OC, HPC, UHPC and UHPFRC Corrosion Performance in the Marine Environment

[EN] This work aims to study the corrosion performance of six concretes in the marine environment: three ordinary concretes (C30, C40 and C50); one high-performance concrete (C90); two ultra high-performance concretes, one without fibres (C150-NF) and another one with steel fibres (C150-F). To this end, porosity and chloride ingress resistance were analysed at different ages. Resistivity was also evaluated and the corrosion rate in the embedded rebars was monitored. The results showed that C30, C40 and C50 had porosity accessible to water percentages and capillary absorption values between six- and eight-fold higher than C90 and C150-NF and C150-F, respectively. Similar differences were obtained when oxygen permeability was analysed. Chloride ingress resistance in the ordinary concretes was estimated to be one-fold lower than in C90 and two-fold lower than in C150-NF and C150-F. Presence of fibres in C150-F increased the diffusion coefficient between 5% and 50% compared to C150-NF. Fibres also affected resistivity: C150-NF had values above 5500 ohm m, but the C150-F and C90 values were between 700 and 1000 ohm m and were one-fold higher than the ordinary concretes. After 3 years, the corrosion damage in the embedded rebars exposed to a marine environment was negligible in C90, C150-NF and C150-F (9.5, 6.2 and 3.5 mg mass loss), but with higher values (between 170.4 and 328.9 mg) for C3, C40 and C50. The results allow a framework to be established to make comparisons in future studies.This research was funded by the Spanish Government, grant number PID2020-119744RB-C21 funded by MCIN/AEI/10.13039/501100011033Lliso-Ferrando, JR.; Gandía-Romero, JM.; Soto Camino, J.; Valcuende Payá, MO. (2023). OC, HPC, UHPC and UHPFRC Corrosion Performance in the Marine Environment. Buildings. 13(10):1-27. https://doi.org/10.3390/buildings13102439127131

MICROSTRUCTURE AND MECHANICAL PROPERTIES EVALUATIONS OF HEAT TREATED DISSIMILAR METAL JOINT WELDMENT BETWEEN API 5CT C90 AND ASTM A182 F22

In this research, dissimilar metal welding of API 5CT C90 and ASTM A182 F22 is used to connect between the upset riser pipe and the riser connector of a marine riser. API 5CT C90 material is the material have high carbon content that lead to its high hardness and low weldability. Proper welding parameters need to be qualified so that the welding process will give desired mechanical properties, less costly and consume less time. Therefore, post-weld heat treatment (PWHT) is needed to reduce the hardness and increase the impact energy of the weldment as the intermixture zone at fusion line between the base metal and weld metal has potential of having high hardness due to residual stress in the intermixed microstructure after high temperature welding

Reka bentuk pembelajaran atas talian bagi program kejuruteraan mekanikal Kolej Vokasional

Reka bentuk pembelajaran atas talian merupakan suatu proses yang menyokong kepada konsep pembelajaran bestari di sekolah. Kajian ini bertujuan untuk mengenalpasti reka bentuk pembelajaran atas talian bagi program Kejuruteraan Mekanikal Kolej Vokasional. Terdapat dua aspek yang ditekankan dalam kajian ini iaitu domain pembelajaran yang terdiri daripada kognatif, afektif dan psikomotor dengan elemen reka bentuk seperti teks, video, audio, grafik, animasi, antaramuka dan warna. Reka bentuk kajian yang dijalankan adalah secara tinjauan dengan menggunakan kaedah kuantitatif melalui instrumen soal selidik yang diadaptasi daripada kajian lepas bagi mendapatkan maklumat. Seramai 169 orang pensyarah dari Jabatan Kejuruteraan Mekanikal di Kolej Vokasional Negeri Johor yang terlibat dalam kajian ini. Kajian ini mengandungi dua fasa iaitu fasa pertama merupakan proses pencarian maklumat berkaitan kajian manakala fasa kedua merupakan proses bagi menganalisis dapatan kajian. Hasil dapatan kajian menunjukkan terdapat hubungan positif yang kuat dan signifikan di antara domain pembelajaran dengan elemen reka bentuk. Kesimpulanya, kajian ini diharapkan berguna bagi membantu pensyarah dalam membangunkan platform pengajaran dan pembelajaran atas talian yang interaktif untuk pelajar Kolej Vokasional

Producing Lightweight Foam Concrete Building Units Using Local Resources

Brick is one of the most building units used in construction. Locally, this product suffer from many defects; technical, production, specification, and environment impact. Beside the inefficient quality control on the properties of produced building units that lead to negative effects on the overall construction processes. This research aims to produce sustainable alternative bricks using lightweight foam concrete made of local materials to substitute the traditional fired clay bricks. Lightweight foam concrete considered as new construction buildings materials used in construction sector in Iraq, it can produce from available local materials; Portland cement, fine sand, and foaming agent. Detailed information and data was derived from intensive experimental study and laboratory tests for the alternative brick units. Briefly; with density of (1200 to 2000 kg/m3) and brick size of (230*110*70 mm), lightweight foam concrete (LWFC) bricks were produced with properties can efficiently compete the fired clay bricks. The compressive strength was (4-45 MPa), water absorption (1-26%), thermal conductivity (0.10130-0.25375 w/k.m), and shrinkage (0.011-0.056%), with no efflorescence and very little tolerances in all dimension. these results show that there is a possibility for the use of LWFC units as construction units that can compete the fired clay bricks. Keywords: Clay Brick, Lightweight foam concrete, Building units, Mechanical properties

