Construction Materials In Terms Research Articles

Life cycle assessment and economic analysis of Reusable formwork materials considering the circular economy

Economic development and population growth have impacted on fossil-based energy consumption, contributing to environmental pollution. Adopting circular economy research is more pressing than ever to ease pressure on the environment and the economy. Evaluating the best construction materials is not new. To date, many researchers have assessed materials using various criteria. Formwork differs from other construction materials in terms of serviceability and reusability. These materials may be reused multiple times (from 7 to around 50 times). This raises the question of which material is the best from a sustainability perspective. In this paper we have evaluated four of the most widely-used formwork materials used in the construction of buildings in Malaysia. These include plastic, steel, plywood and timber. Evaluations of life cycle assessment (LCA), embodied energy, and life cycle cost (LCC) were conducted from cradle to cradle. For a single use of formwork, timber is best in all categories except human non-carcinogenic toxicity. However, when 50 reuses are considered for the same wall a completely different result arises. In the environmental category, steel formwork produces the lowest emissions and impact in all categories except global warming potential (GWP). Plastic formwork has the lowest carbon emissions. In terms of embodied energy and cost, plastic formwork presents the best option being approximately 20% lower than steel formwork. Because of the inconsistency in the results for LCA, embodied energy, and LCC for 50-cycles of usage, a multi-criteria decision-making (MCDM) tool was used to normalize the results. The MCDM shows that plastic formwork is an ideal choice for sustainability among the alternatives considered.

Corrosion Evaluation of Austenitic and Duplex Stainless Steels in Molten Carbonate Salts at 600 °C for Thermal Energy Storage

Next-generation concentrated solar power (CSP) plants are required to operate at temperatures as high as possible to reach a better energy efficiency. This means significant challenges for the construction materials in terms of corrosion resistance, among others. In the present work, the corrosion behavior in a molten eutectic ternary Li2CO3-Na2CO3-K2CO3 mixture at 600 °C was studied for three stainless steels: an austenitic grade AISI 301LN (SS301) and two duplex grades, namely 2205 (DS2205) and 2507 (DS2507). Corrosion tests combined with complementary microscopy, microanalysis and mechanical characterization techniques were employed to determine the corrosion kinetics of the steels and the oxide scales formed on the surface. The results showed that all three materials exhibited a corrosion kinetics close to a parabolic law, and their corrosion rates increased in the following order: DS2507 < SS301 < DS2205. The analyses of the oxide scales evidenced an arranged multilayer system with LiFeO2, LiCrO2, FeCr2O4 and NiO as the main compounds. While the Ni-rich inner layer of the scales presented a good adhesion to the metallic substrate, the outer layer formed by LiFeO2 exhibited a higher concentration of porosity and voids. Both the Cr and Ni contents at the inner layer and the defects at the outer layer were crucial for the corrosion resistance for each steel. Among the studied materials, super duplex stainless steel 2507 is found to be the most promising alternative for thermal energy storage of those structural components for CSP plants.

Assessment of the impact of construction materials on the building’s thermal behaviour and indoor thermal comfort in a hot and semi-arid climate

ABSTRACT This paper aims to identify the most suitable construction materials in terms of building’s energy performance and indoor thermal comfort for a hot and semi-arid climate. An experimental validated TRNSYS-based numerical model was set to carry out dynamic simulations for the energy performance assessment of four similar houses built with different materials, namely Cinder Blocks, Reinforced Concrete, Fired Bricks, or Rammed Earth. The results show that the rammed earth house had the best thermal performance thanks to its high thermal mass, which helped maintain a stable indoor air temperature for optimal thermal comfort. Adding shading and night natural ventilation contributed to the further improvement of the rammed earth house's thermal performance. Indeed, the annual heating/cooling load of the rammed earth house was 23%, 11% and 3% lower than the reinforced concrete, cinder blocks and fired bricks houses, respectively. These thermal load differences were much more reduced to 51%, 24% and 5%, respectively, after adding the shading and night natural ventilation techniques. Furthermore, this study evaluated the use of low embodied energy and weak carbon footprint construction materials to achieve a good building's thermal performance and acceptable indoor thermal comfort.

