Recently, there has been great interest on the applicability of Recycled Concrete Aggregate (RCA) as a new ecological construction material that can be sustainable in a gradually expanding construction industry. This paper reports the structural performance particularly on shear behaviour of high strength reinforced recycled concrete beams. Compressive cube strength of the tested beams ranged from 65-74 MPa at the age of 28-days. The experimental program compared conventional concrete mix with concrete mix having substitution of 25% recycled concrete aggregates of grade 25-30 MPa. In this study, three 150 mm x 200 mm x 1200 mm simply supported rectangular concrete beams in each mix were tested under a four-point bending static load with various shear span to effective depth ratios (a/d = 1.0, 1.5, 2.0). Subsequently, the shear behavior of the beams was investigated through studies of load-deflection responses, effect of a/d ratios and crack patterns. The test results reported that the substitution of 25% recycled concrete coarse aggregates barely affects the shear capacity of the high strength reinforced concrete beams with a/d of 1.5 onwards. Finally, experimental results were compared using existing design codes by ACI 318, Eurocode-2 and AS3600 which lie on the safe side.
Reinforced concrete (RC) box girders are a common structural member for road bridges in modern construction. The hollow cross-section of a box girder is ideal in carrying eccentric loads or torques introduced by skew supports. This study employed acoustic emission (AE) monitoring on multicell RC box girder specimens subjected to laboratory-based torsion loading. Three multicell box girder specimens with different cross-sections were tested. The aim is to acquire AE analysis data indicative for characterizing torsion fracture in the box girders. It was demonstrated through appropriate parametric analysis that the AE technique could be utilized to effectively classify fracture developed in the specimens for describing their mechanical behavior under torsion. AE events localization was presented to illustrate the trend of crack and damage propagation in different stages of fracture. It could be observed that spiral-like patterns of crack were captured through AE damage localization system and damage was quantified successfully in different stages of fracture by using smoothed b-value analysis.
Matched MeSH terms: Construction Materials/standards*
The construction sector is among the fastest growing sectors in Malaysia; it consumes a vast amount of natural resources and produces a massive volume of construction and demolition waste. The waste is collected in a decentralised manner by sub-contracted companies. It is challenging to obtain reliable information on the amount of construction waste generated, because it is hard to determine its exact quantity and composition. Therefore, this study proposes a quantitative construction waste estimation model for residential buildings according to available data collected from the Construction Industry Development Board, Malaysia. In the development of this model, a theoretical investigation of the construction procedure and the construction waste generation process was conducted. The waste generated rate was determined as 25.79 kg m-2 for new residential constructions, which translates into about 553,406 t of anticipated waste annually.
At present, soil and mineral based building material such as bricks are one of the main components in building construction in Malaysia. This building material is a direct source of radiation exposure since it contains naturally occurring radioactive materials (NORM). In this study, clay brick samples used were obtained from 7 factories in Selangor and Johore, Malaysia. The activity concentrations of 226 Ra, 232 Th and 40 K in these samples of clay bricks were determined using a comparative method and was analysed using gamma spectrometry with HPGe detector. The mean values of activity concentrations for 226 Ra, 232 Th and 40 K were found to be in the range of 39.04 ± 0.88 Bqkg-1 - 73.61 ± 5.32 Bqkg-1, 43.38 ± 2.60 Bqkg-1 - 73.45 ± 1.51 Bqkg-1, and 381.54 ± 11.39 Bqkg-1 - 699.63 ± 15.82 Bqkg-1, respectively. The radiation hazard of NORM in the samples was estimated by calculating the radium equivalent activity (Raeq), external hazard index (Hex) and internal hazard index (Hin). Radium equivalent activity (Raeq) determined was in the range of 151.90 Bqkg-1 - 194.22 Bqkg-1 which is lower than the limit of 370 Bqkg-1 (equivalent to 1.5 mSvyr-1 ) recommended in the NEA-OECD report in 1979, whereas external hazard index (Hex) and internal hazard index (Hin) were between 0.20 – 0.26 and 0.52 - 0.71 respectively. The annual effective dose rate exposure to a dweller received from the clay bricks was calculated to be in the range of 0.35 ± 0.18 mSvy-1 - 0.43 ± 0.09 mSvy-1.
