Durable Construction Research Articles

Experimental and numerical simulation of bond-slip in textile-reinforced concrete for multiple bond lengths

The rise in the use of lightweight and sustainable structural systems in the construction industry opened the chance to improve conventional construction methods. To produce a slender structural member, the use of textile in concrete, herein referred to as textile-reinforced concrete (TRC), has been explored. The textile used is primarily carbon, producing a lightweight and durable construction material. The TRC possesses vast possibilities in terms of its usage, however, identification of accurate bond-slip behaviour at the materials interface is one of the limitations that need to be addressed. Based on the literature, there are difficulties in determining the bond-slip relationship both experimentally and numerically, creating inconsistency in the results. This study aims to determine the bond-slip relation of TRC through pull-out tests and finite element analysis in order to replicate the actual bond-slip behaviour at the interface. The bond characteristics of TRC were assessed using pull-out specimens with different bond lengths of textile, i.e.; 20 mm, 40 mm, and 60 mm. A double-sided unsymmetrical test setup with equal clamp lengths is used for the experimental work. Using a tri-linear bond-slip interface relation, the numerical model is developed to establish the microscopic interface behaviour. The bond failure due to pull-out and rupture are observed in the pull-out test. Finally, the experimental results are compared with numerical modelling, and the results are in good agreement.

Evaluation of Fire Resistance of Polymer Composites with Natural Reinforcement as Safe Construction Materials for Small Vessels

In small vessels, for example, yachts, polymer–glass composites are mainly used for their construction. However, the disposal and/or recycling of composite units is very difficult. It is advisable to solve the problem of disposing of post-consumer items as soon as possible. Therefore, alternative, environmentally friendly, but also durable and safe construction materials are being sought. Such materials can be polymer–natural composites, which can be used as a potential material (alternative to polymer–glass composites) for the construction of small vessels. However, its performance properties should be investigated as new construction materials. The possibility of using polymer–hemp composites was assessed in terms of safety, i.e., the fire resistance of these materials. This paper compares selected characteristics that the reaction of composite materials has to fire with glass fiber and hemp fiber reinforcements. During the study, a natural composite reinforced with hemp fabric was investigated. Based on the laboratory test, it was found that this composite showed better susceptibility to energy recycling, with a relatively small deterioration in fire resistance compared to the composite reinforced with glass fiber. This material could therefore be a potential construction material for small vessels if we consider fire resistance in terms of the safety of the vessel’s operation.

Creep analysis of cementitious materials in seawater using a poro-chemo-mechanical model

With the rapid growth of the offshore engineering sector, studying the durability of offshore structures becomes primordial. Evaluating experimentally the coupling between mechanical and chemical degradation of the cement-based materials and structures is a challenging task because it requires tracking the evolution of the micro-mechanisms associated with the degradation in real time for long periods. To tackle this issue, a numerical approach is proposed, based on the micromechanics and the coupling between a creep-damage model and a chemical model at the microstructural scale. The seawater chemical effect on cement paste is simulated by considering the penetration fronts of the aggressive water and the attack by layers in the material. The aim of this study is to provide a tool for the rapid mechanical evaluation of the offshore structures and therefore a tool that can be used for the optimization and the development of durable marine constructions. The results highlight the competition between protective and damaged layers formed due to seawater attack, and that the global mechanical behaviour strongly depends on the chemically modified phases in the cement paste.