Design optimization of hybrid steel/timber structures for minimal environmental impact and financial cost: A case study

In the overall aim to build more sustainably, the energy performance of buildings has received a lot of attention in the past decade. In consequence, the embodied impact of buildings has become relatively more important. As the load-bearing structure is responsible for a large share of this embodied impact, it is important to design it in such a way that its environmental impact is as low as possible. Unfortunately, the best construction materials in terms of environmental impact are not necessarily the cheapest. Reducing the environmental impact of the design may therefore lead to a higher financial cost, which may exceed the available budget. In such cases, hybrid structures, consisting of two (or more) different materials, might offer a solution, as they allow the designer to finetune the trade-off between environmental impact and financial cost. In this paper, we present a method to determine the best design of hybrid steel/timber structures in terms of environmental impact within the limits of the available budget. The method is based on the solution of a multi-objective structural design optimization problem involving environmental life cycle assessment and life cycle costing. It is applied to two test cases: a statically determinate and a statically indeterminate truss structure. The structures are optimized for three different design scenarios and typical load cases. This results in a Pareto front in the environmental and financial life cycle cost spectrum, allowing the designer to select the most appropriate solution, given the available budget. The results show that, depending on the design conditions, hybrid steel/timber structures are in some cases Pareto-optimal.

Lowering carbon foot print of Portland cement by class F fly ash substitution in mortar mixture in terms of workability and strength properties

In the experimental work, recycling by inclusion of class F fly ash in mortar was investigated in terms of workability and strength of mortar to fabricate an environment friendly construction material. For this aim, class F fly ash were used as cement replacement at 10%, 30%, 50% and 70% ratios in mortar. Water-binder ratios were 0.40, 0.45 and 0.50. A total of 15 different mortar mixtures including control Portland cement and fly ash mortar were produced. Workability of fresh mortar was measured using mini flow testing. Flexural and compressive strength of hardened standard sized samples were measured after completion of their specified curing time at 1d, 3d, 7d 28d, 3m and 6m. Experimental results showed that inclusion of fly ash in mortar improved workability with respect to control Portland cement mortar. Recycling low amount of fly ash in mortar did not show detrimental but beneficial influence on strength properties of mortar. However, employing high amount of fly ash in mortar reduced flexural and compressive strength at early ages, however, the reduction in flexural and compressive strengths were remedied due to pozzolanic reaction of fly ash at longer curing time compared to control Portland cement mortar. It was concluded that current fly ash was a suitable pozzolanic material to be recycled by replacement with Portland cement in mortar to manufacture clean construction material in terms of workability and strength concern.

High-volume use of limestone in ultra-high performance fiber-reinforced concrete for reducing cement content and autogenous shrinkage

Abstract In spite of superior mechanical performance, ultra-high performance fiber-reinforced concrete (UHPFRC) is one of the most inefficient construction materials in terms of Portland cement usage. In this study, low-cement UHPFRC is proposed using high-volume limestone powder as a binder. Under ambient curing conditions, ultra-high strength (150–180 MPa) at 91 days was achieved with cement amount of 400–600 kg/m3. Efficient cement consumption of the concrete was quantitatively evaluated based on cement consumption index (CCI). In addition, autogenous shrinkages of UHPFRCs were effectively mitigated owing to the filler effect of limestone powder and the cement dilution effect which increases the water-to-cement ratio. Although this type of concrete incorporates quartz powder as physical filler, cement hydration was further accelerated with increasing limestone powder content. Accelerated cement hydration owing to the limestone powder shortens not only the dormant period but also the duration of the early stage during which risk of cracking is exceptionally high because of rapid shrinkage and low mechanical property. The production strategy suggested herein can practically contribute to reducing demand for Portland cement, along with advantages in dimensional stability.

