scholarly journals Characteristics of Preplaced Aggregate Concrete Fabricated with Alkali-Activated Slag/Fly Ash Cements

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 591
Author(s):  
Salman Siddique ◽  
Hyeju Kim ◽  
Hyemin Son ◽  
Jeong Gook Jang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Water Absorption ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cement Grout ◽  
Aggregate Concrete ◽  
Alkali Activated ◽  
Alkali Activated Cement

This study assesses the characteristics of preplaced aggregate concrete prepared with alkali-activated cement grout as an adhesive binder. Various binary blends of slag and fly ash without fine aggregate as a filler material were considered along with different solution-to-solid ratios. The properties of fresh and hardened grout along with the properties of hardened preplaced concrete were investigated, as were the compressive strength, ultrasonic pulse velocity, density, water absorption and total voids of the preplaced concrete. The results indicated that alkali-activated cement grout has better flowability characteristics and compressive strength than conventional cement grout. As a result, the mechanical performance of the preplaced aggregate concrete was significantly improved. The results pertaining to the water absorption and porosity revealed that the alkali-activated preplaced aggregate concrete is more resistant to water permeation. The filling capacity based on the ultrasonic pulse velocity value is discussed to comment on the wrapping ability of alkali-activated cement grout.

scholarly journals Effect of alkali content and slag content on the fresh and hardened properties of air-cured alkali activated mortar containing fly ash

2021 ◽  
Author(s):  
Thushara Raju ◽  
Namitha S ◽  
Muhammed Nabil K ◽  
Mohammed Rafeeque N. V ◽  
Reshma Sundhar ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Construction Material ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Alkali Content ◽  
Hardened Properties ◽  
Alkali Activated ◽  
Slag Content

Alkali Activated Material (AAM) is introduced as a pioneering construction material in the construction diligence to trim down the utilization of Ordinary Portland Cement (OPC) and to curtail the amount of carbon dioxide released during the production of OPC. Modestly refined industrial by products or natural materials rich in alumino silicates are the binding agents used in AAM. Generally, heat curing is needed for the alkali activated mortar to achieve the required hardened properties and this difficulty can be overcome by adding slag to the mix. In this experimental analysis, the alkali activated mortar mixes with different proportions of glassy granulated slag and Class F fly ash were prepared without the usage of superplasticizers, with alkali to binder (a/b) ratios of 0.7, 0.8 and 0.9. The rheological characteristics of mortar were studied using flow table apparatus and hardened properties were studied using compressive strength test and ultrasonic pulse velocity (UPV) test by testing cylindrical specimens of size 25 mm diameter and 50 mm height. The mortar specimens were air-cured, and the compressive strength and UPV test were conducted after 3 and 7 days. The test results showed that due to the presence of higher alkali content and the decrease in slag content, the workability of alkali activated mortar was improved, but the measure of strength decreased. The mix with 100% slag and a/b ratio of 0.8 had the best UPV value, indicating its quality among the various mortar mixes studied. This study portrays the significance of optimising the alkali and slag content in tailor making an alkali activated mortar system with good hardened properties.

scholarly journals A Study on Tannery Sludge as a Raw Material for Cement Mortar

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1562 ◽  
Author(s):  
Jurgita Malaiškienė ◽  
Olga Kizinievič ◽  
Viktor Kizinievič
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Cement Mortar ◽  
Ultrasonic Pulse Velocity ◽  
Xrd Analysis ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Raw Material ◽  
Tannery Sludge ◽  
Limit Values

The paper analyses the properties (chemical and mineral composition, microstructure, density, etc.) of recycled tannery sludge (TS) and the possibilities for using it in cement mortar mixture. Mortar specimens containing 3–12% of tannery sludge by weight of cement and 3–9% of tannery sludge by weight of sand were tested. Flowability, density, ultrasonic pulse velocity (UPV), flexural and compressive strength, water absorption and sorptivity of the mortar were analysed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis of tannery sludge and mortar are presented. The tests revealed that replacement of 6% of cement with tannery sludge in the mix increased flexural and compressive strength and UPV values, whereas water absorption decreased. SEM and XRD analysis revealed that specimens with tannery sludge contained lower amounts of ettringite and higher amounts of portlandite; the obtained structure was denser and contained more calcium hydrosilicates (C-S-H). Chromium leaching values in cement mortars were found not to exceed the limit values set forth in Directive 2003/33/EC.

scholarly journals Empirical Investigation on Compressive Strength of Geopolymer and Conventional Concretes by Nondestructive Method

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
B. Ravali ◽  
K. Bala Gopi Krishna ◽  
D. Ravi Kanth ◽  
K. J. Brahma Chari ◽  
S. Venkatesa Prabhu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Nondestructive Method ◽  
Geopolymer Concrete ◽  
River Sand ◽  
Rebound Hammer ◽  
Compressive Strength Of Concrete

Need of construction is increasing due to increase in population growth rate. The geopolymer concrete is eco-friendly than ordinary concrete. Current experimental investigation was conducted on ordinary and geopolymer concrete using nondestructive testing (NDT) tests like ultrasonic pulse velocity (UPV) test and rebound hammer (RH) test. Cube specimens of dimensions 150 mm × 150 mm × 150 mm are used to conduct these tests at 7, 14, and 28 days. Proportions considered for concrete are cement-fly ash-river sand (100-0-100% and 60-40-100%), cement-fly ash-robo sand (100-0-100% and 60-40-100%) whereas geopolymer concrete fly ash-metakaolin is taken in proportions of 100-0%, 60-40%, and 50-50%. Alkaline activators (sodium hydroxide and sodium silicate with molarity 12M) were used in preparing geopolymer concrete. The major objective of the current study is to obtain relation between compressive strength of concrete and UPV values.

