scholarly journals Compressive Strength of Uncured Concrete Cylinders Fully Wrapped with Post-Tensioned Metal Straps (PTMS).

2021 ◽  
Author(s):  
Wrya A. Abdullah ◽  
◽  
Serwan Khwrshid Rafiq ◽  
Keyword(s):  
Compressive Strength ◽  
New Method ◽  
Number Of Layers ◽  
Three Samples ◽  
Concrete Cylinders ◽  
Control Samples ◽  
Post Tensioned

During a national lock down and a curfew, most of the concrete projects are left without curing and therefore, the elements of the building need strengthening. An effective way in strengthening is using Post-Tensioned Metal Straps (PTMS) which is a relatively new method. Therefore, in this study, the effectiveness of using PTMS is tested in strengthening cylinder samples without curing. For this purpose, 15 cylinders are cast and 12 of them are left without curing for 28 days. Three samples are tested without any strengthening and are used as control samples. The rest are strengthened using 1, 2, 3, and full layers of PTMS. To compare the strength of the cylinders, 3 cylinders of the same batch are prepared and cured for 28 days. It is proved that the compressive strength of the cylinders can increase by 39%, 57%, 84% and 125% if the samples are strengthened using 1, 2, 3, and full layers of PTMS. It is also found that the failure becomes ductile as the number of layers is increased.

POTENTIAL USE COCONUT MILK AS ALTERNATIVE TO ALKALI SOLUTION FOR GEOPOLYMER PRODUCTION

2016 ◽  
Vol 78 (11) ◽  
Author(s):  
Gahasan Fahim Huseien ◽  
Jahangir Mirza ◽  
Mohd Warid Hussin ◽  
Mohd Azreen Mohd Ariffin
Keyword(s):  
Compressive Strength ◽  
Alkali Solution ◽  
Coconut Milk ◽  
Fine Aggregate ◽  
Strength Tests ◽  
Last Stage ◽  
The Cost ◽  
The Impact ◽  
Potential Use ◽  
Control Samples

This work aims to verify the feasibility of utilizing coconut milk as the alkali activator solution in geopolymer production and the impact on mortar properties; geopolymer mortar is  still more expensive than ordinary Portland cement mortar simply because the cost of alkali solution. Coconut milk is extensively available in Malaysia and very rich in potassium and sodium. In this research, the coconut milk was used as alkali solution (100%) at first, and then replaced by NaOH, Na2SiO3 and in the last stage mixed with NaOH and Na2SiO3 at 50%. Normal solution component of Na2SiO3 and NaOH with 8 M, and used as control samples. Binder to fine aggregate (B:A) and solution to binder (S:B) ratios were fixed at 1.5 and 0.30 respectively. Multi blend binder based geopolymer mortar are used in this study. The samples were cured with different conditions, cured at room temperature and oven temperature of 60 and 90°C. Compressive strength tests were carried out to determine the properties of hardened mortar. The samples prepared with coconut milk showed low compressive strength as compared to control samples, The results demonstrated that using coconut milk as alternative to alkali solution in geopolymer industry is not a viable option.

scholarly journals AN EFFECTIVE WAY TO RECYCLE 3D PRINTING CONCRETE SCRAP

2021 ◽  
Vol 4 (2) ◽  
pp. 12-18
Author(s):  
D.A. Tolypin ◽  
N. Tolypina
Keyword(s):  
Compressive Strength ◽  
3D Printing ◽  
Portland Cement ◽  
Quartz Sand ◽  
Raw Materials ◽  
Electricity Consumption ◽  
Cement Matrix ◽  
Fine Aggregate ◽  
Fine Grained ◽  
Control Samples

the article proposes a rational method for processing 3D printing concrete scrap using vibration equipment, which allows obtaining a multicomponent building material with minimal electricity consumption. As a crite-rion for the degree of grinding of concrete scrap, it is proposed to use the specific surface area of the finely dispersed part of concrete scrap, which should correspond to 400-500 m2/kg. The possibility of reusing the resulting product instead of the traditional fine aggregate of quartz sand is shown. It was found that the con-crete scrap without the addition of Portland cement hardens, reaching up to 48% of the compressive strength of the control samples by 28 days. When 10% of the binder CEM I 42.5 N was added to the concrete scrap processing product, the compressive strength of fine-grained concrete increased by 106.6%, and 20% of Portland cement - by 112.2 %, compared to the strength of control samples of a similar composition on tra-ditional quartz sand after 28 days of hardening. It is noted that this is primarily due to the weak contact zone of quartz sand and the cement matrix of concrete. The use of the product of processing concrete scrap al-lows obtaining building composites based on it with the complete exclusion of natural raw materials

