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Corrosion of steel reinforcement in underwater concrete structures continues to be a problem in the modern era. The possibility of employing pultruded glass fibre reinforced polymer (GRFP) I beams to replace traditional steel reinforcement in an encased beam is still being explored. The purpose of this research is to further investigate the effects of incorporating treated recycled concrete aggregate (RCA) and discrete synthetic fibres, specifically Polyolefin (PO) and Fibrillated Polypropylene (PP) fibres, in the production of concrete beam reinforced with GFRP I beam for underwater construction. Five beams were constructed and tested in this investigation using a four-point loading arrangement. The load–deflection curve, stress–strain curve, and initial and ultimate fracture loads are all included in the test parameter set. The results indicate that treating RCA and fibres greatly increases the flexural capacity of modified recycle aggregate concrete (RAC) beams compared to unmodified RAC beams.

This study aims to explore the inclusion of microfibre in fine recycled aggregate (FRA) mortars under dynamic impact load. A 12-mm-diameter Split Hopkinson Pressure Bar (SHPB) was employed to test the impact of a recycled mortar with a single and hybrid fibre system and to determine potential improvements in its dynamic mechanical properties. In recycled mortar production, two microfibres with different sizes and types, namely, polypropylene and nylon, were added whilst keeping the amount of microfibres at a volumetrical fraction of 0.6%. An impact loading test was conducted by using the striking bar of SHPB at impact speeds of 2, 4 and 6 m/s. The effects of fibre on failure mode, tensile curve, compressive strength and dynamic increase factor (DIF) were then analysed. Experimental findings show that the improved mortar fibre mix has superior quasi-static and dynamic compression power compared with the reference mortar mix. Meanwhile, compared with the single fibre mix, the hybrid fibre mix is more effective in enhancing the dynamic compressive ability of the recycled mortar. The recycled-hybrid-fibre-enhanced mortar showed lower DIF values compared with the reference mortar, and the inclusion of fibre reinforcement can reduce the fragmentation of the recycled mortar mix after being subjected to impact.

This paper presents a study that aimed to assess the chloride penetration depth of recycled aggregate concrete (RAC) modified by using treated coarse recycled concrete aggregate (RCA), adding polyolefin (PO) or polypropylene (PP) fibre and comparing with normal concrete. The coupling effects of the treated RCA and fibres on the chloride penetration of RAC were analysed after two different curing regimes (i.e. normal and seawater) and tested at different curing ages (i.e. 90, 180 and 300 days). Results showed that the inclusion of treated coarse RCA can reduce porosity, thereby decreasing the chloride penetration of RAC. However, the coupling effects of treated coarse RCA and fibre, especially on the use of PO fibre, can enhance the results.

This study also investigates the effectiveness of multiple surface modification of recycled concrete aggregate (RCA) with respect to mechanical properties of the resultant recycled aggregate concrete (RAC) when exposed to various curing conditions, namely, normal water (Nw) and seawater (Sw). The properties included compressive and flexural strength and impact resistance. Findings show that effect inclusion of the treated coarse RCA is significant in enhancing the mechanical properties of RAC. The exposure to Sw appears to affect the degradation of the compressive strength of RAC remarkably in a marine environment. In this case, however, using of treated RCA is found beneficial in decreasing the deterioration in the compressive strength of RAC.

This study aims to investigate the dynamic behavior of recycled mortar under impact loading using a split Hopkinson pressure bar (SHPB). Several mortar mixtures were produced by adding various fine recycled aggregates (FRA) to the mixture in replacement percentages of 0%, 25%, 50%, 75%, and 100% of the natural fine aggregate (NFA). The effects of strain rate on compressive strength and specific energy absorption were obtained. Results show that the dynamic compressive strength and specific energy absorption of recycled mortar are highly strain rate dependent; specifically, they increase nearly linearly with the increase in peak strain rate. However, the compressive strength and specific energy absorption of recycled mortar are generally lower than those of NFA mortar (reference samples) under similar high strain rates. The findings of this research can help researchers and construction practitioners to ascertain the appropriate mix design procedure to optimize the impact strength properties of recycled mortar for protective structural application.

