Norbaya Sidek

Polyurethane Foams in Soil Stabilization: A Compressibility Effect

The use of polyurethane foam is so-called as a low cost technique in soil stabilization. The workable characteristic of polyurethane foam suits the construction needs which increase the strength performance while reducing the compression index. The research permits a reliable prediction of compressibility effects of stabilized soils in which the polyurethane foam contents are the variables. The unstabilized soils are taken from the current residential projects and the physical properties are investigated. The research is performed by an experimental work in accordance with BS 5930. The compressibility effects of stabilized (with the addition of polyurethane foams) and unstabilized soils are presented by the percentage of compression and swelling indices. These indices reduce between 40–50 % and the void ratio is also reduced between 30–50 % with the addition of polyurethane foams. The research also presents the physical and engineering properties of the stabilized and unstabilized soils.

A low cost nephelometric turbidity sensor for continual domestic water quality monitoring system

This paper focuses on the design and development of a low cost nephelometric turbidity sensor for the continuity of domestic monitoring of water quality. The electronic turbidity sensor operates based on the scattered light intensity with regards to light scattering in solids and liquids. The electronic turbidity sensor used Light Emitting Diode (LED) as light transmitter, Light Dependent Resistor (LDR) as receiver, PIC 16F777 as a main processor and RS232 module for the integrated sensor communication between the computer. Laboratory experiments have been done by comparing the self-developed sensor with commercial turbidity meter (Hach 2100P) output of NTU. The advantages of the electronic turbidity sensor are lightweight, user friendly, low-power consumption, easy to monitor and low cost. Conclusively, the electronic turbidity sensor can be used as part of a low-cost sensor to provide continuous turbidity information of water quality directly to consumer. Laboratory tests are conducted and proven that the proposed devices produced a comparable NTU reading as commercial turbidity sensor. Moreover, with a low development cost of RM196.95, has been savings money compared to commercial turbidity sensor. Therefore, the development of this device can save cost and benefited to consumer by providing the water quality reading instantaneously.

Strength Characteristics of Polyurethane (PU) With Modified Sand

Soil stabilisation is defined as a technique to improve the engineering characteristics in order to improve the parameters such as shear strength, compressibility, density, hydraulic conductivity. There are many techniques that can be used for different purposes by enhancing some aspects of soil behaviour and improve the strength and properties of soil. One of the cheapest techniques is by using Polyurethane grout, which is workable for construction and enhances the performance of soil compressive strength. Polyurethane (PU) foam is non-toxic, having an indefinite life span and non-environment unfriendly. PU is a chemical substance that normally used in polymer industries for instance resilience foam seating, rigid foam insulation panels and microcellular foam seals. In this research, different percentages of PU content are mixed with sand to test the compressive strength of modified sand. The compressive strength of sand is determined by conducting the Unconfined Compression Test (UCT) with the mold samples of 50mm diameter and 100mm height. The test determines the compressive strength and generates the stress-strain relationship of the modified sand. It is shown that the compressive strength of modified sand will gradually increase with an increasing PU content percentage (varying from 10% (20 kPa) – 95% (500 kPa). Conclusively, this research could be used as the benchmark of ground improvement technique.

Effect of Nanoclay in Soft Soil Stabilization

The effectiveness of using nanoclay in soft soil stabilization was investigated by mean of laboratory testing to evaluate the compressive strength, effective shear strength and Atterberg limit test parameters. The soft soil sample, classified as slightly sandy CLAY of intermediate plasticity was used in this studies. The nanoclay was produced from pulverizing soft soil sample into nano sized using ball milling process. From the scanning electron microscopic (SEM) test and nano size analysis, it was found that the nanoclay particles were obtained from the milling process. However, only 3 % nanoclay was used in this study due to the limited samples produced from milling process. The first objective of this study was to determine the compressive strength of 3 % nanoclay mixed with soft soil and the second objective was to determine the effective shear strength of 3 % nanoclay mixed with soft soil. Meanwhile, the third objective of this study was to determine the Atterberg limit parameter: liquid limit (LL), plastic limit (PL) and plastic index (PI) of 3 % nanoclay mixed with soft soil. This study involved three main testing such as unconfined compression strength to determine the compressive strength and consolidated drained test to determine the effective shear strength. Meanwhile, the Atterberg limit test were conduct to determine the liquid limit (LL) and plastic limit (PL). The result showed that the mixing of 3 % nanoclay with soft soil was improved the soil strength and effectiveness of the shear strength.