Durability and waterproofing investigations of the building envelope

textDurability of the building envelope is an important characteristic to monitor and test on a structure to ensure it does not fail prematurely from water penetration. Due to the building envelop failures existing today, the described testing herein aims to evaluate different building components in an effort to express deficiencies in testing or products so as to better influence the building envelope product market and lessen the possibility of future failures. This thesis describes the background and protocol for testing water resistive barrier full-scale mockups for long-term durability. An auxiliary study of the product nail sealability testing was also conducted, providing supporting visibility into inconsistencies between manufacturer and test results. Elastomeric sealants were also tested according to a new standard, ASTM C1589, which evaluates products for the long term based on both movement and weathering--a much needed standardized testing scenario. Initial results show the need for primed, silicone, and SWR Institute validated products. The water penetration characteristics of concrete masonry units were also analyzed using both ASTM C90 and RILEM tube testing. The results emphasized the need for redundancy in water repellents for porous units and the significant leniency of ASTM C90. Lastly, masonry veneer anchor guidelines were discussed, and it was found that the prescriptive nature of the MSJC code does not provide adequate guidance on installation of anchors for unique architectural or structural details. Suggestions for placement in these instances are given. Much of the testing described in this thesis represents best practice suggestions and initial product evaluation. Since this testing has been developed as long-term experiments, the next few years will provide the needed information on failure mechanisms and methods to prevent these failures.Civil, Architectural, and Environmental Engineerin

Compressive Strength and Water Absorption of Sand Cement Brick that Incorporated with Construction Tiles Waste

Ceramic Tiles Waste (CTW) is one of the major sources of construction and demolition (C&D). Recycling the C&D waste is one of the most effective ways to develop sustainable building elements. In this study, the CTW were used as a partial sand replacement in sand cement brick. The percentages replacement of CTW are 0%, 10%, 20%, 30%, 40% and 50% by mass of the sand with mix design ratio of 1:3 and 0.6 water cement ratio. All the bricks were curing up to 90 days. The density, compressive strength and water absorption of sand cement bricks were also determined for its mechanical and durability performance. The experimental results reveal that the optimum replacement of CTW in sand cement brick is in range of 10% to 40% that give a good performance in compressive strength. The compressive strength of sand cement bricks increases in range of 10.17% up to 30.82% for each stage of curing days from 7 days up to 90 days. Meanwhile, the percentage of water absorption of sand cement bricks at 28 days up to 90 days of curing are below 12% as per stated in ASTM C90.

Final Project Report for Bricks from Recyclables

The Bricks from Recyclables team is dedicated to designing and constructing an eco-friendly concrete brick that incorporates plastic to tackle the issue of plastic waste in the environment. The sponsor, Samadhi Yoga Retreat, plans to use this innovative product as a building material on-site to recycle and repurpose plastic, thereby eliminating the impracticality of transporting plastic waste to a recycling center in the remote location. The team conducted tests on four essential subsystems: shredder, mixer, mold, and brick. The shredder tests involved evaluating the shredder\u27s capability and speed. The capability test demonstrated that the shredder could process both PET and HDPE plastic effectively into appropriate sizes, with HDPE producing slightly more of the targeted size. The speed test demonstrated that the shredder could process five bottles of both plastic types in under five minutes. These tests showed that the shredder adhered to the shredder functionality working criteria. The mixer test evaluated whether the mixture could produce a visually uniform blend in less than five minutes. All mixtures created in the mixer successfully met the criteria. However, the team recommends using a larger mixer for producing full-size bricks. The mold functionality test evaluated the effectiveness of the molds utilized to fabricate the coupons. The 3-D printed molds demonstrated excellent performance, with easy ejection of coupons and convenient cleaning and reusability. However, the melamine coupon mold proved less efficient due to being hand-manufactured and requiring the application of messy silicone for sealing. To accommodate the size limitations of the 3-D printers available to the team, the full-size mold comprises a combination of melamine and 3-D printed components. This test showed that the 3D printed mold adhered to the mold functionality working criteria. The brick tests included a compression test to determine the optimum plastic-concrete formulation and a weather resistance test to assess the brick\u27s water resistance. The compression test showed that pure Quikrete achieved a compressive strength of over 1900 psi for water ratios ranging from 7-7.5%. The team selected 7.5% water as it retained plastic particles more effectively. PET outperformed HDPE in compression tests. However, none of the coupons with plastic ratios ranging from 1 to 15 percent plastic on a mass basis, or 1.54 to 23.11 percent on a volume basis, met the 1900 psi requirement mandated by ASTM C90 [1]. The team recommends longer curing times as a way to increase compressive strength. The final phase of compression testing was anisotropic tests, which tested the bricks\u27 performance in a more consistent orientation with how full-size bricks will be loaded. The results indicated that an increase in plastic particle size resulted in an increase in compressive strength. The rough surfaces of the coupons, caused by molds designed for testing in the other orientation, led to some of the lower fatigue stresses. This test demonstrated that modifying the mold\u27s orientation could increase the compressive strength and potentially lead to a formulation that meets the 1900 psi requirement. The team recommends further research and testing on the anisotropic orientation. The weather resistance test evaluated the water absorption capacity and the formation of salt deposits as the bricks/coupons dried. All specimens underwent both tests and successfully passed. To meet the requirements of the absorption test, the bricks/coupons needed to absorb less than 20% of their original weight. The full-size ASTM C90 bricks performed better, with a range of 6-7%, compared to the coupons, which had a range of 8.8-14.9%