Analysis of fly ash from PLTU Asam-Asam as a construction material in terms of its physical and mechanical properties

Nowadays, PLTU Asam-Asam produced enormous amounts of combustion waste in the form of coal ash. On the contrary, only a little effort has been made to utilize coal ash from PLTU Asam-Asam, especially from the research side. In fact, due to its siliceous material, when reacting with CH in concrete, will form CSH hence improves concrete strength. In this study, in order to analyze the physical and mechanical properties of concrete using fly ash from PLTU Asam-Asam, 54 concrete samples were prepared according to SNI-03-2834-2000. The examination of concrete samples workability was conducted based on the slump test according to SNI 1972:2008. Moreover, the compressive tests were carried out in accordance with SNI 1974:2011. The slump test results show that the pozzolanic reaction of fly ash contributes to the improvement of concrete workability. Furthermore, the variation in w/b ratio was also affecting the results of the slump test. As for the compressive strength, in general speaking, the replacement ratio of 30% of cement with fly ash in concrete could produce concrete strength up to 30 Mpa. It is also important to note that due to the pozzolanic reactions tends to delayed, it is expected that at later ages (above 28 days) concrete with fly ash will gain much more strength compared to ordinary concrete.

Transportation matters – Does it? GIS-based comparative environmental assessment of concrete mixes with cement, fly ash, natural and recycled aggregates

The urban world is expanding and densifying fast. This requires and produces huge amounts of new construction materials and construction and demolition waste (CDW) every year. Concrete is not only the most important construction material in terms of sheer amount but also regarding embodied greenhouse gas emissions. Alternative concrete mixes have been developed by introducing supplementary cementitious materials (e.g. fly ash (FA)) and CDW (e.g. recycled aggregates (RA)). So far, environmental assessments focus mostly on the production of concrete mixes without considering the transportation-related impacts. This paper appraises the importance of transportation-related impacts of raw materials for concrete production and proposes a new method combining Life Cycle Assessment and geospatial analysis of road transportation of materials. Environmental impacts (EI) of different mixes are assessed for the specific locations of concrete plants. Traditional and alternative concrete mixes are compared to choose site-specifically the mix with lower impacts. For that purpose, two Portuguese cities were considered as case studies. The new method uncovers if and how location of supply and demand for concrete production is important. The results show that for traditional concrete and for mixes incorporating low FA ratio and/or RA, transportation does not matter. However, it matters when choosing between already drastically improved mixes: then, distances from raw materials suppliers to concrete plants can tip the scales of total EI. In fact, the distances to FA and recycling plants influence the selection of the most environmental friendly concrete mix. The method can be applied to other case studies and materials.

Life Cycle Assessment of a Three-Bedroom House in Saudi Arabia

The building sector is one of the crucial stakeholders in the global energy and environmental scenario. Life cycle assessment (LCA) is a tool widely used to evaluate the environmental performance of buildings, materials and activities. Saudi Arabia has a rapidly growing construction sector with over $1 Trillion of ongoing projects. The housing sector, annually needing over 2.32 million new residential units in coming years, is yet to entertain environmental performance of buildings in its list of priorities. The present work undertakes a LCA study of a three-bedroom modern villa located in Dhahran. Providing the structural details of the villa, an account of the 18 main construction materials in terms of quantity and application has been produced. Embodied energy of these materials has been estimated adopting ‘cradle-to-gate’ approach. Environmental impacts of the materials have been modeled with the help of SimaPro software. The results suggest that concrete accounts for more than 43% of the total embodied energy of the house and is also the predominant material in terms of the overall environmental impacts. Steel is the second most prominent material both in terms of quantity and embodied energy.

