Stabilisation and solidification of contaminated soil using cement and sugarcane bagasse ash (SCBA)

Soil that is contaminated with heavy metals has become a major issue worldwide. However, proper remediation techniques such as stabilisation/solidification (S/S) method can be employed and is capable of controlling these heavy metals. Conventionally, the common S/S method used cement as binder on remediating the contaminated soil particularly heavy metals. This research is to investigate the effect of physical and leachability of contaminated soil in S/S method when Sugarcane Bagasse Ash (SCBA) is added to remedy contaminated soil. Landfill contaminated soil was used to test the effectiveness of those binder. Cement was added at a proportion of 5%, 10%, 15% and 20% in sample weights without SCBA while in another sample; the cement was replaced by SCBA at a proportion of 2.5%, 5%, 7.5% and 10%. All samples are to be allowed to harden and cured at room temperature for 7, 14 and 28 days. The effectiveness of the treatment was assessing by conducting physical testing such as Unconfined Compression Strength, Water Absorption and Permeability test. In addition, leaching tests were performed to identify the leachate behavior of heavy metals during treatment. Three leaching tests were conducted and they were the Toxicity Characteristic Leaching Procedure (TCLP), Synthetic Precipitation Leaching Procedure (SPLP) and Dynamic Leaching Test (DLT). Through the physical testing, samples containing 10% OPC mixed with 10% SCBA were found to improve the compressive strength, reduced the water absorption and water permeability measuring 1550 MPa, 17.94% and 4.41 x 10 -10 m/s respectively. In the same way, through the statistical analysis, the R-squared for UCS with respect to mixed design is high at 98%. However, the value for both water absorption and permeability recorded to be marginally low, compared to the value for strength at 89% and 88% respectively. Through the TCLP and SPLP test, results indicated that when SCBA added to OPC content in soil samples, less heavy metal been leached out from the S/S sample. In average, the satisfying result was shown by samples containing 10% OPC + 10% SCBA where reduction of heavy metals in final leachate is more than 90% for As, Cd, Cr, Pb and Zn. Through the Dynamic Leaching Test, sample containing 10% OPC +10% SCBA showed the satisfactory leachability index (Lx) at 9.17, 9.17, 8.81, 8.17 and 6.97 for As, Cd, Cr, Pb and Zn respectively. This indicates that the use of cement and SCBA as a binder was successful in remediating the contaminated soils through the S/S method

Stabilization/solidification of lead contaminated soil using cement incorporated with sugarcane bagasse

Soil that is contaminated with heavy metals, especially lead (Pb) has become a major issue worldwide. Pb is reported to be a metal that affects human health and is related to have caused serious diseases that interrupts the nervous system, blood vessels and kidneys. However, proper treatment techniques such as Stabilization/Solidification (S/S) method can be employed and is capable of controlling these heavy metals from contaminating the soil strata and groundwater resources. This research is to investigate the effect of soil strength and leachability of lead in S/S method when sugarcane bagasse (SCB) is added to remedy contaminated soil. Synthetic contaminated soil was prepared in bulk by mixing soil samples with lead nitrate, Pb (NO3)2 to achieve the concentration of 500 ppm. After that, cement is added at a proportion of 5%, 10% and 15% in sample weights without SCB while in another sample, the cement replaces SCB at a proportion of 2.5%, 5% and 7.5%. All samples were allowed to harden and cured at room temperature for 7, 14 and 28 days. The effectiveness of the treatment was assessed by conducting physical testing such as Unconfined Compression test, Density test and Water Absorption test. In addition, leaching tests were performed to identify the leachate criteria of lead during treatment. Two leaching tests were conducted and they were the Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP). Results indicate that pH and leachability are found to have major influence on metal release. The final pH after leaching tests showed improvements especially samples containing SCB. In addition, the concentration of lead in the TCLP and SPLP test after the curing period of 28 days were detected to be below the leachability limit as regulated by the United States Environmental Protection Agency (US EPA). As a whole, the results obtained from testing showed that soil samples : 7.5% cement : 7.5% SCB is the most effective and is the optimum mix since this proportion succeeded in minimising the leachability of Pb as low as 2.11 mg/L or a total reduction by 99%, and it even produced the strength of 1389 kPa within 28 days. In conclusion, partial replacement of cement with SCB in the binder system has been successful in increasing the strength and reducing the leachability compared to the controlled sample

Strength Properties of Untreated Coal Bottom Ash as Cement Replacement

Coal Bottom Ash (CBA) is a mineral by-product of thermal power plants obtained from the combustion of coal. In many countries, CBA wastes are identified as hazardous materials. The utilization of CBA can help in alleviating environmental problems; thus, this research was carried out to explore the possibility of its use as cement replacement in concrete manufacturing. Presently, In Malaysia, research that concerns about the use of CBA as cement replacement is very limited. Therefore, this study was aimed to investigate the properties of CBA as cement replacement and to identify the optimum percentage of untreated CBA as cement replacement. The CBA used in this study were taken from the Tanjung Bin power plant. In this research, the amount of CBA in the concrete mixture varied from 20% to 40% to replace cement. The properties of concrete containing CBA as cement replacement was examined through slump test, sieve analysis, concrete compressive strength test and splitting tensile strength test. The compressive strength test and splitting tensile strength test were performed at 7 and 28 days of curing time. Based on this research, it can be concluded that the optimum percentage of CBA as cement replacement is 25% for a curing time of both 7 and 28 days with the concrete compression strength of 45.2 MPa and 54.6 MPa, respectively. Besides, the optimum percentage for tensile strength is also at 25% CBA for a curing period of both 7 and 28 days with the tensile strength of 2.91 MPa and 3.28 MPa, respectively.

