Effect of particle size and amount of nonmetallic PCB materials on the mechanical properties of rHDPE/PCB composites

Composites based on recycled high density polyethylene (rHDPE) and nonmetallic printed circuit board (PCB) waste were made through melt compounding and compression molding. In this study, the chemical compositions of the nonmetallic PCB material were determined via XRF and it was confirmed that it contains predominantly 72.7% of glass fiber materials which improve the mechanical performances of the rHDPE matrix. The main aim of this study is to determine the effect of different particle sizes and loadings of nonmetallic PCB on mechanical properties of rHDPE/PCB composite. The results indicated that mechanical properties of composites were excellent when nonmetallic materials with particle size from 0.09 to 0.15 mm and adding amount was 30 wt%. Microscopic images revealed that nonmetallic particles with the size of 0.07-0.09 mm and 0.09 -0.15 mm contained majority of single glass fibers whereas, bigger particle sizes of 0.15-0.3 mm and 0.3-0.5 mm, contained glass fibers in the form of bundles and large resin sheet

A review of chemical and physical properties of coconut shell in asphalt mixture

Coconut shell is an agricultural waste which is abundant to the environment and also rise the risk to health as well as environment. Currently, most of the researchers are investigate the use of waste material which can reduce the costof construction and increase the strength. Some of thewaste materials are used in construction for instance palm oil fuel ash, rice husk, fly ash slag, sludge, coconut shell and etc. Hence, coconut shellwas selected for this study. Generally, the chemical and physical properties of coconut shell in road construction was highlighted in this paper and compared with others raw materials. In addition, the chemical and physical characteristics of coconut shell was presented according to X-ray Fluorescence (XRF), Scanning Electron Microscopy (SEM),Fourier Transform Infrared Spectroscopy (FTIR) Analysis and X-ray Diffraction (XRD). A review of using coconut shell in asphalt mixture has better potential than others raw materials to constribute in construction field

Mechanical properties of self-compacting geopolymer concrete containing spent garnet as replacement for fine aggregate

Millions of tons of spent garnet, a by-product of surface treatment operations, are disposed of in landfills, oceans, rivers, and quarries, among others every year, thus it causes environmental problems. The main objective of this study is to evaluate spent garnet as a sand replacement in concrete prepared with ground granulated blast furnace slag (GGBS)-based self-compacting geopolymer concrete (SCGC). Concrete mixtures containing 0%, 25%, 50%, 75% and 100% spent garnet as a replacement for river sand were prepared with a constant Liquid/Binder (L/B) mass ratio equal to 0.4. Compressive, flexural and splitting tensile strengths as well as workability tests (slump, L-box, U-box and T50) were conducted on concrete containing spent garnet. As per specification and guidelines for self-compacting concrete (EFNARC) standard, the test results showed that the concrete’s workability increased with the increase of spent garnet, while all the other strength values were consistently lower than conventional concrete (SCGC) at all stages of replacement. The results recommended that spent garnet should be used in concrete as a sand replacement up to 25% to reduce environmental problems, costs and the depletion of natural resources

Experimental and modelling of alkali-activated mortar compressive strength using hybrid support vector regression and genetic algorithm

This paper presents the outcome of work conducted to develop models for the prediction of compressive strength (CS) of alkali-activated limestone powder and natural pozzolan mortar (AALNM) using hybrid genetic algorithm (GA) and support vector regression (SVR) algorithm, for the first time. The developed hybrid GA-SVR-CS1, GA-SVR-CS3, and GA-SVR-CS14 models are capable of estimating the one-day, three-day, and 14-day compressive strength, respectively, of AALNM up to 96.64%, 90.84%, and 93.40% degree of accuracy as measured on the basis of correlation coefficient between the measured and estimated values for a set of data that is excluded from training and testing phase of the model development. The developed hybrid GA-SVR-CS28E model estimates the 28-days compressive strength of AALNM using the 14-days strength, it performs better than hybrid GA-SVR-CS28C model, hybrid GA-SVR-CS28B model, hybrid GA-SVR-CS28A model, and hybrid GA-SVR-CS28D model that respectively estimates the 28-day compressive strength using three-day strength, one day-strength, all the descriptors and seven day-strength with performance improvement of 103.51%, 124.47%, 149.94%, and 262.08% on the basis of root mean square error. The outcome of this work will promote the use of environment-friendly concrete with excellent strength and provide effective as well as efficient ways of modeling the compressive strength of concrete

Sistem pengurusan penyenggaraan bangunan bagi struktur konkrit bertetulang

A building is an asset which needs to be maintained to ensure that its value is not eroded. Lack of maintenance will result in unfortunate economic and safety consequences. The objectives of this study are to study the maintenance management system for reinforced concrete structures of the buildings and to propose an efficient management system that could be adopted by the owner. Five (5) organizations in Kelantan were chosen to represent the old and new buildings, government and public sector. Data were collected through visits to respected sites and interviews with the involved personnel. Cracking of internal and external elements are studied in this project

Chloride resistance of blended ash geopolymer concrete (chloride resistance & microstructural analysis)

