Assessment of mechanical and fire resistance for hybrid nano-clay and steel fibres concrete at different curing ages

2019 ◽  
Vol 11 (2) ◽  
pp. 189-203 ◽  
Author(s):  
Ola Bakr Shalby ◽  
Hala Mohamed Elkady ◽  
Elsayed Abdel Raouf Nasr ◽  
Mohamed Kohail
Keyword(s):  
Compressive Strength ◽  
Residual Strength ◽  
Low Cost ◽  
Partial Replacement ◽  
Fire Exposure ◽  
Content Type ◽  
Steel Fibres ◽  
Concrete Properties ◽  
Nano Clay ◽  
Concrete Mix

Purpose Nano-Clay (NC) is reported as a candidate partial replacement for cement, due to its abundance and relatively low cost - beside reported promotion of different concrete properties. On the other hand, Steel Fibres (SF) has proven to have a positive effect on post fire exposure residual strength of concrete. This paper aims to present the outcomes of a comprehensive research program assessing a hybrid mix between NC and SF in concrete mixtures (NCSF-CRETE). Design/methodology/approach Physical chemical and physical characterization of NC is performed using different tools as XRF spectrometer, and TEM micrograph. Fresh concrete properties of NSCF-CRETE as slump and air content are investigated. Enhancement in permeability using NSCF is verified by comparing its resistance to the penetration of chlorides resistance with regular concrete mix. Besides, the proposed NCSF-CRETE compressive strength is evaluated compared to mixes with NC and SF each used separately at different curing ages. Besides, NSCF and compared mixes are exposed to an indirect fire testing program – two hours exposure – for: 300, 450 and 600°C. Degradation in compressive strength was investigated after exposure to different temperatures and percentage of residual strength is reported. Findings Results indicated an improved performance of NCSF -CRETE of about 40% compared to regular concrete in compressive strength at normal conditions. This improvement extended to its behavior when subjected to indirect fire exposure NSCF also maintained 40% more strength than the residual in regular concrete mix – which suffered severe damage – after 2 h exposure to 600°C. Originality/value Using NCSF-Crete allows retrofitting the structure after exposure to such drastic conditions.

Diatomaceous earth aggregates based composite masonry blocks for bushfire resistance

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Indunil Erandi Ariyaratne ◽  
Anthony Ariyanayagam ◽  
Mahen Mahendran
Keyword(s):  
Compressive Strength ◽  
Fire Resistance ◽  
Residual Strength ◽  
Side Surface ◽  
Fire Exposure ◽  
Compression Tests ◽  
Content Type ◽  
Absolute Volume ◽  
Before And After ◽  
Volume Method

PurposeThis paper presents the details of a research study on developing composite masonry blocks using two types of mixes, conventional and lightweight mix, to enhance their fire/bushfire resistance and residual compressive strength.Design/methodology/approachComposite masonry blocks (390 × 190 × 90 mm) were fabricated using conventional cement–sand mix as the outer layer and lightweight cement–sand–diatomite mix as the inner layer. Material properties were determined, and all the mixes were proportioned by the absolute volume method. After 28 days of curing, density tests, compression tests before and after fire exposure and fire resistance tests of the developed blocks were conducted, and the results were compared with those of conventional cement–sand and cement–sand–diatomite blocks.FindingsDeveloped composite blocks satisfy density and compressive strength requirements for loadbearing lightweight solid masonry units. Fire resistance of the composite block is –/120/120, and no cracks appeared on the ambient side surface of the block after 3 h of fire exposure. Residual strength of the composite block is higher compared to cement–sand and cement–sand–diatomite blocks and satisfies the loadbearing solid masonry unit strength requirements.Practical implicationsComposite block developed in this research can be suggested as a suitable loadbearing lightweight solid masonry block for several applications in buildings in bushfire prone areas.Originality/valueLimited studies are available for composite masonry blocks in relation to their fire resistance and residual strength.