Utilization of sugarcane BagAsse ash for stabilization/solidification of lead-contaminated soils

Recently, many researchers are interested in using agricultural waste as an additive to remediate the contaminated soils. In this study, the effectiveness of sugarcane bagasse ash (SCBA) as the substitution binder to Ordinary Portlant Cement (OPC) content in Stabilization/Solidification (S/S) method was investigated through the physical and chemical characteristics namely the Unconfined Compressive Strength (UCS) and Toxicity Characteristic Leaching Procedure (TCLP). Synthetic contaminated soil was prepared in bulk by mixing soil samples with lead nitrate to achieve the concentration of 500 ppm. The OPC and SCBA varying from 5% to 20% were added to stabilize and solidify the contaminated soils. The cylindrical specimens (D = 38 mm, H = 76 mm), was compacted in five layers with 50 blows each. A further 3, 7, 14 and 28 days were allowed for curing in the temperature 25±2 ?C and humidity > 80%. Results indicate that all samples containing OPC and SCBA satisfy the US EPA strength requirement of 0.35 MPa for S/S sample. The TCLP testing shows that sample containing OPC with SCBA has been successful treated which produced the leachability below US EPA limit for lead of 5 mg/L. In conclusion, the use of SCBA as part of replacement of OPC has been successful in increasing the strength and reducing the leachability compared to untreated sample

Mechanical properties of concrete containing untreated palm oil fuel ash and egg shell powder

This study aims to use two (2) waste products, namely Palm Oil Fuel Ash (POFA) and Egg Shell Powder (ESP) as cement replacement in concrete. This is because the properties of POFA and ESP are similar to the properties of cement. The objective of this study is to determine the mechanical properties (compressive strength and tensile strength) of concrete containing POFA and ESP as cement replacement. With both properties known, the optimum percentage of POFA and ESP as cement replacement can then be determined. The percentage of replacement of POFA was fixed at 20%, however the percentages of ESP varied from 0 to 20%. Six 100 � 100 � 100 mm cubes and six 100 � 200 mm cylinders were prepared for each variation of percentages. The cubes and cylinders were tested for compressive and tensile strength after 7 and 28 days of water curing. Generally, as the percentages of ESP increased, the workability, compressive strength and tensile strength of the concrete sample decreased. In conclusion, the combination of POFA and ESP as cement replacement in concrete is only able to achieved 76% of targeted strength

Sound absorption for concrete containing polyethylene terephthalate waste

Plastic solid waste generation increases every year with the current consumption habit prevalent in society nowadays. The improper disposal of plastic has been a major concern to the environment as it is not easily degradable. The issue of environmental pollution caused by polyethene terephthalates (PET) has been extensively discussed and the best solution proposed is recycling. Fibre Concrete (FC) was a composite material resulting from the addition of fibres to ordinary concrete. The objective of this research was to determine the acoustic absorption coefficient of concrete containing 0%, 0.5%, 1.0%, 1.5%, 2.0% of PET fibre compared to normal concrete. In this study, straight and irregular recycled PET fibres were used. The fibres were simply cut from PET plastic bottles. The length and width of recycling PET fibre were fixed at 25 mm and 5 mm respectively. The chosen percentages were 0.5%, 1.0%, 1.5% and 2.0% of fiber. A water-cement ratio of 0.45 was acceptable for all ranges. The tests that were conduct include the slump test, compression test, and impedance tube test. The specimens were tested on day 7 and day 28 after the concrete is mixed. The end of this research results for the compressive strength of normal concrete after 28 days of curing was 48.2 MPa while concrete with 0.5% PET, 1.0 % PET, 1.5% PET and 2.0% PET recorded a compressive strength of 50.9 MPa, 49.8 MPa, 47.9 MPa and 46.6 MPa respectively. The result of the impedance test received at age 28 days was 0.13 for normal concrete and 0.16, 0.14, 0.16 MPa, and 0.14 for 0.5% PET, 1.0 % PET, 1.5% PET and 2.0% PET respectively. In conclusion, the aspect ratio of the fibres to the concrete must be correlated to avoid reducing durability. In conclusion, the addition of 0.5% PET recycled fibre into concrete showed the best value in terms of strength and 0.16 for the sound absorption coefficient

