Key Engineering Materials Vol. 879

Abstract: Malaysia has been recognized in recent decades as one of the world's leading palm oil producers and exporters. The number of palm oil mills multiplies each year, increasing the capacity of fresh fruit bunch waste or effluent discharged. Countless numbers of research and development, as well as implementation, have been dedicated to advancing the pollution control technologies. Most of the research is to treat and manage liquid and solid waste generated from palm oil mills. The main reason for such tremendous efforts is that the waste coming from palm oil mills has been declared as one of the pollution sources in the world. Thus, the purpose of this study was to utilize treated palm oil mill effluent (POME) sludge from the electrocoagulation process to produce bricks. Here, three different dilution rates, which was 60%, 90% and 100% of POME concentration have been analyzed in the electrocoagulation process, respectively. After the electrocoagulation process, the characteristics of POME effluents were evaluated, and the treated POME sludge was collected. Instead of being discarded after the treatment, the treated waste sludge from the electrocoagulation process was used to make bricks. Three different bricks labelled (A, B and C) from treated POME sludge from the electrocoagulation process (60%, 90% and 100%) were fabricated. These bricks have been analyzed based on the JKR Standard Specifications for Building Works. Data obtained showed that the compressive strength for the bricks (A, B and C) after seven days were 6.076, 8.233, and 6.344 N/mm². Meanwhile, the bulk density of the bricks (A, B and C) were 2247.92, 2233.95, and 2094.33 kg/m³. The results showed that the compressive strength for these brick samples had met the JKR Standard Specification for Building Works of 5.2 N/mm². It can be deduced that the bricks from treated POME can be a greener product compared to the traditional bricks. Moreover, the concept of a circular economy is adapted in this study to eliminate waste for a long-term sustainable environment.

Abstract: This paper presents the feasibility study of adding recycled Polyethylene Terephthalate (PET) fiber obtained from drinking water bottle as admixture material in the concrete. A few numbers of tests were conducted to determine the physical and mechanical properties of recycled PET fiber reinforced concrete such as slump test, compressive strength test and flexural strength test. The effect of incorporating the recycled PET fiber on various volume fractions of concrete by 0.5%, 1%, and 1.5% of weight of cement were experimentally investigated. The test specimens comprising of cubes and beams were prepared and tested at 3, 7, 14 and 28 days after curing process completed. Generally, it was found that the workability of concrete reinforced recycled PET has reduced as the volume fraction of PET fiber increased. The compressive strength of concrete reinforced recycled PET has reached the highest value at volume fraction of 0.5%. However, the flexural strength of concrete was significantly increased by incorporating 1.0% of recycled PET fiber. It can be concluded that the concrete which contains 0.5% of recycled PET fiber has the highest of average percentage of relative. Hence, it can be categorized as the optimum percentage of recycled PET fiber to be utilized in concrete. It is recommended to use recycled PET fiber in concrete for the construction of structures and infrastructures as a green construction material in order to achieve clean and sustainable environment in the year future.

Abstract: The numbers of Malaysian construction industry had been increasing in several years with the large construction building and infrastructures projects had been constructed. Therefore, these developments led to an increase of cement production. The production of cement will cause wider environmental implication such are air pollution, water pollution and soil pollution which are very dangerous for human health. This is due to the manufacturing of cement that release dust, toxic and carbon dioxide emissions, which is a significant contributor of greenhouse gases. To overcome this problem, several researches had been conducted for the past few decade to find a new waste material that have same mechanical properties which can replace cement content in construction. One of the most promising materials that shows great potential is eggshell as a cement replacement. It is reported that the global egg production will increase to about 90 million tons by 2030, therefore the waste of eggshell will be increased too. This paper study the mechanical properties of eggshell as a cement replacement in concrete. Several papers had been reviewed and the results are presented in order to shows the performance of eggshell in concrete. The result shows that the concrete with less than 15% replacement of eggshell produced higher compressive and tensile strength compared to normal concrete. Moreover, the flexural strength of concrete containing eggshell up to 20% replacement shows comparable results with normal concrete. From the results, by replacing cement with eggshell up to 15% show a good performance as well as can reduce the use of cement and reduce the eggshell wasted in landfill.

Abstract: Solid waste management is one the leading problems in Malaysia. Rapid development and population growth have prompted researches to improve the recycling and reusing of waste material for sustainable development. Chicken eggshell is discarded in Malaysia as municipal waste, while waste tyre is a waste that is difficult to handle and often ends up in the landfill. This paper presents the properties of high performance concrete with eggshell powder and tyre rubber crumb as partial replacement of cement and sand. Grade 45 concrete was prepared with 5% tyre rubber crumb as sand replacement and up to 15% of eggshell powder as cement replacement. The mechanical strength of concrete was investigated for up to 90 days while durability properties were studied through water absorption and carbonation test. Results show that concrete with 5% eggshell powder is optimal for high mechanical properties, lower water absorption and low carbonation depth. X-Ray Diffraction of concrete shows increase of calcite compound which contributes to the gain of strength. Microstructure analysis with SEM and EDX provides insight of the improved performance, which is attributed to a denser C-H-S gels and finer pore structure.