- Chloride attack on concrete is a mechanism of deterioration which causes corrosion of steel reinforcement. Geopolymer, an alternative aluminosilicate binder material, has attracted attention for its structural and durability performance as well as for environmental benefits in reducing the CO2 emissions associated with concrete production. However, the understanding of its behaviour in the chloride resistance of geopolymer concrete especially from mixtures of pulverized fuel ash (PFA) and palm oil fuel ash (POFA) is scarce. In this study, geopolymer concrete using blended ashes from agro-industrial waste were tested for chloride content using ASTM 1543-10a (Standard Test Method for Determining the Penetration of Chloride Ion into Concrete). The geopolymer concrete samples were prepared using a mix of the PFA and POFA as the main binder components at the range of alkaline/binder ratio of 0.4 together mixed with coarse and fine aggregates. The ambient temperature (26-30°C) of curing regimes was used. The specimens were cast in 100mm3 molds. After achieving the targeted compressive strength (25-30 MPa), the specimens were immersed for 18 months to 2.5% solution of sodium chloride (NaCl). The normal OPC concrete with similar compressive strength were also prepared for direct comparison. X-ray diffraction (XRD), Fourier Transformed Infrared Spectrometer (FTIR), Thermogravimetry analyser (TGA-DTG) and Field Emission Scanning electron microscopy images with energy dispersive X-ray (FESEM-EDX) were performed to analyze the microstructural characterisation of the materials. In particular, geopolymer concrete had shown a better resistance to chloride penetration as compared to OPC concrete

Mix design and compressive strength of geopolymer concrete containing blended ash from agro-industrial wastes

Geopolymer concrete is a type of amorphous alumino-silicate cementitious material. Geopolymer can be polymerized by polycondensation reaction of geopolymeric precursor and alkali polysilicates. Compared to conventional cement concrete, the production of geopolymer concrete has a relative higher strength, excellent volume stability and better durability. This paper presents the mix design and compressive strength of geopolymer concrete manufactured from the blend of palm oil fuel ash (POFA) and pulverized fuel ash (PFA) as full replacement of cement with a combination of sodium silicate and sodium hydroxide solution used as alkaline liquid. The density and strength of the geopolymer concrete with various PFA: POFA ratios of 0:100, 30:70, 50:50 and 70:30 together with sodium silicate to sodium hydroxide solution by mass at 2.5 and 1.0, are investigated. The concentrations of alkaline solution used are 14 Molar and 8 Molar. Tests were carried out on 100x100x100 mm cube geopolymer concrete specimens. Specimens were cured at room temperature and heat curing at 60°C and 90°C for 24 hours, respectively. The effects of mass ratios of PFA: POFA, the alkaline solution to PFA: POFA, ratio and concentration of alkaline solution on fresh and hardened properties of concrete are examined. The results revealed that as PFA: POFA mass ratio increased the workability and compressive strength of geopolymer concrete are increased, the ratio and concentration of alkaline solution increased, the compressive strength of geopolymer concrete increases with regards to curing condition

Realisation of enhanced self-compacting geopolymer concrete using spent garnet as sand replacement

Garnets are a waste spin-off of surface treatment operations and thus remain a major environmental concern worldwide. The robust engineering properties of these waste garnets offer the opportunity to obtain efficient construction materials by way of their appropriate recycling. In this spirit, the authors evaluate the capacity of spent garnets as sand replacement for achieving self-compacting geopolymer concrete (SCGPC). Such SCGPC specimens are prepared using ground granulated blast-furnace slag (GGBFS) wherein the river sand is replaced by spent garnet at varying contents (0 to 100%) under constant liquid/binder (L/B) mass ratio of 0.4. Performance evaluations of the developed SCGPC samples are made using several tests, including durability, workability and flexural, compressive and splitting tensile strength conforming to the Efnarc standard. Test results reveal an enhancement in the workability of the proposed SCGPC specimen with the increase of spent garnet contents. Furthermore, other strengths are discerned to be lower compared to the control sample at all stages of replacement. It is established that the spent garnet is a prospective candidate for sand replacement up to 25% in terms of environmental friendliness, cost effectiveness and conservation of natural resources

Performance evaluation of concrete with Arabic gum biopolymer

Arabic gum biopolymer (AGB) has demonstrated the good potential to be used as a water-reducing admixture in concrete to enhance its physical and mechanical properties as well as durability performance. The utilization of AGB in concrete is an attractive because of technological, economic, and ecological advantages. This paper highlights the results of an experimental investigation on the performance of concrete incorporating AGB as an admixture. Furthermore, durability of concrete in the acidic environment is conducted to provide objective evidence and support for previous finding. Six mixes with different percentages of AGB varying from 0 to 1.1% were cast. The specimens were cured in water and tested for fresh and hardened properties. The studied properties included soundness, ultrasonic pulse velocity (UPV), compressive strength, and acid resistance. It was observed that the addition of AGB significantly reduces the soundness of concrete. By adding AGB the compressive strength of concrete was enhanced by 8% to 41 MPa and UPV values were increased by about 40%. Also, the resistance of concrete containing AGB to acid attack was higher than that of plain concrete. X-ray diffraction was preformad to help explain the influence of AGB on the macroscopic behavior of concrete. The findings of study demonstrated that there is a promising future for the use of AGB as an admixture in the production of concrete with adequate mechanical and durability properties