masonry columns confined with Fabric Reinforced Cementitious Matrix (FRCM) jackets (also refered to as TRM - Textile Reinforced Mortar or TRCC - Textile Reinforced Cementitious Composites), that contains the results from 226 confined specimens, was collected. Data were critically analyzed with the aim of identifying the influence of the most important parameters considered within the dataset (i.e., fibers type and number of layers, masonry type and unconfined strength, mortar type and mechanical strength, the effective lateral pressure, etc.). Further, a review of the main models proposed in different Codes and in literature was carried out, which were then applied to the dataset, highlighting some discrepancies in their predictions. Thus, a new formulation for the confined strength of masonry columns was proposed, aiming to consider also some other influencing variables such as the compressive strength of the masonry blocks and that of the mortar joint. Lastly, the validity of the proposal was verified on a new set of experimental results, which were obtained by the authors testing three unconfined and confined clay brick masonry columns. Specimens were subject to monotonic axial loading under displacement control until failure, and stress and strains were monitored continuously during the test. The jacketing system was realized with one layer of glass-based FRCM (GFRCM).

Shear stress analysis in the textile-to-matrix and TRC-to-masonry interfaces of Textile-Reinforced Cement (TRC) applied to masonry using distributed fibre optic sensors

Masonry has been used extensively in civil engineering for centuries. However, various factors can reduce its performance over time. To extend its life and increase its load-bearing capacity, it needs to be reinforced. Strengthening with composite materials, in particular with Textile-Reinforced Cementitious (TRC) matrix composites, has proven to be effective. However, the assessment of the load transfer between TRC and masonry, as well as between matrix and textile at the core of the TRC remains a significant scientific challenge for optimal reinforcement. In this context, this paper aims to contribute to the understanding of the load transfer mechanisms at these interfaces, particularly for shear behaviour.To this end, this study investigates the reinforcement of masonry using TRC. Six different configurations of TRC-to-masonry prisms were subjected to single-lap shear bond tests: two types of textile reinforcements, two types of matrices and two reinforcement ratios. These six configurations were instrumented by distributed fibre optic sensors in the core of the TRC. These sensors measured the mechanical strains of the matrix and textile in the core of TRC with millimetric spatial resolution. From these strains, the local shear stresses and bond behaviour of the textile-to-matrix and TRC-to-masonry interfaces were experimentally quantified, assessed and analysed. A decreasing parabolic trend of these shear stresses along the effective length was obtained before the appearance of cracks, while cracks considerably modify this trend.The contributions of the matrix and the textile to the interface shear stresses were assessed. Before cracking, the contribution of the matrix prevails, while after cracking, the contribution of the textile is predominant. The shear stresses over the TRC thickness were also quantified and analysed. The debonding at the textile-to-matrix interface was tracked and analysed before, during and after crack propagation in TRC. The results obtained confirm that this debonding evolution can be predicted by pull-out tests.

Elastic and electromagnetic monitoring of TRC sandwich panels in fracture under four-point bending

Textile-reinforced cementitious (TRC) sandwich panels with insulation core are mechanical- and material-efficient composites, however, under service loads might develop complex fracture that is still inadequately detected. Among damage mechanisms, the weak core-facing interfacial bond can substantially reduce its load-bearing capacity and lead to premature failure; therefore, early detection of damage is crucial to guarantee optimal long-term structural performance. Periodic inspection is necessary during the service life, however, there is neither a standardized methodology nor monitoring protocol that detects and characterizes premature interfacial debonding. In this study, a novel multi-modal monitoring is developed for the first time, based on acoustic emission (AE), digital image correlation (DIC), and millimeter wave (MMW) spectrometry, to characterize the response to bending of TRC sandwich beams. The core-facing interlaminar bond is artificially weakened during casting to simulate manufacturing defects. The proposed methodology showed high sensitivity to damage and complementarity of the techniques, where, AE allowed to characterize and locate damage, MMW showed high sensitivity to progressive failure, and DIC provided the strain data to validate and interpret AE, and MMW results.

