Determination of optimum insulation and cement plaster thickness for bungalow buildings through a simulation-statistical approach using response surface methodology

Insulating interior side of external wall and finishing by cement plaster is one of the most appropriate methods of reducing annual energy consumption in available buildings. The aim of this study is to determine the optimum expanded polystyrene (EPS) and cement plaster thickness for bungalow building in Malaysia. The present study evaluates the effect of different thermal insulation and interior cement plaster thicknesses on the annual cooling energy consumption. Furthermore, the optimum thickness of EPS and plaster is estimated based on wall type and building orientation. Two different types of walls made of concrete and brick are considered. EPS and plaster were used in the range of 20 to 100 mm and 0 to 20mm, respectively. The results show that both thermal insulation and plaster thickness have a direct effect on annual cooling energy consumption, however, the influence of wall thermal insulation thickness is more significant than cement plaster thickness. Further, the optimum EPS thickness decreases with the increment in cement plaster thickness for different orientations and wall types. The optimum EPS thickness ranges from 31.5 mm to 53.1 mm based on wall type, orientation and cement plaster thickness. Utilizing optimum EPS and cement plaster thicknesses can thus reduce annual energy consumption by about 6 to 12 in different directions. © 2019, University of Malaya. All rights reserved

Propiedades térmicas del mortero de cemento con diferentes proporciones de mezcla

The energy required for the heating and cooling of buildings is strongly dependant on the thermal properties of the construction material. Cement mortar is a common construction material that is widely used in buildings. The main aim of this study is to assess the thermal properties of cement mortar in terms of its ther­mal conductivity, heat capacity and thermal diffusivity in a wide range of grades (cement: sand ratio between 1:2 and 1:8). As there is insufficient information to predict the thermal conductivity and diffusivity of a cement mortar from its physical and mechanical properties, the relationships between thermal conductivity and diffu­sivity and density, compressive strength, water absorption and porosity are also discussed. Our results indicate that, for a cement mortar with a 28-day compressive strength in the range of 6–60 MPa, thermal conductivity, specific heat and thermal diffusivity are in the range of 1.5–2.7 W/(m.K), 0.87–1.04 kJ/kg.K and 0.89–1.26 (x10-6 m2/s), respectively. The scanning electron microscope (SEM) images showed that pore size varied from 18 μm to 946 μm for samples with different cement-to-sand ratios. The porosity of cement mortar has a signifi­cant effect on its thermal and physical properties. For this reason, thermal conductivity and thermal diffusivity was greater in cement mortar samples with a higher density and compressive strength.La energía reque­rida para la calefacción y la refrigeración de los edificios depende en gran medida de las propiedades térmicas del material de construcción. El mortero de cemento es un material de construcción común que se usa ampliamente en edificios. El objetivo principal de este estudio es evaluar las propiedades térmicas del mortero de cemento en términos de su conductividad térmica, capacidad térmica y difusividad térmica en una amplia gama de grados (relación cemento: arena entre 1: 2 y 1: 8). Como no hay información suficiente para predecir la conductividad térmica y la difusividad de un mortero de cemento a partir de sus propiedades físicas y mecánicas, también se discuten las relaciones entre la conductividad térmica y la difusividad y la densidad, la resistencia a la compresión, la absorción de agua y la porosidad. Los resultados indican que, para un mortero de cemento con una resistencia a la compresión de 28 días en el rango de 6–60 MPa, la conductividad térmica, el calor específico y la difusividad térmica están en el rango de 1.5–2.7 W / (mK), 0.87–1.04 kJ / kg·K y 0.89–1.26 (x10-6 m2/s), respectivamente. Las imágenes del microscopio electrónico de barrido (SEM) mostraron que el tamaño de poro variaba de 18 μm a 946 μm para muestras con diferentes proporciones de cemento:arena. La porosidad del mortero de cemento tiene un efecto significativo en sus propiedades térmicas y físicas. Por esta razón, la conductividad térmica y la difusividad térmica fueron mayores en las muestras de mortero de cemento con mayor densidad y resistencia a la compresión

Mix design and mechanical properties of oil palm shell lightweight aggregate concrete: a review

To build environmentally sustainable structures, especially in developing countries, the possibility of using some agricultural wastes and industrial by-products from different industries as construction materials will be highly desirable and has several practical and economic advantages. Oil palm shell (OPS) is a form of agricultural solid waste in the tropical regimes. Research over the last two decades shows that OPS can be used as a lightweight aggregate for producing structural lightweight aggregate concrete. The density of OPS concrete is around 20 - 25 lower than normal weight concrete. Generally, mechanical properties of OPS concrete are slightly lower than the other types of lightweight aggregate concrete. It seems that from the summary and analysis of the existing information concerning OPS concrete and comparing it with other lightweight aggregate concrete it appears that significant achievements can be attained

Durability of Mortar Incorporating Ferronickel Slag Aggregate and Supplementary Cementitious Materials Subjected to Wet–Dry Cycles

This paper presents the strength and durability of cement mortars using 0–100% ferronickel slag (FNS) as replacement of natural sand and 30% fly ash or ground granulated blast furnace slag (GGBFS) as cement replacement. The maximum mortar compressive strength was achieved with 50% sand replacement by FNS. Durability was evaluated by the changes in compressive strength and mass of mortar specimens after 28 cycles of alternate wetting at 23 °C and drying at 110 °C. Strength loss increased by the increase of FNS content with marginal increases in the mass loss. Though a maximum strength loss of up to 26% was observed, the values were only 3–9% for 25–100% FNS contents in the mixtures containing 30% fly ash. The XRD data showed that the pozzolanic reaction of fly ash helped to reduce the strength loss caused by wet–dry cycles. Overall, the volume of permeable voids (VPV) and performance in wet–dry cycles for 50% FNS and 30% fly ash were better than those for 100% OPC and natural sand

