Compressive Strength
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2021 ◽  
Vol 2 (2) ◽  
pp. 40
Author(s):  
Fardatul Azkiyah ◽  
Drs. Djony Izak Rudyardjo, M.Si. ◽  
Jan Ady

Research on the synthesis and characterization of porous hydroxyapatite with the addition of ZnO nanoparticles has been carried out through a combination of foam immersion and injection methods. This research was conducted to optimize the previous research by increasing the variation of ZnO composition and adding the injection method to the research process. The materials used in this research include hydroxyapatite nanoparticles, ZnO nanoparticles, Aquades, PVA and polyurethane foam. Manufacturing is done by immersing polyurethane foam into a slurry. Slurry is a mixture of PVA and hydroxyapatite solutions with variations in the addition of ZnO nanoparticles (8 wt%, 10 wt%, 12 wt%, and 14 wt%). Then inject the remaining slurry into the foam. After that the sample was dried and heated at a temperature of 650ºC to remove foam and PVA, then the sample was sintered at a temperature of 1200ºC for 3 hours. Based on SEM analysis, porosity test, and compressive strength test, the best results were shown by sample IV because it had a pore diameter of 142.9 – 371.4 m with a porosity of 69.983%, a compressive strength value of 1.8653 MPa and non-toxic. The best results have not met the standard for bone filler application. In further research, improvements need to be made by using other additives such as ZrO2, so that it can improve the mechanical properties of porous hydroxyapatite to meet standard bone filler applications.


2021 ◽  
Vol 6 (7) ◽  
pp. 82-86
Author(s):  
A. J. Adese ◽  
O. D. Olajide

The frequent collapse of buildings in Nigeria has necessitated carrying out a quality check not only on the structural design of these buildings but also on the materials used in their construction. Sandcrete blocks are used as a walling unit mostly because they are cheap and fast to produce. They can also be use as either load-bearing or non-load bearing purpose. Hence, this paper gives an in-depth quality assessment of sandcrete blocks commercially produced in Okitipupa Local Government Area of Ondo State, Nigeria. Six sandcrete block producing locations were visited within the local government and both six inches (6″) blocks (450×150×225 mm) and nine inches (9″) blocks (450×225×225 mm) from each location were randomly collected, together with their soil samples. Twenty-four control samples of 6″ and 9″ sandcrete blocks were also produced in accordance with the Nigerian Industrial Standard (NIS 87: 2007). Specific gravity test, silt/clay content and sieve analysis test were performed on each soil samples from different locations to check their suitability for block production, in addition, bulk density, compressive strength and water absorption were performed on the collected sandcrete blocks. In general, the compressive strength of the block samples was between 1.09 N/mm2 to 1.19 N/mm2 for six inches and 1.37 N/mm2 to 1.64 N/mm2 for nine inches which falls below the 2.5 N/mm2 and 3.45 N/mm2 minimum recommendation given by the NIS.


2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Ding Cong ◽  
Guo Liping ◽  
Ren Jinming ◽  
Wang Yongming ◽  
Li Xinyu ◽  
...  

The fiber length has a significant impact on the fiber bridging capacity and the mechanical properties of high ductility cementitious composites (HDCCs), which is related to fiber/matrix interfacial bonding. However, this fundamental knowledge of HDCCs design has rarely been investigated systematically. To this end, this study deeply investigates the effect of the fiber length on the bridging stress and the complementary energy with various fiber/matrix interfacial bonds in theory. Then, the mechanical performances of HDCCs with various fiber lengths and compressive strengths were evaluated experimentally. In micromechanical design, longer fibers can achieve stronger bridging stress and more sufficient complementary energy regardless of the fiber/matrix interfacial bonding properties. However, it should be noted that the increase in bridging capacity was quite slow for the overlong fibers and excessive interfacial bonding. The experiments indicated that overlong fibers (18 mm and 24 mm) easily twined on the mixer blade and were hard to disperse evenly. The HDCCs with shorter fibers displayed better workability. The compressive strength was less affected by the fiber length, and most striking differences were less than 5.0%, while the flexural properties and the tensile properties first increased and then decreased when the fiber length ranged from 6 mm to 24 mm. Consequently, the fibers with lengths of 9 mm and the fibers with lengths of 12 mm were better candidates for the HDCCs with compressive strengths of 30 MPa to 80 MPa, and fibers with lengths of 9 mm caused the HDCCs to exhibit higher ductility properties in general.