A review on FRP bars and supplementary cementitious materials for the next generation of sustainable and durable construction materials

As the problem of environmental deterioration becomes increasingly prominent, demand for reinforced concrete with favorable sustainability, durability and mechanical properties is growing. Fiber reinforced polymer (FRP) bar is more durable than traditional steel rebar. Supplementary cementitious materials (SCMs) are used as substitutions for cement, to reduce carbon emissions. A well-organized review on previous studies on FRP and SCMs is therefore necessary for developing the next generation of sustainable and durable construction materials. Therefore, this study aims to systematically compare the sustainability, durability and mechanical performances of FRP bars and SCM blended concrete. The sustainability of both materials are evaluated by their carbon emissions. The durability performance of FRP bars mainly includes resistance against alkali, chloride and freeze–thaw cycles. The durability performance of concrete includes resistance against alkali, chloride, sulfate attack, freeze–thaw cycles and carbonation. The effects of various SCMs on concrete are quantitatively analyzed. Analyses indicate that the alkaline corrosion of FRP bars may be mitigated by carbonating concrete. The combination of BFRP bars and carbonated SCM concrete potentially represents the next generation of sustainable and durable construction materials.

Optimization of the Granular Mixture of Natural Rammed Earth Using Compressible Packing Model

Rammed earth (RE) construction is an ancestral technique that allows for the building of durable and resistant constructions. RE buildings are sustainable and environment-friendly, and ensure energy optimization during the construction cycle. For these reasons, many of the following RE characteristics are studied: mechanical strength, seismic resistance, and thermal performance. However, the mix design of RE soils has been rarely studied. There is practically no scientific approach that allows for defining precise dosages of clay, silt, sand, and gravel used in RE materials. The broader aim of this article is to determine a scientific mix design method to find an optimal RE granular mixture. The compressible packing model (CPM) is applied to study the effect of every granular class on compactness and define the optimum mixture. Many tests have been conducted such as the Modified Proctor, compression test, and ultrasonic velocity pulse test to evaluate the relevance of this model. The results suggest many granular corrections for RE material that considerably enhance compactness and unconfined compressive strength (UCS). It was found that one granular correction provides a 137% increase in the initial UCS. Therefore, this approach enables the defining of which granular class is to be added or reduced to optimize the mechanical properties of RE.

Upcycling waste plastics to fabricate lightweight, waterproof, and carbonation resistant cementitious materials with polymer-nano silica hybrids

Most of the plastic waste, that rapidly and massively accumulates in the environment, does not get recycled but ends up in landfills and oceans causing pollution of water, soil, and air. This work presents an enhanced recycling scheme of waste plastics as aggregates in cementitious materials with ethylene-vinyl acetate (EVA) and nanosilica (nS) hybrids. 10% and 15% of natural sand were replaced by recycled waste plastic (RWP), and density, mechanical properties, capillary sorptivity and carbonation resistance of the RWP cementitious materials were evaluated. Results showed that not only the fabricated RWP specimens were 15%–18% lighter than the reference mixture but also the hybrid effect of EVA-nS was efficient in mitigating mechanical strength reductions and improving ductility up to 107%. Significant ameliorations of around 50% were observed in waterproof performance owing to the polymeric films created by EVA, while over 70% increase in carbonation resistance was noted owing to the filling and pozzolanic effects of nS. The replacement of natural sand with RWP by 10% would have the potential of reducing the annual sand consumption by 0.56–1 billion tons, which would substantially decrease the global CO2 emissions by 2.8–13.9 million tons annually. These findings pave a green path for upcycling RWPs in the sustainable, durable and lightweight construction material industry.

Repair mortars with water treatment plant sludge (WTPS) and sugarcane bagasse ash sand (SBAS) for more eco-efficient and durable constructions

Water treatment plant sludge (WTPS) and sugarcane bagasse ash sand (SBAS) can be used as fine aggregate in cementitious composites. This paper aims to evaluate carbonation depth, chloride penetration, steel corrosion probability, and corrosion rate of cementitious repair mortars produced with 3% WTPS and 30% SBAS. The results showed SBAS mortars have the best performance in relation to carbonation and chloride penetration tests. WTPS mortars have similar results to the reference sample. Both mixes with by-products were able to provide a more protective environment for steel reinforcement. They presented a delayed steel corrosion probability of 25% (for 3WTPS) and 113% (for 30SBAS) in comparison to the reference sample. This is due to increased alkalinity and refinement of pores given by incorporation of fine waste materials. Moreover, 3WTPS and 30SBAS can significantly reduce corrosion rates of steel reinforcement in the order of 70% and 97%, respectively. Therefore, 3WTPS and 30SBAS composites can be satisfactory used in jacketing repair mortars for more eco-efficient and durable constructions.