This study investigated the effect of replacing natural fine aggregate (NFA) or natural sand with fine recycled concrete aggregate (FRCA) on the mechanical properties, including density, compressive strength, and flexural strength, of high-strength cement-based mortar. Several mortar mixtures were produced by adding various FRCAs to the mixture in percentages of replacing 0%, 25%, 50%, 75%, and 100% of NFA content. The dynamic behavior of the recycled mortar under impact loading using a Split–Hopkinson pressure bar (SHPB) was also evaluated. Overall, results showed that the mechanical performance of the recycled mortar decreased with increasing FRCA replacement level. FRCA at ratios of up to 25% exerted minimal adverse effects on the mechanical properties of mortar.

This paper reviews several key issues related to the use of natural aggregate (NA) for concrete production, in view of the high demand for materials to meet the rapid construction development in Malaysia. The current paper aims to discuss the potential of recycling waste concrete to generate recycled aggregates (RA) that may be used as alternative aggregate sources in the production of concrete. Moreover, several major challenges to the use of RA for concrete production are also highlighted. This paper also provides an action plan to encourage the construction industry’s wide usage of RA to achieve sustainable construction.  Keywords: construction; recycled aggregate; sustainable; waste concreteeISSN 2398-4279 © 2018. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open-access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.Â

This paper examines the mechanical and durability properties of concrete incorporated with treated recycled concrete aggregate (RCA) under different curing conditions. Three different curing regimes were applied, namely, continuous normal water curing (NW), initial water curing for 28 days before exposure to an open air environment (OA), and initial water curing for 28 days before exposure to seawater (SW). Two concrete mixes were produced by replacing 60% of the coarse aggregate using treated and untreated RCA with one control specimen (100% natural coarse aggregate) to examine the mechanical strength (compressive and flexural strength) and durability (water absorption, oxygen permeability, and also porosity) properties of the concrete. Meanwhile, the microstructure of these mixes was studied via scanning electron microscopy (SEM). The inclusion of untreated RCA generally reduces the mechanical strength and durability of the concrete regardless of the curing conditions. The compressive strength of the concrete containing untreated RCA is more detrimental in SW than in the other two curing conditions. Moreover, the concrete with RCA have poor intrinsic air permeability and porosity because their intrinsic porosity and effect are more significant when the curing is performed in OA than in the other curing conditions. Incorporating the treated RCA helps limit the reduction in the mechanical strength and durability of the concrete particularly under a prolonged curing period.

Continuous reduction of construction mineral resources, such as sand and cement, which influence the increase in cost of raw materials, has stimulated initiatives to look for alternative sustainable materials. This research aims to determine the potential and feasibility use of recycled fine aggregate (RFA) generated from demolition waste rubble wall as aggregate to replace natural sand in the production of cement and sand bricks. The brick specimens are prepared by using 100% natural sand, which is then replaced by RFA at 25%, 50%, 75%, and 100% by weight of natural sand. Research parameters, such as dimension, compressive and flexural strength, density, and water absorption, are adopted to evaluate the physical and mechanical properties of the brick specimens. In addition, the thermal conductivity of the bricks composed using different RFA proportions are studied. Experimental results clearly indicate that manufacturing cement and sand brick by incorporating RFA is possible, and the effect inclusion of RFA at certain proportions causes a significant improvement in the mechanical properties of bricks. However, to obtain better mechanical strength results, RFA dosages to replace sand should reach up to 50%.

