Concrete Facades Research Articles

Effect of Recycled Concrete Aggregate Utilization Ratio on Thermal Properties of Self-Cleaning Lightweight Concrete Facades

In today’s environment, where energy is desired to be used more efficiently, it has been understood that the interest in the use of lightweight concrete with superior performance in terms of thermal insulation properties has increased. On the other hand, it has been stated that construction waste increases rapidly, especially after severe earthquakes. In this context, encouraging the use of recycled concrete waste and efficient disposal of construction and demolition waste is of great importance for the European Green Deal. It is also known that pollutants such as COx and NOx stick to facades over time, causing environmental pollution and visual deterioration. It has been reported that materials with photocatalytic properties are used in lightweight concrete facade elements to prevent such problems. This study examines the effect of using recycled concrete aggregates on the thermal properties of self-cleaning lightweight concrete mixtures (SCLWC). For this purpose, an SCLWC containing 1% TiO2 and 100% pumice aggregate was prepared. By replacing pumice aggregate with recycled concrete aggregate at the rates of 15%, 25%, 35%, 45% and 50%, four different SCLWCs with self-cleaning properties were produced. High-temperature resistance, thermal conductivity performance, microstructure analysis and photocatalytic properties of the produced mixtures were examined. It has been understood that the unit volume weight loss of SCLWC mixtures exposed to high temperatures generally decreases due to the increase in the recycled concrete-aggregate substitution rate. However, it was determined that the loss of compressive strength increased with the increase in the amount of recycled concrete-aggregate replacement. Additionally, it was determined that the thermal-conductivity coefficient values of the mixtures decreased with the use of pumice. After SCLWC mixtures were exposed to 900 °C, small round-shaped crystals formed instead of C–S–H crystals.

Effects of utilizing various types of facade material on the Embodied and operational energy; a case study of apartment building in Indonesia

ABSTRACT This study investigates the impact of using prefabricated facade materials on the embodied energy (EE) and operational energy (OE) consumption of apartment buildings. To analyze the total EE, a life cycle assessment (LCA) was conducted, which calculated the EE from cradle-to-use each of the products employed. In addition, a building energy simulation was performed for the case study building using various prefabricated facade materials to assess its OE. The findings reveal that the selection of facade wall materials with low energy intensity must be favored to optimize building energy and that layered materials, such as insulated panels, can reduce the cooling energy load due to their higher thermal resistance (r- values). Furthermore, the LCA results showed that solid precast concrete materials with thicknesses of 120 and 150 mm have EE and greenhouse gas emissions that are more than twice the average of all materials tested. In contrast, uninsulated Glass-Fiber Reinforced Concrete (GRC) removable walls (disassembly panels) exhibited the lowest EE, corresponding to 50% of the average. Finally, the results of the OE simulations using EnergyPlus software indicate that insulated GRC removable walls with a thickness of 120 mm can reduce the cooling energy load by 29.5% compared to precast concrete facades.

Experimental and Numerical Investigation of Mould Growth Risk on Wooden Load-Bearing Structure in Hemp-lime Concrete Facades

The need for reducing the environmental impact of the production of building materials has accelerated the emergence of new types of bio-based façade systems. Some of these systems are claimed to have hygro-thermal properties that eliminate the need for a dedicated air and/or vapour barrier as a part of the façade buildup. This paper presents a risk assessment of moisture-related deterioration of the wooden load-bearing structure in an existing hemp-lime concrete building façade system constructed without a dedicated air or vapour barrier in Aarhus, Denmark. Destructive investigation found no mould on structure. The façade was then modelled in WUFI 2D and calibrated using time series data from field measurements of temperature and relative humidity internally in the construction and in its surroundings. The calibrated WUFI model was used to simulate the annual moisture cycle using different initial conditions and weather data. The simulation output was analysed for the risk of mould growth at the wooden load-bearing structure using the Mould Growth Index. Results indicate that the initial moisture content of materials, the position of the wood structure, and the season of construction completion is important to consider to minimise risk of mould growth in the build-up.