Synthesizing and Assessing Fire-Resistant Geopolymer from Rejected Fly Ash

Ordinary Portland cement is a widely favored construction material because of its good strength and durability and its reasonable price; however, spalling behaviour during fire exposure can be a serious risk that can lead to strength degradation or collapse of a building. Geopolymers, which can be synthesized by mixing aluminosilicate source materials such as metakaolin and fly ash, and alkali activators, are resistant to fire. Because the chemical composition of geopolymers controls the properties of the geopolyers, geopolymers with various Si:Al ratios were synthesized and evaluated as fire resistant construction materials. Rejected fly ash generated from a power plant was quantitatively analyzed and mixed with alkali activators to produce geopolymers having Si:Al ratios of 1.5, 2.0, and 3.5. Compressive strength of the geopolymers was measured at 28 days before and after heating at 900℃. Geopolymers having an Si:Al ratio of 1.5 presented the best fire resistance, with a 44% increase of strength from 29 ㎫ to 41 ㎫ after heating. This material also showed the least expansion-shrinkage characteristics. Geopolymer mortar developed no spalling and presented more than a 2 h fire resistance rating at 1,050℃ during the fire testing, with a cold side temperature of 74℃. Geopolymers have high potential as a fire resistant construction material in terms of their increased strength after exposure to fire.

A Study on the Strength Properties of Mortar Using Limestone Powder

According to the recent community-based structures enlargement, specification, and diversification. It needs appropriate construction materials in terms of intensity and environmental aspects. Thus, in manufacturing the cement using micro limestone powder that is main material. It is also expected to save energies and reduces CO2, by using the blast furnace slag and fly ash which are mitigated environmental load construction materials that emerged. In this research, the durability aspect tries to be grasped considering the chemical property according to the coherence of the hydration product. Consequently, the compressive strength was measured over 30Mpa on 3rd. In addition, according to the content of the limestone powder, the setting time is promoted. It has the feature expanded in the length change. And it is determined because the possibility of replacing the existing for construction material such as it is measured compared with the time to use the portland cement usually that flexural strength is high with the age 7 days ago, so it is sufficient.

Suitability of UNS S31603 steel for geothermal brines in volcanic areas – Influence of different physicochemical conditions on its corrosion behavior

Geothermal sources are found to be the most aggressive natural environments for construction materials in terms of corrosion. This study was focused on investigating the suitability of stainless steel UNS S31603 in volcanic areas of geothermal sites Sibayak and Lahendong (Indonesia). Influence of different factors (temperatures up to 175°C, chloride content up to 1500mg/L and pH down to 2) was assessed to determine a “safe operating window” of a power plant and assure the system integrity. Investigations were performed by means of electrochemical methods and long-term exposure tests.

Experimental Investigation of the Mechanical Properties of Jointed Rubber Wood Using Two Types of Adhesives

Wood, a potentially good construction material in terms of sustainability, has less structural use now in India. Due to easy availability, low cost and good working quality there is a scope for the value addition of rubber wood in the Country. Finger jointing technology benefits high economic advantage by upgrading rubber wood. There is a dearth of information for the influence of adhesive on the mechanical properties of jointed rubber wood in India. This study was conducted to evaluate the effects of adhesive type on the end jointing and face gluing of rubber wood. The end jointing adopted for the study was the most common finger joint configuration of the wood industry in Kerala, the largest producer of rubber wood in the Country. The adhesives were polyvinyl acetate (PVAc) and phenol resorcinol formaldehyde (PRF). The face gluing evaluation was done based on the adhesive bond strength and percentage wood failure. The integrity of glue types to delamination was also tested .The results of the study have indicated glue type has no statistically significant effect on modulus of rupture, modulus of elasticity of finger joints and the shear strength of adhesive bond in the dry stage with the same wood failure percentage. The joint efficiency of PRF adhesive was superior to PVAc in tension and compression of finger joints. The PRF adhesive exhibited excellent performance in the exterior exposure condition durability test.

