Fly Ash as an Ingredient in the Contaminated Soil Stabilization Process

Fly ash is the main by-product of coal combustion characterized by a large specific surface area. In addition to oxides, it also contains unburned coal and trace elements. This study aimed to investigate the possibility of using fly ash from pit-coal combustion (CFA) for the treatment of benzene-contaminated soil (S). The CFA was used as a mixture with Portland cement (PC) (70% PC + 30% CFA). The soil was treated with a PC-CFA mixture in amounts of 40, 60, and 80% of soil mass. During the process, the concentration of benzene was monitored with the flame-ionization detector. Produced monoliths (S+(PC-CFA)x) were tested for compressive strength and capillary water absorption. The experiment confirmed that the PC-CFA mixture limited benzene emission. The highest reduction in benzene concentration (34–39%) was observed for samples treated with the PC-CFA mixture in an amount of 80% (S+(PC-CFA)80). The average compressive strength of monoliths S+(PC-CFA)40, S+(PC-CFA)60, and S+(PC-CFA)80 was 0.57, 4.53, and 6.79 MPa, respectively. The water absorption values were in the range of 15–22% dm.

Condition Assessment Using None Destructive Tests at Montauk Bridge Deck

Ground penetrating radar (GPR) and portable seismic property analyzer (PSPA), was used in concrete structures for monitoring, quantifying, and mapping the deterioration of bridge decks. The Montauk Bridge deck was assessed based on PSPA and GPR data. Based on the analysis of the PSPA data, it was determined that over 65% of bridge conditions were rated serious to poor condition with an average compressive strength of less than 2500 psi; less than 35% of bridge deck conditions were rated fair to good with an average compressive strength over 2500 psi. Based on GPR data, it was determined that 72% of the bridge deck was in serious to poor condition, and only 28% of the bridge deck was in fair to good condition. Additionally, the analyses of the ground penetrating radar data indicated possible rebar corrosion in places. For these reasons, it is recommended that the Montauk bridge’s deck be completely replaced. Keywords: Condition assessment, NDT, GPR, PSPA, bridge deck

PENGARUH PENAMBAHAN SERAT IJUK PADA PAVING BLOCK BERBAHAN PLASTIK HDPE

The waste problem continues to be a complex issue. On the one hand, the use of plastic still cannot be abandoned by humans, but on the other hand the waste produced is very difficult to decompose. In Indonesia, in 2015 the amount of waste reached 64 million tons / year. Palm fiber is one of the materials that can be used as composite fiber. In this study, a research will be conducted on the manufacture of paving blocks made from HDPE plastic combined with variations of 0%, 1%, 2% and 3% palm fiber. Plastic waste is melted and put into a mold and then combined with palm fiber. From the test results, the highest compressive strength (2% fiber variation) was 45.91 kg/cm2 and the average compressive strength was 45.28 kg/cm2. This compressive strength is under the minimum compressive strength standard of SNI Permasalahan sampah masih terus menjadi isu kompleks. Di satu sisi, penggunaan plastik masih belum bisa ditinggalkan manusia, namun di sisi lain sampah yang dihasilkan sangat sulit terurai. Di indonesia, pada tahun 2015 tercatat banyaknya sampah mencapai 64 juta ton/tahun. Ijuk merupakan salah satu material yang dapat digunakan sebagai serat komposit. Pda penelitian ini akan dilakukan penelitian mengenai pembuatan paving block berbahan dasar plastik HDPE yang dikombinasikan dengan variasi serat ijuk 0%, 1%, 2 % dan 3%. Limbah plastik dilelehkan dan dimasukkan ke dalam cetakan lalu dipadukan dengan serat ijuk. Dari hasil pengujian, didapatkan kuat tekan tertinggi (variasi serat 2%) sebesar 45,91 kg/cm2 dan kuat tekan rata-ratanya sebesar 45,28 kg/cm2. Kuat tekan ini berada di bawah standar kuat tekan minimal dari SNI.