Engineering Structural Strength Properties of Lateritic Soil-Cement Mix for Road Pavement Stability

Qualitative construction materials in highway pavement prompted addition of cement at different proportion of 2 - 10% to lateritic soils for enhanced performance. Engineering geological tests were performed on the soil-cement mixture to determine their highway pavement suitability for durable road construction. Furthermore, modelling of the strength characteristics of the mixture presents the correlation between the structural properties and cement mix. Thus, increase in soil-cement California bearing ratio (CBR) and unconfined compressive strength (UCS) values with higher cement mix of 8%, revealed enhanced soil improvement. The soil strength is also affected by the curing period. Better quality strength characteristics obtained decreases pavement thickness with reduced cost in road construction. Relationship between the soil strength properties and cement mix content are represented by polynomial model. This reveals stronger bearing capacity of soil cement mix cured in 14 days with R2 ≥ 0.8. The lateritic soil cement mix at 8% cement content could serve as highway subbase and base construction materials. Cement mix having positive effects on soil geotechnical properties are indication of its effectiveness in enhancing volume stability of different soils. Prolong curing time is essential for compacted soil cement mix for enhanced geotechnical engineering properties and to improve the quality of lateritic soil used as road construction materials. Thus, cement-stabilized lateritic soil reduces cost of road construction, its persistent failure, human and environmental losses.

Economical Robust Mix Proportioning of Self-Compacting Concrete Mixes - A Comparative Study

Concrete being the second largest consumed material after water needs attention towards sustainable construction with an increase in infrastructure. The world is moving towards innovative techniques and methodologies for sustainable and durable construction of concrete structures. The selection of suitable ingredients for making concrete and determining the relative amounts with an objective of producing a concrete of required strength and durability is the need of the hour. Standard mix proportioning of concrete should satisfy the workability requirements and also meet the requirement for mechanical properties, durability, economy, and even ecology of engineering applications. The study would focus on quality control aspects in mix proportioning the concrete as per the requirements of the industry. It includes mix proportioning of self-compacting concrete as per the standards prescribed in national construction community and Indian standards, plastic viscosity, and EFNARC based mix proportioning of self-compacting concrete. The mix proportioning would focus on utilizing various industrial and agro wastes as a suitable cement replacement material, locally available fine and coarse aggregate materials along with their alternates, appropriate dosage of admixtures, etc. The outcomes of the study include the formulation of handouts and readymade mix proportions of self-compacting concrete used in the construction of buildings and pavements along with their cost estimation. The study also provides information on some of the key points to be considered in making concrete using optimization concepts which would further reduce the cost of construction. The optimized mix proportions will be handy for the ready-mix plants especially in dealing with multiple large-scale construction activities. Mix proportioning using plastic viscosity approach was proven to be economical compared to other mix design methods.

Corrosion Behavior in RC Member with Different Cover Depths under Cyclic Chloride Ingress Conditions for 2 Years

Concrete structures are considered as durable construction material, but corrosion of the embedded steel reinforcement occurs under chloride exposure as concrete has porous properties. Herein, a cyclic drying–wetting test was performed for two years using saltwater to accelerate steel corrosion in a reinforced concrete (RC) member. The open-circuit potential (OCP) was measured using a newly developed and replaceable agar sensor. The corrosion potential was measured considering the chloride concentration, water-to-cement (w/c) ratio, and cover depth at three levels. Furthermore, its relationships with influential parameters were evaluated using averaged OCP results. The measured OCP showed a linear relationship with the cover depth, and this tendency was more distinct with increasing retention period and higher chloride concentration. For the highest w/c ratio (0.6), values below −100 mV were monitored after only six months regardless of the cover depth, and values below the critical potential level (−450 mV) were evaluated at lower cover depths (30 and 45 mm). The results of regression analysis considering the exposure environment showed a clear relationship in the case of high chloride concentration (7.0%). A linear relationship between cover depth and OCP was derived with a reasonable determination coefficient ranging from 0.614 to 0.771.