This study investigates the effect of inclusion of polyolefin and polypropylene fibers at various volume fractions in single and hybrid forms on the mechanical properties of recycled aggregate concrete (RAC) mix that consists of treated coarse recycled concrete aggregate (RCA). Testing parameters, such as compressive strength, flexural strength, static modulus of elasticity, and impact load resistance, are utilized to evaluate the mechanical strength of specimens. The various properties of the modified RAC are also analyzed and compared with those of normal concrete and unmodified RAC specimens. Findings indicate that the mechanical strength properties of RAC mixture using treated RCA were significantly enhanced by adding fibers. The overall optimized mechanical strength results could be obtained in RAC mixtures with fiber in hybrid form, where their compressive strength at long-term curing age, can be significantly improved by 7% upto 11% higher than normal concrete. In addition, RAC mix with hybrid fibers produced the highest flexural strength and impact load resistance by an increase of 5% and 175%, respectively as compared with the control concrete.

Building Tnformation Modeling (BTM) is known as a tool for collaboration among construction organisations in generating and managing data across the construction lifecycle. Despite from the advantages of engaged from BTM (i.e; reduce the number of clashes within the construction process, improve the building visualization, and shorten the planning period), most of the contractor’s organisations are still hesitant to deploy the technology. The aim of this paper is to comprehend the challenges in adopting BTM across project phases. A semi-structured interview was conducted through eight respondents from contractor’s organisations which adopt BTM. The interview data were recorded and analysed using ATLAS.ti software. As a result, the finding demonstrated eight (8) substantial challenges in adopting BTM including staff resistance, selection of software and hardware, lack of knowledge an information of BTM, lack of data of return on investment of BTM, implementation cost and benefits, lack of demands from the clients, lack of supply chain buy-in, and lack of standards-policy makers. Meanwhile, another ten (10) challenges for instance training and education, culture change, ownership and intellectual property, contractual agreement, authenticity, product liabilities risks, legal uncertainties and affection to the business environment are remarked as least challenges revealed by the participants. Tn spite, two (2) additional challenges which are not mentioned by the previous researchers were disclosed by the participants which are trustworthiness and organisation’s politic. On this balance, all the challenges grouped into six major elements; people, software and hardware, cost, product, standard, and others. Thus, it is expected that the finding shall bring significant and knowledge for the construction practices to understand the challenges in adopting BTM across construction projects.

This study is aimed at studying the effect of replacing natural fine aggregate (NFA) or natural sand with fine recycled concrete aggregate (FRCA) in producing high-strength cement-based mortar. Several mortar mixtures were produced by adding various FRCAs to the mixture in percentages of replacing 0%, 25%, 50%, 75%, and l00% of the NFA content. Properties of fresh (slump test) and hardened (density, compressive strength, and flexural strength) mortars were evaluated. The physical characterization showed a higher fineness modulus, lower density, and higher absorption in the FRCA than the NFA. Thus, these results make the use of admixture crucial to maintaining the appropriate consistency for mortar mixtures. Results of the replacement amount study indicated that the mortars prepared using the FRCA present poorer behavior than mortars produced using the NFA. However, no adverse effects on the mechanical properties of mortar are observed when the FRCA are used as replacements at ratios of up to 25%.

In recycling concrete, the crushing process leaves weak mortar particles and surface cracks throughout the recycled concrete aggregates (RCA). Thus, the process is detrimental, resulting in inferior aggregate properties. This experimental study presents a method to improve the properties of coarse RCA by modifying their surface structure through the combination of two different surface treatment methods. In this study, coarse RCA are first treated by soaking in hydrochloric (HCl) acid at 0.5 mol (M) concentration. They are then impregnated with calcium metasilicate (CM) solution to coat their surface with CM particles. The effects of both surface treatments on the properties of RCA before and after treatment are determined. Moreover, the effect of the replacement of natural coarse aggregates with 60% treated coarse RCA on the mechanical strength of concrete is evaluated. The findings of this study show that the effect of the combination of these two surface treatment methods is beneficial, as the combined methods not only modify RCA surface but also enhance RCA properties. More specifically, after treatment, the particle density, water absorption, and mechanical strength of RCA are significantly improved. Consequently, the incorporation of treated RCA in concrete results in a mechanical strength that approximates concrete prepared with natural aggregates and surpasses the strength of concrete prepared with untreated RCA. In addition, the effect use of treated RCA tends to reduce the drying shrinkage of concrete.