Recycling of the waste rubber tire crumbs (WRTCs) for the concretes production generated renewed interest worldwide. The insertion of such waste as a substitute for the natural aggregates in the concretes is an emergent trend for sustainable development towards building materials. Meanwhile, the enhanced resistance of the concrete structures against aggressive environments is important for durability, cost-saving, and sustainability. In this view, this research evaluated the performance of several modified rubberized concretes by exposing them to aggressive environments i.e., acid, and sulphate attacks, elevated temperatures. These concrete (12 batches) were made by replacing the cement and natural aggregate with an appropriate amount of the granulated blast furnace slag (GBFS) and WRTCs, respectively. The proposed mix designs' performance was evaluated by several measures, including the residual compressive strength (CS), weight loss, ultrasonic pulse velocity (UPV), microstructures, etc. Besides, by using the available experimental test database, an optimized artificial neural network (ANN) combined with the particle swarm optimization (PSO) was developed to estimate the residual CS of modified rubberized concrete after immersion one year in MgSO4 and H2SO4 solutions. The results indicated that modified rubberized concrete prepared by 5 to 20% WRTCs as a substitute to natural aggregate, provided lower CS and weight lose expose to sulphate and acid attacks compared to control specimen prepared by ordinary Portland cement (OPC). Although the CS were slightly declined at the elevated temperature, these proposed mix designs have a high potential for a wide variety of concrete industrial applications, especially in acid and sulphate risk.
Conventional building materials (CBMs) made from non-renewable resources are the main source of indoor air contaminants, whose impact can extend from indoors to outdoors. Given their sustainable development (SD) prospect, green building materials (GBMs) with non-toxic, natural, and organic compounds have the potential to reduce their overall impacts on environmental and human health. In this regard, biocomposites as GBMs are environmentally friendly, safe, and recyclable materials and their replacement of CBMs reduces environmental impacts and human health concerns. This study aims to develop a model of fully hybrid bio-based biocomposite as non-structural GBMs and compare it with fully petroleum-based composite in terms of volatile organic compound (VOC) emissions and human health impacts. Using a small chamber test (American Society for Testing and Materials (ASTM)-D5116) for VOC investigation and SimaPro software modeling with the ReCiPe method for evaluating human health impacts. Life cycle assessment (LCA) methodology is used, and the results indicate that switching the fully hybrid bio-based biocomposite with the fully petroleum-based composite could reduce more than 50% impacts on human health in terms of indoor and outdoor. Our results indicate that the usage of biocomposite as GBMs can be an environmentally friendly solution for reducing the total indoor and outdoor impacts on human health.
Matched MeSH terms: Construction Materials/adverse effects*
Malaysia is facing an increase in the generation of waste and of accompanying problems with the disposal of this waste. In the last two decades, extensive building and infrastructure development projects have led to an increase in the generation of construction waste material. The construction industry has a substantial impact on the environment, and its environmental effects are in direct relation to the quality and quantity of the waste it generates. This paper discusses general characteristics of the construction contractors, the contractors' willingness to pay (WTP) for improved construction waste management, determining factors which affect the amount of their willingness to pay, and suggestions and policy implications in the perspective of construction waste management in Malaysia. The data in this study is based on contractors registered with the construction industry development board (CIDB) of Malaysia. Employing the open ended contingent valuation method, the study assessed the contractors' average maximum WTP for improved construction waste management to be RM69.88 (1US$=3.6 RM) per tonne of waste. The result shows that the average maximum WTP is higher for large contractors than for medium and small contractors. The highest average maximum WTP value is RM88.00 for Group A (large contractors) RM78.25 for Group B (medium-size contractors) and RM55.80 for Group C (small contractors). One of the contributions of this study is to highlight the difference of CIDB registration grade in the WTP for improved construction waste management. It is found that contractors' WTP for improved waste collection and disposal services increases with the increase in contractors' current paid up capital. The identified factors and determinants of the WTP will assist the formulation of appropriate policies in addressing the construction waste problem in Malaysia and indirectly improve the quality of construction in the country.
