Alkaline activation of mortars made from solid construction waste [Activación alcalina de morteros fabricados a partir de residuos sólidos de construcción]

In the present investigation the influence of the percentage by weight of replacement of portland cement (PC) by recycled concrete powder (RCP), alkaline activated, in percentages of 10%, 20%, 30%, 40% and 50%, was evaluated. which were selected from construction rubble left in the Buenos Aires spa, Víctor Larco Herrera district, Trujillo province. After being washed, they went to the grinding and sieving process (400 mesh), using only the through material. Specimens were manufactured according to the ASTM C-109 standard for the compression test in cement mortars, for the alkaline solution NaOH (4M) was used. The mortars obtained were cured in an oven at 70 ° C for 72 hours, and subsequently the curing was completed at room temperature, for a total time of 28 days. The results of the average compression test were 12.15 MPa, in the case of the PC mortar and 14.25 MPa in the best case (PC mortar and RCP-10%), the increase being 17.28%. The mix design using coarse sand and binder was kept constant at (3: 1), while the water / cement ratio (w / c) was 0.6 in all cases. The reason for the increase in compressive strength is due to the reaction between the RCP particles, alkaline solution and the calcium hydroxide produced during the hydration of the cement particles, which generate gels (CASH), which occupy the spaces left by the hydration process of the aforementioned cement particles, as they need calcium hydroxide. For all cases of the compression test, a total of 10 repetitions were carried out.

Design and Development of an Electronic Sieving for Sand Separation using Node MCU System

Sand sieving is now considered one of the essential needs in the construction industry. Where businesses collaborate to find the best and highest-quality methods for extracting pure sand suitable for construction. These businesses always require high-quality machines to complete the process flawlessly. This is also to prove its market power and guarantee its products. This research talks about the various mechanisms for designing and manufacturing sand sieving. The sand sieving process expresses the filtering of sand from the rest of the components such as stones or gravel. The literature department studied ten different studies in the design and manufacture of sand sieving machine in different ways. Where these methods vary between using the engine and electricity and using the primitive manual method. After performing these machines several tests and evaluation of the process, it was found that the engine speed affected the energy consumed to sift the sand. Also, the sieve holes are affected by the size of the sifted sand. Where sieves are manufactured in different sizes to suit the size of the sand to be purified. On the other hand, this article contains the future recommendation of the machine to avoid errors and give effective results as needed.

Proposal for an initial screening method for identifying microplastics in marine sediments

Marine debris, which is often called microplastics, is widespread in marine environments, particularly in sediments, and is recognized as an environmental hazard because it concentrates contaminants, forms biofilms, and sinks into marine sediments. In sediments, it may be ingested by benthos and have a negative impact on higher food chain levels. In this study, a new protocol was developed to identify microplastics in various sediment fractions. This protocol combined sieving and staining based on ordinal geotechnical/geological testing methods. The sieving process was derived from the conventional particle size distribution test, and nontoxic dyes were employed in the staining process. The protocol is safe and easy to perform as it merely involves the use of conventional geological/geotechnical testing equipment. The new protocol was successfully employed to stain and categorize different types and sizes of microplastic particles from contaminated sediments. This safe, easy-to-use, and efficient protocol can serve as the basis for a new alternative approach to study microplastics present in sediments, which can be performed using basic materials familiar to geotechnical/geological engineers.

Innovative process and technology for the production of wood mulch

Plant nurseries usually control weed growth with N-(phosphonomethyl) glycine treatment. Some studies have suggested potential impacts of this treatment on both the environment and users. A possible ecological alternative is the use of ground wood particles for mulching. However, the production of the required wood particles for use in potted plants is challenging. In this article, the classical chipping and sieving process is compared with a new proposed process involving chipping and refining phases. The two processes were applied to wood logs (spruce) from the forests of the Tosco-Emiliano Apennine. The tests were performed over a week using the machinery available at the Mo.To.R.E. (Montagna Toscana Ricerca Energie) consortium. Although the results achieved were based on preliminary evaluations, they indicated the potential superiority of the new process in terms of both economic and ecological efficiency. These findings can pave the way to the development of optimized processes aimed at a significant reduction in the use of chemical herbicides for weed control.

Analysis of Spatter Removal by Sieving during a Powder-Bed Fusion Manufacturing Campaign in Grade 23 Titanium Alloy

The Laser-based Powder Bed Fusion (L-PBF) process uses a laser beam to selectively melt powder particles deposited in a layer-wise fashion to manufacture components derived from Computer-Aided Design (CAD) information. During laser processing, material is ejected from the melt pool and is known as spatter. Spatter particles can have undesirable geometries for the L-PBF process, thereby compromising the quality of the powder for further reuse. An integral step in any powder replenishing and reuse procedure is the sieving process. The sieving process captures spatter particles within the exposed powder that have a diameter larger than a defined mesh size. This manuscript reports on Ti6Al4V (Grade 23) alloy powder that had been subjected to seven reuse iterations, focusing on the characterisation of powder particles that had been captured (i.e., removed) by the sieving processes. Characterisation included chemical composition focusing upon interstitial elements O, N and H (wt.%), particle morphology and particle size analysis. On review of the compositional analysis, the oxygen contents were 0.43 wt.% and 0.40 wt.% within the 63 µm and 50 µm sieve-captured powder, respectively. Additionally, it was found that a minimum of 79% and 63% of spatter particles were present within the captured powder removed by the 63 µm and 50 µm sieves, respectively.

Processing of Iraqi Attapulgite For Using as Drilling Muds: A Comparison Study

Clay mineral processing is in charge on quality, quantity and functional properties of final produced clay. In this work, Iraqi attapulgite (Palygorskite) clay was processed with dry sieving, dispersing agent and wet sieving processes to make it suitable in oil and gas wells drilling fluids preparation. Yield of clay (quality) and yield of process (quantity) were taken as preferring criteria in choosing the proper process of Iraqi attapulgite clay preparation. XRD and FESEM tests were used for mineralogical and morphological identification respectively. OFITE viscometer was used to measure the rheological properties of the drilling fluids prepared with the produced attapulgite from the investigated processes. The results of this work showed that dry sieving process was failed in attapulgite separation. Moreover, dry grinding was a destructive process of the attapulgite crystalline structure which reduced the rheological properties up to 80%. The results showed that the dispersing agents process produces attapulgite clay with higher quality (101.94 and 89.87 barrle/ton) with fresh and salt water respectively and at low quantity of about 7%. While wet sieving process produces attapulgite clay with quality equals to (94.21 and 79.93barrel/ton) with fresh and salt water respectively and quantity reaching 40%. It follows that wet sieving was the recommended process in preparing Iraqi attapulgite to be suitable for oil and gas wells drilling fluid

Compositional Optimization of In718 Superalloy Powder for Additive Manufacturing

In this research, a composition optimized In718 superalloy powder suitable for additive manufacturing has been developed by using the vacuum induction melting gas atomization (VIGA) and the powder sieving process. VIGA which combines the vacuum induction melting (VIM) and gas atomization (GA) processes uses high pressure inert gas to atomize the metal melt formed by VIM to form metal droplets. These metal droplets are solidified to form metal powders during the falling process in the atomized chamber. After the sieving process, the mean particle size D50 of the powder is less than 35 μm and the particle size distribution (PSD) ranges from 10 to 55 μm (D10~D90). Besides, the produced powder has high flowability (ICarr ≦15), which is suitable for selective laser melting (SLM) additive manufacturing (AM). After the SLM process, the tensile tests are conducted at room temperature and high temperature of 650°C. The results show that the high temperature properties of the optimized In718 superalloy are superior to the commercial In718 superalloy.