A comparative study of the behaviour of treated and untreated tyre crumb mortar with oil palm fruit fibre addition

An incorporation of waste tyre particles in concrete has been established to produce a green concrete. However, despite its advantages, strength reduction is an obvious handicap. To improve the strength, pre-treatments of the waste tyre particles and addition of Oil Palm Fruit Fibre (OPFF) were chosen and reported in this study. The addition of OPFF was to influence the internal structure in order to improve shrinkage and other strength properties. Performance of the composites in compressive, split tensile and flexural strengths, as well as shrinkage and microstructure were observed. Results showed better behaviour of the treated tyre crumb mortar rather compared to the untreated tyre, with the replacement of up to 40% by volume of the treated tyre crumb particles and 0.5- 1.0% OPFF addition by mass of cement content

Thermal resistance of two layers precast concrete sandwich panels

The main difference between normal precast wall and precast sandwich wall panel (PCSP) is the thermal insulation layer which is introduced not only to reduce the weight of the panel but more importantly is to improve the thermal resistance of the panel. Besides the type of insulation material, thermal performance of the sandwich wall panel is also influenced by the arrangement of the shear connector and the contact area between the concrete layers. This approach eliminates the direct transmission path between the two concrete layers at the same time. Hence, this study is conducted to determine the influence of shear connector spacing to the thermal path of PCSPs. A total of four specimens and each size of 500 mm x 500 mm by 150 mm thickness was prepared for the Hot Box Test. The staggered shear connector is spaced at 200 mm, 300mm, 400mm for P2, P3 and P4 specimen, respectively. While the control (P0) have steady shear connector at 200mm spacing. Based on the results, the control specimen achieved the highest thermal conductivity and the lowest is achieved by P4, a panel with shear connector at 400 mm spacing. Hopefully this two layers PCSP will provide to the industry a lighter weight and higher thermal resistance load bearing wall panel in the near future

Efficient structural sandwich wall panels devoid of thermal bridges

Reinforced concrete sandwich wall panels are developed to reduce the effect of thermal transmission across the wall systems. The reduction of the thermal transmission is achieved through incorporation of an insulating layer. However, this insulating layer led to a reduction of structural performance. The provision of shear connection in the sandwich system improved its structural integrity and increased with increase in a number of shear connectors. However, if the shear connectors are placed directly across the layers of the concrete wythes, it will decrease its thermal efficiency. The thermal and structural performance works in contrary effect to an increasing number of shear connectors. Hence, optimizing both structural and thermal efficiencies simultaneously in reinforced concrete sandwich system has been a challenge for a very long time. Therefore, this paper presents an alternative approach focusing on the thermal path method to produce an optimum shear connector used. This approach eliminates the direct transmission path between the two wythes and, at the same time, avoids the use of alternative materials such as fibre-reinforced polymers which could be uneconomical. With this method, both thermal and structural efficiencies are optimized using only conventional concrete and steel materials

Thermal resistance of insulated precast concrete sandwich panels

Many nations are already working toward full implementation of energy efficiency in buildings known as Green Building. In line with this perspective, this paper aims to develop a thermally efficient precast concrete sandwich panels (PCSP) for structural applications. Therefore, an experimental investigation was carried out to determine the thermal resistance of the proposed PCSP using Hotbox method and the results were validated using finite element method (FEM) in COMSOL Multiphysics Software. The PCSP were designed with staggered shear connectors to avoid thermal bridges between the successive layers. The staggered connectors are spaced at 200 mm, 300 mm and 400 mm on each concrete layer, while the control panel is designed with 200 mm direct shear connection. In the experimental test, four (4) panels of 500 mm×500 mm and 150 mm thick were subjected to Hotbox Test to determine the thermal resistance. The result shows that thermal resistance of the PCSP with staggered shear connection increases with increase in spacing. The PCSP with 400 mm staggered shear connectors indicates the best thermal efficiency with a thermal resistance (R value) of 2.48 m2 K/W. The thermal performance was verified by FEA which shows less than 5% error coupled with a precise prediction of surface temperature gradient. This indicates that, with conventional materials, thermal path approach can be used to develop a precast concrete building with better thermal resistant properties. Hopefully, stakeholders in the green building industry would find this proposed PCSP as an alternative energy efficient load bearing panel towards sustainable and greener buildings

Structural performance of precast foamed concrete sandwich panel subjected to axial load

In this paper, experimental and simple analytical studies on the structural behavior of Precast Foamed Concrete Sandwich Panel (PFCSP) were reported. Full-scale tests on six PFCSP panels varying in thickness were performed under axial load applications. Axial load-bearing capacity, load-deflection profiles, load-strain relationships, slenderness ratio, load-displacement, load-deformation, typical modes of failure and cracking patterns under constantly increasing axial loads were discussed. Nonlinear Finite Element Analysis (FEA) using LUSAS software to investigate the structural behavior of PFCSP was contacted. The computed ultimate strength values using American Concrete Institute equation (ACI318) and other empirical formulas developed by pervious researchers which applicable to predict the ultimate strength capacity of sandwich panels were compared with the experimental test results and FEA data obtained; therefore, very conservative values resulted, a significant agreement with the FEA data that presented a high degree of accuracy with experiments and an increase in slenderness function

