Distrontium Cerate as a Radiopaque Component of Hydraulic Endodontic Cement

This study aimed to synthesize distrontium cerate (2SrO·CeO2: S2Ce) and evaluate its properties as an alternative component of the endodontic cement. S2Ce cement was prepared through calcination of strontium hydroxide and cerium carbonate. Subsequently, the crystal phase was confirmed using X-ray diffraction. S2Ce cement exhibited a rapid setting time (121 min) and achieved a high compressive strength (72.1 MPa) at 1 d after mixing, comparable to the compressive strength of a commercial mineral trioxide aggregate (MTA) cement (ProRoot MTA) after 28 d post mixing. However, the compressive strength decreased after 28 d of storage when the W/P ratio was 0.30–0.40 (p < 0.05). Ion dissolution test of the S2Ce cement showed that strontium ions were released after immersion in water (5.27 mg/mL after 1 d), whereas cerium dissolution was not detected. S2Ce exhibited approximately three times higher radiopacity (9.0 mm aluminum thickness equivalent) compared to the commercial MTA (p < 0.05). These findings suggest that S2Ce is a possible component for hydraulic endodontic cement that demonstrates a rapid setting and high radiopacity.

KCl Extracted from Chlorine Bypass Dust as Activator for Plain Concrete

This study demonstrated the use of KCl separated from chlorine bypass dust (CBD) as an activator for plain concrete. The separated KCl was mixed with either ground granulated blast-furnace slag (BFS) alone, or a mixture of BFS and cement. The mixed paste of separated KCl and BFS set within 24 h, and exhibited a compressive strength of 22.6 MPa after 28 d. The separated KCl, cement, and BFS mixture exhibited a more rapid setting and a higher initial activity. Further, the compressive strength at 28 d was 57.7 MPa, which was 26.2% higher than that of the mixture without the activator. Water curing of samples with added separated KCl led to the generation of hydrocalumite, or Friedel’s salt. However, this hydrocalumite was decomposed while being cured under autoclave conditions at 180 °C. Overall, KCl was an effective activator for composite materials containing cement, and resulted in superior properties compared to mineral admixtures without an activator.

Comparative Analysis of Recycled Plaster Composition Determined by X-ray Powder Diffraction and Thermogravimetric Analyses

Plaster is primarily used as a building material obtained by the calcination of gypsum. Its rapid setting time (time for the mixture to solidify) and the low quality of labor generate a large amount of nonused material. Due to its solubility in water, wasted gypsum cannot be disposed of in the environment, and its recycling process is encouraged. In this work, quantitative phase analyses (QPA) using X-ray powder diffraction (XRPD) data and the Rietveld method were carried out to determine the amounts of each compound present in commercial, hydrated, and laboratory-recycled plasters, and the results compared with those obtained by thermogravimetric analysis (TGA). It was inferred that the Rietveld method associated with XRPD data is quite efficient since it identifies compounds not seen in the TGA. Furthermore, the amount of water used in the preparation of hydrated samples influences the proper hydration of the material and, consequently, the recycled composition of the samples.

Alternatives for large crater repairs using Rapid Set Concrete Mix®

Research was conducted at the U.S. Army Engineer Research and Development Center (ERDC) in Vicksburg, MS, to identify alternative repair methods and materials for large crater repairs using Rapid Set Concrete Mix®. This report presents the technical evaluation of the field performance of full-depth slab replacement methods conducted using Rapid Set Concrete Mix® over varying strength foundations. The performance of each large crater repair was determined by using a load cart representing one-half of the full gear of a C-17 aircraft. Results indicate that using rapid-setting concrete is a viable material for large crater repairs, and the performance is dependent on surface thickness and base strength.

Long-Term Durability of Cold Weather Concrete : Phase II

Recent laboratory results confirm that it is possible to protect concrete from freezing solely using chemical admixtures and indicate that the amount of admixture required may be significantly less than previously recommended. Researchers have also verified that admixture-based freeze protection can produce concrete that is durable to winter exposure for a minimum of 20 years, through petrographic examination of core specimens obtained from past field demonstrations. Freeze protection for concrete using chemical admixtures alone has been an area of active research for 3 decades; however, the most recent methodology recommends very high addition rates of accelerating and corrosion inhibiting admixtures, which result in significant challenges, including slump loss, rapid setting, and potentially excessive temperature rise. As part of a laboratory study, researchers systematically varied the dosage of freeze protection admixtures used in concrete cured in a 23 °F environment. Preliminary findings indicate that a 50% reduction in admixture dose maintained adequate freeze protection and resulted in compressive strengths exceeding those of room-temperature controls at 7 and 28 days. The combination of improved handling, reduced cost, and verified durability associated with the use of admixtures for freeze protection makes a compelling case for broader adoption of this technique in winter operations

Robust rapid-setting antibacterial liquid bandages

Bandaging is a steadfast but time-consuming component of wound care with limited technical advancements to date. Bandages must be changed and infection risk managed. Rapid-set liquid bandages are efficient alternatives but lack durability or inherent infection control. We show here that antibacterial zinc (Zn) and copper (Cu) species greatly enhance the barrier properties of the natural, waterproof, bio-adhesive polymer, shellac. The material demonstrated marked antibacterial contact properties and, in ex-vivo studies, effectively locked-in pre-applied therapeutics. When challenged in vivo with the polybacterial bovine wound infection ‘digital dermatitis’, Zn/Cu-shellac adhered rapidly and robustly over pre-applied antibiotic. The bandage self-degraded, appropriately, over 7 days despite extreme conditions (faecal slurry). Treatment was well-tolerated and clinical improvement was observed in animal mobility. This new class of bandage has promise for challenging topical situations in humans and other animals, especially away from controlled, sterile clinical settings where wounds urgently require protection from environmental and bacterial contamination.

ANALISIS KARAKTERISTIK TANAH DASAR LEMPUNG MENGGUNAKAN METODE STABILISASI ASPAL EMULSI

Struktur jalan paling akhir menerima beban pada konstruksi jalan adalahtanah dasar. Kemampuan tanah dasar (daya dukung) dapat diperoleh darihasil pemeriksaan California Bearing Ratio (CBR) laboratorium ataupun dariCBR lapangan. Permasalahan yang sering dihadapi terutama jalan diProvinsi Riau khususnya pekanbaru tanah dasar merupakan tanah lunakberupa lempung dengan plastisitas tinggi. Salah satu cara untukmeningkatkan daya dukung tanah dasar tersebut menggunakan metodestabilisasi tanah dengan aspal emulsi. Penelitian ini bertujuan untukmengetahui nilai karakteristik tanah dasar lempung organik denganplastisitas tinggi (CH) berdasarkan Unified Soil Clasification System (USCS).Stabilisasi menggunakan aspal emulsi jenis Cationik Rapid Setting (CRS)dengan variasi penambahan 4%, 6%, 8% dan 10%. Hasil pengujian diperolehnilai CBR tertinggi pada penambahan kadar aspal emulsi 8% sebesar 6,05%.Pengujian terhadap kuat tekan bebas diperoleh pada penambahan aspalemulsi kadar 10% sebesar 0,174 MPa. Hasill pengujian yangdirekomendasikan untuk tanah lempung organic dengan plastisitas tinggiadalah pemakaian kadar aspal 8%, dengan nilai CBR 6,05% dan UCS 0,141MPa.