This paper reports the experimental works performed to improve the properties of recycled concrete aggregate (RCA) by using different acid molarities at low concentration as agent for surface treatment. The effects of using RCA after treatment on the improvement in the strength of concrete were evaluated and compared. The findings reveal that this treatment can enhance the physical and mechanical properties of RCA. Moreover, treated RCA particles can significantly promote surface contact between the new cement paste and the aggregate, thereby improving the strength of concrete.

One method to promote and encourage maximum recycled concrete aggregate (RCA) utilisation for structural concrete applications is to minimise the adverse effects of RCA on concrete performance. The formulation of an appropriate recycling process in RCA production with improved properties is desirable. This study aims to develop a potential treatment of RCA by using low-concentration acid as an alternative method to produce high quality RCA for structural concrete applications. This work aims to study the effect of using different molarities of acid solvent and age of treatment (soaking) on properties of RCA, as well as the influence of using this treated aggregate on the properties of concrete. The results show that the use of different acid molarities to remove or minimise loose mortar particles attached on the surfaces of RCA can significantly improves its physical and mechanical properties. In addition, the reduction of loose mortar that covers RCA particles can significantly improves surface contact between the new cement paste and the aggregate which subsequently resulted in a significant improvement in the strength of concrete mechanical. However, the effectiveness of these treatment methods remains dependent on several factors that require further consideration.

This paper presents a recycled aggregate concrete (RAC) mix that has been modified by adding treated recycled concrete aggregate (RCA) and various types of fiber-reinforced systems. The effectiveness of these modifications in terms of energy absorption and impact resistance was evaluated and compared with that of the corresponding regular concrete, as well as with unmodified RAC specimens. Results clearly indicate that although modification of the RAC mix with treated RCA significantly enhances the impact resistance of RAC, further diversification with additional fiber, particularly those in hybrid form, can optimize the results.

This study investigated the hybrid effects of two types of microfiber, namely, polypropylene and nylon, on the mechanical properties of high-strength mortar, which produced fine recycled aggregate (FRA). The amount of microfibers was maintained at a volumetric fraction of 0.6%. The microstructure and mechanical strength properties (compressive strength and flexural strength) of recycled mortar reinforced with hybrid-size microfibers were evaluated at various curing ages. Experimental results show that the inclusion of hybrid fibers significantly influenced the mechanical performance of the recycled mortar. The hybridization fiber at volume fraction 0.3% polypropylene + 0.3% nylon yielded the most promising mechanical performance. Enhancements of 8% on compressive and 11% flexural strength were achieved at 28 days. Scanning electron microscopy observations revealed that reinforcement at the microscale prohibited the initiation and growth of cracks at the micro level. High loads were required to form macrocracks within composites, thereby improving the mechanical strength of the mortar matrix.

The low strength property of recycled concrete aggregates (RCAs) limits its widespread application in the production of high-strength recycled aggregate concrete (RAC). In this study, RCA properties were improved prior to its incorporation into an RAC mixture through surface treatment. This mixture was subsequently diversified considering the benefits of adding various fiber-reinforced systems to enhance RAC performance. Two types of short discrete synthetic fibers, namely, polyolefin and polypropylene, were added in single and hybrid forms. This study aimed to investigate the effectiveness of the diversified modification of RAC mixture production on the mechanical strength of the resulting RAC. Various properties of the modified RAC were analyzed. Although the modified RAC mixture using treated RCA significantly enhanced the mechanical strength of this RAC, the diversification of the RAC mixture with additional polyolefin and polypropylene fibers, particularly in the hybrid form, further optimized the RAC performance.