석회석(石灰石) 미분말(微粉末)을 이용(利用)한 그린모르타르의 강도(强度) 특성(特性)에 관한 연구(硏究)

최근 사회기반 구조물이 대형화, 특수화, 다양화 되어감에 따라 강도적인 측면과 환경적인 측면에 부합하는 건설재료를 필요로 하고 있다. 따라서, 시멘트 제조시 주원료인 석회석 미분말을 사용하여 에너지 감축과 <TEX>$CO_2$</TEX>발생을 절감하고자 하였으며, 환경부하 저감형 건설재료로 부각되고 있는 고로슬래그, 플라이애쉬를 사용하고자 하였다. 본 연구에서는 수화생성물의 결합력에 따른 화학적 특성을 고려해 내구성 측면을 파악하고자 한다. 그 결과 3일 압축강도가 30 Mpa 이상 측정되었다. 또한 석회석 미분말의 사용량이 증가함에 따라 응결시간이 빨라지고, 길이변화에서 팽창되는 특징을 가지고 있다. 그리고 보통 포틀랜드 시멘트를 사용하였을 때와 비교하여 재령 7일 이전에는 휨강도가 높은 것으로 측정되는 등 기존 건설용 재료를 대체할 가능성이 충분하다고 판단되어진다. According to the recent community-based structures enlargement, specification, and diversification. It needs appropriate construction materials in terms of intensity and environmental aspects. Thus, in manufacturing the cement using micro limestone powder which is main material. It is also expected to save energies and reduces <TEX>$CO_2$</TEX>, by using the blast furnace slag and fly ash which are mitigated environmental load construction materials that emerged. In this research, The durability aspect tries to be grasped considering the chemical property according to the coherence of the hydration product. Consequently, The compressive strength was measured over 30 Mpa on 3rd. In addition, according to the content of the limestone powder, the setting time is promoted. It has the feature expanded in the length change. And it is determined because the possibility of replacing the existing for construction material such as it is measured compared with the time to use the portland cement usually that flexural strength is high with the age 7 days ago, so it is sufficient.

Mechanical properties of natural fiber-reinforced normal strength and high-fluidity concretes

An experimental investigation of mechanical properties of jute fiber-reinforced concrete (JFRC) has been reported for making a suitable construction material in terms of fiber reinforcement. Two jute fiber reinforced concretes, called jute fiber reinforced normal strength concrete (JFRNSC) and jute fiber- reinforced high-fluidity concrete (JFRHFC), were tested in compression, flexure and splitting tension. Compressive, flexural and splitting tensile strengths of specimens were investigated to four levels of jute fiber contents by volume fraction. From the test results, Jute fiber can be successfully used for normal strength concrete (NSC) and high-fluidity concrete (HFC). Particularly, HFC with jute fibers shows relatively higher improvement of strength property than that of normal strength concrete.

Out-of-plane behaviour of existing stone masonry buildings: experimental evaluation

Masonry structures can be considered as the simplest type of structures concerning its assemblage but, at the same time, it is one of the most complex construction materials in terms of mechanical properties and correct behaviour assessment. In this context, the work herein presented aims at describing an experimental testing campaign recently carried out in order to characterize the out-of-plane behaviour of traditional masonry constructions. Taking advantage of the existence of a traditional two-storey masonry building abandoned after the 1998 Azores earthquake, several in-situ tests were defined and performed with the application of quasi-static cyclic loads at the building top level in the out-of-plane direction. In addition, the efficiency of retrofitting and/or strengthening techniques applied during the 1998 Azores reconstruction process was also experimentally evaluated. Finally, an overall discussion of these techniques is presented, resorting also to previous tests’ results carried out by the same authors, aiming at inferring and suggesting quantifications of strengthening techniques’ contributions for future interventions on existing buildings. For this purpose, simple analytical mechanical approaches were adopted in order to provide numerical estimates of strength that were found in good agreement with the experimental results.

