Ridho Bayuaji

Mechanical Properties of MIRHA-Fly Ash Geopolymer Concrete

This paper provides a report about the results of an investigation carried out to understand the effect of Microwave Incinerated Rice Husk Ash (MIRHA) on the mechanical properties of fly ash geopolymer concrete to access the concrete performance development. Fly ash (350kg/m3) and MIRHA (0%, 3%, and 7%) were used as the source materials to replace cement, NaOH and Na2SiO3 solutions used as the alkaline liquids for the medium of polymeric reaction. In addition, sugar was used as retarder, as well as three different types of curing regime (ambient, external exposure or oven curing regime). The concrete mixing procedure was adjusted to obtain the proper homogeneity of dry materials and wet ones. In this project, a number of mechanical tests have been conducted including the pull-out test, compressive strength test, flexural strength test, and modulus of elasticity test. It was then observed that the performance of mechanical properties of MIRHA-fly ash geopolymer concrete improved with the use of oven curing as the curing regime for the concrete samples.

A Comprehensive Characterization and Determination of Fly Ashes in Indonesia Using Different Methods

This paper presents an observation on fly ash quality in East Jawa, Indonesia. The ash samples were collected from 16 fly ashes produced by some Indonesian power plants. The samples are majority categorized as class F fly ashes with good pozzolanic characteristics according to the standard. The samples were examined for their physical, chemical and mechanical properties with compression test. The test was conducted by making some mortars and paste containing fly ash as cement replacement in accordance with three methods. The compressive strength results were compared with the control specimens made from ordinary Portland cement to obtain a strength activity index (SAI). The results showed that physical properties of fly ash influenced the mechanical properties of mortars more than those showed by chemical characterization.

The Effect of Pb2+ and Cd2+ Addition to Mechanical Properties of Fly Ash Geopolymer Paste

Immobilization of heavy metal ions using geopolymer paste is a promising way to solve the problem with heavy metal waste from industries. This research focused on the immobilization of Pb2+ and Cd2+ which are common heavy metal waste with distinctive cation size. The cations were immobilized by geopolymerization process to form geopolymer paste. The paste was prepared by using fly ash from a power plant in Cilacap, Indonesia, with SiO2/Al2O3 ratio = 3 and S/L = 1.6. According to XRF analysis, the ash is type C fly ash and additional Al(OH)3 was needed to achieve the SiO2/Al2O3 ratio. A solution of Cd2+ or Pb2+ from their respective nitrate salts was added to the geopolymer mixture to make an immobilized Cd2+ or Pb2+ in a fly ash geopolymer matrix. Compressive strength tests showed that the maximum strength was achieved when 3855 ppm of Cd2+ or 765 ppm of Pb2+ was added to the geopolymer mixture. The change of strength is explained to be caused by the filling of geopolymer cavities that were formed during the geopolymerization process. Due to the smaller size of Cd2+ than Pb2+, the strongest geopolymer paste was achieved at higher Cd2+ concentration than Pb2+. X-ray diffraction analyses results show that the addition of Cd2+ or Pb2+ shift the position on hump to larger 2θ.

The Influence of Chloride Environment on Compressive Strength of Geopolymer Concrete with Fly Ash Using Taguchi Approach

This study is conducted to determine the effect of four variables on compressive strength of geopolymer concretes. These four variables are binder/aggregate, Alkalinene/fly ash, effect of superplasticizer (SP) addition and curing system. The compressive strength is important mechanical properties for construction material. Taguchi experimental design method is used to compile the concrete composition of geopolymer to achieve the maximum compressive strength. Specimens concrete used is a cylinder with 100 mm diameter and 200 mm height. Compressive strength test is performed at 28 day using SNI 03-6825-2002, Indonesian National Standard. This study concludes that the chloride environment has a beneficial effect on the compressive strength of the concrete. In addition, the Alkalinene/fly ash ratio and binder/aggregate give a significant effect on the compressive strength of geopolymer concretes.

Utilization of High Calcium Content Fly Ash: Flexural Strength of Geopolymer Concrete Beams in Sea Water Environment

This paper presents a study of the flexural strength of geopolymer concrete beam using high calcium content fly ash (FA) in marine environment, without high heat curing. Two series of beam specimens were loaded to failure to study the effect of chloride environment on the flexural strength of geopolymer concrete beams. Series I specimens were subjected to sea environment, whereas series II were kept at room temperature. Tests performed on concrete cylinders show that the sea water has no effect on compressive and splitting tensile stress of high calcium content FA based geopolymer concrete. However, the ratio of splitting and compressive strength for both series was approximately 44%, almost double than that of normal concrete. In addition, the flexural test of concrete beams shows that the average cracking load for series I specimens was 275% higher than that of series II. However, the ultimate load, crack pattern and deflection characteristic for both series were very similar.

