scholarly journals COMPRESSIVE STRENGTH OF FOAMED CONCRETE IN RELATION TO POROSITY USING SEM IMAGES

2019 ◽  
Vol 10 (1) ◽  
pp. 34-44
Author(s):  
Paybar Ali Shawnim ◽  
Fouad Mohammad
Keyword(s):  
Compressive Strength ◽  
Shape Factor ◽  
Fine Sand ◽  
High Porosity ◽  
Structural Elements ◽  
Pore System ◽  
Sem Images ◽  
High Compressive Strength ◽  
Foamed Concrete ◽  
Curing Method

Foamed concrete specimens were examined for compressive strength at (28 and 180) days air sealed curing, as well as at 28 days water cured. Also, the microstructure of fifteen selected FC specimens was investigated for porosity in relation to compressive strength using Scanning Electron Microscopy (SEM) images. Twenty two batches of FC specimens of the densities (1100, 1600 and 1800) kg/m3 were made with fine sand and brick aggregates with toner and metakaolin (MK) inclusion as additives, they were casted in polystyrene cube moulds of (100x100x100) mm. Results show, it is possible to produce FC with high compressive strength in the range of (28.5 to 59.2) N/mm2, with a variety of materials, while the 1600 kg/m3 density with the inclusion of toner and MK20 is the favourite, which can be used for structural elements. Conventionally, compressive strength is in an inverse relationship with porosity, as porosity increases, compressive strength decreases, but using toner and MK20 can alter this relationship between porosity and compressive strength, where by it is possible to produce a relatively light weight high porosity FC matrix to exhibit high compressive strength. Maturity of the FC at 180 days, can demonstrate an increase in the compressive strength. The microstructural investigations through SEM images revealed, the FC mix made with sand or brick only, exhibits an irregular shape factor of the micro pore system with the pore size in the range of (10 to 70) µm, while those made with the inclusion of toner and MK20 have a regular shape factor of a matrix of finer micro pore system of the sizes in the range of (0.01 to 10.0) µm, all of which are evenly distributed, and have a big influence on the properties of the FC, particularly, on compressive strength. Contrary to the conventional method of air sealed curing for FC, water curing method can equally give the same or a slightly better result in respect of compressive strength for some particular densities.

scholarly journals POROSITY, PERMEABILITY AND MICROSTRUCTURE OF FOAMED CONCRETE THROUGH SEM IMAGES

2019 ◽  
Vol 10 (1) ◽  
pp. 22-33 ◽  
Author(s):  
P. Shawnim ◽  
F. Mohammad
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Pore Size ◽  
High Porosity ◽  
Capillary Water ◽  
Sem Images ◽  
Microstructural Investigation ◽  
Capillary Water Absorption ◽  
Foamed Concrete ◽  
Percentage Ratio

This paper examined the foamed concrete (FC) for permeability of total and capillary water absorption, at 28 days of air sealed curing. The microstructure of 15 selected FC specimens was investigated to determine permeability in relation to porosity and density using Scanning Electron Microscopy (SEM) images. The FC specimens of the densities (1100, 1600, and 1800) kg/m3 were made using fine sand and brick aggregates with toner and MK inclusion as additives. The microstructural investigation of the FC revealed, porosity measure as a percentage ratio of the area under investigation to be in the range of (39.65 to 77.7) %. The pore size is in the range of (0.01 to 70) µm, depending on the type of additive, for the mixes containing toner and MK, it is in a fine range of (0.01 to 10.0) µm. For the FC specimens, the finer the pore size, the less permeable and the stronger it is. Permeability is porosity and strength dependent, whereby high porosity leads to high permeability and low compressive strength for FC mixes made with sand or brick only with no additive inclusion. Meanwhile, the FC mixes made with the inclusion of additives, such as the toner and MK20 mixes, showed an evenly spread net of independent air voids with a regular shape within their matrix, which is beneficial in decreasing permeability. Therefore, besides the porosity and strength, the fineness of the pore matrix and the shape factor of the pores are two other key factors in controlling permeability. Toner and MK20 inclusion can enhance the capillary water absorption to reach almost water tight. Besides, MK30 and MK50 inclusion displayed adverse effect on permeability. Depending on the type of filler, the additive, and the percentage ratio of the porosity of the FC matrix at (1600 and 1800) kg/m3 densities, it is possible to produce FC with compressive strength between (55.1 and 30) N/mm2.

scholarly journals Effect of Curing Method on Properties of Lightweight Foamed Concrete