건축공사 주요자재별 에너지소비량 및 CO2 배출 원단위 값 산출에 산업연관표 적용 적정성 검토 연구 -2005년, 2007년 산업연관표를 중심으로-

한국은행에서 2000년도에 발행된 산업연관표를 적용한 주요 건축자재의 에너지소비량과 <TEX>$CO_2$</TEX> 배출에 대한 원단위 DB는 있지만 2005년, 2007년에 발행된 산업연관표를 이용한 원단위 DB는 없는 실정이다. 본 연구에서는 최근에 발행된 2005년, 2007년도 산업연관표를 이용하여 주요 건축자재에서 발생되는 에너지소비량 및 <TEX>$CO_2$</TEX> 배출 원단위 값을 산정하고자 한다. 주요 건축자재의 에너지소비량 및 <TEX>$CO_2$</TEX> 배출원단위 산출을 위한 방법은 산업연관표를 이용한 DB 구축 방식을 바탕으로 산출하였으며, 건설현장에서 주로 사용되는 16가지의 건설자재는 선별하여 적용하였다. 기존 연구결과에서 제시한 2000년도 산업연관표를 적용하여 산출된 원단위 DB 값과 비교한 결과 근소한 차이를 보이고 있어 본 연구의 산출방법이 적정한 것으로 판단하였다. 2005년, 2007년도 산업연관표를 이용하여 산출한 에너지소비량과 <TEX>$CO_2$</TEX> 배출 원단위 값은 감소세를 보이고 있는 것으로 나타났으며, 시멘트와 철근을 주원료로 하는 자재에서 가장 많은 에너지소비량 및 <TEX>$CO_2$</TEX> 배출 원단위 값을 나타났다. 본 연구의 결과를 통해 국내 실정에 적합한 건설자재 생산단계에서 발생되는 환경부하의 간접적인 예측이 가능할 것으로 사료된다. Currently, there is database for per unit requirements of major construction materials in terms of energy consumption and <TEX>$CO_2$</TEX> emission based on the input-output table published by the Bank of Korea in 2000, but no database for per unit requirements based on input-output tables was published in 2005 and 2007. The purpose of this study was to calculate the unit requirement values of major construction materials in terms of energy consumption and <TEX>$CO_2$</TEX> emission generated by using the input-output tables published in 2005 and 2007. To estimate the unit requirement values, a database building method with the input-output tables was adopted by selecting 16 types of construction materials in wide use on construction sites. When the study results were compared with existing unit requirement values based on the input-output table of 2000, there were small discrepancies, from which it can be interpreted that the method used in the study is reasonable. Unit requirement values estimated based on input-output tables of 2005 and 2007 tended to decrease, and the highest value of energy consumption and <TEX>$CO_2$</TEX> emission were found in the materials using cement and rebar.

Fish assemblages associated with artificial reefs of concrete aggregates or quarry stone offshore Miami Beach, Florida, USA

Few studies have compared the suitability of different artificial reef construction materials in terms of their efficacy in acquiring diverse faunal assemblages. We compared the fishes associated with 12 co-located reefs constructed of limestone quarry boulders, concrete-gravel aggregate, or concrete-tire aggregate (four of each substrate) in 7 m of water, 200 m offshore Miami Beach, Florida, USA. All 12 reefs were deployed 100 m apart the same day in two lines of six. The four quarry stone reefs consist of a pile of 50 boulders each. The remaining eight reefs, of concrete-gravel aggregate and concrete-tire aggregate, were each constructed with 25 1.5 m edge and 25 1.2 m edge tetrahedron modules. Every two months from October 1998 to February 2001, SCUBA divers recorded fish species, abundance, and length, as well as spiny lobster, Panulirus argus, abundance. One hundred and forty-six species of fishes were recorded during the study period. The abundance and species richness of fish on each treatment exhibited a significant ( p<0.05) seasonal variation with summer months having the greatest numbers and winter the lowest. There was no significant difference in total fish or spiny lobster abundance or fish biomass amongst the three reef types ( p>0.05). Likewise, multi-dimensional scaling of Bray-Curtis dissimilarity indices did not indicate clustering of fish assemblages by reef type. Comparison of pre-deployment fish counts from the reef sites and neighboring hard bottom and jetty with counts from the same sites two years post-deployment indicate the artificial reefs increased both fish abundance and richness in the local area.