Radon-222 emanation from selected locally produced samples of building materials, used in Malaysia were measured using the Professional Continuous Radon Monitor Model 1027, which is a patented electronic detecting-junction photodiode sensor to measure the concentration of radon gas. Each sample was placed for 72 hours inside a 3.11 x 10 -2 m 3 sealed container. It was found that the average radon concentration Bqm -3 of air for concrete bricks, concrete brick with cemented coatings, concrete brick with cemented coatings and paint samples were, 303.7 Bq/m 3, 436.6 Bqm -3, and 410.7 Bqm -3, respectively. (Bqm -3 ) for brown clay brick, brown clay brick with cemented coatings, brown clay brick with cemented coatings and paint were 166.5 Bqm -3, 166.5 Bqm -3, and 148 Bqm -3, respectively. (Bqm -3 ) for sample of compact ceramic tile was 0 Bqm -3. The findings show that concrete brick samples are important source of radon emanation, while brown clay brick have been accepted as the recommendation of the U.S. Environmental Protection Agency (EPA), and ceramic tiles had no emanation of radon gas due to their compact surface, or the glazed layer created on the tile surface during the manufacturing process, which blocks radon emanation. A positive correlation between radon emanation and radium content has been observed for both brown clay brick and concrete brick samples whereas a negative correlation for ceramic tile has been observed. Consequently from the findings, in order to reduce radon emanation and radon exposure in house dwellings and in addition to EPA recommendation of sealed cracks and established good ventilation, we recommend concrete walls to be painted and concrete floors to be paved with ceramic tiles.
The present study examines the use of collars and geobags for reducing local scour around bridge piles. The efficiency of collars and geobags was studied experimentally. The data from the experiments were compared with data from earlier studies on the use of single piles with a collar and with a geobag. The results showed that using a combination of a steel collar and a geobag yields the most significant scour reduction for the front and rear piles, respectively. Moreover, the independent steel collar showed better efficiency than the independent geobag below the sediment level around the bridge piles.
Matched MeSH terms: Construction Materials/standards*
Research for alternative binders has become a necessity due to cement's embodied carbon, climate change, and depletion of natural resources. These binders could potentially reduce our reliance on cement as the sole binder for concrete while simultaneously enhancing the functional characteristics of concrete. Theoretically, the use of finer particles in the cement matrix densifies the pore structure of concrete and results in improved properties. To validate this hypothesis, current research was designed to investigate how the value-added benefits of nano-silica (NS) and metakaolin (MK) in fly ash (FA)-blended cement affect the mechanical and durability characteristics of concrete when used as ternary and quaternary blends. Additionally, the cost-benefit analysis and environmental impact assessment were conducted. It was observed that the synergy of MK and NS used in FA-blended cement had a greater impact on enhancing the functional characteristics of concrete, while 10% MK as ordinary Portland cement (OPC) replacement and 1% NS as an additive in FA-blended OPC concrete was the optimum combination which achieved 94-MPa compressive strength at the age of 91 days and showed more than 25% increment in the flexural and splitting tensile strengths compared to the control mix (MS00). The ultrasonic pulse velocity and dynamic modulus of elasticity were significantly improved, while a significant reduction in chloride migration of 50% was observed. In terms of environmental impact, MS100 (30% FA and 10% MK) exhibited the least embodied CO2 emissions of 319.89 kgCO2/m3, while the highest eco-strength efficiency of 0.268 MPa/kgCO2·m-3 with respect to 28-day compressive strength was exhibited by MS101. In terms of cost-benefit, MS00 was determined the cheapest, while the addition of MK and NS increased the cost. The lowest cost of producing 1 MPa was exhibited by MS01 with a merely 0.04-$/MPa/m3 reduction compared to MS00.