Improvement and innovation in building visualization, project coordination and communication are the major benefits generated by Building Information Modelling (BIM) for construction organisations. Thus, as many firms across the world would adopt BIM, however they do not know the clear direction in which path they are moving as there is no specific reference available for them to refer to. Hence, the paper seeks to identify the factors of BIM adoption from previous research. The methodology used in this paper is based on literature review from various sources such as conference articles and journals. Then, the findings were analysed using content analysis. The findings show that there are 24 factors found from literature that influence the adoption of BIM and four (4) factors such as vendor, organisational vision, knowledge, and implementation plan are among the least factors mentioned by previous researchers.

This study examined the properties of fresh and hardened concretes as influenced by the moisture state of the coarse recycled concrete aggregates (RCA) after surface treatment. Surface treatment was performed by immersing the coarse RCA in a calcium metasilicate (CM) solution. The treated coarse RCA was maintained in three controlled moisture states, namely, air-dried, oven-dried, and saturated surface-dried (SSD), prior to its use in a concrete mix. The physical properties of coarse RCA were evaluated after surface treatment during the first phase of the experiment to determine the density and the water absorption characteristics of the RCA. The second phase involved the evaluation of the slump, slump loss, density, and compressive strength of the concretes that were prepared with different proportions of natural and treated coarse RCA. Controlling the moisture state of the coarse RCA after surface treatment was found to significantly influence the properties of the fresh and hardened concretes.&nbsp