scholarly journals The effects of adding waste plastic fibers on some properties of roller compacted concrete

2018 ◽  
Vol 162 ◽  
pp. 02008 ◽  
Author(s):  
Adil Abed ◽  
Abdulkader Al-Hadithi ◽  
Ahmed Salih Mohammed
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Water Absorption ◽  
Design Method ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Dry Density ◽  
Waste Plastic ◽  
Roller Compacted Concrete

An attempt to produce of roller compacted concrete (RCC) improved by adding waste plastic fibers (WPFs) resulting from cutting the PET beverage bottles was recorded in this study. The method which is used for production of RCC is an approved design method for ACI committee (5R-207,1980)[1]. WPF was added by volumetric percentages ranging between (0.5 to 2 %) and reference concrete mix was produced for comparison reason. Many tests were conducted on the models produced by rolling compacted concrete like compressive strength, flexural strength, modulus of elasticity, dry density, water absorption and ultrasonic pulse velocity. The analysis of the results showed that the use of plastic waste fibers (1%) had led to improvement in the properties of each of the compressive strength and flexural strength compared with reference concrete. Results also showed that the addition of these, fibers increase water absorption and reduce the speed of Ultrasonic pulse velocity.

scholarly journals Performance of Fly Ash Geopolymer Concrete Incorporating Bamboo Ash at Elevated Temperature

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3404 ◽  
Author(s):  
Ishak ◽  
Lee ◽  
Singh ◽  
Ariffin ◽  
Lim ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Control Sample ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Air Cooling ◽  
Geopolymer Concrete ◽  
Water Cooling ◽  
Control Samples

This paper presents the experimental results on the behavior of fly ash geopolymer concrete incorporating bamboo ash on the desired temperature (200 °C to 800 °C). Different amounts of bamboo ash were investigated and fly ash geopolymer concrete was considered as the control sample. The geopolymer was synthesized with sodium hydroxide and sodium silicate solutions. Ultrasonic pulse velocity, weight loss, and residual compressive strength were determined, and all samples were tested with two different cooling approaches i.e., an air-cooling (AC) and water-cooling (WC) regime. Results from these tests show that with the addition of 5% bamboo ash in fly ash, geopolymer exhibited a 5 MPa (53%) and 5.65 MPa (66%) improvement in residual strength, as well as 940 m/s (76%) and 727 m/s (53%) greater ultrasonic pulse velocity in AC and WC, respectively, at 800 °C when compared with control samples. Thus, bamboo ash can be one of the alternatives to geopolymer concrete when it faces exposure to high temperatures.

scholarly journals Performance Degradation and Microscopic Analysis of Lightweight Aggregate Concrete after Exposure to High Temperature

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1566 ◽  
Author(s):  
Weijing Yao ◽  
Jianyong Pang ◽  
Yushan Liu
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Lightweight Aggregate ◽  
Strength Loss ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Damage Degree

This study analyses the deterioration of mechanical properties in lightweight concrete after exposure to room temperature (20 °C) and high temperature, i.e., up to 1000 °C, including changes in visual appearance, loss of mass, and compressive strength. All-lightweight shale ceramsite aggregate concrete (ALWAC) and semi-lightweight shale ceramsite aggregate concrete (SLWAC) are prepared using an absolute volume method to analyse the relationships between relative ultrasonic pulse velocity, loss rate of compressive strength, damage degree, and temperature levels. Our results show that, under high temperature, the lightweight aggregate ceramsite concrete performs better compared to normal concrete. After exposure to 1000 °C, the ALWAC shows a strength loss of no more than 80%, while the normal concrete loses its bearing capacity, with a similar strength loss as the SLWAC. Furthermore, the relative ultrasonic pulse velocity and damage degree are used to evaluate the effects of high temperature on the concretes, including the voids and cracks on the surface and inside of the specimens, which induces the deterioration of mechanical properties and contributes to the thermal decomposition of the cementing system and the loss of cohesion at the aggregate interface. Based on internal structure analyses, the results from this study confirm that the lightweight aggregate concrete shows a high residual compressive strength after exposure to the high temperature.

Effect of Treated Sago Pith Waste Ash and Silica Fume to the Mechanical Properties of Fly Ash-Based Geopolymer Brick

2021 ◽  
Vol 879 ◽  
pp. 100-114
Author(s):  
Izwan B. Johari ◽  
Md Azlin Md Said ◽  
Mohd Amirul B. Mohd Snin ◽  
Nur Farah Aqilah Bt. Ayob ◽  
Nur Syafiqah Bt. Jamaluddin ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Partial Replacement ◽  
Rebound Hammer ◽  
Compressive Strength Test ◽  
Sago Pith Waste

This paper investigates the effect of partial replacement of fly ash with sago pith waste ash and silica fume in fabricating the geopolymer mortar concrete. The mixtures of geopolymer mortar concrete were prepared by replacing sago pith waste ash and silica fume at 5% of total weight of fly ash. There were six specimens of geopolymer mortar cubes and bricks fabricated in this study. The specimens are tested with compressive strength test, rebound hammer test and ultrasonic pulse velocity test. The results from the tests are compared with some existing published works as to clarify the effect of replacing the fly ash with sago waste and silica fume on the strength of concrete. Comparisons had been made and concluded that the molarity of alkaline solution, Al3O2 and CaO influenced the development of compressive strength along the curing time of fly ash based geopolymer concrete.

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