Acoustical behavior of camellia sinensis/ananas comosus fiber based uni-directional corrugated panel for sound damping application

To achieve a durable, rigid, and lightweight construction material, a new class of Camellia sinensis/Ananas comosus fiber-enhanced corrugated sandwich panel was designed and produced. The crushed core layer comprises sinusoidal corrugation and is manufactured by a method of mould pressing in an attempt to assess this material’s sound absorption ability. In addition, the influence of airgap and micro perforation on sound absorption properties was investigated. The samples with a greater perforation ratio and air gap are found to have a noise reduction coefficient (NRC) of 0.745, which can be used to attenuate mid- and high-range frequencies in industrial environments.

Early settlement construction in Southeast Asia: lime mortar floor sequences at Loc Giang, southern Vietnam

Research on prehistoric mainland Southeast Asia is dominated by mortuary contexts, leaving processes such as the transition to sedentism relatively understudied. Recent excavations in southern Vietnam, however, have recovered new evidence for settlement. The authors report on investigations at the neolithic site of Loc Giang (3980–3270 cal BP) in southern Vietnam, where excavation revealed a vertical sequence of more than 30 surfaces. Microarchaeological analyses indicate that these features are carefully prepared lime mortar floors; the lime was probably produced from burnt shell. The floors date to between 3510 and 3150 cal BP, providing the earliest-known evidence for the use of lime mortar, and for durable settlement construction, in this region.

Assessment of hygrothermal and mechanical performance of alkali activated Borassus fiber reinforced earth-based bio-composite

This investigation presents the results of a multiscale examination of the hygro-thermal and mechanical properties of designed earth-base bio-composite. The matrix and the fiber reinforcement were processed naturally to achieve eco-friendliness manufacturing technique. The bio-composite was produced using a reconstituted soil matrix and natural Borassus fruit fiber as the reinforcing phase. One-part alkaline activation of in-situ earth matrix is considered as the manufacturing process in addition to the mechanical compaction technique used to optimize the sample performance. The adhesion of the Borassus fruit fiber to the earthen matrix was evaluated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and Fourier transform infra-red (FTIR). Compressive and flexural strength testing were used to assess the mechanical properties of the bio-composite in addition to the hygric characterization or water sensibility's analysis. The thermal behavior of the bio-composite was investigated using the hot disk technique. All the characterizations were carried out on the bio-composite after 7-, 14- and 90-days curing. The Borassus natural fiber inclusion at 0.5 wt% resulted in the improvement of compressive and flexural strength due to crack propagation barrier-like feature. Water sensitivity, thermal conductivity was optimal with 0.75 wt% Borassus natural fiber content. The implications of the results are aimed to develop earth-based matrix reinforced with natural fiber produced locally from agro-waste for durable construction with low energy consumption during life-service. • Microstructural examinations were carried out to link their effect to the macrostructural performance. • Agro-waste reinforcement and soil reconstitution are used to investigate the mechanical, hygro-thermal properties of the bio-composite. • The agro-waste content on the bio-composite properties were examined. • Hygro-thermal properties of the bio-composite were resorted to inspect the water sensitivity and thermal comfort of the bio-composite.