Behavior of Normal Concrete Reinforced with Fiber

Concrete is a material with the ability to withstand a fairly high pressure, yet it has a low ability to withstand tension. To be utilized as a structure material, improvements need to be made to increase its tensile strength. Addition of fiber in the concrete mixture is recognized to be one among the existing methods to increase the tensile strength. Considering its high tensile strength, This study aimed to examine the compressive strength, the split tensile strength, the flexural and elastic modulus of the normal concrete with Menjalin fibers. The examination was conducted using a cylinder with the diameter of 15 cm and the height of 30 cm and a beam with the size of 15x15x60 cm. Fiber addition was 0.65% of the total concrete materials with various fiber lengths ranging from 2.5 cm, 5 cm, 7.5 cm to 10 cm. The experiment was made by the means of a concrete cylinder compressive test and a flexural test of unreinforced concrete blocks. Results of the study showed, at the age of 21 days, the highest average compressive strength value of 194.37 kg/cm2 and the split tensile strength of 30.43 kg/cm2 in the concrete with fiber of 5 cm long were obtained. The highest flexural modulus value of concrete occurred in the specimen with the fiber length of 7.5 cm (55.7 kg/cm2), while the highest elasticity of concrete occurred in the specimen with the fiber length of 5 cm (2.45x105 kg/cm2).

Efficient chemical stabilization of tannery wastewater pollutants in a single step process: Geopolymerization

The treatment of tannery wastewaters is a complex task due to the complexity of the waste: a mixture of several pollutants, both anionic and cationic as well as organic macromolecules which are very hard to treat for disposal all together. Geopolymers are a class of inorganic binders obtained by alkali activation of aluminosilicate powders at room temperature. Such activation process leads to a cement like matrix that drastically decreases mobility of several components via entrapment. This process taking place in the matrix can be hypothesized to be the in-situ formation of zeolite structures. In this work we use a metakaolin based geopolymer to tackle the problem directly in an actual industrial environment. To obtain a geopolymer, the metakaolin was mixed with 10 wt% of wastewater added with sodium hydroxide and sodium silicate as activating solutions. This process allowed a rapid consolidation at room temperature, the average compressive strength was between 14 and 43 MPa. Leaching tests performed at different aging times confirm a high immobilization efficiency close to 100%. In particular, only the 0.008 and 2.31% of Chromium and Chlorides respectively are released in the leaching test after 7 months of aging.

The Difference of Composite Resin Compressive Strength with Sidikalang Coffee Soaking

Composite resin is a caries filling material. Generally, dentists choose this type ofresin as a restoration material because this material has a high compressivestrength. There are several factors that influence the compressive strength ofcomposite resins, including beverages consumed such as coffee. This study aims todetermine the difference in the compressive strength of the composite resin withSidikalang coffee immersion in 9 hours, 27 hours and 54 hours immersion time.This type of research is experimental laboratories with posttest only control groupdesign. The research sample was composite resin measuring 8 mm in diameter and4 mm in height. The sample size is determined by the Federer formula and a totalsample of 24 was obtained for the four treatment groups. Measurement ofcompressive strength using a three-point bending tool on a universal testingmachine. Data were analyzed by using the oneway Anova test. Based on the resultsof the study, the average compressive strength of composite resin in the groupwithout immersion, 9 hours, 27 hours and 54 hours of immersion was 20.69 ± 0.84,18.94 ± 0.41, 14.36 ± 0.66 and 6.70 ± 0.48. From the results of the study it can beconcluded that the ads are a significant difference in the average compressivestrength of composite resin after immersion in Sidikalang coffee for 9 hours, 27hours and 54 hours.

Study of Light Weight Fibre Reinforced Concrete by Partial Replacement of Coarse Aggregate with Pumice Stone

As the demand for the structural members application in the concrete industry is continuously increasing simultaneously many a times it is required to lower the density of concrete enabling light weight which helps in easy handling of the concrete and its members. In this research an experimental endeavour has been made to equate conventional concrete with light weight by partially substituting the coarse aggregate with the pumice stone aggregate in M30 grade mix design. Simultaneously small fibres of Recron3's Polypropylene have been applied to the concrete as a reinforcing medium to minimize shrinkage cracking and improve tensile properties. The coarse aggregate was substituted by the pumice aggregate in 10, 20, 30, 40, and 50 percent and fibres respectively in 0.5, 1, 1.5, 2 and 2.5 percent. The experiment is focused on strength parameters to determine the most favourable optimum percent with respect to conventional concrete. Keywords: OPC (Ordinary Portland Cement)1, FA (Fine Aggregate)2, CA (Coarse Aggregate) 3, fck (Characteristic Compressive Strength at 28days)4, Sp. Gr (Specific Gravity)5, WC (Water Content)6, W/C (Water Cement Ratio)7, S (Standard Deviation)8, Fck (Target Average Compressive Strength at 28days)9.