Abstract: Around 1000 million waste tyres are generated annually and over 5000 million more are estimated to be discarded by 2030. It is estimated that one waste tyre is discarded per person in developed areas, hence 1 billion waste tyres are disposed worldwide. Waste tyre is difficult to manage as it takes up space, is difficult to compress and combustion of tyre releases highly toxic substance into the air. Hence, most of them end up in the landfill, as past research data estimated that currently 4 billion waste tyres can be found in landfills. In this study, up to 30% tyre rubber with a fine grind size of 300nm to 500nm was used as partial sand replacement in type N cement mortar. The rubber was treated with 1M NaOH solution to enhance its ability to bond with the other constituent materials. Tests were conducted to determine the properties of rubberised mortar, including consistency, compressive strength, flexural strength, water absorption and acid attack. From the test result, tyre rubber reduced the consistency and strength of mortar. Mathematical regression model showed that reduction of strength occurred in a second-order polynomial function with percentage of rubber. It was concluded that at up to 20% replacement rubberised mortar has the best resistance against water absorption and acid attack while still achieving the target strength.

Abstract: Environmental degradation caused by deforestation activities for harvesting of limestone from the hills and its calcination process at cement factory along with disposal of cockle shell waste from fisheries industries is in need of resolution. In view of sustainable green environment, approach of utilizing cockle shell waste as partial cement replacement in cement production would reduce pollution caused by both industries. Thus, this research investigates the effect of cockle shell powder as partial cement replacement on setting time and compressive strength of mortar. A total of five types of mortar mixes consisting different percentage of cockle shell powder as partial cement replacement from 0%, 10%, 20%, 30%, and 40% by weight of cement were prepared. Setting time test were conducted on fresh paste. All specimens were subjected to water curing until the testing age. Compressive strength test were conducted on hardened mortar cubes at 3, 7 and 28 days. Finding shows that integration of cockle shell powder as partial cement replacement influences the setting time and compressive strength of mortar. Suitable combination of 10% cockle shell powder successfully enhances the compressive strength of mortar. Conclusively, success in transforming the cockle shell waste to be used as partial cement replacement in mortar production able to reduce cement consumption, save landfill usage for trash dumping and promote cleaner environment for healthier lifestyle of community nearby.

Abstract: Nowadays, intensive research in production of highly reactive pozzolanic materials from industrial waste to replace cement is crucial. This action expected to increase industrial waste recycling rate and at the same time reduce extraction of non-renewable resources of limestone. Unique characteristics of coal bottom ash as one of the industrial based pozzolan gained less popularity because of its low reactivity and heavy metal leaching due to conventional method used for disposal. Therefore, an alternative approach was deliberated in this research to utilize coal bottom ash into soluble form and enhance the quality of bottom ash as pozzolanic material. Coal bottom ash after the acid washing with optimum parameter was then undergoes solution-gelification process with various alkali based solution for 2 hours soaking durations. The conversion of coal bottom ash into soluble silica in this study demonstrates good pozzolanic performance in a state of siliceous gel pozzolan compared to the raw ones. 5% of cement replacement by soluble silica from CBA shows good strength development from early and later age. The physical dispersion effect is the cumulative effect of enhancement cement hydration due to the availability of increased the nucleation sites on soluble silica particles.

Abstract: Steel slag (SS) is a kind of industrial solid waste usually been dumped at landfills and causes environmental pollution. Previous studies have demostrated that SS can be an alternative material to be used for making concrete and could achieve good mechanical properties, which not only reduce natural resources depletion but also improve environmental quality. This study aims to evaluate the effectiveness of SS as supplementary cementitious material (SCM) partially replacing cement on workability and mechanical properties of fresh and hardened concrete. X-ray flouresence test, slump test, compressive strength test and ultra pulse velocity test have been conducted. Mix designs are determined with replacement proportion of cement by SS of 0, 10%, 20%, 30%, 40% and 50%. Results show that replacement of cement by SS up to 50% increase the workability of concrete. The density of concrete ranges from 2083 to 2373 kg/m³, with and without replacement of SS at curing age of 1-day, 3-day and 28-day. Compressive strength of concretes incorporating SS is lower than that of plain concrete. 1-day and 3-day compressive strength of concrete incorporating SS decrease with the increase in replacement of SS while 28-day compressive strength reach peak at 30% replacement and further replacement of SS reduce 28-day compressive strength. The UPV value of concrete have good relationship with compressive strengh with the correlation coefficient of 0.92, 0.87 and 0.70 of 1-day, 3-day and 28-day experiment data, respectively. This study indicates the SS can be used for making concrete.

Abstract: Soft marine clay soil is characterized with highly compressible behavior, in which associated with poor bearing capacity and low in shear resistance. Soil improvement works are carried out to reduce the soil failure and destruction to the superstructure. Various techniques available for soil stabilization including the use of admixture to improve the engineering properties of the problematic soil. This paper aims to report on the use of waste steel dust retrieved from the medication supply industry as soil stabilization agent. Several series of Atterberg limit test and Unconfined Compressive Test were carried out to foresee the potential use of the waste steel dust for the purpose of civil engineering applications. The significant findings from this study is evident that the waste steel dust ranges from 5% to 15% did not able to serve as soil stabilization agent. It can reduce the plastic behavior of the soil sample; however, it also caused the strength of the soil declined. In comparison with previous studies, the presence of activated agent could possibly enhance the performance of waste steel dust as an alternative treatment agent to soil improvement works. The use of activated agent is to serve as pozzolanic materials to create cementitious bonding in between the soil interparticles matrix.