The Aesthetics of Concrete

We cover the external facades of our buildings with different materials, which significantly determine the appearance, and aesthetics of the building while meeting many requirements. The article covers the number of ways and how facades created with concrete elements, concrete cladding or exposed concrete can be shaped, and how they react to external influences and conditions. The article examines how today’s modern concrete facades, in addition to providing the necessary technical function, can give an aesthetic façade appearance or even how the façade can even represent the spirit of the building. In addition to the already established concrete façade technologies, what new procedures are there in the construction industry and what additional possibilities are there in this material during façade use.

Impact of Environmental Factors on the Formation and Development of Biological Soil Crusts in Lime Concrete Materials of Building Facades

Microbial colonization leads to the formation of biological soil crusts (BSCs) on the surface of architecture, which causes the deterioration of construction materials. However, little information is available on the formation of BSCs on lime concrete materials of early architecture. In this study, the variances of microbial communities, physicochemical properties, and surrounding environmental factors of the lime concrete facades from the early architecture of Wuhan University were investigated. It was found that the surface of lime concrete materials was internally porous and permeable, embedded with biofilms of cyanobacteria, mosses, bacteria, and fungi. Redundancy analysis (RDA) analysis showed that the abundances of photoautotrophic microorganisms depended on light intensity and moisture content of construction materials, while that of heterotrophic microorganisms depended on total nitrogen (TN) and NO3−-N content. The deposition of total carbon (TC), NH4+-N, and total organic carbon (TOC) was mainly generated by photoautotrophic microorganisms. The lime concrete surface of early architecture allowed internal growth of microorganisms and excretion of metabolites, which promoted the biodeterioration of lime concrete materials.

Comparative Analysis of Facade Work Using Kumkang Precast, Concrete Precast, and Curtain Wall Methods in terms of Cost and Time

The development of the construction world in terms of innovation has become one of the methods of supporting success to gain advantages in terms of cost and time, one of which is the outer wall which can generally categorize into cast-in-situ and precast methods. (1) Comparison of the cost of implementing precast kumkang materials, precast concrete facades, and curtain wall facades. The precast kumkang method is 24% cheaper than the precast concrete method, the precast kumkang method is 87% cheaper than the curtain wall method, and the precast concrete method is 52% cheaper than the curtain wall method. Sorted from the cheapest to the most expensive are precast kumkang facades, precast concrete facades, and curtain wall facades.
 (2) Comparison of the working time of precast kumkang materials, precast concrete facades, and curtain wall facades with the results, namely curtain wall facades for 31 weeks, kumkang material precast facades for 53 weeks, and precast concrete facades for 55 weeks. Sorted from the fastest to longest, namely curtain wall facades, precast kumkang material facades, and then precast concrete facades.

Restoring serenity: conservation of Minoru Yamasaki's North Shore Congregation Israel

ABSTRACT The North Shore Congregation Israel complex was designed by modernist architect Minoru Yamasaki and completed in 1964. Yamasaki's notable work includes the Pacific Science Center (1962), World Trade Center (1971), and many other significant large scale projects. North Shore Congregation Israel exemplifies his early work, which included low-rise modernist structures with decorative concrete facades. Yamasaki was very interested in the design potential of precast and cast in place concrete and the materials versatility as both a structural and decorative material, as illustrated in this complex. After several decades, spalling was observed along the edge of the architectural precast concrete panels. Previously installed concrete patch repairs were visually apparent and many were no longer serviceable. Wiss, Janney, Elstner Associates, Inc. was engaged to perform an assessment of the existing architectural precast concrete, document the extent and types of distress, and develop repair documents. The paper will describe and illustrate the process of developing concrete repairs for North Shore Congregation Israel, including an overview of the assessment process and development of repair details, concrete cleaning procedures to address soiling and biological growth present on the building, and concrete mix design and finishing procedures to blend the repairs with the existing concrete.