Influence of adhesive and layer composition on compressive strength of mixed cross-laminated timber

Different types of wood can be used for making cross-laminated timber (CLT), which is useful as a structural material. Therefore, to assess the viability of mixed cross-laminated timbers prepared with different adhesives, their compressive strength performances were evaluated. Laminae of Japanese larch, red pine, and yellow poplar were used to manufacture eight types of mixed CLTs, which were then tested in a universal testing machine for obtaining the compressive strength. The results were then compared to those obtained from the finite element (FEM) simulation of the CLTs at proportional limit load. The compressive strength of CLTs consisting of Japanese larch laminae, with a high modulus of elasticity, tended to increase. Mixed CLT with polyurethane adhesives showed an average compressive strength that was 14% lower than that of larch CLT, while mixed CLT consisting of red pine and yellow poplar showed an average compressive strength that was 18% lower than that of the larch CLT. The CLT prepared with phenol-resorcinol-formaldehyde adhesive yielded the highest compressive strength among the three adhesives. The FEM-predicted strengths were found to be close to the actual values in all specimens. The obtained results will be useful for selecting material and adhesive for future endeavors.

Processing and Characterization of Self-Reducing Briquettes Made of Jarosite and Blast Furnace Sludges

Jarosite sludge coming from the hydrometallurgical zinc production route is a hazardous material, which is currently neutralized and landfilled by the so-called Jarofix® process. The present study aims to assess the mechanical and metallurgical properties of briquettes made of jarosite powder with blast furnace sludges, acting as a reductant material, to recover the iron oxide in the form of pig iron and produce an inert slag, increasing the recovery of materials considered as wastes nowadays. Starch was used as a binder (0, 5, 10 wt%), and two different briquetting pressure levels were used (20 and 40 MPa). The results show that briquetting without a binder is not desirable, as the agglomerating forces provided by pressure only are not sufficient, as the briquettes are very fragile and not handy. The binder addition increased noticeably the briquettes resistance, however, only little distinction between the 5 and 10 wt% levels were seen. The briquetting pressure, on the other hand, showed a bigger role on the cold mechanical properties of the bound briquettes. The briquettes pressed at 40 MPa reached an average compressive strength higher than 12 MPa and good abrasion and drop resistance were seen, also showing that their production with starch as a binder is feasible. A special remark is done regarding the roasting treatment of the jarosite powder before the briquetting process, as an undesirable compound (thenardite) was formed within some briquettes due to a non-uniform heating of the powder, which hindered the briquettes mechanical properties. Metallurgical properties open the possibility to use such briquettes for iron production in cupola furnaces. Graphical Abstract

Experimental Analysis of Mechanical Properties and Durability of Cement-Based Composite with Carbon Nanotube

In order to study the mechanical properties and durability of cement-based composite with carbon nanotube, the test and analysis experiments are designed. Raw materials and related pharmaceutical instruments are prepared, to obtain cement-based composite with carbon nanotube samples by catalytic pyrolysis according to different proportions. The prepared sample is taken as the experimental object, and different bearing capacities are applied on different positions of the sample, to observe the change of the sample, and then, the experimental results of the mechanical properties of composite materials are obtained. The durability test results are obtained by combining the impermeability and frost resistance of the test object. The average compressive strength is 84.09 MPa, the average flexural strength is 16.9 MPa, and the crack resistance index is 22.5. In addition, the structure and diffusion coefficient of the sample also change in different degrees after the solution immersion and freeze-thaw treatment. Through longitudinal comparison, the more the carbon nanotubes are added into cement-based composite, the better its mechanical properties and durability are.