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.

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.

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 The Fire Resistance Performance of Concrete Columns with Different Compressive Strength

2021 ◽  
Author(s):  
Rafid Saeed Atea
Keyword(s):  
Compressive Strength ◽  
Cross Section ◽  
Fire Resistance ◽  
Concrete Columns ◽  
Fire Exposure ◽  
Temperature Changes ◽  
Axial Strength ◽  
Axial Forces ◽  
Resistance Performance ◽  
Concrete Elements

Abstract Four full concrete columns have been created Tested below high temperature for The fire resistance of concrete elements in concrete with particular compressive strengths. The standard concrete with compressive strength values of C25 were made of one of the four specimens, while the rest were made of C35, C60 and C75 respectively, respectively. During simulation of Within the laboratory furnace, the same For the specimens, axial forces were applied. Many experimental outcomes parameters were evaluated in contrast, including temperature changes, Vertical moving, side deflection, fire resistance and Failed properties of the specimen. The results have shown a rise in the compressive strength of the concrete for the concrete columns from the outside up to the inside of the column. Of columns of the the same cross section of the lower compressive forces of concrete display better fire resistance efficiency with the same initial axial strength ratio. The C35, C60 and C75 columns' fire resistance is higher than standard concrete columns. The initial and secant rigidity of the columns of Reinforced concrete ( RC) has also The percentage decreased dramatically after fire exposure and the temperature increased from 25 to 750 ° C.

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 Fire Resistance of Bamboo Fiber Reinforced SCC with GGBS and Alccofine Partially in Place of Cement

2021 ◽  
Vol 1 (1) ◽  
pp. 38-46
Author(s):  
S. Kavitha ◽  
T. Felix Kala
Keyword(s):  
Compressive Strength ◽  
Fire Resistance ◽  
Elevated Temperatures ◽  
Diameter Ratio ◽  
Common Occurrence ◽  
Strength Parameters ◽  
Before And After ◽  
Bamboo Fibers ◽  
Fire Accidents

Fire accidents have become a common occurrence which results in loss of lives and property, in preliminary stage while selecting material and designing, the performance of every structure against condition of fire has to be considered. The fire resistance is important durability characteristic which evaluate the quality of the material. In this investigation, fire resistance capacity of the NSCC with GGBS and alccofine and the BFRSCC with GGBS and alccofine is evaluated by considering the weight and strength parameters before and after exposing to the temperatures of 200 ͦC, 400 ͦC, 600 ͦC, 800 ͦC and 1000 ͦC for one hour duration. The test for assessing compressive strength for 150mm x 150mm x 150mm concrete requires cube of and allowed in water for 28 days. The bamboo fibers of 1% (length to diameter ratio=40) of 4.9 mm measurement lengthwise to the mass of cement are mixed to the SCC where cement is partially placed with 30% of GGBS along with 10% Alccofine. As noted from the results the strength decreased by increasing the temperatures. Less strength is decreased at lesser elevated temperatures but massive reduction occurred in the higher elevated temperatures. The weight and compressive strength of the material has minor reduction till 800oc which is acceptable as a building material.

scholarly journals Variations of Density and Compressive Strength Before and After Charring of Some Selected Construction Timber Species of Southwestern Nigeria

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Oluwaseun A Adetayo ◽  
Bamidele IO Dahunsi
Keyword(s):  
Compressive Strength ◽  
Tectona Grandis ◽  
Percentage Change ◽  
Timber Species ◽  
Fire Exposure ◽  
Southwestern Nigeria ◽  
Before And After ◽  
Density Values ◽  
Nauclea Diderrichii ◽  
Milicia Excelsa

This study aimed to evaluate the percentage variations of density and compressive strength of some selected timber species mostly used for constructional purposes in Southwestern Nigeria after undergoing fire exposure. The species are: Terminalia superba (Afara), Milicia excelsa (Iroko), Nauclea diderrichii (Opepe), Khaya ivorensis (Mahogany), Mansonia altissima (Mansonia), Tectona grandis (Teak).The densities and the compressive strengths of the species were determined at Moisture Contents (MC) of 9.0, 12.0, and 15.0%. Nine specimen per species, were exposed to fire at various temperature ranges.The results of analysis by variance revealed that at 9% MC, Mahogany had the lowest density value of 439±10.58Kg/m³. At 12 and 15% MC, Afara had the lowest density values of 444±4.18Kg/m³ and 469±7.07Kg/m³ respectively. At 9, 12 and 15% MC, Opepe had the highest density values of 630±28.85Kg/m³, 686±22.64Kg/m³ and 752±17.22Kg/m³ respectively. Afara of 9, 12 and 15% MC had the lowest compressive strength parallel to the grain values of 9.59±1.08N/mm2, 9.59±1.08N/mm2 and 8.13±1.01N/mm2 respectively, while Mahogany had the highest compressive strength parallel to the grain values of 16.57±0.50N/mm2, 15.17±0.49N/mm2 and 12.12±0.42N/mm2 at the three MC levels. Post fire exposure revealed that Afara had the highest percentage change in density and compression in parallel values, while both Iroko and Mahogany exhibited the lowest percentage change in density and compression in parallel values. This study indicated that Mahogany and Iroko species which had lowest post fire change in density and compression in parallel values are useful and recommended to ensure the safety in case of fire outbreaks.