The production of cement releases an enormous amount of CO2 into the environment. Besides, industrial wastes like silica fume and fly ash need effective utilization to reduce their impacts on the environment. This research aims to explore the influence of silica fume (SF) and fly ash (FA) individually and combine them as binary cementitious material (BCM) on the hardened properties and embodied carbon of roller compacted concrete (RCC). A total of ten mixes were prepared with 1:2:4 mix ratio at the different water-cement ratios to keep the zero slump of roller compacted concrete. However, the replacement proportions for SF were 5%-15%, and FA were 5%-15% by the weight of cement individually and combine in roller compacted concrete for determining the hardened properties and embodied carbon. In this regard, several numbers of concrete specimens (cubes and cylinders) were cast and cured for 7 and 28 days correspondingly. It was observed that the compressive strength of RCC is boosted by 33.6 MPa and 30.6 MPa while using 10% of cement replaced with SF and FA individually at 28 days, respectively. Similarly, the splitting tensile strength of RCC is enhanced by 3.5 MPa at 10% cement replaced with SF and FA on 28 days, respectively. The compressive and splitting tensile strength of RCC is increased by 34.2 MPa and 3.8 MPa at SF7.5FA7.5 as BCM after 28 days consistently. In addition, the water absorption of RCC decreased while using SF and FA as cementitious material individually and together at 28 days. Besides, the embodied carbon of RCC decreased with increasing the replacement level of SF and FA by the mass of cement individually and combined.
This paper presents the experimental results of an on-going research project on geopolymer lightweight concrete using two locally available waste materials--low calcium fly ash (FA) and oil palm shell (OPS)--as the binder and lightweight coarse aggregate, respectively. OPS was pretreated with three different alkaline solutions of sodium hydroxide (NaOH), potassium hydroxide, and sodium silicate as well as polyvinyl alcohol (PVA) for 30 days; afterwards, oil palm shell geopolymer lightweight concrete (OPSGPC) was cast by using both pretreated and untreated OPSs. The effect of these solutions on the water absorption of OPS, and the development of compressive strength in different curing conditions of OPSGPC produced by pretreated OPS were investigated; subsequently the influence of NaOH concentration, alkaline solution to FA ratio (A/FA), and different curing regimes on the compressive strength and density of OPSGPC produced by untreated OPS was inspected. The 24-hour water absorption value for OPS pretreated with 20% and 50% PVA solution was about 4% compared to 23% for untreated OPS. OPSGPC produced from OPS treated with 50% PVA solution produced the highest compressive strength of about 30 MPa in ambient cured condition. The pretreatment with alkaline solution did not have a significant positive effect on the water absorption of OPS aggregate and the compressive strength of OPSGPC. The result revealed that a maximum compressive strength of 32 MPa could be obtained at a temperature of 65°C and curing period of 4 days. This investigation also found that an A/FA ratio of 0.45 has the optimum amount of alkaline liquid and it resulted in the highest level of compressive strength.
The addition of a photocatalyst to ordinary building materials such as concrete creates environmentally friendly materials by which air pollution or pollution of the surface can be diminished. The use of LiNbO3 photocatalyst in concrete material would be more beneficial since it can produce artificial photosynthesis in concrete. In these research photoassisted solid-gas phases reduction of carbon dioxide (artificial photosynthesis) was performed using a photocatalyst, LiNbO3, coated on concrete surface under illumination of UV-visible or sunlight and showed that LiNbO3 achieved high conversion of CO2 into products despite the low levels of band-gap light available. The high reaction efficiency of LiNbO3 is explained by its strong remnant polarization (70 µC/cm(2)), allowing a longer lifetime of photoinduced carriers as well as an alternative reaction pathway. Due to the ease of usage and good photocatalytic efficiency, the research work done showed its potential application in pollution prevention.