Experimental determination of the residual compressive strength of concrete columns subjected to different fire durations and load ratios

2020 ◽  
Vol 11 (4) ◽  
pp. 529-543
Author(s):  
Anjaly Nair ◽  
Osama (Sam) Salem
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Concrete Columns ◽  
Fire Exposure ◽  
Fire Performance ◽  
Content Type ◽  
Residual Compressive Strength ◽  
Standard Fire ◽  
Strength Capacity

Purpose At elevated temperatures, concrete undergoes changes in its mechanical and thermal properties, which mainly cause degradation of strength and eventually may lead to the failure of the structure. Retrofitting is a desirable option to rehabilitate fire damaged concrete structures. However, to ensure safe reuse of fire-exposed buildings and to adopt proper retrofitting methods, it is essential to evaluate the residual load-bearing capacity of such fire-damaged reinforced concrete structures. The focus of the experimental study presented in this paper aims to investigate the fire performance of concrete columns exposed to a standard fire, and then evaluate its residual compressive strengths after fire exposure of different durations. Design/methodology/approach To effectively study the fire performance of such columns, eight identical 200 × 200 × 1,500-mm high reinforced concrete columns test specimens were subjected to two different fire exposure (1- and 2-h) while being loaded with two different load ratios (20% and 40% of the column ultimate design axial compressive load). In a subsequent stage and after complete cooling down, residual compressive strength capacity tests were performed on each fire exposed column. Findings Experimental results revealed that the columns never regain its original capacity after being subjected to a standard fire and that the residual compressive strength capacity dropped to almost 50% and 30% of its ambient temperature capacity for the columns exposed to 1- and 2-h fire durations, respectively. It was also noticed that, for the tested columns, the applied load ratio has much less effect on the column’s residual compressive strength compared to that of the fire duration. Originality/value According to the unique outcomes of this experimental study and, as the fire-damaged concrete columns possessed considerable residual compressive strength, in particular those exposed to shorter fire duration, it is anticipated that with proper retrofitting techniques such as fiber-reinforced polymers (FRP) wrapping, the fire-damaged columns can be rehabilitated to regain at least portion of its lost load-bearing capacities. Accordingly, the residual compressive resistance data obtained from this study can be effectively used but not directly to adopt optimal retrofitting strategies for such fire-damaged concrete columns, as well as to be used in validating numerical models that can be usefully used to account for the thermally-induced degradation of the mechanical properties of concrete material and ultimately predict the residual compressive strengths and deformations of concrete columns subjected to different load intensity ratios for various fire durations.

scholarly journals Performance of Polymer Concrete Seeded with Steel Fibres and Stone Powder

2019 ◽  
Vol 8 (4) ◽  
pp. 9844-9847
Keyword(s):  
Compressive Strength ◽  
Bisphenol A ◽  
Mathematical Models ◽  
Experimental Work ◽  
Strength Properties ◽  
Polymer Concrete ◽  
Cement Concrete ◽  
Steel Fibres ◽  
Concrete Mix

This paper presents the fiber effect in the polymer concrete. The concrete is prepared with 10% Bethemcharla stone powder as replacement to cement and 10% of Bisphenol-A polymer to the concrete mixes. The fibers were incorporated to the concrete in the proportion of 0,1 and 2% by volume of specimen. The study mainly focused to evaluate compressive, split, shear and flexural strengths of concrete. Tests conducted on cube, cylinder and beam specimens and from the results it is found that, the fiber seeding to mixes enhances the strength properties. In addition to the mixes, plan cement concrete mix without stone powder and polymer is prepared and tested for the same strengths, this mix is considered as reference mix for comparison purpose. For present experimental work few mathematical models are established to assess strengths in association of cube compressive strength.

scholarly journals PEMANFAATAN LIMBAH CANGKANG KERANG HIJAU DENGAN VARIASI SUHU PEMBAKARAN SEBAGAI BAHAN PENGGANTI SEBAGIAN SEMEN PADA PEMBUATAN BETON

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Julia Widia Nika ◽  
Anisah Anisah ◽  
Rosmawita Saleh
Keyword(s):  
Compressive Strength ◽  
Chemical Substance ◽  
Mix Design ◽  
Partial Replacement ◽  
Concrete Compressive Strength ◽  
Mussel Shell ◽  
Concrete Mix Design ◽  
Concrete Mix ◽  
Shell Waste ◽  
And Control

