Zaiton Haron

Chemical properties of waste tyre rubber granules

This research aims to examine the chemical properties of waste rubber tyre granules. Rubber granules were analysed by using X-ray fluorescence to establish its chemical composition. Thermogravimetry and differential thermogravimetric analyses were performed to investigate the relationship between temperature and the minerological compositions of rubber granules to determine its suitability as an aggregate replacement in concrete mix. Fourier Transform Infra-Red (FTIR) indicated that due to the stability of the structures developed in OPC samples, the reactions between the structure bonds are less at the range of 650-1500 cm-1. Scanning electron microscopy (SEM) was performed to examine the physical properties of rubber granule particles and to magnify the bonds between cement and rubber granules in a concrete mix. The results of the SEM analysis showed that carbon, zinc, magnesium, and calcium are the major components of waste tyre rubber granules.

Elastomeric Effect of Natural Rubber Latex on Compressive Strength of Concrete at High Temperatures

The inclusion of elastomeric substances into concrete aimed at improving performance properties may pose a serious threat, particularly at high temperatures. This paper presents experimental findings regarding the elastomeric influence of natural rubber latex on compressive strength of concrete at elevated temperatures. Normal and modified concrete specimens were prepared, heated, and subsequently tested for compressive strength. Five temperatures—ambient temperature (27°C), 150, 300, 500, and 800°C—were applied. Microstructural samples were observed through scanning electron microscopy (SEM), and the role of poly(1,4-isoprene) particles in the modified system was evaluated using thermogravimetric analysis (TGA) conducted on hardened cement paste, latex film, and cement-latex blend. Finally, compressive strength of the modified concrete was observed to depreciate at the softening point temperature of the latex films in the comatrix, eventually with more strength loss. At 800°C, the strength loss was 50.5%...

Noise Produced By Transverse Rumble Strips: A Case Study on Rural Roadways

Transverse roadway strips (TRS) are a common approach used by the local authorities in Malaysia for the purpose of road safety on rural roadway. However, there were complaints made by residents about the excessive noise pollution produced by TRS. The objective of this study was to evaluate the external noise produced by the application of TRS, to evaluate and to anticipate the annoyance response due to installation of TRS. The investigations were carried out through the changes of noise level indices, estimation of the annoyance response using the traffic noise index (TNI) and anticipation of resisident response anoyance. Measurements of the external noise level produced by the TRS were taken for two hours at two location with and without TRS. Results showed that TRS increased the equivalent noise level, LAeq1hour, L101hour and L901hour by as much as 14 dB(A), 16 dB(A) and 9 dB(A) respectively. TNI values also increased as much by as 42% and exceeded the suggested value for planning purposes of 74 dB (A) for 3% annoyance from the social surveys. This investigation shows that TRS noise has a very strong impact on the community and this was the reason behind the complaints made by people living in study area.

Probability Approach for Prediction of Construction Site Noise

Abstract This paper describes an alternative method of predicting noise from construction sites using a probability approach. The basis of the approach is the separation of the source characteristics from the propagation characteristics. A site area is divided into a number of square patches in which the source can be located at the centre of any patch or node. The approach assumes that the probability that the noise source of certain acoustic power is at a particular node is the same as for all other nodes. The noise level from each patch is obtained and the temporal noise level distribution during the working day period can be constructed. LAeq accompanied with standard deviation and noise indices during a working day period can be estimated. The effect of the duty cycle of equipment and number of items of equipment were incorporated in the approach. When validated with the current procedure, the model LAeq value has good agreement with those obtained from BS 5228, and thus indicates that the probability approach is capable of predicting the equivalent noise level. The method could be used as the basis of an operational management tool for a noise abatement scheme.

A Stochastic Simulation Framework for the Prediction of Strategic Noise Mapping and Occupational Noise Exposure Using the Random Walk Approach

Strategic noise mapping provides important information for noise impact assessment and noise abatement. However, producing reliable strategic noise mapping in a dynamic, complex working environment is difficult. This study proposes the implementation of the random walk approach as a new stochastic technique to simulate noise mapping and to predict the noise exposure level in a workplace. A stochastic simulation framework and software, namely RW-eNMS, were developed to facilitate the random walk approach in noise mapping prediction. This framework considers the randomness and complexity of machinery operation and noise emission levels. Also, it assesses the impact of noise on the workers and the surrounding environment. For data validation, three case studies were conducted to check the accuracy of the prediction data and to determine the efficiency and effectiveness of this approach. The results showed high accuracy of prediction results together with a majority of absolute differences of less than 2 dBA; also, the predicted noise doses were mostly in the range of measurement. Therefore, the random walk approach was effective in dealing with environmental noises. It could predict strategic noise mapping to facilitate noise monitoring and noise control in the workplaces.