Matched MeSH terms: Construction Materials/analysis; Construction Materials/radiation effects*
The production of cement contributes to 10% of global carbon dioxide (CO2) pollution and 74 to 81% towards the total CO2 pollution by concrete. In addition to that, its low strength-to-weight ratio, high density and thermal conductivity are among the few limitations of heavy weight concrete. Therefore, this study was carried out to provide a solution to these limitations by developing innovative eco-friendly lightweight foamed concrete (LFC) of 1800 kg/m3 density incorporating 20-25% palm oil fuel ash (POFA) and 5-15% eggshell powder (ESP) by weight of total binder as supplementary cementitious material (SCM). The influence of combined utilization of POFA and ESP on the fresh state properties of eco-friendly LFC was determined using the J-ring test. To determine the mechanical properties, a total of 48 cubes and 24 cylinders were prepared for compressive strength, splitting tensile strength and modulus of elasticity each. A total of 24 panels were prepared to determine the thermal properties in terms of surface temperature and thermal conductivity. Furthermore, to assess the environmental impact and eco-friendliness of the developed LFC, the embodied carbon and eco-strength efficiency was calculated. It was determined that the utilization of POFA and ESP reduced the workability slightly but enhanced the mechanical properties of LFC (17.05 to 22.60 MPa compressive strength and 1.43 to 2.61 MPa tensile strength), thus satisfies the ACI213R requirements for structural lightweight concrete and that it can be used for structural applications. Additionally, the thermal conductivity reduced ranging from 0.55 to 0.63 W/mK compared to 0.82 W/mK achieved by control sample. Furthermore, the developed LFC showed a 16.96 to 33.55% reduction in embodied carbon and exhibited higher eco-strength efficiency between 47.82 and 76.97%. Overall, the combined utilization of POFA and ESP as SCMs not only enhanced the thermo-mechanical performance, makes the sustainable LFC as structural lightweight concrete, but also has reduced the environmental impacts caused by the disposal of POFA and ESP in landfills as well as reducing the total CO2 emissions during the production of eco-friendly LFC.
Uncontrolled stormwater runoff not only creates drainage problems and flash floods but also presents a considerable threat to water quality and the environment. These problems can, to a large extent, be reduced by a type of stormwater management approach employing permeable pavement systems (PPS) in urban, industrial and commercial areas, where frequent problems are caused by intense undrained stormwater. PPS could be an efficient solution for sustainable drainage systems, and control water security as well as renewable energy in certain cases. Considerable research has been conducted on the function of PPS and their improvement to ensure sustainable drainage systems and water quality. This paper presents a review of the use of permeable pavement for different purposes. The paper focuses on drainage systems and stormwater runoff quality from roads, driveways, rooftops and parking lots. PPS are very effective for stormwater management and water reuse. Moreover, geotextiles provide additional facilities to reduce the pollutants from infiltrate runoff into the ground, creating a suitable environment for the biodegradation process. Furthermore, recently, ground source heat pumps and PPS have been found to be an excellent combination for sustainable renewable energy. In addition, this study has identified several gaps in the present state of knowledge on PPS and indicates some research needs for future consideration.
Matched MeSH terms: Construction Materials/analysis
Road distress results in high maintenance costs. However, increased understandings of asphalt behaviour and properties coupled with technological developments have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, polymers have become extremely popular as modifiers to improve the performance of the asphalt mix. This study investigates the performance characteristics of epoxidized natural rubber (ENR)-modified hot-mix asphalt. Tests were conducted using ENR-asphalt mixes prepared using the wet process. Mechanical testing on the ENR-asphalt mixes showed that the resilient modulus of the mixes was greatly affected by testing temperature and frequency. On the other hand, although rutting performance decreased at high temperatures because of the increased elasticity of the ENR-asphalt mixes, fatigue performance improved at intermediate temperatures as compared to the base mix. However, durability tests indicated that the ENR-asphalt mixes were slightly susceptible to the presence of moisture. In conclusion, the performance of asphalt pavement can be enhanced by incorporating ENR as a modifier to counter major road distress.