Combining 3D textiles and synthetic microfibers for a sustainable strain-hardening behavior in cementitious materials

Concrete and traditional cement have a significant environmental impact. As they will continue to be used abundantly, solutions are necessary to ensure a more sustainable application. The use of metallic reinforcements in cementitious material leads to environmental and durability concerns as well, such as corrosion. A new way of reinforcing cementitious materials is combining 3D textiles with synthetic microfibers. This reinforcement combination, with naturally higher corrosion resistance, can lead to slender, lighter, and more durable structures. The 3D textiles guarantee the loadbearing capacity while the synthetic microfibers limit the crack widths to an acceptable range in which the cracks can be healed through the autogenous healing of the cementitious material. This limits the necessity for maintenance and repair works, increasing the service life of future civil works. Synthetic microfibers, 3D textiles and cementitious matrix synergistically interconnect, leading to a different mechanical performance which needs to be studied. In this paper, the effect of the addition of microfibers to 3D Textile Reinforced Cements (3D TRCs) is investigated, evaluating the influence of the fibers themselves, as well as their content and length. Two types of polypropylene (PP) microfibers with a length of 3 mm and 6 mm are selected. Using four-point bending tests linked with Digital Image Correlation (DIC) monitoring, the strain-hardening behavior, bending behavior and crack formation of 3D TRC specimens with and without added microfibers are investigated. Generally, using 3D textiles, a superior flexural response is already obtained compared to 2D textiles due to the anchorage mechanism of the transversal connections. However, a higher ultimate load and post-cracking stiffness are achieved upon using synthetic microfibers, showing the positive effect of the reinforcement combination. A higher fiber content and longer fiber length amplify this effect. Furthermore, the addition of microfibers generally results in the formation of more and narrower cracks.

Sustainable insulation solutions for hydroponic greenhouses: The effects of textile waste reinforcement on thermal microclimate

Recycling waste into construction materials represents an adequate solution to both the problem of energy shortage and environmental pollution problem. This study investigated the impact of incorporating textile waste in cementitious blocks to improve the microclimate of greenhouses. The study involved a year-long experimental investigation of a transparent greenhouse (Ref_Gh) and a thermally insulated hydroponic greenhouse (THP_Gh), followed by the development of a numerical model to assess the thermal environment of a hydroponic greenhouse (TRC_Gh) built with cement blocks made by replacing 30% of the sand volume with textile fibers. The results showed that the daytime temperature variation inside the TRC_Gh was 2 °C higher than in the THP_Gh, but still much lower than that in the Ref_Gh. However, the reference greenhouse showed the lowest temperature values at night. The TRC_Gh showed a significant heat demand at night, higher than the demand for the THP_Gh but still lower than the demand for transparent shelter, peaking at 90 W/m2 in December. The study concluded that a hydroponic greenhouse built with textile-reinforced cement blocks offers better thermal performance than a greenhouse made with Plexiglas, but thermal-panel greenhouses still offer the best thermal performance. However, an economic analysis showed that a TRC_Gh has a 1.3-year shorter payback period than a THP_Gh. Overall, this study highlights the benefits of recycling textiles into construction insulation materials. The novelty of this work lies in its approach to improving the microclimate of hydroponic greenhouses by integrating a new insulation material in an efficient and environmentally friendly way.

Multimodal NDT monitoring of TRC sandwich under bending and early detection of interlaminar debonding