Eksperimentalno ispitivanje spregnute ploče od valovitog čeličnog lima i betona

Spregnute ploče s čeličnim limovima sastavljene su od običnog betona i valovitog čeličnog lima. Čvrstoća spregnute ploče ovisi o djelovanju posmika između betona i čeličnog lima. Ovo međudjelovanje ovisi o nekoliko čimbenika, a kriteriji odnosa za svojstva međudjelovanja nisu definirani u analitičkom smislu. Stoga se proračunske metode provode pomoću empirijske analize. U ovom radu prikazano je eksperimentalno ispitivanje kako bi se razvila nova metodologija ispitivanja posmične otpornosti spregnute ploče.

Occupational Noise Exposure of Construction Workers at Construction Sites in Malaysia

Noise exposure is one of the hazards in construction site that could lead to accidents and also negative impacts on human health. However, most of the construction workers lack in awareness about the impacts of the noise emission to their health. The aim of this research is to investigate the occupational noise exposure levels among construction workers during working hours and then it was compared to the permissible exposure limit regulated by Factories and Machinery Regulation (Noise Exposure) 1989 (FMR). Dosimeter was used to measure the noise exposure level for 1 h work duration and 30 construction workers were involved in this research. The results showed that 33% of construction workers were exposed to high noise level more than 90 dB(A) due to noises emitted by the machineries in the construction sites. It shows that the construction site emits high noise level because majority of the working equipment are machineries. However, the construction workers do not apply the proper PPE when performing the works even though they know that noise is a general problem. Furthermore, continuous exposure to noise could lead to health problems if no safety measures are taken by the employer and construction workers themselves.

Disturbance of Traffic Noise: Evaluation on the Effects and Management on Road Corridors

Several adverse of stimuli can cause annoyance due to the characterized by such effects of distraction on health and delay in activities. Noise annoyance mainly due to the increasing in traffic volume has recognized as important environmental stressor which associated to anxiety and depression. In this manner, it can impose serious damage to human wellbeing, human comfort ability and reduces labour productivity. Hence, this paper aims in evaluating the effects on traffic noise and managing the precaution on road corridors in order to reduce the traffic noise. This case study had been conducted at residential area which is located at Taman Mutiara Rini, residential area located in the southern region of West Peninsular Malaysia. The traffic noise index (TNI) and noise pollution level (NPL) were recorded for a whole day in order to evaluate noise performance with different time durations. From the study, it was shown that the noise level at the Mutiara Rini is above than 75 dBA at most of time which is exceed the permissible limit from the guidelines recommended by the World Health Organization (WHO) and Department of Environment (DOE). According to the guidelines, the maximum limitation for noise pollution during daytime at residential area is about 55 dBA. From the interviewed conducted, it shows that reduction on the traffic noise can be improved by proposing and providing the noise barrier which includes the restoration of trees and concrete wall which can reduce the effects on the traffic noise.

Disparities in Generated Noise Between Predictions and Measurements from Construction Sites

In order to avoid excessive noise exposure and to improve construction environmental performance, noise should be predicted at the planning stage and appropriate mitigation measures should be implemented. There are various noise prediction methods that have been practiced by the respected parties. The simplest and most recommended method of noise prediction is the procedure of BS 5228-1:2009. However, previous studies have claimed that this method was inaccurate because of several factors. Therefore, this study attempts to assess the difference between the prediction using this method and the noise obtained from the measurement. The study was conducted by measuring noise emissions from earthwork, piling work and structural work at selected measurement stations, investigating the individual noise emission of construction equipment and predicting construction noise using the measured data. Several related variables were also measured to identify their effects on outdoor sound propagation. The results of t-test showed that all the stations have the significant disparities between prediction and measurement. The highest over prediction of 5 dBA was due to the use of several moving machines during operation processes and high noise emission level of machines. Consequently, this affects the distance between the sound source and the measurement station (geometry factor).

Low Noise and Properties of Double Layer Concrete Paving Blocks

Double layer rubberized concrete block (DL-RCPB) was introduced to effectively make use of waste tyre and to improve the performance of concrete pavement block. This study was carried out to justify the effectiveness of using waste tyre rubber as aggregate. In this study, there were eight series of concrete mix with 10 and 20 % waste tyre rubber replacement level and different thickness of facing layer; 10, 20, 30 and 40 mm. The compressive strength was reduced when the percentage of waste tyre rubber was increased. Remarkably, all types of DL-RCPB with rubber percentage up to 20 % achieved minimum required compressive strength of 45 MPa. Moreover, DL-RCPB (20 %) with 40 mm top layer was proven to have the most effective sound absorption concrete mix design with up to 36 % of sound adsorption recorded. Reduction in block density was found when the percentages of rubber were increased. Porosity up to 17 % was recorded for DL-RCPB (20 %). The rough surface of rubber particles tends to attract air on the rubbers’ surface and the trapped air tends to produce voids once the concrete hardened. Porosity of DL-RCPB was increased when the rubber was added to concrete mix, thereby decreasing the density of DL-RCPBs. Low density and high porosity increased the intensity of sound absorption and relatively gives positive impact on the development of low noise CBP as long as the compressive strength was sufficient.