Matched MeSH terms: Construction Materials/analysis*
This aim of this study is to study the effects of various contents of Automotive Windscreen Glass Waste Powder (WGWP) as a cement replacement. Mortar incorporating several compositions of WGWP (0%, 5%, 10%, 15% and 20%) by weight of cement was prepared. Three batching systems of cement to sand (C:S) ratios of 1:2.5 superplasticizers (SP), 1:3.0 SP and 1:3.5 SP was also employed. Fixed water to cement (w/c) ratio of 0.5 was used. The samples were water cured and the assessment of the strength performance of mortar cubes carried out at 7 and 28 days. Studies conducted have shown that WGWP has good pozzolanic properties. In term of compressive strength, it was observed that employing C:S ratio of 1:3.5 SP is better than 1:2.5 SP and 1:3.0 SP.
Diverting waste material from landfill sites has a big implication for the creation of new markets and has environmental benefits through offsetting the need for the extraction of raw materials. Besides, the major attention especially in construction industry is the problem to make natural resources sustainable for three to four decades in future. However, in this study finely glass powder with pozzolanic properties is found to be a partial replacement for cement and can acts as filler in the microstructure of a mortar block. Thus, a study was conducted to see the effects of various proportions of windscreen glass waste powder (WGWP) in determining the degree of water absorption on mortar incorporated with WGWP and to determine the optimum replacement to the ordinary Portland cement (OPC) with WGWP. Several compositions of WGWP (0%, 5%, 10%, 15% and 20% by cement weight) of mortar cube sample were prepared and cured at 7, 28 and 60 days to undergo a water absorption test. From this research, it shows that the use of WGWP was found to be the best features pozzolanic enough to use as a partial replacement for cement and it can reduced the pores of mortar by blocking the large voids in the hydrated cement paste through pozzolanic reaction. In the term of water absorption, the lowest reading was achieved in 15% and it can be said that 15% replacement is the optimum replacement of OPC.
In recent years, the research direction is shifted toward introducing new supplementary cementitious materials (SCM) in lieu of in place of Portland cement (PC) in concrete as its production emits a lot of toxic gases in the atmosphere which causes environmental pollution and greenhouse gases. SCM such as sugarcane bagasse ash (SCBA), metakaolin (MK), and millet husk ash (MHA) are available in abundant quantities and considered as waste products. The primary aim of this experimental study is to investigate the effect of SCBA, MK, and MHA on the fresh and mechanical properties of concrete mixed which contributes to sustainable development. A total of 228 concrete specimens were prepared with targeted strength of 25MPa at 0.52 water-cement ratio and cured at 28 days. It is found that the compressive strength and split tensile strength were enhanced by 17% and 14.28%, respectively, at SCBA4MK4MHA4 (88% PC, 4% SCBA, 4% MK, and 4% MHA) as ternary cementitious material (TCM) in concrete after 28 days. Moreover, the permeability and density of concrete are found to be reduced when SCBA, MK, and MHA are used separately and combined as TCM increases in concrete at 28 days, respectively. The results showed that the workability of the fresh concrete was decreased with the increase of the percentage of SCBA, MK, and MHA separately and together as TCM in concrete.
Globally, concrete is widely implemented as a construction material and is progressively being utilized because of growth in urbanization. However, limited resources and gradual depravity of the environment are forcing the research community to obtain alternative materials from large amounts of agro-industrial wastes as a partial replacement for ordinary cement. Cement is a main binding resource in concrete production. To reduce environmental problems associated with waste, this study considered the recycling of agro-industrial wastes, such as sugarcane bagasse ash (SCBA), rice husk ash (RHA), and others, into cement, and to finally bring sustainable and environmental-friendly concrete. This study considered 5%, 10%, and 15% of SBCA and RHA individually to replace ordinary Portland cement (OPC) by weight method then combined both ashes as 10%, 20%, and 30% to replace OPC to produce sustainable concrete. It was experimentally declared that the strength performance of concrete was reduced while utilizing SCBA and RHA individually and combined as supplementary cementitious material (SCM) at 7, 28, 56, and 90 days, respectively. Moreover, the initial and final setting time is increased as the quantity of replacement level of OPC with SCBA and RHA separates and together as SCM in the mixture. Based on experimental findings, it was concluded that the use of 5% of SCBA and 5% of RHA as cement replacement material individually or combined in concrete could provide appropriate results for structural applications in concrete.