Preparation and Characterization of Sodium Aluminum Silicate-Polymer Composites and Effects of Surface Roughness and Scratch Directions on Their Flexural Strengths

Although efforts have been put into the research in polymer-infiltrated ceramic network composites (PICNs), data are needed to understand the relationship between surface roughness and flexural strength. In this work, a novel dental restorative composite was fabricated via infiltrating mixtures of Bis-GMA/TEGDMA and UDMA/TEGDMA into partially sintered porous sodium aluminum silicate blocks and curing. Bars with different surface conditions were produced by sanding with abrasive and polishing. Flexural strength was measured using three-point-bending. Scanning electron microscopy (SEM) was employed to observe the microstructure of surface areas. One-way analysis of variance was applied for statistical calculations, with p < 0.05 being considered significant. Weibull plots were used to evaluate the reliability of flexural strength. The results demonstrated that the flexural strength of the resultant composites was affected by the scratch direction and the value of roughness. The flexural strength increased with decrease of surface roughness. A higher strength value was found for parallel types than for vertical types with nearly the same surface roughness. A large roughness value and a scratch direction perpendicular to tensile stress produced a low Weibull modulus. Of particular importance with this work is that these factors should be taken into consideration when using PICNs as dental restorative composites.

Analisa Struktural Batuan Andesit di Desa Laksanamekar Bandung Jawa barat

This article discusses structural analysis in Laksanamekar Village, Bandung. The sample is in the form of andesite D and A *. Sample size (1 x 1) cm, with thickness (x) 0.4 cm. Sample D comes from the mountains of Laksanamekar Village Bandung at depths (15-20) m and samples (A *) from the Code River Yogyakarta. The results showed that the sample was a type of dry andesite rock and had layers in the grain. Andesite D has a denser composition, higher iron content and smoother surface texture than A*. The XRD results are known to be phase-identified andesite A * Sodium aluminum Silicate with a composition of 46.5% and andesite D phase of Titanium Calcium Sodium Magnesium Iron Manganese Silicon Aluminum Oxide of 10% so that andesite rocks have higher quality than A * samples.

Characterization of Reclaimed Asphalt Pavement (RAP) as a road pavement material (National Road Waru, Sidoarjo)

Reclaimed Asphalt Pavement (RAP) is a dredging pavement material using Cold Milling Machine. The application of Reclaimed Asphalt Pavement is increased year by year. Due to the increasing application of RAP year by year which implicates environment condition, especially in damaging natural resources, the research on material used in RAP needs to be conducted, so RAP can be optimally utilized. To achieve optimal performance, data of RAP characteristics reviewed from microstructural analysis is necessary. The objective of this research is to obtain the characteristics of Reclaimed Asphalt Pavement. The method used was literary study based on previous research. Material tests used were XRF, SEM and FTIR. The object of study was RAP material taken from national road Waru Sidoarjo. The major compositions of Reclaimed Asphalt Pavement obtained were Kaolin, Lithium, Tetraborate, Dextrin. SEM graphics showed the morphological and surface texture of RAP. FTIR graphic presented the functional group of Reclaimed Asphalt Pavement showing O-H C-O acid in the peak of graphic. From XRD result, the major compounds of Reclaimed Asphalt Pavement obtained were Calcium, Sodium, Aluminum, Silicate.

Deterioration and Microstructural Evolution of the Fly Ash Geopolymer Concrete against MgSO4Solution

Fly ash geopolymer concrete (FAGC) and ordinary Portland cement concrete (OPCC) specimens were immersed in 5% MgSO4solution undergoing 32 wetting-drying and heating-cooling cycles. Their compressive behavior was investigated after every 8 cycles. Several microstructure analysis techniques were applied on the samples to identify the materials formed due to magnesium sulfate attack, including XRD, FTIR, SEM, and EDS. Experimental results elucidated that the compressive strength loss ratio in the heating group of FAGC was 12.7%, while that of OPCC was 17.8%, which means that FAGC had better magnesium sulfate resistance than OPCC. The compressive strength loss of OPCC was due to the formation of gypsum under the magnesium sulfate attack exposed to wetting-drying and heating-cooling cycles. The deterioration mechanisms of FAGC against MgSO4solution were discovered to be that sodium aluminum silicate hydrate (N-A-S-H) gels reacted with MgSO4, leading to the creation of low strength magnesium aluminum silicate hydrate (M-A-S-H) gels.

Synthesis of Analcime Crystals and Simultaneous Potassium Extraction from Natrolite Syenite

Analcime single crystals were successfully synthesized from natrolite syenite powder (K2O 10.89%) and 92.6% of potassium was extracted simultaneously by means of soda roasting followed by alkali-hydrothermal method. Effects of NaOH concentration, reaction temperature, and holding period on the analcime formation and potassium extraction were investigated systemically. The results indicated that NaOH concentration plays an important role in determining the chemical composition of zeolites and size distribution; by turning the NaOH concentrations, three different pure zeolites (i.e., the phillipsite-Na, the analcime, and the sodalite) were prepared. Besides, a higher temperature could accelerate the dissolution of K+ions and enhance the crystallinity degree of zeolite. The reactions involved in the analcime synthesis can be summarized as follows: sodium aluminum silicate dissolution→precipitation and dissolution of metastable zeolite-P→analcime nucleation→analcime growth. The extraction ratio of K+is associated with the types of synthesized zeolites, among which analcime is the most effective to promote potassium leaching out from zeolite lattice position. The optimal condition for analcime crystallization and K+leaching is found to be as follows: 175°C for 4 h in 0.5 mol/L NaOH solution.

Effect of Polymer Surfactants on the Inhibition of Beta-Dicalcium Silicate Decomposition in Sodium Aluminate Solution

The decomposition behavior of synthetic β-2CaO•SiO2 by adding sodium polyacrylate (NaPAA), polyethylene glycol (PEG) and their mixture at 80°C in sodium aluminate solution was investigated. The SiO2 concentration in the reacted sodium aluminate solution decreases as the polymer surfactant charge increases, but does not change obviously when each surfactant is added over 12.5 mg/L. The amount of CaCO3, hydro-garnet and sodium aluminum silicate hydrate in the decomposed solid with polymer surfactant addition is much smaller than that without surfactant addition. The losses of Na2O and Al2O3 are greatly decreased due to polymer surfactant addition. The inhibition sequence of β-2CaO•SiO2 decomposition by polymer surfactants in sodium aluminate solution is mixture of NaPAA and PEG, NaPAA, PEG.