Repositioning of the global epicentre of non-optimal cholesterol

High blood cholesterol is typically considered a feature of wealthy western countries(1,2). However, dietary and behavioural determinants of blood cholesterol are changing rapidly throughout the world(3) and countries are using lipid-lowering medications at varying rates. These changes can have distinct effects on the levels of high-density lipoprotein (HDL) cholesterol and non-HDL cholesterol, which have different effects on human health(4,5). However, the trends of HDL and non-HDL cholesterol levels over time have not been previously reported in a global analysis. Here we pooled 1,127 population-based studies that measured blood lipids in 102.6 million individuals aged 18 years and older to estimate trends from 1980 to 2018 in mean total, non-HDL and HDL cholesterol levels for 200 countries. Globally, there was little change in total or non-HDL cholesterol from 1980 to 2018. This was a net effect of increases in low- and middle-income countries, especially in east and southeast Asia, and decreases in high-income western countries, especially those in northwestern Europe, and in central and eastern Europe. As a result, countries with the highest level of non-HDL cholesterol-which is a marker of cardiovascular riskchanged from those in western Europe such as Belgium, Finland, Greenland, Iceland, Norway, Sweden, Switzerland and Malta in 1980 to those in Asia and the Pacific, such as Tokelau, Malaysia, The Philippines and Thailand. In 2017, high non-HDL cholesterol was responsible for an estimated 3.9 million (95% credible interval 3.7 million-4.2 million) worldwide deaths, half of which occurred in east, southeast and south Asia. The global repositioning of lipid-related risk, with non-optimal cholesterol shifting from a distinct feature of high-income countries in northwestern Europe, north America and Australasia to one that affects countries in east and southeast Asia and Oceania should motivate the use of population-based policies and personal interventions to improve nutrition and enhance access to treatment throughout the world.Peer reviewe

Relationship of Physical Parameters in Pb-Contaminated by Stabilization/Solidification Method

This research was performed to investigate the relationship between compressive strength, density and water absorption of Pb-contaminated soil treated by Ordinary Portland cement (OPC) incorporated with sugarcane bagasse (SCB) using the Stablisation/Solidification (S/S) method. The SCB and OPC varying from 5% to 15% was added to stabilize and solidify the Pb-contaminated soil. The cylindrical samples were prepared and cured at room temperature for 28 days. Unconfined compression test, density test and water absorption test were conducted on these samples. The relationship between these variables were determined using simple statistical method by Analysis of Variance (ANOVA). Results indicate that there is a strong relationship between compressive strength and density with a regression coefficient of 77.4%. There is also a significant relationship between density and water absorption of approximately 70.7%. In addition, compressive strength and water absorption produced a strong relationship which is 73.6% of variability in strength development. In a nutshell, the strong relationship between these three variables represent the actual physical characteristics in S/S application

Relationship of Physical Parameters in Pb-Contaminated by Stabilization/Solidification Method

This research was performed to investigate the relationship between compressive strength, density and water absorption of Pb-contaminated soil treated by Ordinary Portland cement (OPC) incorporated with sugarcane bagasse (SCB) using the Stablisation/Solidification (S/S) method. The SCB and OPC varying from 5% to 15% was added to stabilize and solidify the Pb-contaminated soil. The cylindrical samples were prepared and cured at room temperature for 28 days. Unconfined compression test, density test and water absorption test were conducted on these samples. The relationship between these variables were determined using simple statistical method by Analysis of Variance (ANOVA). Results indicate that there is a strong relationship between compressive strength and density with a regression coefficient of 77.4%. There is also a significant relationship between density and water absorption of approximately 70.7%. In addition, compressive strength and water absorption produced a strong relationship which is 73.6% of variability in strength development. In a nutshell, the strong relationship between these three variables represent the actual physical characteristics in S/S application

Durability and Acoustic Performance of Rubberized Concrete Containing POFA as Cement Replacement

Given that rubber tires are almost immune to biological degradation, this vast amount of solid waste is a major environmental concern worldwide. Reuse of these waste tires in the construction industry is one of the strategies to minimize their environmental pollution and landfill problems, while contributing to more economical building design. Thus, we assessed the improved traits of rubberized concrete made by combining palm oil fuel ash (POFA) with tire rubber aggregates (TRAs). Studies on the effects of POFA inclusion on the durability properties of rubberized concrete with TRAs as the replacement agent for fine or coarse aggregates remain deficient. Herein, the rubberized concrete contained 20% POFA as ordinary Portland cement (OPC) substitute, and various amounts of TRAs (5, 10, 20 and 30%). The proposed mixes enclosing three types of TRAs (fiber, fine and coarse aggregates) were characterized to determine their durability and acoustic performance. The water absorption, fire endurance performance, chloride penetration, and acoustic properties of the proposed concrete were evaluated. The designed concrete showed a systematic increase in water absorption and chloride penetration with the increase in rubber amount and particle size. These POFA-modified rubberized concretes displayed a satisfactory performance up to 500 °C, and superior acoustic properties in terms of sound absorption. The presence of TRA as 30% coarse aggregate replacement was found to improve the sound absorption properties by as much as 42%