Climate change and asphalt binder selection across ontario: A quantitative analysis towards the end of the century

The climate across the world and especially across Canada is becoming warmer. Recent research suggests that, on average, past and projected warming in Canada are about twice those of global values. As part of the Superpave Mix design system, Performance Grade (PG) of the asphalt binder is selected based on historical climatic conditions in relation to the expected in-service temperature spectrum of the pavement surface. Given the effects of climate change, it is important to ascertain how projected ambient conditions may impact pavement surface temperatures and therefore the suitable PG towards more durable and resilient pavement construction in the future. In this study, new regression models, to predict pavement surface temperatures, were developed using air temperatures and latitude of a site. These models were developed to determine the relationships between asphalt pavement surface temperature and ambient weather data from weather stations within the Ontario Ministry of Transportation's Road Weather Information System (RWIS). The developed models were used to predict the pavement temperatures for future climate data from different Global Circulation Models (GCMs) and Representative Concentration Pathways (RCPs), and the results were compared with that of latest Long-Term Pavement Performance (LTPP) models. According to the results of this study, based on the scale of the expected warming, changes in the asphalt binder grades across Ontario are expected in the future. The results of this study also suggest that different types of PGs including 52–34, 58–28, 64–28and 70–22 may need to be adopted by the end-century. This study provides practical recommendations that road authorities and planners may use to adapt paving materials to changing temperature conditions.

Top advances in lymphoma for 2021.

Chimeric antigen receptor (CAR) T-cell therapy, antibody-drug conjugates, bispecific T-cell redirectors, and agents targeting tonic B-cell receptor signaling have altered the paradigm for three of the most common lymphomas in the year 2021. For diffuse large B-cell lymphoma, the POLARIX study has shown improvement on the standard backbone of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone in the frontline setting, a feat that had not been achieved despite great efforts over the past 20years. In the relapsed and refractory setting, two unique CAR T-cell products have displaced autologous transplantation to the third line, and they allow patients with chemotherapy-resistant disease to receive approved therapy earlier. CAR T-cell products, once used exclusively in the aggressive lymphoma arena, are now showing high response rates and durable activity against indolent lymphomas. The investigation of mosunetuzumab in indolent lymphomas offers another option for patients who have received multiple lines of cytotoxic drugs. On the basis of these trends, PI3K inhibitors are being displaced in favor of safer and more durable constructs. In addition, within the past year, the approval and implementation of zanubrutinib for marginal zone lymphoma have filled a need for later line therapy, especially for less fit and elderly patients.

Flexural Behavior of Fly ash and GGBS Based Ambient Cured Geopolymer Concrete Beams

Abstract: Concrete is the world’s most versatile, durable and reliable construction material. Next to water, concrete is the most used material, which required large quantities of Portland Cement. Ordinary Portland Cement production is the major generator of carbon di oxide, which polluted the atmosphere. In addition to that large amount energy was also consumed for the cement production. Hence, it is essential to find an alternative material to the existing most expensive, most resource consuming Portland Cement.The study describes experimental investigation on flexural behavior of reinforced GPC. A total of eighteen beams were tested. From this, nine were of M20 mix, i.e., conventional concrete beams while nine were of geopolymer concrete,from this nine beams, three beams with the ratio of binder i.e., flyash:GGBS ratio as 75:25, other three with 70:30 while remaining three beams with 65:35. Also, 12 cubes & 12 cylinders were also casted and tested for compressive strength and split tensile strength respectively. From them, three were of conventional concrete while other nine of GPC with three different ratios as mentioned above. The reinforcement was designed considering a balanced section for the expected characteristic strength. All the beam specimens were tested under two point static loading. The studies demonstrated, the study of conventional and geopolymer concrete beams related to deflection, first load at which crack appeared and their crack patterns.

Building on the past: Refining our current understanding of Lapita stilt structures

This paper reviews our current knowledge of Lapita stilt structures in the Bismarck Archipelago, Papua New Guinea, and contributes new data from the analysis of a wooden post belonging to a Lapita-era stilt structure identified in the site of Adwe in the Arawe Islands. Via taxonomic analysis, the wooden post is identified as Intsia bijuga (Moluccan ironwood or Pacific teak), a saltwater-resistant species that would have proven to be a highly durable construction material. The selective usage of sturdy timber including Intsia bijuga, cf. Cordia subcordata, Diospyros sp., cf. Terminalia catappa and Calophyllum inophyllum as building materials at various Lapita sites, suggests that the Lapita populations had a clear understanding of locally available timber resources. This paper also details a world-first attempt at radiocarbon wiggle-match dating a Lapita-age wooden artefact.

