nan Triwulan

Characterization of Fly Ash on Geopolymer Paste

The effect of loss of ignition, specific gravity, fineness, specific surface area and soluble fly ash to compressive strength of geopolymer paste were studied. Six fly ashes from two different sources and different time of collection were evaluated. Sodium hydroxide and sodium silicate were used as alkali activator. Concentration of sodium hydroxide and mass ratio of sodium hydroxide to sodium silicate were fixed 14M and one respectively. The result indicated that the improvement in compressive strength of geopolymer paste was more influenced by fineness, specific surface area and soluble content of fly ash. Soluble content of fly ash greatly affected the compressive strength of geopolymer paste compare to the compressive strength of cement paste with 20% fly ash replacement.

Light Weight Geopolymer Paste made with Sidoarjo Mud (Lusi)

This paper presents the efforts of how to use the solid form of Sidoarjo mud as a base material of lightweight-geopolymer paste. The mud, which is called Lusi was mixed with a class F fly ash. Some experimental results have shown that mixing mud with fly ash and alkali was potential to become a binder in concrete, instead of Portland cement. Alkaline solutions used in the mixture were NaOH of 12 M and 14 M and Na2SiO3 combined in the ratio of 1:2.5 by weight. Aluminum powder was applied as a foaming agent. It showed that the strength of paste made with mixing Sidoarjo mud and fly ash was influenced by mud content. The effect of chemical admixture and curing temperature was observed as well. A steam curing method at 60°C was applied to the paste for three and six hours. Test results showed that the compressive strength of the paste varied with the concentration of alkaline solution, mud content, admixture and curing temperature. The maximum strength of the lightweight paste at 21 days was 2.8 MPa with the density of 722 kg/m3.

The Influence of Alkali Activator Concentration to Mechanical Properties of Geopolymer Concrete with Trass as a Filler

This paper describes one of the varying factors influencing the mechanical properties of geopolymer concrete. Fly ash and volcanic material called trass was used as raw materials, while sodium Hydroxide (NaOH) and Sodium silicate (Na2SiO3) was applied as an alkali activator. Mechanical properties were assessed by compressive test, the concentration of NaOH used in this study was eight and ten Molars, and ratio of Na2SiO3 to NaOH by mass was 0.5, 1, 1.5, 2, and 2.5. Test results indicated that the strength of geopolymer concrete and binder were hardly influenced by concentration of NaOH in solution and the activator ratio. Binder with activator ratio of 2.5 has the highest compressive strength both in 8M and 10M NaOH system. However, in concrete, there are a few difference, concretes made with 8M NaOH and activators ratio of 2 have the highest compressive strength. This result might due to the low workability of fresh geopolymer concrete. On the other hand, binder and concrete made with 10M NaOH, showed the highest compressive strength when they were made with the activator ratio of 2,5.

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.

Application of Pozzolan as Materials of Geopolymer Paste

This research use metakaolin and clay containing amorphous silica and alumina after calcination at 700°C. Mechanical properties and fire resistance of geopolymer paste increase as the ratio of silica to alumina. Mix design composition on this research based on the ratio of silica to alumina. The ratio of silica to alumina for metakaolin paste are 1.4 and 1.8. While for clay paste the ratio that used are 2.8 and 3.2. Na2SiO3 and NaOH with 10 M and 8 M were used as alkali activator at this research. Based on analysis the effect of increasing the ratio of silica to alumina increase fire resistance ability for both metakaolin and clay. However initial compressive strength is effected not only by ratio of silica to alumina but also the ratio of water to solid and SiO2/Na2O. The compressive strength decrease as the ratio of water to solid increases. Meanwhile compressive strength increase as the ratio of SiO2/Na2O increase.

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.

Effect of PVA Fiber in Increasing Mechanical Strength on Paste Containing Glass Powder

This paper presents some experimental results related to mechanical properties of fibrous concrete with polyvinyl alcohol (PVA) fiber application. The use of fibers in paste is to improve the performance of concrete as well as increasing the ductility of concrete.The mix proportion of paste was varied into 17 basic paste without fiber. Glass powder as silica source was used as cement replacement from 0-25% by cement weight. The powder was replaced by silica fume which varied from 0 – 60% by glass powder weight. Five compositions with the highest strength at 28 days and one composition of variable control (100% cement) were selected to make fibrous pastes with additional PVA fibers. Low water to the binder ratio of 25% was applied to all the mixture. Material and mechanical analysis were conducted for material reactivity, mineral composition, porosity, compressive and tensile strength.Replacement of cement with glass powder and silica fume produced the highest compressive strength of 93.26 MPa at 28 days. The highest compressive strength of fibrous paste of 99.85 MPa showed that fiber can increase the paste strength.It was also proved that application of glass powder and silica fume increased the tensile strength up to 27.22%. With the addition of PVA fibers, split tensile strength pastes increased almost 200% from original split tensile of bare paste without fiber. However, the addition of PVA fibers decreased the workability and increased the porosity of matrix.

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.

Lightweight Geopolymer Binder Base on Sidoarjo Mud

Sidoarjo mud has been a disaster for society and government of Indonesia, but this material contains of SiO2, Al2O3 and Fe2O3 so that significantly to be expected as a potential pozzolanic material. It would be very useful to take the advantages of the material. Moreover, lightweight concrete is widely applied especially at high-rise buildings in order to reduce the risk of earthquake. In general lightweight concrete is made with less Portland Cement associated with lime and pozzolanic materials as a binder. In this paper, calcined-Sidoarjo mud was introduced as pozzolanic material to create geopolymer paste. Geopolymer binders were made with a mixture of calcined-Sidoarjo mud, fly ash and alkaline activator. The specimens were then mixed with a commercial chemical foamed agent to get lightweight geopolymer binders. The results showed that the mixing with the ratio of fly ash : NaOH: Na2SiO3 were 33,3% : 33,3% : 9,52 % : 23,81% and superplasticizer was 2,5% of binder weight achieved the compressive strength of 55,6 MPa. With additional 1% of foaming agent, the compressive strength of lightweight geopolymer binder was 7.1 MPa

Effect of Activators on Strength of Hybrid Alkaline Cement

Hybrid alkaline cement is a class of alkaline cement resulted from alkali activation of the medium calcium content of aluminosilicate materials. This paper presents an experimental analysis of alkali activators effect on strength of hybrid alkaline cement produced from 80% fly ash and 20% ordinary Portland cement. Two alkali activators were observed i.e. 5% sodium sulfate and a combination of 5% of sodium sulfate-1.1 M SiO2 of sodium silicate solution. Compressive strength tests were performed on 20mmx 40mm cylinder paste specimens while setting time tests were conducted by Vicat needle. Scanning electron microscopy analysis and measurement of fly ash reaction degree were performed to explain the compressive strength of paste. It is concluded that addition of soluble silicate on the dry mix of hybrid cement-sodium sulfate activator reduce compressive strength and shorten the setting time. Both of activators give relative low fly ash reaction degree.