Experimental and modelling study of mixture design optimisation of glass fibre-reinforced concrete with combined utilisation of Taguchi and Extreme Vertices Design Techniques

Micro and short fibre inclusions to concrete mixtures increase their precrack resistance, and random distribution of fibres improve the properties of concrete in all directions. In this study, general design optimisation of glass fibre (GF)-reinforced concrete (GRC) was conducted to help professionals in producing industrial concrete facades and walls. The effects of ingredients, including paste and silica sand used as aggregate metakaolin (MK) and GF contents, were examined in terms of their compressive and flexural strengths. Fresh concrete properties, such as workability, were investigated through fibre content tests. Concrete specimens containing various GF% and MK amounts (0%, 5%, 10% and 15% by weight of cement) were evaluated during the experiments. Test results were analysed and used in the optimisation phase of the study. The optimum ingredient contents and their relations with concrete performance were determined through combined utilisation of Taguchi, ANOVA and extreme vertices design methods. Results obtained from these optimisation methods were applied to the specimens. The proposed design and optimisation method is effective in optimising the mechanical properties of GRC mixtures.

Environmental Impact of Textile Reinforced Concrete Facades Compared to Conventional Solutions-LCA Case Study.

Pitch-faced concrete is becoming a very popular element of modern architecture in the 21st century. In particular, the demand for concrete facades is increasing globally. On the other hand, climate change, environmental degradation, and limited resources are motivations for sustainable building materials. The construction industry is one the highest emitters of CO2 and other greenhouse gases, in which concrete plays a major role. Thus, reduction in the volume of concrete consumption is essential to control greenhouse gases. One approach to this problem is to use textile reinforced concrete (TRC). The main aim of the present study was to compare the subtle TRC facade made of three different types of technical textile rovings (glass, carbon, and basalt) with ordinary facades reinforced by steel reinforcement (ORC). The goal was to compare the basic environmental impact potential according to product category rules (PCR) for concrete structures. The functional unit was defined as an experimental facade with an area of 60 m2 and a 100-year lifespan. Inventory data were elaborated for concrete, steel, and textile fiber production; the building site; service life; demolition; and final disposal. The main life cycle assessment (LCA) parameters were global warming potential (GWP), ozone depletion (ODP), acidification (AP), eutrophication (EP), abiotic depletion (ADP), and photochemical oxidant creation (POCP). All the data used in the work were related to Czech Republic. Textile reinforced concrete facades appeared to be more environmentally friendly in four of six impact categories by an average of 30%. The results of the present study revealed that, in comparison to ORC, TRC has a lower environmental impact for the given conditions and thus good potential for use in sustainable construction.

Case Study on the 20 Years Propagation of Carbonation in Existing Concrete Facades and Balconies

Abstract In the most service life models of reinforced concrete structures the initiation phase is the most crucial, because according to models, service life of the structure will end underestimation on conservative side when carbonation achieves the reinforcement for the first time. The square root model is widely used in predicting carbonation depth of reinforced concrete. The model is based on diffusion laws and thereby arguable for inhomogeneous concrete. The model was evaluated by field measurements from one existing concrete building by conducting condition investigation twice at a time interval of 20 years. Samples were taken from exposed aggregate concrete sandwich panels and balcony side panels. Compared to the data collected from large number of buildings, the measured carbonation rates were very common for Finnish concrete buildings made during the 1960s and 1970s. According to this study, in solid concrete the progress of carbonation of concrete can be predicted reliably with Fick’s second law. This model, however, gives too pessimistic predictions for concrete suffering from freeze-thaw damage. Therefore, a new model has been presented for damaged concrete.

COMPORTAMIENTO SÍSMICO DE FACHADAS PREFABRICADAS DE CONCRETO DEL TIPO “PISO A PISO”

Durante algunos eventos sísmicos recientes en México, se ha observado que, a pesar de haber un adecuado comportamiento del sistema estructural, no siempre existe un adecuado comportamiento de los sistemas no estructurales. En esta investigación se llevan a cabo análisis no lineales paso a paso para estudiar el comportamiento de fachadas prefabricadas de concreto del tipo “piso a piso”, las cuales han presentado fallas y desprendimientos aun cuando la estructura no ha sufrido daño. Para alcanzar este objetivo, se evalúan los desplazamientos y aceleraciones de cada uno de los pisos de un edificio de 15 niveles y 4 crujías, donde se calcula el nivel de daño de diferentes paneles. Para obtener estas respuestas, se diseña el sistema estructural mencionado utilizando el Apéndice A de las Normas Técnicas Complementarias para Diseño por Sismo del Reglamento de Construcciones del Distrito Federal del 2004 y se realiza un análisis dinámico incremental utilizando el registro sísmico del sismo de Michoacán del 19 de septiembre de 1985, obtenido en la estación de la Secretaría de Comunicaciones y Transportes. Se observa que al reducir las fuerzas sísmicas por ductilidad y sobrerresistencia, se podrían ignorar las fuerzas reales durante un sismo que son mayores a las de diseño, lo que podría provocar daño en las fachadas estudiadas.