Preface

Due to Rapid Infrastructure development that is happening in and around, use of Smart and sustainable materials has become the need of the hour in construction industry. Use of smart materials in civil engineering is definitely a new approach for sustainable and durable construction of important structures. With minimal chance of load exceedance and collapse of structures, the time life of such structures can be increased with the use of smart materials. Therefore, it is very important to develop a smart system for concrete structures, which can minimize internal and external disturbances for structural safety and extension of its service life. The International Conference on Smart Materials for Sustainable Construction in Civil Engineering (ICSSCE) 2022, will show the way forward for the future of the construction industry. The conference will bring together the key players such as Academicians, Researchers, and Industry professional from the construction industry from with the country and around the globe. We hope that our Conference will offer a unique opportunity for interesting and fruitful interactions to all participants, providing them with memorable and pleasant experiences.We take this opportunity to extend our sincere thanks to Hon’ble Chancellor, Vice-Chancellor, Pro- Vice Chancellor, Registrar and faculty and staff of Civil Engineering and the fraternity of REVA University for their guidance and support in organizing the conference. A conference of this kind and magnitude would not have been possible without the dedicated efforts of all people. I would like to express my gratitude to my colleagues, students and many others who are involved in the conference directly or indirectly for their wholehearted support and enthusiasm in organizing the conference. A Special Thanks to Dr. Krishna R. Reddy, Professor, University Scholar and Distinguished Researcher, University of Illinois, Chicago, USA, for working as Editor for this Conference.List of Organizing Committee, Technical committee are available in this pdf.

Multi-scale structure of in-situ polymerized cementitious composites with improved flowability, strength, deformability and anti-permeability

In-situ polymerization of polymers with cement can greatly improve the engineering performances of cementitious composites, the structural mechanisms, however, remain still not fully established. Herein in-situ polymerization modified cementitious composites (iPMCC) with sodium acrylate (SA) in different dosages (0%, 4% and 8%) were fabricated. Flowability, strength, deformability, and water sorptivity of the iPMCCs were tested, and the multi-scale structures in terms of pore size distribution, microscopic morphology, chemical characteristics, and solid structure of calcium-silicate (-aluminate)-hydrates were characterized. Results demonstrate that, compared with neat cement paste, the iPMCC with 4% SA showed the improvement of flowability by 35.1%, the increases of flexural and compressive strength by 109.0% and 11.8%, the rises of flexural and compressive deformation energy by 458.8% and 161.0%, and the decrease of water sorptivity by 19.1%. The in-situ SA polymerizations lead to substantial pore refinement, but macro defects in the iPMCC with 8% SA. Cross-linked sodium polyacrylate networks formed in the cement matrix and interacted with the cement hydrates, accounting for the improved strength, deformability, and water resistance. Cement hydration depression by polymers was evidently supported by the NMR data. The findings would deepen the understandings of multi-scale structure of cementitious composites with polymers, enabling development of highly ductile and durable construction materials.

Biomineralized Materials for Sustainable and Durable Construction

Portland cement concrete, the most used manufactured material in the world, is a significant contributor to anthropogenic carbon dioxide (CO2) emissions. While strategies such as point-source CO2 capture, renewable fuels, alternative cements, and supplementary cementitious materials can yield substantial reductions in cement-related CO2 emissions, emerging biocement technologies based on the mechanisms of microbial biomineralization have the potential to radically transform the industry. In this work, we present a review and meta-analysis of the field of biomineralized building materials and their potential to improve the sustainability and durability of civil infrastructure. First, we review the mechanisms of microbial biomineralization, which underpin our discussion of current and emerging biomineralized material technologies and their applications within the construction industry. We conclude by highlighting the technical, economic, and environmental challenges that must be addressed before new, innovative biomineralized material technologies can scale beyond the laboratory.