This paper presents the experiment results of investigating the effects of adding various types and proportions of fibre on mechanical strength and permeability characteristics of recycled aggregate concrete (RAC), which was produced with treated coarse recycled concrete aggregate (RCA). Two types of synthetic fibres (i.e., barchip and polypropylene fibre) with various volume fractions were added to the RAC, which was calculated by the weight of the cement. The hardened RAC properties such as compressive strength, flexural strength, ultrasonic pulse velocity, water absorption and total porosity at the curing ages of 7 and 28 days were evaluated and compared with the properties of the control specimens. Results indicate that the treated coarse RCA enhances the mechanical strength and permeability properties of RAC and adding barchip fibre further optimises the results. Adding 1.2% barchip fibre has the best effect on the mechanical strength performance of the RAC., {"references":["S. C. Kou, C. S. Poon, and D. Chan, \"Influence of fly ash as a cement addition on the hardened properties of recycled aggregate concrete,\" Materials and Structures, vol. 41, pp. 1191-1201, 2008.","C. S. Poon, Z. H. Shui, L. Lam, H. Fok, and S. C. Kou, \"Influence of moisture states of natural and recycled aggregates on the slump and compressive strength of concrete,\" Cement and Concrete Research, vol. 34, pp. 31-36, 2004.","A. Rao, K. N. Jha, and S. Misra, \"Use of aggregates from recycled construction and demolition waste in concrete,\" Resources, Conservation and Recycling, vol. 50, pp. 71-81, 2007.","F. López-Gayarre, P. Serna, A. Domingo-Cabo, M. A. Serrano-López, and C. López-Colina, \"Influence of recycled aggregate quality and proportioning criteria on recycled concrete properties,\" Waste Management, vol. 29, pp. 3022-3028, 2009.","V. W. Y. Tam, X. F. Gao, and C. M. Tam, \"Microstructural analysis of recycled aggregate concrete produced from two-stage mixing approach,\" Cement and Concrete Research, vol. 35, pp. 1195-1203, 2005.","C. S. Poon, Z. H. Shui, and L. Lam, \"Effect of microstructure of ITZ on compressive strength of concrete prepared with recycled aggregates,\" Construction and Building Materials, vol. 18, pp. 461-468, 2004.","A. K. Padmini, K. Ramamurthy, and M. S. Mathews, \"Influence of parent concrete on the properties of recycled aggregate concrete,\" Construction and Building Materials, vol. 23, pp. 829-836, 2009.","S. C. Kou and C. S. Poon, \"Properties of concrete prepared with PVA-impregnated recycled concrete aggregates,\" Cement and Concrete Composites, vol. 32, pp. 649-654, 2010.","M. Chakradhara Rao, S. Bhattacharyya, and S. Barai, \"Influence of field recycled coarse aggregate on properties of concrete,\" Materials and Structures, vol. 44, pp. 205-220, 2011.\n[10]\tS. W. Tabsh and A. S. Abdelfatah, \"Influence of recycled concrete aggregates on strength properties of concrete,\" Construction and Building Materials, vol. 23, pp. 1163-1167, 2009.\n[11]\tK. Y. Ann, H. Y. Moon, Y. B. Kim, and J. Ryou, \"Durability of recycled aggregate concrete using pozzolanic materials,\" Waste Management, vol. 28, pp. 993-999, 2008.\n[12]\tS. Ismail and M. Ramli, \"Effect of Different Moisture States of Surface-Treated Recycled Concrete Aggregate on Properties of Fresh and Hardened Concrete,\" International Journal of Civil, Architectural, Structural and Construction Engineering vol. 8, pp. 65-71, 2014.\n[13]\tMaruthachalam D. and Muthukumar J., \"Flexural behaviour of hybrid fibre reinforced concrete beams: a general review,\" Indian Journal of Engineering, vol. 2, pp. 14-16, 2013.\n[14]\tY. Şahin and F. Köksal, \"The influences of matrix and steel fibre tensile strengths on the fracture energy of high-strength concrete,\" Construction and Building Materials, vol. 25, pp. 1801-1806, 2011.\n[15]\tA. Peled, J. Jones, and S. P. Shah, \"Effect of matrix modification on durability of glass fiber reinforced cement composites,\" Materials and Structures vol. 38, pp. 163-171, 2005.\n[16]\tV. Corinaldesi and G. Moriconi, \"Durable fiber reinforced self-compacting concrete,\" Cement and Concrete Research vol. 34, pp. 249–254, 2004.\n[17]\tBS 812-103.1, \"Testing aggregates,\" in Methods for determination of particle size distribution, ed. London: British Standard Institution, 1985.\n[18]\tD. C. Teychenné, R. E. Franklin, H. C. Erntroy, D. W. Hobbs, and B. K. Marsh, \"Design of normal concrete mixes,\" Building Research Establishment, Watford, UK1997.\n[19]\tBS 1881-125, \"Testing concrete.,\" in Methods for mixing and sampling fresh concrete in the laboratory, ed. London: British Standards Institution 1986.\n[20]\tBS EN 12390-3, \"Testing hardened concrete.,\" in Compressive strength of test specimens. , ed. London: British Standards Institution, 2009.\n[21]\tBS EN 12390-5, \"Testing hardened concrete.,\" in Flexural strength of test specimens. , ed. London: British Standards Institution, 2009.\n[22]\tBS 1881-201, \"Testing concrete \" in Part 201: Guide to the use of non-destructive methods of test for hardened concrete, ed. London: British Standards Institution, 1986.\n[23]\tBS 1881-122, \"Testing concrete,\" in Part 122: Method for determination of water absorption, ed. London: British Standards Institution, 1983.\n[24]\tRILEM recommendations, \"Absorption of water by immersion under vacuum,\" Material Structure, RILEM CPC 11.3, vol. 101, pp. 393–394, 1984.\n[25]\tH. A. Mesbah and F. Buyle-Bodin, \"Efficiency of polypropylene and metallic fibres on control of shrinkage and cracking of recycled aggregate mortars,\" Construction and Building Materials, vol. 13, pp. 439-447, 1999.\n[26]\tR. Solís-Carcaño and E. I. Moreno, \"Evaluation of concrete made with crushed limestone aggregate based on ultrasonic pulse velocity,\" Construction and Building Materials, vol. 22, pp. 1225-1231, 2008.\n[27]\tC. S. Poon, X. C. Qiao, and D. Chan, \"The cause and influence of self-cementing properties of fine recycled concrete aggregates on the properties of unbound sub-base,\" Waste Management, vol. 26, pp. 1166-1172, 2006."]}