Optimizing Alkali-Concentration on Fresh and Durability Properties of Defected Sanitary Ware Porcelain based Geopolymer Concrete

Introducing defective sanitaryware porcelain as a low-calcium binder for geopolymer mix concrete was regarded as green concrete. Four alkali concentrations (8M, 10M, 12M, and 14M) mixes involving four initial curing temperatures (60°C, 75°C, 90°C, and 105°C) were investigated for porosity, rapid chloride penetration, compressive and abrasive resistance. Tests on geopolymer paste for consistency and initial and final setting times were also assessed. For all the mixes, consistency and setting time decreased with increased alkali concentration levels. An increment in curing temperature increased the setting time rate. Microstructural studies such as X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were carried out, and the results were presented. The compressive and abrasive resistance of the specimen performance increased with an increase in the initial curing temperature and alkali concentration level. Majorly, the mechanical strength of porcelain-based geopolymer specimens increased by increasing the alkali concentration level. Applying 105°C for the initial curing temperature to the specimen, compressive strength, abrasive resistance, and resistibility to chloride ingress of the specimen enhanced. At the 28-days curing period, the ultimate compressive strength was 68.03 N/mm2, the lowest weight loss from abrasive motion was 0.09%, and the lowest passing charge was 1,440.91 coulombs were recorded respectively. As a result, porcelain-based geopolymers required a high initial curing temperature and a high alkali concentration level. It was found that 14M porcelain-based specimens heated at 105°C curing temperature for 24 hours led to an eco-friendly concrete mix with prominent positive results for engineering properties. Doi: 10.28991/CEJ-2024-010-04-05 Full Text: PD

Analysis of the Mechanical Properties of Concrete Blocks Reinforced With Glass Particles and Recycled Paper: A Sustainable Approach

The materials to produce concrete blocks (sand, gravel, and cement) are limited resources that are becoming scarce over time due to their increasing demand in construction. On the other hand, the waste of glass and paper is progressively increasing without being fully utilized through recycling. Therefore, the objective of this scientific research is to evaluate the influence on the mechanical properties of masonry concrete blocks made with recycled glass and paper particles. Likewise, the sample was non-probabilistically selected for convenience, consisting of 192 concrete blocks manufactured with additions of 3% (2% glass particles and 1% recycled paper), 6% (4% glass particles and 2% recycled paper), and 9% (6% glass particles and 3% recycled paper), as well as concrete blocks manufactured without additions. According to the results obtained, at 3%, 6%, and 9% addition of glass and paper particles, the absorption decreased by 4.94%, 3.398%, and 3.52% respectively. However, the warping increased between 1.7mm and 1.8mm, while the compressive strength (f\u27c) increased to 75kg/cm2, 82kg/cm2, and 77kg/cm2, respectively. Similarly, the axial compressive strength (f\u27m) increased to 91.22kg/cm2, 94.45kg/cm2, and 92.80kg/cm2, and the diagonal compressive strength (V\u27m) increased by 8.90kg/cm2, 9.70kg/cm2, and 9.70kg/cm2. Nevertheless, the manufacturing cost of masonry units showed a progressive reduction with the amount of glass + paper addition, amounting to 0.57 USD, 0.55 USD, and 0.53 USD. It was also determined that the optimal addition of these materials in the concrete mix in terms of cost and strength is 9% (glass + paper), resulting in compressive strengths of 77kg/cm2, 92.8kg/cm2, and 9.70kg/cm2, with a cost of 0.53 USD per unit. In conclusion, it can be affirmed that adding glass and recycled paper particles in the production of concrete blocks for use in load-bearing masonry walls positively influences the physical and mechanical properties of the blocks. Additionally, it allows for a reduction in manufacturing costs, leading to significant savings for builders