Lightweight Geopolymer Binder with Abaca Fiber in Different Curing

Light weight buildings are required in Indonesia to reduce the risk due to the earthquakes. Therefore, the presence of lightweight materials are needed. Moreover, fly ash that is a waste of coal combustion process, has a basic ingredient of geopolymer binder. If the geopolymer binder is mixed with a foaming agent, it will be a lightweight geopolymer binder, in which it can be used as wall elements that have light weight. Furthermore, the utilization of fly ash will reduces the pollution due to the release of CO2 during production of Portland cement. Thus the use of fly ash results in environmental safety. This study investigate about fibrous lightweight geopolymer binder, in which the main materials used was fly ash with the alkali activator such as NaOH and Na2SiO3. Foaming agent was used to form micro-pores. Abaca fiber was used as a reinforcement to avoid cracks. Normal curing and steamed curing were utilized at temperature 60°C for 6 hours. Meanwhile, tests conducted were compressive strength, density and porosity. Steam curing method resulted an increase in strength and gives less density even though the same amount of pores was formed.

The effect of fly ash and coconut fibre ash as cement replacement materials on cement paste strength

Concrete is the backbone material in the construction field. The main concept of the concrete material is composed of a binder and filler. Cement, concrete main binder highlighted by environmentalists as one of the industry are not environmentally friendly because of the burning of cement raw materials in the kiln requires energy up to a temperature of 1450° C and the output air waste CO2. On the other hand, the compound content of cement that can be utilized in innovation is Calcium Hydroxide (CaOH), this compound will react with pozzolan material and produces additional strength and durability of concrete, Calcium Silicate Hydrates (CSH). The objective of this research is to explore coconut fibers ash and fly ash. This material was used as cement replacement materials on cement paste. Experimental method was used in this study. SNI-03-1974-1990 is standard used to clarify the compressive strength of cement paste at the age of 7 days. The result of this study that the optimum composition of coconut fiber ash and fly ash to substitute 30% of cement with 25% and 5% for coconut fibers ash and fly ash with similar strength if to be compared normal cement paste.

Influence of Microwave Incinerated Rice Husk Ash on Hydration of Foamed Concrete

This research explains the results of an investigation carried out to understand the influence of a microwave incinerated rice husk ash (MIRHA) powder on foamed concrete (FC) hydration. The experimental work was designed using the Taguchi approach. This method was selected to have a target for the optimum working conditions of the parameter that affects some physical properties of concrete mixtures. The loss on ignition (LOI) method was used to establish the nonevaporable water () content at all selected ages of hydration. It was observed that the MIRHA powder showed lower nonevaporable water contents than the normal FC, indicating that MIRHA powder facilitated enhancement in FC hydration. The optimum FC properties were achieved at 10% MIRHA composition as proven from the highest compressive strength. This level corresponds to the highest values in change in nonevaporable water and degree of hydration.

Case Study of Remaining Service Life Assessment of a Cooling Water Intake Concrete Structure in Indonesia

This paper deals with the assessment of remaining service life of a cooling water intake concrete structure (CWICS) subjected to corrosion due to chloride attacks. Field and laboratory tests were performed to determine the current existing condition of the structure. Both destructive and nondestructive tests were employed to obtain the parameter needed for the assessment. Based on the current condition and test results, structural analysis was carried out and the remaining safety factor of CWICS was determined. From the analysis, it was found that most concrete elements of CWICS had safety factor greater than unity and might fulfil its intended service life up to the year 2033. However, fewer elements require immediate strengthening to extend their service life.

Optimization of Water Recycle at Steam Flood EOR Using Genetic Algorithm

Steam flood is one of the thermal enhanced oil recovery methods widely used to increase production rate. This method injects steam into reservoir formation that will reduce crude oil viscosity. The steam condensate gives additional pressure to push crude oil toward production well. This method is known to be able to increase recovery factor significantly, but there are several things we need to note. The total cumulative water injected per day could reach 200 MT. This number is equivalent to total energy needed for steam generation, and wastewater (water-cut) on production well. Wastewater typically has complex chemistries, including total dissolved solids (TDS), organic carbon content, and concentration of scale-forming minerals (e.g., carbonates and sulfates). High-cost treatment is needed before wastewater can be re-injected. The optimization steam flood operation is required to maximize crude oil production, minimize energy at steam generation, and minimize wastewater (water-cut) on production well. Model of steam flood operation could be derived from Beggs–Brill method and Darcy equation. Mean error from Beggs–Brill method to PIPESIM software is 4.48% for pressure and 0.98% for temperature. Mean error from Darcy equation to COMSOL simulation is 0.39% for pressure and 0.97% for temperature. Before optimization, steam flood runs in 2.2 kg/s of mass steam injection rate, 600 psia of injection pressure, and 80% of steam quality. The profit of those configurations is 7645.37 USD/day. After optimization using genetic algorithm, steam flood operation could reach global optimum at 6.460 kg/s, 1408.53 psia injection pressure, and 87.86% steam quality. The profit of those optimized parameters is 17618.75 USD/day.