Prediction of soil stress-strain response incorporates mobilised shear strength envelope of granitic residual soil

The concept of effective stress has been the principal concept in characterizing soil volume change behavior in soil mechanics, the settlement models developed using this concept have been empirical in nature. However, there remain certain unexplained soil volume change behaviors that cannot be explained using the effective stress concept, one such behaviour is the inundation settlement. Studies have begun to indicate the inevitable role of shear strength as a critical element to be incorporated in models to unravel the unexplained soil behaviours. One soil volume change model that applies the concept of effective stress and the shear strength interaction is the Rotational Multiple Yield Surface Framework (RMYSF) model. This model has been developed from the soil-strain behavior under anisotropic stress condition. Hence, the RMYSF actually measure the soil actual elasto-plastic response to stress rather than assuming it to be fully elastic or plastic as normally perceived by the industry. The frameworks m...

Characterization of aluminium sulphate for control applications

Floods are a natural phenomenon that occur frequently. However, the flood could turn into disasters which causing widespread damage, health problems and deaths. Consequently, these phenomena affect the ecosystems and habitats. The source of drinking water is the most affected component due to floods. Many researchers have designed the methods to purify the turbidity of water. In this study, the water samples are obtained from Damansara river located nearby TTDI Jaya, Shah Alam. In light of this, the optimum aluminum sulfate dosage in purifying the water turbidity is the aim of this study. The outcomes of the research also comply the standard set by World Health Organization (WHO). The aluminum sulfate is used as a coagulant and coagulant auxiliary product, respectively. The efficiencies of coagulation-flocculation process are investigated on these samples. The jar test is conducted in this study which represents a pilot-scale test of the aluminum sulfate dosage used in water treatment plant. The aluminum sulfate dosage is measured based on the performance of coagulation process in the test. However, the accuracy of aluminum sulfate dosage is still underdeveloped for water purification. The optimized dosage of aluminum sulfate needs to meet the drinking water standards set by WHO. Conclusively, the optimum aluminum sulfate dosage could be determined based on the aforementioned standard and respective location. We also proposed an optimum aluminum sulfate controller device in this study.

An Investigation on the Effect of Calcite Bacteria Seeding on Shear Strength of Peat Soil via an Unconfined Compression Test

Peat soils have been known for their problematic characteristics which include high water content, high compressibility and low shear strength. In this study, an attempt was made to investigate the effect of 1 week addition of modified Urea-CaCl2 liquid medium with and without Sporosarcina pasteurii on the shear strength of unsterilized dried peat soil using the Unconfined Compression Test. After the treatment period, significant increase in the shear strength of the soil was found to be highest for peat + medium at 42 kN/m2, moderate for peat + medium + Sporosarcina pasteurii at 27 kN/m2 and unchanged for peat + water control at 24 kN/m2. Although the growth dynamics of all the microbes involved in the calcite formation in the treated peat soil were not known, the addition of the modified Urea-CaCl2 liquid medium into the soil clearly had contributed to the marked increased in the shear strength of the soil. It is probable that the medium had promoted a better growth of indigenous calcite bacteria population in the soil which may have been suppressed by the slow growing S. pasteurii population being added daily to the soil

Strength of Soft Soil Stabilized Using Lime-POFA Mixtures

This paper presents the study on the strength of Malaysian soft soil stabilized using mixing of lime and palm oil fly ash (Lime-POFA). Palm Oil Fly Ash (POFA) additives used in this study is a finely product from waste product from the process of burning palm oil fiber and described as a by-product of thermal power plants where palm oil fiber shell, and empty fruit bunches was burnt at temperatures ranging from 800 to 1,000 °C until it is in fly ash condition. According to ASTM C618, the POFA used in this study has been tested and classified as Class-F fly ash accordingly to ASTM C618 because POFA describe as siliceous and aluminous materials that possess little or no cementitious value. In that condition, POFA need to combines with small quantities of lime for pozzolanic reaction. The samples of soft soil classified as slightly sandy CLAY of intermediate plasticity has been used in this study. The optimum of 3 % hydrated lime used in this study as an active additive to the various percentage mixtures of POFA for the pozzolanic reaction. The first objective of this study is to determine the optimum proportion of POFA to be mixed with 3 % lime to stabilize the clay soil based on the compressive strength at 0, 14 and 28 days of curing periods. The second objective is to determine the strength development of clay soil stabilized at the optimum percentage of POFA mixed with 3 % lime at 0, 14 and 28 days of curing periods. This study involved in unconfined compression strength to determine the strength of stabilized clay soil. The development of compressive strength of soil stabilized using (Lime-POFA) were compared to the compressive strength of unstabilized soil. The result shows, the 6 % POFA mixed with 3 % Lime was the suitable proportion in term of strength and strength development and can be used as additives to stabilize clay soil.