Basalt reinforced concrete structures for retrofitting concrete surfaces

Reinforced concrete facades exist since decades exposed to natural weather conditions. Thus nowadays lot of them are damaged by carbonation induced corrosion and therefor require repairing and retrofitting. The aim of this research project is to investigate the possibilities of basalt fibre reinforced concrete as repairing material and also basalt rebars as additional strengthening reinforcement. Investigations with basalt fibre reinforced mortar prisms showed best results in 3 point bending tests, tensile strength and also compressive strength using 0.3 Vol.-% basalt fibres in mixture. The mechanical properties of basalt rebars made of basalt fibre reinforced polymer were tested, showing higher values in tensile strength and Young´s Modulus than comparable steel reinforcement samples. The basalt rebar reinforced concrete samples achieved higher ultimate loads in three-point bending test compared to SRC samples. But after failure in the bonding area no residual load capacity remained. Finally basalt reinforcement bars seems to be well suited for use as retrofitting material for facade elements, but numerous properties have to be examined in further investigations.

Strength and Behavior of Bolted Ultra-High Performance Concrete Panel Joint with Geometric Parameter

One of the most reasonable ways to connect thin ultra-high performance concrete (UHPC) facades to building structures is bolted joints. To design the joints for the facades economically and safely, a clear investigation of the structural behavior is needed. In this study, the joint strength, failure modes and strain concentration phenomena of the bolted UHPC panels are investigated by direct tensile test. The main experimental variables are the geometric parameters, which are the width of the specimen, its thickness, and the distance from the center of the hole to the edge. Experimental results show that ductility of the joint depends on the failure mode. In addition, it is shown that the increase in the material cost of the panel, such as size and thickness, does not necessarily lead to an increase in the joint strength.

Methodology for service life prediction of architectural concrete facades

In this study, a methodology for the service life prediction of architectural concrete facades is proposed, following a research line previously developed for other types of claddings, to evaluate their durability. The methodology developed is based on the collection of data in visual inspections. In this study, 174 facades were analysed, during the fieldwork phase, through a survey of the different degradation phenomena. This information is used to define degradation curves, which graphically express the loss of performance of architectural concrete facades over time, evaluating the influence of the degradation agents, allowing estimating a reference service life for this type of coating. The model proposed in this study leads to acceptable and consistent results, adequately translating the degradation observed in reality. However, for some characteristics of architectural concrete facades, it is not possible to obtain unequivocal conclusions, which reveals the high susceptibility of these coatings to the aggressive environmental agents, e.g. sea salts, which act simultaneously on the facade, hindering the determination of the separate influence of these characteristics on the degradation found. This study intends to give a contribution to the service life prediction of exterior facades, allowing defining rational maintenance plans and reducing the costs associated to the buildings refurbishment during their life cycle.

Impact of ETICS on Corrosion Propagation of Concrete Facade

The durability of reinforced concrete facades is an important field of research as the majority of dwellings in Northern and Eastern Europe were constructed 30–50 years ago. Recent condition assessments of the façades have indicated damage related to carbonation induced corrosion. Moreover, the problem might escalate since the future climate scenarios predict a significant increase of CO2 in ambient air being a driving force for carbonation.Assessment of residual service life of concrete facades is a complex phenomenon with a high level of uncertainty. A validated method used in this study combines dynamic hygrothermal simulation tool Delphin and existing corrosion models. Corrosion propagation consists of the time needed to concrete cover cracking and further expansion of a crack up to a width of 0.3mm as a limit criterion. Additional exterior thermal insulation (mostly ETICS) is applied to existing dwellings as a renovation scenario in order to decrease the heat loss, improve thermal comfort and prevent the degradation mechanism e.g. carbonation induced corrosion. Hence, reinforcement corrosion before and after installing ETICS with mineral wool, EPS or PIR has to be evaluated. Impact of boundary conditions, e.g. wind-driven rain in addition to material properties, and built-in moisture was included.The results indicate that corrosion propagation after carbonation has reached the reinforcement, is three to six years depending on the ratio of concrete cover depth against the reinforcement diameter. While applying ETICS, corrosion accelerates for a short period of time up to one year. Temperature inside the wall rises above +10°C throughout the year, meaning no more freeze-thaw damage. Corrosion of reinforcement in carbonated concrete after applying ETICS is so slow, that no cracking will develop. Drying out moisture or vapour diffusion from indoor air is not able to propagate corrosion of reinforcement in carbonated concrete.