Properties of tire crumb and oil palm fruit fibre in lightweight mortar

This research work was carried out to investigate the influence of oil palm fruit fibre (OPFF) in tire crumb incorporated mortar. It was necessitated due the increase in the quest for lightweight aggregate concrete which has been growing in recent years as a result of the benefit of reduced density of the self-weight of structural components derived from it. This has led the search for more suitable lightweight aggregate material that could be more suitable in terms of strength and durability. Attempt to use recycled waste tire as aggregate in concrete and mortar has been encouraging due to its low density when compared with natural mineral aggregates concrete. However, employing waste tire aggregates has always resulted in reduced strength properties such as compressive, flexural and tensile strengths. Most attempts made so far to recover the losses in strengths of waste tire concretes and mortars has been made by the use of chemicals, compounds or other additives to either pre-treat the waste tire aggregate surfaces or added to the matrix which may have a long time effect on the concrete material. These will increase cost of the mortar or concrete due to the cost of the chemical usage. Hence this research aims to use OPFF obtained as a by-product of the factory production of palm oil crude at 0.5%, 1% and 1.5% by mass of cement content and tire crumb aggregate content of 0%, 10%,20%, 30%, and 40% by volume of aggregate. Two types of tire crumb aggregates are included; untreated and treated using cement paste. The properties such as workability, density, absorption, compressive, split tensile, flexural strengths, shrinkage and microstructure were investigated. The result showed that for untreated tire crumb mortars, addition of OPFF at 0.5% by weight of cement improved these properties but with 1% and 1.5% OPFF, most of these properties reduce when compared to the control samples. On the other hand, these properties showed excellent performance in treated tire crumb mortars with an addition of 0.5 % -1.5% OPFF. In conclusion, the addition of OPFF in treated tire crumb (0-40%) mortars performed excellently at all fibre content (0.5-1.5%) and in untreated tire crumb of 0.5% OPFF content. Density of the mortar was also found to be decreased with increase in rubber and the addition of fibre did not affect the density significantly. However addition of OPFF showed significant effect on the durability such as water absorption of mixes regardless of the replacement percentages of tire crumb but affected by either treated or untreated tire crumb, with the treated tire crumb showed better results. Therefore, OPFF could be used in the development of structural lightweight mortar; however, more investigations are required to ascertain the durability performance of these composite mortar materials

Structural behaviour of precast concrete sandwich panel with high thermal efficiency

Malaysian Government has targeted the year 2020 for full implementation for energy efficiency in buildings known as Green Building. In line with this perspective, this research aims to develop a thermally efficient and structurally acceptable precast concrete sandwich panels (PCSP) for structural applications. In order to achieve the aims, four objectives are outlined to determine the thermal and structural performance of staggered shear connectors. The staggered shear connector is a method used to avoid thermal bridges between layers. In this research, PCSP is designed with staggered shear connection spaced at 200, 300 and 400 mm on each concrete layers. While the control panel is designed with a direct shear connection at 200 mm. Four panels of 500mm x 500mm and 150mm thick are subjected to Hot Box Test to determine the thermal performance. While for structural performance, four (4) number of a full-scale panel of size 2500mm x 1650mm x 150mm are subjected to flexural test and another four (4) of 3000mm x 1650mm x 150mm size for axial load tests. These experimental results are validated by numerical analysis using the finite element method (FEM). In addition, an empirical equation of axial load capacity of the reinforced concrete wall was modified to determine the PCSP capacity. The hot box test result shows that thermal efficiency of the PCSP with staggered shear connectors increases with increase in spacing. The PCSP with 400 mm staggered shear connectors indicate the best thermal efficiency with a thermal resistance (R-value) of 2.48 m²K/W. The R-value is higher than the maximum value recorded in the literature. The thermal performance was verified by FEA which shows less than 5% error coupled with a precise prediction of isothermal flux lines behaviour. The structural performance of PCSP under flexural loading showed that all PCSP with staggered shear connector achieved full compositeness with no debonding failure observed. The PCSP panel with a staggered shear connector at 300mm is capable of sustaining the axial capacity for five (5) storey load. However, beyond 300 mm staggered shear connector, the PCSP failed due to bucking. The experimental results were verified by FEA with about 4% and 15% error for the flexural and axial loadings, respectively. The empirical equation of axial load capacity of the reinforced concrete wall has overestimated the ultimate load capacity of PCSP. Therefore, the equation is subjected to statistical analysis using particle swarm optimization technique (PSO) by taking into consideration the effect of insulation and shear connection in PCSP. The modified equation has successfully predicted load capacity of PCSP with high accuracy. The result was achieved with objective function (MAE) at swarm 30 with minimum iteration and CoV value of 10%. In conclusion, the PCSP with 300mm staggered shear connectors has met the energy efficiency requirement for sustainable buildings i.e. thermally efficient with excellent structural performance in both axial and flexural behaviour. These results proved that better thermal resistant and structural performance of PCSP can be achieved using conventional steel and concrete materials using staggered thermal path approach. Hopefully, the output of this research will help designers; both architects and engineers to choose PCSP wall to provide better thermal resistance and load bearing structural panels toward green and sustainable buildings

Mechanical properties of lightweight mortar modified with oil palm fruit fibre and tire crumb

This research use oil palm fruit fibre (OPFF) as a greener and more cost-effective approach to improve the tire crumb mortar composite strengths. The mechanical properties of tire crumb and oil palm fruit fibre lightweight mortar with addition of 0%, 0.5%, 1% and 1.5% OPFF and tire-crumb replacement of 0–40% by volume of aggregate were studied. The composite mixtures were subjected to the compression, split tensile and flexural tests. The addition of 0.5% OPFF to the composite was found to improve the compressive strength, split tensile strength and flexural strength of the mortar composites