Efficacy of Quasi Agro Binding Fibre on the Hybrid Composite Used in Advance Application

The choice for natural fibre obtained from agricultural products is on the rise due to its solution to eco-friendly, environmental and improved mechanical properties concerns. Its abundant availability, low cost, emission reduction and adaptability to base material for composite make it a prime material for selection. This review explores diverse perspectives to the future trend of agro fibre in terms of the thermo-mechanical properties as it applies to advanced application in building structures. It is important to investigate the ecofriendliness of the products of composites from fibres in agricultural wastes so as to achieve a green and sustainable environment. This will come to fore by the combined efforts of both researchers and feedback from building stakeholders

Utilization of high-volume treated palm oil fuel ash to produce sustainable self-compacting concrete

Palm oil fuel ash is a supplementary cementitious material (SCM) generated from the combustion of palm oil fibers and shells in palm oil mills to produce electricity, and One approach to reduce the carbon dioxide emissions and increase the sustainability of concrete by substitute a significant amount of ordinary Portland cement (OPC) with it. This study conducted laboratory investigations to evaluate the use of high-volume treated palm oil fuel ash (T-POFA) in producing economical and eco-friendly self-compacting concrete (SCC). The concrete mixtures were prepared with 0%, 50%, 60% and 70% replacement (by mass) of OPC with T-POFA at a constant water/binder ratio of 0.35. Self-compactability testing methods were also employed to evaluate the fresh properties of SCC. Compressive strength and drying shrinkage tests were performed and investigated for up to 6 months and 1 year, respectively. An acid attack resistance test was also conducted on the concrete specimens. Results show that the substitution of OPC with high-volume T-POFA can improve the fresh properties of concrete. At an early age, SCCs containing 50%–70% T-POFA have lower compressive strength than the control SCC mix containing 100% OPC. However, the concrete specimens attained a compressive strength equivalent to that of the control at an age of 28 days and an even higher compressive strength at later ages. The specimens containing high-volume T-POFA have lower drying shrinkage and exhibited better performance against aggressive chemical attack. Cost analysis and carbon dioxide (CO2) emission calculation showed that the T-POFA concrete specimens have 8%–12% lower cost and up to 45% lower CO2 emission than the control SCC mix. The results suggest that T-POFA can be utilized as a cement replacement up to 70% in SCC to produce low-cost and sustainable concrete

An experimental study on shear reinforcement in RC beams using CFRP-bars

Fibre reinforced polymer (FRP) as an alternative to steel in reinforced concrete (RC) beams has become increasingly popular. The merits of FRP include high strength to weight ratio and corrosion resistance, and its advantages cannot be ignored in civil engineering. Consequently, FRP has attracted considerable interest from researchers. In this research, the effects of using CFRP bars as shear reinforcement instead of stirrups in RC beams have been investigated. All beams were cast using a high strength concrete (HSC), which was also a self-compacting concrete (SCC). For this new idea, modes of failure for seven laboratory specimens, including a comparison of the ultimate moment capacity of beams, load-deflection control, load of first crack, crack width and position of the neutral axis (N.A.) were analysed. The results show that using carbon fibre reinforced polymer (CFRP) shear reinforcement can be an acceptable alternative for normal stirrups in RC beams

Strengthening of RC beams using prestressed fiber reinforced polymers - A review

The use of steel and fiber reinforced polymers (FRPs) for strengthening RC beams can significantly improve the flexural strength, fatigue life and the serviceability of the beams compared to un-strengthened beams. Prestressing materials enable the material to become more efficient since a greater portion of its tensile capacity is employed. Investigations have shown that prestressed FRPs are effective materials for strengthening deteriorated structures. This paper presents a comprehensive review on the flexural behavior of strengthened RC beams using prestressed FRPs. The review covers the near surface mounted (NSM), externally bonded reinforcement (EBR) and externally post-tensioned techniques (EPT) and the corresponding advantages and disadvantages are highlighted. Anchorage systems and the effect of pre-stressing levels on the ductility, deformability and bond behavior of prestressed FRPs are also addressed. Recommendations for the future research are also presented. (C) 2015 Elsevier Ltd. All rights reserved

Relationships between compressive strength of cement-slag mortars under air and water curing regimes

In this investigation 12 mortar mixes including three groups were prepared using binder contents 380 and 500 kg/m 3. All the specimens were cured after casting and demoulding in curing regimes, i.e. at room temperature (ac) and in water (wc). The highest strength was obtained for cement-slag mortars 380-wc at later ages as 80 MPa. For all groups of mortars, there could rarely be strength loss at later ages. It was observed that in duration of 3-7 days, wc is the optimum for all groups of mortars with exception of cement mortar 500 and slag mortar 500. In duration of 28-90 days, wc is also the optimum for three groups of mortars with exception of cement mortar 500. It was revealed that an exponential relationship exists between the strengths obtained in air and water curing conditions for each group of mortar, i.e. with and without using ground granulated blast furnace slag. It was proved that higher strengths could be obtained using lower binders' contents for cement and cement-slag mortars provided the specimens were cured in water. This is a new finding having importance from economic and environmental viewpoints; meaning that for producing higher strengths it is not a necessity to use more binders. It was found that increase in level of cement and slag makes the mortars more sensitive to air curing conditions. © 2012 Elsevier Ltd. All rights reserved