Flexural behaviour of reinforced self compacting concrete beams subjected to elevated temperature before and after retrofitting

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sachin B.P. ◽  
N. Suresh
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Carrying Capacity ◽  
Modulus Of Elasticity ◽  
Concrete Beams ◽  
Load Carrying Capacity ◽  
Self Compacting Concrete ◽  
Content Type ◽  
Load Carrying ◽  
Before And After

Purpose The purpose of the paper is to study the effect of elevated temperature on load carrying capacity of reinforced self compacting concrete beams and the performance of deteriorated beams after retrofitting by GFRP sheets. The reinforced beams which were exposed to sustained elevated temperature and tested for flexural load-carrying capacity. Further deteriorated beams (exposed from 500°C to 800°C) were re-strengthened by adopting retrofitting with GFRP sheets. Design/methodology/approach The investigation includes the concrete specimens, i.e. cubes of 150 mm, cylinders of size 150 mm dia with 300 mm height and beams of 150 × 150 × 1,100 mm, reinforced with minimum tension reinforcement according to IS 456–2000. The specimens were subjected to elevated temperature from 300°C to 800°C with an interval of 100°C for 2 h. The residual compressive strength, modulus of elasticity, load at first crack of beams and load-carrying capacity of beams for 5-mm deflection were measured before and after retrofitting. Findings The result shows that there is a gain in residual compressive strength at 300°C and beyond which it decreases. The modulus of elasticity, load at first crack and load-carrying capacity of beams reduces continuously with an increase in temperature. The decrease in load-carrying capacity of beams is observed from 27.55% and up to 38.77% between the temperature range of 500°C–800°C and after the retrofitting of distressed beams, the load carrying capacity increases up to 24.48%. Originality/value Better performance was observed with retrofitting by GFRP sheets when the specimens were distressed due to elevated temperatures.

scholarly journals Study the Fire Resistance of Desert Sand Concrete (DSC) with Interface Phase through Uniaxial Compression Tests and Analyses

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Qian Zhang ◽  
Haifeng Liu ◽  
Qiang Liu ◽  
Jialing Che ◽  
Weiwu Yang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Constitutive Model ◽  
Uniaxial Compression ◽  
Fire Resistance ◽  
Elevated Temperatures ◽  
Fine Aggregate ◽  
Compression Tests ◽  
Desert Sand ◽  
Simulation Results

The shortage of sand resources and high-rise building fires are becoming increasingly prominent. Desert sand (DS) with smaller particles can effectively fill the concrete voids and further improve its working performance; it is used as a fine aggregate to produce concrete. This article studied the performance of desert sand concrete (DSC) against fire resistance by using mathematical modeling for simulation. The stress-strain curves of desert sand mortar (DSM) after elevated temperatures were tested, and the constitutive model was established. By comparing the experiment and simulation results, it was verified that the model is suitable to be adopted in this study. Data from experiment and past literature can serve as parameters for the subsequent simulation. The destruction process of DSC under uniaxial compression after elevated temperature was simulated by using ANSYS. The simulation results indicated that, after elevated temperature, compressive strength reduced with increase of interface thickness. The compressive strength of DSC had a substantially linear increase as the interface compressive strength increased. For two-grade coarse aggregate, the optimum volume content was 45%, and particle size of it showed a significant effect on the compressive strength of DSC. The DSM constitutive model and simulation results can provide a sound theoretical basis and technical support for DSC engineering applications.

PROPERTIES OF CONCRETE MADE WITH RECYCLED COARSE AGGREGATES FROM OLD CONCRETE CUBES

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
I. H. Adebakin ◽  
J. T. Adu ◽  
O. M. Ofuyatan
Keyword(s):  
Compressive Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Low Grade ◽  
Aggregate Concrete ◽  
Coarse Aggregates ◽  
Natural Aggregate ◽  
Absolute Volume ◽  
Close Proximity ◽  
Volume Method

Sustainability in the construction industry is a global concern, and one way of handling this is the idea of recycling old concrete rubbles in the production of fresh concrete. Recycled aggregate concrete is normally classified as light weight concrete and recommended for use in production of low-grade non-structural elements. This study examined the properties of crushed old concrete cubes as replacement for natural aggregate. Five specimens 150x150mm concrete cubes with varying percentages of coarse recycled aggregate of 0 %( control), 25, 50, 75 and 100% were prepared. All the mixes were proportioned using the absolute volume method with a targeted compressive strength of 30N/mm2 and varying w/c ratio. The result shows that with up to 75% replacement of natural aggregate with recycled aggregate, the 28 days compressive strength of concrete is in close proximity with that of normal concrete. While the strength of exclusive recycled aggregate concrete is about 15% lesser than that of exclusive natural aggregate. The result of this research confirms that crushed old concrete cubes can be safely used in the production of high grade concrete.

scholarly journals The Fire Resistance Performance of Concrete Columns With Different Compressive Strength

2021 ◽  
Author(s):  
Rafid Saeed Atea
Keyword(s):  
Compressive Strength ◽  
Cross Section ◽  
Fire Resistance ◽  
Concrete Columns ◽  
Fire Exposure ◽  
Temperature Changes ◽  
Axial Strength ◽  
Axial Forces ◽  
Resistance Performance ◽  
Concrete Elements

Abstract Four full concrete columns have been created Tested below high temperature for The fire resistance of concrete elements in concrete with particular compressive strengths. The standard concrete with compressive strength values of C25 were made of one of the four specimens, while the rest were made of C35, C60 and C75 respectively, respectively. During simulation of Within the laboratory furnace, the same For the specimens, axial forces were applied. Many experimental outcomes parameters were evaluated in contrast, including temperature changes, Vertical moving, side deflection, fire resistance and Failed properties of the specimen. The results have shown a rise in the compressive strength of the concrete for the concrete columns from the outside up to the inside of the column the same cross section of the lower compressive forces of concrete display better fire resistance efficiency with the same initial axial strength ratio. The C35, C60 and C75 columns' fire resistance is higher than standard concrete columns. The initial and secant rigidity of the columns of Reinforced concrete (RC) has also The percentage decreased dramatically after fire exposure and the temperature increased from 25 to 750 ° C.

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