2018 ◽  
Vol 7 (2.29) ◽  
pp. 927 ◽  
Author(s):  
Bishir Kado ◽  
Shahrin Mohammad ◽  
Yeong Huei Lee ◽  
Poi Ngian Shek ◽  
Mariyana Aida Ab Kadir
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Water Absorption ◽  
Precast Concrete ◽  
Construction Materials ◽  
Splitting Tensile Strength ◽  
Structural Members ◽  
Lightweight Construction ◽  
Foamed Concrete ◽  
Curing Method

Lightweight construction is aimed to achieve a sustainable feature by reducing transportation frequency and construction materials usage during construction phase. Lightweight precast concrete may serve an alternative for the lightweight construction. There are rarely application can be found for structural members as lightweight panels always to be used for secondary or non-load bearing members. This paper presents an experimental study on properties (compressive strength, splitting tensile strength, water absorption) of lightweight foamed concrete (LFC) at two different curing methods. LFC with densities of 1500, 1700, and 1800 kg/m3, cement-sand ratio of 2:1 and water-cement ratio of 0.5 were investigated. The results showed LFC can be produced with the properties ofdensity range of 1500 to 1800 kg/m3 and corresponding compressive strength of 10 to 39 MPa. The higher the density of LFC, the less the water absorption for all the curing method considered, the highest and the lowest water absorption was 11.3% and 2.0% for 1500 kg/m3 cured in water and 1800 kg/m3 cured in air respectively. Compressive strength of LFC increases with age and density while water cured LFC has high compressive strength. Splitting tensile strength increases with density of LFC, but air cured LFC has more splitting tensile strength than water cured of the same density. The highest splitting tensile strength recorded was 3.92 MPa for 1800 kg/m3 cured in air, which was about 16% of its compressive strength at 28 days of curing age. These properties are important and can be applied to LFC precast structural members with air or water curing method which have less references for LFC in structural usage.  

Effects of Aluminum Concentrations on Microstructure and Compressive Strength of Porous Concrete

2017 ◽  
Vol 751 ◽  
pp. 563-569
Author(s):  
Oratai Jongprateep ◽  
Napamas Jaroonvechatam ◽  
Supicha Stienkijumpai ◽  
Sicha Kaewsuwan ◽  
Thanawat Meesak
Keyword(s):  
Compressive Strength ◽  
Microstructural Analysis ◽  
High Water ◽  
Chemical Compositions ◽  
High Porosity ◽  
Sem Images ◽  
Porous Concrete ◽  
Practical Applications ◽  
Aluminium Powder ◽  
Aluminium Addition

High porosity in porous concretes contributes to benefits in terms of lightweight, high water permeability, and superior insulation properties in the concretes. Nevertheless, excessive porosity can lead to diminished compressive strength. This study, therefore, aimed at fabricating porous concretes with porosity and compressive strength in the range suitable for practical applications. Since addition of aluminium powder is a well-known technique for porosity production, this study also assessed effects of aluminium addition on properties of porous concretes. Relationships among concentrations of aluminium, porosity, and compressive strength of the specimens were examined. Microstructural analysis from scanning electron microscope (SEM) images and compressive strength testing according to ASTM C109 revealed that the specimens with 0.15 wt% Al demonstrated porosity and compressive strength were in an acceptable range. Additionally, porosity production and specimen strengthening were discussed with respect to chemical compositions.

scholarly journals Toner Used In The Development of Foamed Concrete For Structural Use

2018 ◽  
Vol 9 (1) ◽  
pp. 27-33 ◽  
Author(s):  
P. A. Shawnim ◽  
F. Mohammad
Keyword(s):  
Compressive Strength ◽  
Structural Material ◽  
Ordinary Portland Cement ◽  
Published Data ◽  
Structural Elements ◽  
Water Penetration ◽  
Foaming Agent ◽  
Foamed Concrete ◽  
New Material ◽  
The Right

This paper investigates the effect of toner as a new material on enhancing compressive strength and permeability of foamed concrete (FC). The aim is to develop the FC through testing the reaction of toner with the cement of the FC, to produce a hydrophobic lightweight FC to use for structural elements. Foamed concrete is generally made of ordinary Portland cement (OPC), sand, foaming agent, and water with a well spread pore structure. The experiment was carried out on 100 mm cubes. Results for toner inclusion of all the mixes, when added in the right quantities, showed high improvement for water penetration and compressive strength in comparison to the published data on FC for the use as structural material, which is a step forward in the advancement of FC to meet the aim of this research.