Textile Reinforced Cementitious (TRC) sandwich composites provide a load-bearing, noncorrosive, lightweight, and durable alternative for steel-reinforced sandwich elements, and/or traditional steel-reinforced concrete. However, the composite nature of the material and slender nature of the facings render the fracture behavior complex. Insufficient interlaminar bond can cause premature debonding, substantially reducing the loadbearing capacity of the composite. Non-Destructive Testing (NDT) techniques seem the obvious choice to monitor the damage progression of the material without affecting, nor compromising the behavior of the composite, and predict their service life. In this study, TRC sandwich composites, subjected to quasistatic four-point bending, are monitored with three NDTs. Digital Image Correlation (DIC) allows to measure the surface strains and displacements. MMW Spectrometry, used for the first time in bending damage monitoring, allowed to detect damage such as cracking, or debonding, while Acoustic Emission (AE) allowed to localize and characterize internal cracking. In order to simulate premature debonding, the bond between the tensile TRC facing and the insulation, in the central zone, where the bending moment is maximum, was artificially destroyed. Results show that a weak interlaminar bond reduced the ultimate load of the composite by more than 50%. Additionally, DIC, AE and MMW Spectrometry proved useful to monitor and characterize damage. Multimodal data gathered from the multimodal NDTs showed to be complementary. DIC allowed to interpret AE and MMW Spectrometry data from a surface viewpoint, while AE parameters permit predictions at low load conditions, and detect internal cracking. For instance, the AE behavior at early load stage (less than 15% of the maximum load) of the TRC sandwich with destroyed bond showed significant differences than for the reference TRC sandwich. Specifically, it showed higher RA values, and lower AF than the reference TRC sandwich, suggesting more shear related early activity for, promoted by the damaged bond. Results were corroborated with DIC, while MMW Spectrometry seemed to follow closely the level of damage of TRC sandwich composites under quasi-static four-point bending. EWGAE 35, Ljubljana, Slovenia, 13th – 16th Sep. www.ewg

Acoustic emission monitoring of the textile reinforced cement (trc)-to-masonry shear bond

This study focuses on the potential of Textile Reinforced Cementitious (TRC) composites with alkali-resistant glass textile to reinforce masonry structures. In particular, a better identification of the debonding mechanisms is a crucial point for a more efficient use of these composites. Twelve single-lap shear bond tests are performed to investigate four strengthening configurations - two matrices and two reinforcement ratios. This paper discusses the applicability of acoustic emission to assess the damage state of TRC during adherence testing. The flexibility of the matrix used and the amount of reinforcement of the TRC affect the cumulative amplitude distributions. The accumulation of the partial frequency associated with high frequency (above 400 kHz) is a precursor of a strong contribution of the textile in the load transfer.

Improving the Anchorage in Textile Reinforced Cement Composites by 3D Spacer Connections: Experimental Study of Flexural and Cracking Behaviors

Textile-reinforced cement (TRC) composites can lead to significant material (and dimensional) savings compared to steel-reinforced concrete, particularly when applied in thin-walled structures such as façade panels, shells, etc. In conditions where the geometrical restrictions do not allow for sufficient anchorage, however, the exploitation of this reinforcement may be suboptimal and the TRC’s mechanical properties may decrease. As shown in the literature, the use of 3D textile reinforcement can lead to an improved anchorage in the reinforcement points and superior post-cracking behavior in terms of bending. The question remains as to whether similar improvements can be achieved using 3D spacer connections, inserted post-manufacturing of the textiles. Therefore, this research experimentally investigated the effect of discretely inserted spacer connections on the flexural properties and cracking behavior of TRCs. Six different TRC beam configurations—varying in the placement of the spacer connections over the span—were investigated. Moreover, a comparison was made with two additional configurations: one equivalent 2D TRC system (using the same in-plane textiles but without through-thickness connections) and one 3D TRC system using knitted 3D textiles (with spacer yarns uniformly distributed). The four-point bending tests were monitored via digital image correlation (DIC) to visualize the full-field cracking pattern. The experimental results showed that the spacer connections could strongly improve the post-cracking bending stiffness and the modulus of rupture (MOR) when placed close to the free end of the sample and could also lead to reduced crack widths when placed around the midspan.