This paper reports on the influence of surface-treated coarse recycled concrete aggregate (RCA) on developing the compressive strength of concrete. The coarse RCA was initially treated by separately impregnating it in calcium metasilicate (CM) or wollastonite and nanosilica (NS) prepared at various concentrations. The effects of both treatment materials on concrete properties (e.g., slump, density and compressive strength) were evaluated. Scanning electron microscopy (SEM) analysis was performed to examine the microstructure of the resulting concrete. Results show that the effective use of treated coarse RCA significantly enhances the compressive strength of concrete. This result is supported by the SEM analysis, which indicates the formation of a dense interface between the treated coarse RCA and the cement matrix. Coarse RCA impregnated in CM solution results in better concrete strength than NS, and the optimum concentration of CM solution recommended for treated coarse RCA is 10%., {"references":["S. C. Kou and C. S. Poon, \"Properties of concrete prepared with PVA-impregnated recycled concrete aggregates,\" Cement and Concrete Composites, vol. 32, pp. 649-654, 2010.","V. W. Y. Tam, X. F. Gao, and C. M. Tam, \"Microstructural analysis of recycled aggregate concrete produced from two-stage mixing approach,\" Cement and Concrete Research, vol. 35, pp. 1195-1203, 2005.","S. Ismail, K. W. Hoe, and M. Ramli, \"Sustainable Aggregates: The Potential and Challenge for Natural Resources Conservation,\" Procedia - Social and Behavioral Sciences, vol. 101, pp. 100-109, 2013.","S. Marinkovic, V. Radonjanin, M. Malesev, and I. Ignjatovic, \"Comparative environmental assessment of natural and recycled aggregate concrete,\" Waste Management, vol. 30, pp. 2255-2264, 2010.","A. Katz, \"Treatments for the Improvement of Recycled Aggregate,\" Journal of Materials in Civil Engineering, vol. 16, pp. 597-603, 2004.","J. J. Kim, S. H. Youn, M. J. Cho, H. T. Shin, J. B. Yoon, K. H. Hwang, and D. S. Lee, \"The effect of pozzolanics on the recycled aggregates by surface treatment \" Materials Science Forum vol. 486 - 487, pp. 305-308, 2005.","S. Kutcharlapati, A. K. Sarkar, and N. P. Rajamane. Nanosilica Improves Recycled Concrete Aggregates [Online]. Available: http://www.nbmcw.com/articles/concrete/admixtures-additives/20929-nanosilica-improves-recycled-concrete-aggregates.html","M. Tsujino, T. Noguchi, M. Tamura, M. Kanematsu, and I. Maruyama, \"Application of conventionally recycled coarse aggregate to concrete structure by surface modification treatment,\" Journal of Advanced Concrete Technology, vol. 5, pp. 13-25, 2007.","D. C. Teychenné, R. E. Franklin, H. C. Erntroy, D. W. Hobbs, and B. K. Marsh, \"Design of normal concrete mixes,\" Building Research Establishment, Watford, UK1997.\n[10]\tBS 1881-125, \"Testing concrete.,\" in Methods for mixing and sampling fresh concrete in the laboratory, ed. London: British Standards Institution 1986.\n[11]\tBS EN 12350-2, \"Testing fresh concrete. ,\" in Slump-test., ed. London: British Standards Institution, 2009.\n[12]\tBS EN 12390-7, \"Testing hardened concrete. ,\" in Density of hardened concrete., ed. London: British Standards Institution 2009.\n[13]\tBS EN 12390-3, \"Testing hardened concrete.,\" in Compressive strength of test specimens. , ed. London: British Standards Institution, 2009.\n[14]\tJ. Li, H. Xiao, and Y. Zhou, \"Influence of coating recycled aggregate surface with pozzolanic powder on properties of recycled aggregate concrete,\" Construction and Building Materials, vol. 23, pp. 1287-1291, 2009.\n[15]\tA. M. Soliman and M. L. Nehdi, \"Effects of shrinkage reducing admixture and wollastonite microfiber on early-age behavior of ultra-high performance concrete,\" Cement and Concrete Composites, vol. 46, pp. 81-89, 2014.\n[16]\tJ. Tikkanen, \"A novel application of mineral powders in normal strength concrete,\" Doctor of Science in Technology Doctoral Dissertations Department of Civil and Structural Engineering, Aalto University, Helsnki, Finland, 2013."]}