scholarly journals Investigation of Thermal, Mechanical and Transport Properties of Ultra-Lightweight Foamed Concrete (ULFC) Strengthened with Alkali Treated Banana Fibre

2021 ◽  
Vol 86 (1) ◽  
pp. 123-139
Author(s):  
Mohammed Hassan Nensok ◽  
Md Azree Othuman Mydin ◽  
Hanizam Awang
Keyword(s):  
Compressive Strength ◽  
Thermal Properties ◽  
Water Absorption ◽  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
High Porosity ◽  
Control Specimen ◽  
Sem Images ◽  
Banana Fibre

Traditionally, Ultralightweight Foam Concrete (ULFC) is primarily used to replace filling excavations, ditch restoration and underground channels, because of their high porosity, water absorption and low strength. Yet, ULFC is characterized by excellent thermal properties and could be an alternative for sustainable energy-efficient building material. This study investigates the properties of an ULFC strengthened with alkali-treated banana fibre. The low density ULFC of 600kg/m3 was fabricated and strengthened with alkali-treated banana fibre. Fibre volume fraction of 0.25%, 0.35%, 0.45% and 0.55% were compared to the unreinforced specimens, serving as the control specimen (no fibre addition). Mix proportioning of 1:1.5:0.45 of cement, sand, and water was respectively adopted throughout the mix. The alkali treated banana fibre strengthened ULFC was tested for compressive strength, sorptivity and thermal properties. Morphology of the treated fibre and ULFC composites was studied using SEM micrograph. The result depicts that ULFC exhibited the optimum compressive strength of 1.1604N/mm2 with the fibre volume fraction of 0.35%. Sorptivity or rate of water absorption was testified to upsurge, after 24 hours duration at fibre volume fraction of 0.55%, recording a 56.12% increment compared to the control specimen. The finding displays that at the highest-fibre volume fraction of 0.55%, thermal conductivity and diffusivity decrease by 13.17% and 28.16%, correspondingly, whiles the specific heat capacity increases to 37.17% all compared with unreinforced specimens. SEM images reveal that the presence of lumen and the nature of porous and fibrous alkali-treated banana fibre. Hence, it is endorsed that ULFC produced with alkali-treated banana fibre should be utilized as an infill material for composite system.

scholarly journals Models for Strength Prediction of High-Porosity Cast-In-Situ Foamed Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Wenhui Zhao ◽  
Junjie Huang ◽  
Qian Su ◽  
Ting Liu
Keyword(s):  
Compressive Strength ◽  
Prediction Model ◽  
Raw Materials ◽  
Dry Density ◽  
High Porosity ◽  
Curing Time ◽  
Composite Function ◽  
Construction Period ◽  
Foamed Concrete

A study was undertaken to develop a prediction model of compressive strength for three types of high-porosity cast-in-situ foamed concrete (cement mix, cement-fly ash mix, and cement-sand mix) with dry densities of less than 700 kg/m3. The model is an extension of Balshin’s model and takes into account the hydration ratio of the raw materials, in which the water/cement ratio was a constant for the entire construction period for a certain casting density. The results show that the measured porosity is slightly lower than the theoretical porosity due to few inaccessible pores. The compressive strength increases exponentially with the increase in the ratio of the dry density to the solid density and increases with the curing time following the composite function A2ln⁡tB2 for all three types of foamed concrete. Based on the results that the compressive strength changes with the porosity and the curing time, a prediction model taking into account the mix constitution, curing time, and porosity is developed. A simple prediction model is put forward when no experimental data are available.

Performance of Lightweight Foamed Concrete with Replacement of Concrete Sludge Aggregate as Coarse Aggregate

2013 ◽  
Vol 689 ◽  
pp. 265-268 ◽  
Author(s):  
Mohamad Ibrahim Norlia ◽  
Roshazita Che Amat ◽  
Nur Liza Rahim ◽  
Shamshinar Sallehuddin
Keyword(s):  
Compressive Strength ◽  
Construction Industry ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Construction Material ◽  
Partial Substitution ◽  
Structural Elements ◽  
Mixing Processes ◽  
Optimum Proportion ◽  
Foamed Concrete