Effect of accelerated aging and silica fume addition on the mechanical and microstructural properties of hybrid textile waste-flax fabric-reinforced cement composites

Incorporating eco-friendly substances obtained from recycled resources and industrial by-products is gaining increased acceptance among building materials. In this context, a cementitious matrix containing supplementary cementitious materials (SCMs) reinforced by recycled fibers may be a promising solution from both a durability and sustainability perspective. This study presents an extensive experimental program carried out on a cement-based composite with Silica Fume (SF), reinforced with recycled textile waste (TW) nonwoven fabric. Initially, the mechanical strength (compression and flexure) of the Portland cement paste substituted with variable SF content (0%–30%) was characterized. Based on the results, laminate plates having six TW fabric layers impregnated with three different cement pastes −0%, 15%, and 30% SF− were produced, and both the mechanical (flexural and direct tension) and durability (against wet-dry and freeze-thaw cycles) properties of the composite were assessed through testing. Experimental microstructural techniques including thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning and backscattered scanning electron microscopy (SEM and BSEM) were also used to complement the analysis of the mechanical characterization. The results suggested that the composite modified by 30% SF could protect fibers from embrittlement, thereby offering the greatest durability by increasing flexural and tensile resistances by up to 45% and 55%, respectively, as compared to the sample without SF in the wet-dry cycles. Indeed, the treated composite with 30% SF had almost equal performance in both unaged and aged conditions, showing a flexural strength in the range of 14.5–15.5 MPa and flexural toughness of 8.0–8.7 kJ/m2, suitable for the targeted applications including ventilated façades. The results and outcomes of this study may serve as the basis for future research on these composites and their potential use in structural applications in the building construction and housing industries.

Analysis of bond behaviour of textile-reinforced cement (TRC) applied to masonry using distributed fibre optic sensors and acoustic emission

The global and local mechanical bond behaviours of textile-reinforced cementitious (TRC) matrix composites bonded to masonry elements were investigated in this study. Single-lap shear bond tests were performed for six different configurations: two matrices, two textiles, and two reinforcement ratios. These composites were instrumented with distributed fibre optic sensors (DFOS), acoustic emission (AE) sensors, and digital image correlation (DIC). The DFOS were used to measure the evolution of the local internal strains of the TRCs before, during, and after the appearance of cracks. The AE sensors were used to assess the damage mechanisms of the TRC bonded to the masonry. The crack widths were measured using DIC. Combining these measurement techniques facilitated the assessment of the effects of the matrix, textile, and reinforcement ratio on the effective bond length of the TRC-to-masonry prisms. The results obtained from the TRC-to-masonry shear bond tests were then compared with the results of the tensile tests of the TRC composite to highlight the effect of the boundary conditions on crack widths.

Experimental characterization of comfort performance parameters and multi-criteria sustainability assessment of recycled textile-reinforced cement facade cladding

Within the building construction sector, fiber cement boards have attracted interest as facade cladding materials in the last ten years, especially those that incorporate –for reinforcing purposes– natural and/or recycled synthetic fibers (i.e, from the textile industry). So far, the design-governing parameters of facade cladding panels have been mechanical strength, durability, constructability, aesthetics, insulation capacity, and fire resistance. From the sustainability perspective, the impact of the facade on the economic and energy efficiency performance is most often the parameter that leads the decision-making process. Within this context, the quantification of the sustainability performance of the facade –accounting for economic, environmental, and social indicators– is unfrequently carried out in design and project phases, this being attributed to the lack of methodologies that allow considering and quantifying some relevant indicators representative of the facade sustainability performance. As consequence, decisions made based on solely economic and on some of the environmental indicators might lead to solutions with lower sustainability performance than that required (or expected). Recycled textile waste fabric-reinforced cement board as a facade-cladding material for building envelopes is the focus of this research. In order to characterize the fire resistance, and thermal and acoustic insulation –as relevant serviceability parameters– of this material, an experimental program was carried out. Likewise, the sustainability performance of this facade-cladding is assessed through a method based on the Integrated Value Model for Sustainability Assessment (MIVES). This multi-criteria decision making (MCDM) model relies on the value function concept and the multi-disciplinary participation of experts to identify and quantify the relevant indicators of the facade sustainability performance and the relative importance of indicators and requirements. The MIVES-based model generated for this research can be straightforwardly used for assessing the sustainability performance of facade-cladding techniques made of any material and for any type of building (and location). The application of the MIVES model led to the sustainability index of this new material for facade-cladding ranging from 0.68 to 0.71 (/1.00) for different weighting scenarios.

