scholarly journals The Effects of Nanosilica on Mechanical Properties and Fracture Toughness of Geopolymer Cement

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2178
Author(s):  
Cut Rahmawati ◽  
Sri Aprilia ◽  
Taufiq Saidi ◽  
Teuku Budi Aulia ◽  
Agung Efriyo Hadi
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Agricultural Waste ◽  
X Ray ◽  
Geopolymer Cement ◽  
Direct Tensile ◽  
Direct Tensile Strength ◽  
Geopolymer Paste

Nanosilica produced from physically-processed white rice husk ash agricultural waste can be incorporated into geopolymer cement-based materials to improve the mechanical and micro performance. This study aimed to investigate the effect of natural nanosilica on the mechanical properties and microstructure of geopolymer cement. It examined the mechanical behavior of geopolymer paste reinforced with 2, 3, and 4 wt% nanosilica. The tests of compressive strength, direct tensile strength, three bending tests, Scanning Electron Microscope-Energy Dispersive X-ray (SEM/EDX), X-ray Diffraction (XRD), and Fourier-transform Infrared Spectroscopy (FTIR) were undertaken to evaluate the effect of nanosilica addition to the geopolymer paste. The addition of 2 wt% nanosilica in the geopolymer paste increased the compressive strength by 22%, flexural strength by 82%, and fracture toughness by 82% but decreased the direct tensile strength by 31%. The microstructure analysis using SEM, XRD, and FTIR showed the formation of calcium alumina-silicate hydrate (C–A–S–H) gel. The SEM images also revealed a compact and cohesive geopolymer matrix, indicating that the mechanical properties of geopolymers with 2 wt% nanosilica were improved. Thus, it is feasible for nanosilica to be used as a binder.

scholarly journals Performance of Ultra High Strength Concrete Expose to High Rise Temperature

2021 ◽  
Vol 45 (4) ◽  
pp. 351-359
Author(s):  
Noor Alhuda Sami Aljabbri ◽  
Mohammed Noori Hussein ◽  
Ali Abdulmohsin Khamees
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fire Resistance ◽  
High Strength Concrete ◽  
High Strength ◽  
Splitting Tensile Strength ◽  
Explosive Spalling ◽  
Strength Concrete ◽  
Direct Tensile ◽  
Direct Tensile Strength

Fire or high temperature is a serious issue to ultra-high-strength concrete (UHSC). Strength reduction of UHPCs may amount to as high as 80 percent after exposure to 800℃. A sum of four UHSC mixes was synthesized and evaluated in this study after getting exposed to extreme temperatures that reach 1000°C. Steel and polypropylene (PP) fibers were used in this experiment. A total of four mixes were made of UHSC without fibres as a control mix (UHSC-0), UHSC with 2% steel fibres (UHSC-S), UHSC with 2% PP fibres (UHSC-P) and UHSC with 1% steel fibres + 1% PP fibres (UHSC-SP). Workability, direct tensile strength, compressive strength, and splitting tensile strength were examined. Particularly, emphasis was devoted to explosive spalling since UHPCs are typically of compact structure and hence more prone to explosive spalling than other concretes. It was determined that the mixture UHSC-SP had high fire resistance. Following exposure to 1000℃, this mixture preserved a residual compressive strength of 36 MPa, splitting tensile strength of 1.62 MPa and direct tensile strength of 0.8 MPa. On the other hand, UHSC-P also had good fire resistance while UHSC-0 and UHSC-S experienced explosive spalling after heating above 200ᴼC. The incorporation of steel fibers in UHSC-S and UHSC-SP mixtures reveals higher tensile and compressive strength findings at different elevated temperatures as compared to UHSC-0 and UHSC-P. In addition, the result of direct tensile strength appears to be lower than splitting tensile strength at different raised temperatures.

A Direct Method to Evaluate the Tensile Strength of Polyolefin Fiber Cement-Based Composites

2012 ◽  
Vol 586 ◽  
pp. 99-102
Author(s):  
Ta Yuan Han ◽  
Wei Ting Lin ◽  
An Cheng ◽  
Chin Cheng Huang
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Silica Fume ◽  
Fiber Length ◽  
Direct Method ◽  
Impact Resistance ◽  
Strength Properties ◽  
Fiber Content ◽  
Direct Tensile ◽  
Direct Tensile Strength

This study is aimed to evaluate the tensile strength of cement-based composites which comprise polyolefin fibers and silica fume in the mixes. Material variables include water-cementitious ratio, dosage of silica fume, steel fiber length and dosage. Test results indicate that the compressive strength and direct tensile strength of specimens for fiber length of 25 mm are higher than that of 50 mm. The strength properties increase with increasing fiber content. Incorporation of fiber and silica fume in composites achieves significantly higher increase in compressive strength and direct tensile strength than only use of fiber or silica fume. In addition, the compressive strength, splitting tensile strength, direct tensile strength and impact resistance are fairly correlated. It contributes that the fiber content influences crack arresting ability and the silica fume influences interfacial bonding effectively.