2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Wujian Yan ◽  
Fuhang Niu ◽  
Xinxin Tian

To study the antifreezing durability of internal coating silicon fume concrete with different external coatings, fast freeze-thaw (FT) cycle testing was performed for three types of external coatings applied to the internal coatings of silicon fume concrete. Using ultrasonic testing and compressive strength tests, we analysed the relationships between the ultrasonic pulse velocity and the mechanical and physical properties of concrete under freeze-thaw action. The results show that the compressive strength and pulse velocity of the studied concrete changed little before the first 100 FT cycles but varied significantly after being subjected to 100 FT cycles and diminished linearly with increasing FT cycles. The dynamic elastic parameters of the concrete were inferred using pulse velocity calculations, and the dependence on FT cycles was very similar to that of ultrasonic pulse velocity. The concrete strength was strongly and positively correlated with ultrasonic pulse velocity. The linear regression model of between ultrasonic pulse velocity, kinetic coefficient, and compressive strength of concrete was also established. The damage incurred to the external coating material (XT-HPA + XT-SS and XT-HPS) was small, and the good performance of the concrete with the added inorganic coating after freeze-thaw cycles indicates good frost resistance.


Author(s):  
Pawandeep Singh ◽  
RK Mishra ◽  
Balbir Singh

This study aimed at discovering the influence of low-cost eggshell ash (ESA) and boron carbide (B4C) addition on microstructure and mechanical characteristics of ZA-27 hybrid composites. Six different composites were fabricated utilizing the stir casting technique with different weight percentages of ESA and B4C particles varied from 0-5 wt.%. Composites were tested for density, hardness, compressive strength, tensile strength, and impact strength. X-ray diffraction (XRD) and scanning electron microscope (SEM) were utilized for the characterization of composites. Microstructure examination using SEM exhibited homogeneously dispersed reinforcements in the matrix. ESA particles decreased the composite density by 3.12%, and after the addition of B4C particles, density was found to be increased but was still lower than the base ZA-27 alloy. The hardness, tensile and compressive strength of the composites increased with the addition of reinforcements. However, composite reinforced with maximum wt.% of B4C particles showed a decreasing trend. The impact strength of the composites decreased when compared with the base alloy, but the reduction was marginal. Improved hardness, tensile and compressive strength of the composites was attributed to homogeneously dispersed ESA and B4C particles in the matrix. Higher tensile strength resulted from strong interfacial bonding between reinforcements and metal matrix, and low impact strength was due to brittle failure and plastic deformation.


Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7375
Author(s):  
Xiaoshuang Shi ◽  
Cong Zhang ◽  
Yongchen Liang ◽  
Jinqian Luo ◽  
Xiaoqi Wang ◽  
...  

Geopolymer concrete (GPC) has drawn widespread attention as a universally accepted ideal green material to improve environmental conditions in recent years. The present study systematically quantifies and compares the environmental impact of fly ash GPC and ordinary Portland cement (OPC) concrete under different strength grades by conducting life cycle assessment (LCA). The alkali activator solution to fly ash ratio (S/F), sodium hydroxide concentration (CNaOH), and sodium silicate to sodium hydroxide ratio (SS/SH) were further used as three key parameters to consider their sensitivity to strength and CO2 emissions. The correlation and influence rules were analyzed by Multivariate Analysis of Variance (MANOVA) and Gray Relational Analysis (GRA). The results indicated that the CO2 emission of GPC can be reduced by 62.73%, and the correlation between CO2 emission and compressive strength is not significant for GPC. The degree of influence of the three factors on the compressive strength is CNaOH (66.5%) > SS/SH (20.7%) > S/F (9%) and on CO2 emissions is S/F (87.2%) > SS/SH (10.3%) > CNaOH (2.4%). Fly ash GPC effectively controls the environmental deterioration without compromising its compressive strength; in fact, it even in favor.


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