Numerical Investigation of Textile Reinforced Cement Structural Stay‐in‐Place Formwork Designed as Beam‐Column Joint Shear Reinforcement

This study investigates the feasibility and structural performance of textile reinforced cement (TRC) stay‐in‐place (SiP) formwork designed as shear reinforcement for beam‐column joints under monotonic loading through the nonlinear finite element package ABAQUS. This was achieved by conducting numerical analysis on 24 beam‐column joints using different parameters that affect the joints’ performance, including column axial load ratio, concrete compressive strength, beam tensile reinforcement ratio, joint shear reinforcement ratio, and thickness of TRC. The models were first calibrated to the results obtained from the experimental program of previous studies. The start of the yielding behavior of the composite beam‐column (73 kN) corresponds well to the conventional beam‐column joint (72 kN). A similar correlation can be observed at the ultimate load with only a 3.7% difference, 84 kN in the case of the composite beam‐column joint and 81 kN in the case of the conventional beam‐column joint. The findings of this investigation showed that a beam‐column with a full steel stirrup and TRC SiP formwork as shear reinforcement at the joint exhibits similar yielding behavior, such that TRC SiP formwork can replace the full steel stirrup at the joint, as proved by comparison analysis. Furthermore, the numerical analysis results due to the effect of these essential parameters on the structural performance of the beam‐column with TRC SiP formwork at the joint were also discussed.

Using acoustic emission to assess the tensile behaviour of textile reinforced cementitious (TRC) matrix composites

The tensile behaviour of textile reinforced cementitious matrix composites (TRC) is investigated using acoustic emission monitoring. Three carbon-TRC-composites with different reinforcement ratios are tested. An unsupervised pattern recognition technique is used to classify the signals. In combination with tests on TRC-components, these clusters of signals are correlated with matrix cracking, textile–matrix interface damage, shear frictional mechanisms and textile tensile behaviour. The contribution of each mechanism during loading is quantified. Finally, the acoustic data are compared qualitatively with the evolutions of crack width (measured by Digital Image Correlation) and load-transfer length (obtained by Distributed Fibre Optic Sensing measurement). A model to predict crack width from load-transfer length is proposed and gives satisfactory results. This paper shows that the local behaviour of TRC is reflected in acoustic activity and that AE offers valuable information about damage processes in TRC-composites.

Experimental Investigation on the Bending Behaviour of Textile Reinforced Concrete (TRC)

Textile-Reinforced Cement (TRC) was used in structural retrofitting and strengthening existing structures. While at present, recent studies have turned around using TRC as an independent structural element. This research presented an experimental study on the flexural behavior of TRC plates. Several parameters were taken into account, specifically, (a) the number layer of textile fiber materials (1, 2, and 3); (b) the configuration of the reinforcement (together or interface); (c) thickness of TRC plate (50, 70) mm. This study included preparing and testing twelve specimens; two specimens were un-reinforced, whereas the rest ten specimens were reinforced by dry carbon fiber textile. The results found that increasing the number of layers for both reinforcement configurations led to increased flexural capacity. Increasing the thickness of the plate has a negative effect on the flexural capacity for both reinforcement configurations. Finally, the interface reinforcement configuration with thickness 50 mm or 70 mm had higher flexural capacity than the specimens with together reinforcement configuration.

Size Effect on the Acoustic Emission Behavior of Textile-Reinforced Cement Composites

Acoustic emission (AE) is applied for the structural health evaluation of materials. It commonly uses piezoelectric sensors to detect elastic waves coming from energy releases within the material. Concerning cementitious composites as well as polymers, AE parameters have proven their potential to not only detect the existence of a defect, its location and the fracture mode, but also the developing strain field even before visible damage evolves. However, the wave propagation distance, wave dispersion due to plate geometry, heterogeneity and reflections result in attenuation and distortion of the AE waveforms. These factors render the interpretation more complex, especially for large samples. In this study, the effect of wave propagation on plain glass textile-reinforced cement (TRC) plates is investigated. Then, curved plates with different widths are mechanically loaded for bending with concurrent AE monitoring. The aim is to evaluate to what extent the plate dimensions and propagation distance influence the original AE characteristics corresponding to a certain fracture mechanism.