This research aims to utilize green mussel shell waste as a partial replacement for cement by establishing the best temperature that should be used to obtain the chemical substance if the sehell ashes to optimize the chemical substance for replacement of cement. This research replaces 10% of total weight cement with shell ash which has been combusted with a temperature of 700 ° C, 800 ° C and 900 ° C and control concrete. The compressive strength of the concrete plan is 20 MPa. Concrete mix design is 1:2:3. The results of this study indicate with subtitutes 10% semen with green shell ash with temperature 700 ° C, 800 ° C and 900 ° C is 20,53MPa; 16,76 MPa and 19,74 MPa and for control concrete has compressive strength 20,18 MPa. The maximum concrete compressive strength was obtained on the concrete of green shell ash with a combustion temperature of 700 ° C which is 20.53 MPa. In the concrete the green shells ash with a burning temperature above 700 ° C experience a decrease in compressive strength and cannot meet the compressive strength of the plan.

scholarly journals SUITABILITY OF BURNT AND CRUSHED COW BONES AS PARTIAL REPLACEMENT FOR FINE AGGREGATE IN CONCRETE

2017 ◽  
Vol 36 (3) ◽  
pp. 686-690
Author(s):  
NM Ogarekpe ◽  
JC Agunwamba ◽  
FO Idagu ◽  
ES Bejor ◽  
OE Eteng ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Fine Aggregates ◽  
Concrete Mix ◽  
Average Compressive Strength ◽  
Curing Age

The suitability of burnt and crushed cow bones (BCCB) as partial replacement for fine aggregate in concrete was studied. The percentages of replacements of fine aggregates of 0, 10, 20, 30, 40 and 50%, respectively of BCCB were tested considering 1: 2: 4 and 1: 11/2 :3 concrete mix ratios. The cow bones were burnt for 50 minutes up to 92oC before being crushed. Ninety-six (96) concrete cubes of 1: 2: 4 mix ratio and ninety-six (96) concrete cubes of 1 : : 3 mix ratio measuring 150x150x150mm were tested for the compressive strength at 7, 14, 21 and 28 days respectively. The research revealed that the BCCB acted as a retarder in the concrete. Water-cement ratio increased with the increase in the percentage of the BCCB. The mixes of 1:2:4 and 1::3 at 28 days curing yielded average compressive strengths in N/mm2 ranging from 16.49 - 24.29 and 18.71 - 29.73, respectively. For the mix ratios of 1:2:4 and 1:: 3 at 28 days curing age,  it was observed that increase in the BCCB content beyond 40 and 50%, respectively resulted to the reduction of the average compressive strength below recommended minimum strength for use of concrete in structural works.http://dx.doi.org/10.4314/njt.v36i3.4

Effect of Elevated Temperature on the Strength and Ultrasonic Pulse Velocity of Glass Fiber and Nano-Clay Concrete

2010 ◽  
Vol 163-167 ◽  
pp. 1532-1539 ◽  
Author(s):  
Chung Ming Ho ◽  
Wei Tsung Tsai
Keyword(s):  
Compressive Strength ◽  
Glass Fiber ◽  
Residual Strength ◽  
Elevated Temperatures ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Nano Clay ◽  
Compressive Strength Of Concrete ◽  
Temperature Exposure

The objectives of this paper are to find the strength and ultrasonic pulse velocity (UPV) of concrete adding admixtures by glass fiber and nano-clay. Residual strength and residual UPV of concrete specimens subjected to elevated temperatures are investigated. Experiment results showed that adding glass fiber and nano-clay would be beneficial for the later-age compressive strength of concrete. Adding nano-clay could considerably increase the flexural and split strength and the toughness of concrete. It is revealed that adding nano-clay could significantly maintain residual compressive and split strength of specimens after high temperature exposure. Regression analysis results revealed that the residual strength and residual UPV of concrete specimens had a high relevance after elevated temperatures exposure.