This study examined the properties of fresh and hardened concretes as influenced by the moisture state of the coarse recycled concrete aggregates (RCA) after surface treatment. Surface treatment was performed by immersing the coarse RCA in a calcium metasilicate (CM) solution. The treated coarse RCA was maintained in three controlled moisture states, namely, air-dried, oven-dried, and saturated surface-dried (SSD), prior to its use in a concrete mix. The physical properties of coarse RCA were evaluated after surface treatment during the first phase of the experiment to determine the density and the water absorption characteristics of the RCA. The second phase involved the evaluation of the slump, slump loss, density, and compressive strength of the concretes that were prepared with different proportions of natural and treated coarse RCA. Controlling the moisture state of the coarse RCA after surface treatment was found to significantly influence the properties of the fresh and hardened concretes.

The inferior properties of the recycled concrete aggregate (RCA), as compared with the natural aggregate, are caused by the presence of the porous residual mortar with numerous micro-cracks, which is attached to the original aggregates. The inferior qualities of RCA have limited its use in structural concrete production. Thus, this study investigated the feasibility of combining two different methods of surface treatment to enhance the properties of coarse RCA. This treatment process involves soaking coarse RCA at low acid concentrations to remove loose particles on the RCA surface and then impregnating the RCA with a calcium silicate (CS) solution. The results revealed that the combined method significantly improved the physical properties of coarse RCA. CS provided a coating layer on the RCA and functioned as a microfiller that can refill and treat the cracks and pores on the RCA surface. In addition, the CS particles on the RCA surface caused a pozzolanic reaction during concrete hardening that could improve the microstructure of concrete by strengthening the bonds between RCA and the cement paste and consequently further enhancing the compressive strength of concrete.

This study aims to examine contractors' service quality performance and to explore the relationship between service quality and client satisfaction when undertaking refurbishment projects for public institutions of higher education in Malaysia. Data were collected through a structured questionnaire. The questionnaire was generated based on the five service quality determinants in SERVQUAL, namely, reliability, responsiveness, assurance, empathy, and tangibles. From these five determinants, thirty-two attributes that may affect project service quality in refurbishment projects are identified to ascertain clients' service quality expectations. The results indicate that the reliability factor is the most important variable of service quality and that clients at public institutions of higher education have high expectations in terms of service quality from refurbishment contractors. The results also show that the values of service quality scores were negative for all attributes and that contractors are not currently meeting clients' expectations in refurbishment projects. Finally, the study indicates that the dimensions of empathy and assurance had significant effects on customer satisfaction.

This research aims to study the possible use of recycled fine aggregate made from waste rubble wall. We investigated recycled fine aggregates from rubble walls collected from damaged structures. The waste underwent mechanised crushing and sieving to produce fine aggregate (below 5 mm). The brick specimens were prepared using 100% natural sand. These were then replaced by recycled fine aggregate at 25, 50, 75, and 100% vis-a-vis the weight of natural sand. A series of tests was performed to study the effect of recycled aggregate on the physical and mechanical properties of bricks. The results indicate that it is possible to manufacture bricks containing recycled fine aggregate provided that the percentage of recycled fine aggregates is limited to 50-75%. This project also demonstrates that it is feasible to use alternative construction materials to manufacture a commercial product that can compete with similar products made with standard natural aggregate.