Comparing durability of steel reinforced grout (SRG) and textile reinforced mortar (TRM) for structural retrofitting

We assess tensile performance of Steel Reinforced Grout (SRG) and Fabric Reinforced Cementitious Matrix/Textile Reinforced Mortar, upon exposure to aggressive environments. Galvanized and brass-coated Ultra High Tensile Strength Steel fabrics are considered for SRG, while carbon, AR-glass, basalt and PBO fabrics are investigated for TRM, in a common cement mortar. Exposure to the aggressive environments is realized by specimen immersion for 1000 h (41.6 days) at controlled temperature in distilled water as well as alkaline, saline and acid solutions. Mechanical performance of rectangular 1-ply coupons is assessed in uni-axial traction: Ultimate strength and elongation, dissipated energy at failure and environmental conversion factors for design values are calculated and compared. It is found that significant performance difference exists in dependence of the aggressive environment under consideration. As a result, careful selection of the reinforcing fabric leads to substantial advantage in terms of durability, that should be capitalized upon at the design stage. A simple material selection matrix is presented which suggests the best reinforcing textile/aggressive environment combination for design purposes.

Influence of Loading Orientation and Knitted Versus Woven Transversal Connections in 3D Textile Reinforced Cement (TRC) Composites

As previous research has shown, the use of 3D textiles does not only facilitate the manufacturing process of Textile Reinforced Cement (TRC) composites but also influences the mechanical properties of the TRC. A fundamental understanding of the contribution of the transversal connections in the 3D textile to the loadbearing behavior of 3D TRCs is, however, still lacking in the literature. Therefore, this research experimentally investigates two different parameters of 3D TRCs; firstly, the 3D textile typology, namely knitted versus woven transversal connections, is investigated. Secondly, the influence of the stress direction with respect to the orientation of these connections (parallel or perpendicular) is studied. A clear influence of the orientation is witnessed for the woven 3D TRC system while no influence is observed for the knitted 3D TRC. Both woven and knitted 3D TRC systems show an increased post-cracking bending stiffness compared to an equivalent 2D system (with the same textiles but without transversal connections), yet the woven 3D TRC clearly outperforms the knitted 3D TRC.

Design, casting and fracture analysis of textile reinforced cementitious shells

The high potentials of thin, light-weight and slender textile reinforced cementitious (TRC) composites permits multi-layered, effective, highly-aesthetic and elaborated designs as launched nowadays: domes, vaults, free-form structures. Their casting and installation appear challenging requiring textiles secure mounting and in-time mortar casting. In this study, TRC roof shells are cast into a reusable formwork that provides controlled thickness and smooth surfaces. Casting is limited to a few hours with the minimum labor. TRC shells are tested under distributed loading. Digital Image Correlation measures online, in full-field the deflection and cracks opening. Acoustic Emission tracks cracks onset. It is demonstrated that at the early loading, TRC shells behave as a compressive element. Beyond cement strength, the textiles elongate to bear loading. In higher curvature shells, the stiffness rises and several wider cracks form. The catastrophic collapse is evaded, and ductility is achieved. TRCs demonstrate optimal performance with non-confined supports, offering new perspectives on free-form designs.

Experimental analysis and analytical modelling of the textile/matrix interface shear stress in textile reinforced cementitious matrix composites

This research work focuses both on experimental analysis and the development of an analytical model of the shear stress distribution at the textile/matrix interface of Textile Reinforced Cementitious Matrix Composites (TRCMC) in tension.For the experimental part, distributed fibre optic sensing (DFOS) was used, embedded in the core of the TRCMC, allowing strain measurement with a millimetric spatial resolution. Four configurations were studied: two types of matrices and two reinforcement ratios. Experiments comprised pull-out tests of several textile configurations using both matrices, in order to complete the experimental data set obtained by the tensile tests. The analytical model uses as input data the shear stresses obtained by the pull-out tests. This model allows to estimate the evolution and distribution of the interface shear stress of the TRCMC in tension. This model permits also to predict the distribution of strain in the TRCMC, both in the matrix and in textile reinforcement.