Fire resistance of corroded high-strength structural concrete

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Khaled Sobhan ◽  
Dronnadula V. Reddy ◽  
Fernando Martinez
Keyword(s):  
Compressive Strength ◽  
Mass Loss ◽  
Structural Integrity ◽  
Residential Buildings ◽  
Concrete Structures ◽  
Pulse Velocity ◽  
Design Codes ◽  
Fire Exposure ◽  
Structural Concrete ◽  
Content Type

Purpose The exposure of reinforced concrete structures such as high-rise residential buildings, bridges and piers to saline environments, including exposure to de-icing salts, increases their susceptibility to corrosion of the reinforcing steel. The exposure to fire can further deteriorate the structural integrity of corroded concrete structures. This combined effect of corrosion damage and fire exposure is not generally addressed in the structural concrete design codes. The synergistic combination of the effects of corrosion and fire forms the basis of this paper. Design/methodology/approach Concrete beam specimens with different strengths were prepared, moist-cured and corroded with impressed current. Later, they were “crack-scored” for corrosion evaluation, after which half were exposed to fire in a gas kiln. The fire damage was evaluated by nondestructive testing using ultrasonic pulse velocity. Next, all specimens were tested for residual flexural strength. They were then autopsied, and the level of corrosion was determined based on mass loss of the reinforcement. Findings For corroded specimens, the flexural capacity loss because of fire exposure increases as the compressive strength increases. In general, the higher the crack score, the higher the corresponding mass loss, unless some partial/segmental debonding of the reinforcement occurred. The degree of corrosion increases with decreasing compressive strength. The residual moment capacity, based on analytically determined capacities of uncorroded and nonfire-exposed beams, was significantly lower than those of uncorroded beams exposed to fire. Originality/value The combined effects of corrosion and fire on the mechanical properties of structural concrete are relatively unknown, and no guidance is available in the existing design codes to address this issue. Accordingly, the findings of the paper are expected to be valuable to both researchers and design engineers and can be regarded as the initial investigation on this topic.

scholarly journals An Integrated Evaluation of Manufactured Sand and Metakaolin Impacts on Concrete Properties

2019 ◽  
Vol 8 (12) ◽  
pp. 188-192
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Normal Concrete ◽  
Split Tensile Strength ◽  
Natural Sand ◽  
Manufactured Sand ◽  
Concrete Properties ◽  
Concrete Mix

This paper deals with M25 Concrete mix in which replacing Natural Sand by the Manufacturing Sand of 35% and 65% at Cement by Metakaolin of 0, 5, 10, 15 and 20 percentages is compared with concrete had cement with Metakaolin at different percentages without replacement of natural sand .Workability is determined for Concrete and Cylindrical specimens of 150mm*300mm of size are casted to test Concrete properties such as Split Tensile strength(STS) and Compressive Strength(CS) of Concrete. These specimens are placed under curing of 7days, 28days and 60days; after that time placed under testing and compared the results with Normal Concrete.

Effect of different additives on high temperatures of concrete

2018 ◽  
Vol 9 (2) ◽  
pp. 161-170
Author(s):  
Hassan A.M. Mhamoud ◽  
Jia Yanmin
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Design Methodology ◽  
Partial Replacement ◽  
Content Type ◽  
Residual Compressive Strength ◽  
Individual Effects ◽  
Binder Ratio ◽  
Furnace Slag ◽  
Better Than

Purpose This study aims to investigate the effectiveness of different additives (individual effects) in improving the strength of concrete to resist temperatures of up to 60ºC. Design/methodology/approach In all, 13 different mixtures with a constant water/binder ratio of 0.36 and grade M40 were prepared by using ordinary Portland concrete alone, or with partial replacement by fly ash (FA), blast-furnace slag, silica fume (SF) and a combination of all three. After 7 and 28 days under water, their strength and residual strength were measured. Findings The results of testing revealed that the addition of 10 per cent SF was found to result in the greatest increase in compressive strength and flexural strength along with decreased the residual strengths. The addition of FA increased the compressive strength and enhanced the residual compressive strength. However, it also decreased the residual flexural strength. Originality/value The addition of slag achieved better flexural strength and the best residual compressive strength. The combination of additives also enhanced the compressive strength but was not found to be better than using SF alone.

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