The corrosion rate in reinforced concrete facades exposed to outdoor environment

Outdoor concrete structures such as concrete facade panels and balcony frame panels are subjected to various environmental actions causing reinforcement corrosion problems. Long-term field measurement data on reinforcement corrosion in carbonated concrete on these structures was utilized in the creation of a corrosion rate regression model combining weather parameters such as temperature, relative humidity, wind-driven rain and solar radiation to corrosion rate. A versatile model capable of predicting the effect of varying environmental actions on the corrosion rates of carbonation induced corrosion was produced. Wind-driven rain was found to have the greatest impact on corrosion rate in tandem with the micro climate surrounding the building. Due to changes in air temperature, air relative humidity as well as in the amount of wind-driven rain and solar radiation, the corrosion rate on concrete facades and balconies is constantly changing. Despite the high seasonal and yearly variation, the average level of the modelled corrosion rate was quite steady on a longer 30-year perspective. This information is substantial for the long term service life design of concrete structures.

Fire behaviour of EPS ETICS on concrete or masonry facades

Fire behaviour of EPS ETICS on concrete or masonry facades

Evaluation of a carbonation model for existing concrete facades and balconies by consecutive field measurements

The square root model is widely used to predict the initiation phase of reinforcement corrosion induced by carbonation of the concrete cover. The model is based on diffusion laws which makes its validity arguable. The model has been accused of not being able to model accurately carbonation in structures exposed to drying/wetting cycles. The model was evaluated by field measurements on 18 existing concrete buildings conducted twice at an average interval of 8 years. Data from individual parallel samples as well as averaged measurement data were produced. The propagation of carbonation over a certain period of time and variation in the carbonation coefficient were studied using the data. Individual measurements indicated high variation and even inconsistency in carbonation depth. Thus, the carbonation coefficient calculated for the square root model also varied widely. Despite the high scatter, the averaged carbonation of many buildings was found to be closely in line with the prediction of the square root model.

Corrosion products of carbonation induced corrosion in existing reinforced concrete facades

Active corrosion in reinforced concrete structures is controlled by environmental conditions and material properties. These factors determine the corrosion rate and type of corrosion products which govern the total achieved service life. The type and critical amount of corrosion products were studied by electron microscopy and X-ray diffractometry on concrete and reinforcement samples from existing concrete facades on visually damaged locations. The corrosion products in outdoor environment exposed concrete facades are mostly hydroxides (Feroxyhite, Goethite and Lepidocrocite) with a volume ratio to Fe of approximately 3. The results can be used to calibrate calculation of the critical corrosion penetration of concrete facade panels.

Durability demands related to frost attack for Finnish concrete buildings in changing climate

In this study a database of concrete material properties and observed degradation was combined with climate data projections. Due to the predicted increase in precipitation, facades will receive more driving rain in the future. Though the number of freeze-thaw cycles is about the same in the southern coastal and inland areas, the amount of rain is remarkably higher in the southern coastal areas which increases the risk of frost damage. South-facing facades will continue to be most susceptible to climate stress which should be taken into account in designing the details of concrete facades and balconies. As concerns frost durability, climatic conditions in southern Finland will ease remarkably already in 2030. In inland areas outdoor climate will remain the same as presently but in the southern coastal areas conditions will get more severe with the increasing amount of rain and sleet almost to the end of century. Properties that influence degradation initiation time are highly important in ensuring proper service life of a structure. Failure with air entraining fresh concrete results in early frost damage to concrete, i.e. air entrainment of fresh concrete must always be done. Present requirements are sufficient for the future climates.