Effect of Stepped Aging Treatment on Microstructure and Properties of AA7085 Aluminum Alloy

2011 ◽  
Vol 228-229 ◽  
pp. 968-974 ◽  
Author(s):  
Chun Mei Li ◽  
Zhi Qian Chen ◽  
Su Min Zeng ◽  
Nan Pu Cheng ◽  
Quan Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Electrical Conductivity ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Aging Treatment ◽  
Tensile Fracture ◽  
X Ray ◽  
Thermodynamic Factors

The effect of stepped aging treatment including two-stepped retrogression aging and retrogression reaging treatment on the mechanical properties, electrical conductivity and the microstructure of AA7085 has been investigated. Electron microscopy observations were used to analyze the microstructures and tensile fracture surfaces of AA7085 processed via various treatment schedules. Besides, X-ray diffractometer and differential scanning calorimeter were used to explore the thermodynamic factors of heat treatment. Through the investigation of the effect of the retrogression time on the properties and microstructure of AA7085, the optimized retrogression time was confirmed. The results of comparing retrogression aging and retrogression reaging treatment showed that through RRA treatment, higher conductivity and fracture toughness were gained. Through the optimized RRA treatment based on appropriate retrogression time, the tensile strength, elongation, fracture toughness and conductivity of AA7085 were raised to 660MPa, 12%,36.6MPa•m1/2and 38.1%IACS.

Experimental Research on Tensile Strength of Premixed Concrete at Early Ages

2014 ◽  
Vol 556-562 ◽  
pp. 687-691 ◽  
Author(s):  
Xiao Fen Li ◽  
Ping Ren
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Exact Results ◽  
Direct Tension ◽  
Splitting Strength ◽  
Experimental Apparatus ◽  
Structural Applications ◽  
Direct Tensile ◽  
Direct Tensile Strength ◽  
The Relationship

The splitting tensile method for the tensile strength of concrete is usually used in structural applications, so it is great important in the investigating the relation between the direct tensile strength and the splitting strength. But the relationship between the splitting strength and the direct tensile strength is not consolidatly confirmed at home and abroad. In order to obtain the exact results, the experimental apparatus for concrete of the direct tension are designed, which resolves the difficulty of ensuring that the load is truly axial. Tests of the direct tension are performanced on three different concrete mixes (C20,C40,C60) at 3, 7, 14 , 28 and 60 days and the test data do not scatter. The relations between the tensile strength and the cube compressive strength are obtained and a formula for investigating the relation between the direct tensile strength and the splitting strength are proposed.

scholarly journals Effect of Fibers on High-Temperature Mechanical Behavior and Microstructure of Reactive Powder Concrete

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 329 ◽  
Author(s):  
Muhammad Abid ◽  
Xiaomeng Hou ◽  
Wenzhong Zheng ◽  
Raja Hussain
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
High Temperature ◽  
Reactive Powder Concrete ◽  
Peak Strain ◽  
Fiber Reinforced ◽  
Split Tensile Strength ◽  
X Ray ◽  
Reactive Powder

This study was aimed to investigate the effect of steel, polypropylene (PP), and hybrid (steel + PP) fibers on high-temperature mechanical properties of reactive powder concrete (RPC). The mechanical properties considered are cubic compressive strength, axial or prismatic compressive strength, split-tensile strength, flexural strength, elastic modulus, peak strain, and stress-strain behavior. The strength recession due to high temperature was investigated at micro level by scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, mercury intrusion porosity, thermogravimetric, and differential scanning calorimetry analyses. The high-temperature tests were carried out at target temperatures of 120, 300, 500, 700, and 900 °C. The hot-state compressive strength of RPC started to decrease at 120 °C; however, a partial recovery at 300 °C and a gradual decrease above 300 °C were observed. The degradation of split-tensile strength, flexural strength, and elastic modulus were gradual with increasing temperature despite the effect of different fibers. Whereas, the peak strain was gradually increasing up to 700 °C. However, after 700 °C, it remained unchanged. Steel fiber reinforced RPC (SRPC) and hybrid fiber reinforced RPC (HRPC) showed a ductile behavior. PP fiber reinforced RPC (PRPC) showed a quite brittle behavior up to 300 °C; however, further heating made the microstructure porous and it became ductile too. Overall the performance of SRPC and HRPC were superior to PRPC because of higher modulus of elasticity, higher strength, and better fire resistance of steel fibers. Fiber reinforced RPC was found to have better fire resistance than traditional types of concrete based on comparative studies with the provisions of design codes and earlier research. The constitutive equations developed can be utilized in computer programs for structural design of RPC structures exposed to fire.