Compressive Strength of Composite/Concrete Cylinders after Low Energy Impact

2001 ◽  
Vol 20 (10) ◽  
pp. 849-870
Author(s):  
Hsien-Kuang Liu ◽  
Zhi- Chen ◽  
Nyan-Hwa Tai ◽  
Zhi- Chen
Keyword(s):  
Compressive Strength ◽  
Low Energy ◽  
Energy Impact ◽  
Concrete Cylinders

Strength and Ductility of High-Strength Concrete Cylinders Externally Confined with Steel Strapping Tensioning Technique (SSTT)

2014 ◽  
Vol 68 (1) ◽  
Author(s):  
Hoong-Pin Lee ◽  
Abdullah Zawawi Awang ◽  
Wahid Omar
Keyword(s):  
Compressive Strength ◽  
Prediction Model ◽  
High Strength Concrete ◽  
High Strength ◽  
Transverse Strain ◽  
Envelope Curve ◽  
Stress Strain ◽  
Strength Concrete ◽  
Concrete Cylinders ◽  
Strain Relationship

This research study is to introduce and investigate an effective technique of external pre-tensioning using steel strapping (SSTT) to reduce the brittleness and enhance the ductility of high-strength concrete cylinders.  Fifteen cylinders with dimension of 150 mm and 300 mm in diameter and height respectively were casted, pre-tensioned with two and four layers of steel strapping and tested to failure under uniaxial monotonic and cyclic compression. The behaviour of SSTT confined cylinders was studied through their stress-strain relationship upon the longitudinal deflection, transverse strain, mode of failure, confinement ratio, and existence of an envelope curve. It is experimentally proved that SSTT confinement do helps in controlling the brittleness problem of high-strength concrete and at the same time, enhancing both the concrete ductility and compressive strength up to 46.2 % and 112.5 % respectively. The envelope curve of uniaxial cyclic loading also coincides with the corresponding monotonic loading curve, regardless of any loading activity. The observed stress-strain relationship of confined cylinders with different confining ratios are compared with existing strength and strain models and a stress-strain prediction model, the result showed a linear relationship between the compressive strength and strain enhancement and confining ratio, with acceptable agreement between the prediction model.

scholarly journals Strength Development and Thermogravimetric Investigation of High-Volume Fly Ash Binders

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3344 ◽  
Author(s):  
Zhiyuan Zhou ◽  
Massoud Sofi ◽  
Elisa Lumantarna ◽  
Rackel San Nicolas ◽  
Gideon Hadi Kusuma ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Temperature Rise ◽  
Bound Water ◽  
High Volume ◽  
Heat Of Hydration ◽  
New Method ◽  
Hydration Properties ◽  
Adiabatic Temperature Rise ◽  
High Volume Fly Ash

To address sustainability issues by facilitating the use of high-volume fly ash (HVFA) concrete in industry, this paper investigates the early age hydration properties of HVFA binders in concrete and the correlation between hydration properties and compressive strengths of the cement pastes. A new method of calculating the chemically bound water of HVFA binders was used and validated. Fly ash (FA) types used in this study were sourced from Indonesia and Australia for comparison. The water to binder (w/b) ratio was 0.4 and FA replacement levels were 40%, 50% and 60% by weight. Isothermal calorimetry tests were conducted to study the heat of hydration which was further converted to the adiabatic temperature rise. Thermo-gravimetric analysis (TGA) was employed to explore the chemically bound water (WB) of the binders. The results showed that Australian FA pastes had higher heat of hydration, adiabatic temperature rise, WB and compressive strength compared to Indonesian FA pastes. The new method of calculating chemically bound water can be successfully applied to HVFA binders. Linear correlation could be found between the WB and compressive strength.

scholarly journals Strengthening of pre-damaged concrete cylinders using post-tensioned steel straps

2019 ◽  
Vol 172 (10) ◽  
pp. 703-711 ◽  
Author(s):  
Chau-Khun Ma ◽  
Reyes Garcia ◽  
Sofrie Chin Siew Yung ◽  
Abdullah Zawawi Awang ◽  
Wahid Omar ◽  
...  
Keyword(s):  
Concrete Cylinders ◽  
Post Tensioned
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