scholarly journals Evaluation of the Mechanical Properties of a 3D-Printed Mortar

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4104 ◽  
Author(s):  
Hojae Lee ◽  
Jang-Ho Jay Kim ◽  
Jae-Heum Moon ◽  
Won-Woo Kim ◽  
Eun-A Seo
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Nozzle Height ◽  
Number Of Layers ◽  
3D Printed ◽  
Bond Strengths ◽  
Physical Impact ◽  
Direct Tensile ◽  
Direct Tensile Strength ◽  
Tensile Bond Strengths

The mechanical properties of 3D-printed mortars are determined in terms of their compressive and direct tensile bond strengths. To determine such properties using existing methods, a preliminary experiment was conducted. The compressive strength of the printed mortar was compared to mold-casted specimens and it was found that the compressive strength decreased by ~30%. Among the fabrication variables, an increase in nozzle height negatively influenced the direct tensile bond strength. For the same conditions and age, the direct tensile strength decreased by as much as 16–29% when the number of layers increased from 2 to 6. When the specimens were fabricated using a specially designed stainless steel frame and core drill, followed by extraction and the application of physical impact, the 28 days compressive strength of the specimen decreased by ~50%.

Effect of Fiber Length on Direct Tensile and Impact Strength of Cmentitious Materials Containing Silica Fume

2015 ◽  
Vol 764-765 ◽  
pp. 37-41
Author(s):  
Wei Ting Lin
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Silica Fume ◽  
Fiber Length ◽  
Steel Fiber ◽  
Impact Resistance ◽  
Cementitious Materials ◽  
Individual Use ◽  
Direct Tensile ◽  
Direct Tensile Strength

This study is aimed to evaluate the tensile strength and impact resistance of cementitious materials which comprise steel fibers and silica fume in the mixes. Material variables include water-binder ratio, dosage of silica fume, steel fiber length and dosage. A designed tensile strength was used to perform the direct tensile in this study. Test results indicate that the compressive strength, splitting tensile strength and direct tensile strength of specimens for fiber length of 60 mm are higher than that of 35 mm. The inclusion of fibers in specimens containing silica fume has higher compressive and tensile strength; and lower impact resistance than the specimens made with silica fume. Incorporation of steel fiber and silica fume in composites achieves significantly higher increase in compressive strength, splitting tensile strength, and direct tensile strength than only individual use of steel fiber or silica fume and decrease in impact resistance than only individual use of steel fiber. Finally, the proposed direct tensile testing method is suitable for determining the tensile strength of fiber reinforce cementitious materials and generating the tensile stress-strain curves easily.

Engineering Properties of Fiber Cementitious Materials

2015 ◽  
Vol 764-765 ◽  
pp. 42-46
Author(s):  
Wei Ting Lin ◽  
Yuan Chieh Wu ◽  
An Cheng ◽  
Sao Jeng Chao
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Silica Fume ◽  
Steel Fiber ◽  
Cementitious Materials ◽  
Splitting Tensile Strength ◽  
Engineering Properties ◽  
Fiber Volume ◽  
Direct Tensile ◽  
Direct Tensile Strength

Fiber cementitious materials are composed of fibers, pozzolan and cementitious. Addition of fibers in cementitious materials may enhance its mechanical properties, particularly tensile strength, and ductility. This project is aimed to evaluate the mechanical properties of fiber cementitious materials which comprise fibers and silica fume in the mixes. Test variables include dosage of silica fume, mix proportions, steel fiber dosage and type. Compressive strength, direct tensile strength and splitting tensile strength of the specimen were obtained through tests. Test results indicate that the splitting tensile strength, direct tensile strength, strain capacity and ability of crack-arresting increase with increasing steel fiber and silica fume dosages. The optimum composite is the mixture with 5 % replacement silica fume and 2 % fiber volume. In addition, the nonlinear regression analysis was used to determine the best-fit relationship between mechanical properties and test parameters.

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