The use of waste materials in construction industry is very essential in order to reduce the depletion of natural sources. Thus, this study is focused to determine the performance of lightweight foamed concrete made with concrete sludge aggregate (CSA) and to determine the optimum proportion of CSA that can gives optimum compressive strength. Strength is one of the most important properties of concrete since the first consideration in structural design is that the structural elements must be capable of carrying necessary loads. CSA has been use as partial substitution to normal coarse aggregate to manufacture structural lightweight foamed concrete. Two different sets of CSA proportion have been prepared with foamed injected through mixing processes. 25% and 50% of CSA for production of lightweight concrete were designed according to proper mix design. It is found that maximum percentage of CSA that contribute to the highest compressive strength of 25MPa is 50% of CSA replacement. Its density is 1837 kg/m3 with water adsorption of 16.35%. The usage of concrete sludge aggregate as construction material can be further promoted in order to solve major environmental issues.

scholarly journals Unique chemical activity in porous YbB2C2 ceramics with high porosity and high compressive strength

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhihui Li ◽  
Jixin Chen ◽  
Hao Zhang ◽  
Jinxing Yang ◽  
Minmin Hu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Raw Materials ◽  
Chemical Activity ◽  
High Porosity ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Compressive Strength ◽  
Rate Of Reaction ◽  
Unique Chemical

AbstractHigh purity layered YbB2C2 powder is synthesized by a boro/carbothermic reduction method using YbBO3, B4C and graphite powders as raw materials. Its X-ray diffraction data are presented, and the space group P4/mbm (No. 127) is confirmed. The lattice parameters are a = b = 5.3389 Å and c = 3.5683 Å, and the atom positions are Yb (0.0000, 0.0000, 0.0000), B (0.3621, 0.8621, 0.5000), and C (0.1606, 0.6606, 0.5000). Porous YbB2C2 ceramics have a high porosity in the range of 69.89–58.11% and a high compressive strength in the range of 19.49–63.44 MPa. Furthermore, the as-produced porous YbB2C2 ceramics show unique chemical activity. Porous YbB2C2 ceramic with a porosity of 69.89% emits so much heat that it can burn a piece of paper when this ceramic is wetted by water. The rate of reaction between the porous YbB2C2 ceramic and water can be simply controlled by adjusting the porosity. The solid reaction products are YbB6, C and an unknown amorphous phase.

EFFECT OF POST-CURING REGIME ON DENSITY, COMPRESSIVE STRENGTH AND CROSSLINKING OF POLYMER CONCRETE

2015 ◽  
Vol 77 (12) ◽  
Author(s):  
Nur Hafizah A. Khalid ◽  
Mohd Warid Hussin ◽  
Mohammad Ismail ◽  
Mohamed A. Ismail ◽  
Azman Mohamed ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Apparent Density ◽  
Curing Temperature ◽  
Polymerization Process ◽  
Polymer Concrete ◽  
Strength Development ◽  
Sem Images ◽  
Curing Conditions ◽  
Curing Method ◽  
Curing Regime

Polymer concrete is produced from polymer binder, aggregates, and filler. Its curing follows the polymerization process once polymer additive is added, and can be accelerated through post-curing. In this study, the Orthophthalic- and Isophthalic-based polymer concrete (Ortho-PC and Iso-PC) were cured and investigated at different curing temperature (30oC, 50oC and 70oC) and period (1, 3, 6, 16, 24 hours) to complete the compressive strength development. Effect of curing temperature and period on apparent density, compressive strength, and morphology properties were investigated. The outcomes exhibited that all specimens had achieved full compressive strength within 6 hours of curing time at both 50oC and 70oC. When cured at 30oC, this went up to more than 16 hours of curing period to achieve the same compressive strength. The form of crosslinking at different curing conditions was captured in Scanning Electron Microscope, SEM images. Results also showed that curing temperature and period insignificant affected the apparent density. This study can be used as references to manufacturer, fabricator, and engineers when dealing with polymer concrete which goes for post-curing method as curing process.

Carbon Foams with High Compressive Strength Derived from Mixtures of Mesophase Pitch and Si Particles

2010 ◽  
Vol 97-101 ◽  
pp. 1130-1133
Author(s):  
Yang Wei Wang ◽  
Zhi Jin Zhang ◽  
Xiao Dong Yu ◽  
Fu Chi Wang ◽  
Kai Li ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Carbon Foam ◽  
Mesophase Pitch ◽  
High Porosity ◽  
Strut Thickness ◽  
High Compressive Strength ◽  
Carbon Foams ◽  
Si Content ◽  
Si Addition ◽  
Pore Number

Carbon foam with relatively high compressive strength and high porosity was prepared from a mixture of mesophase pitch and Si particles by foaming and carbonization. The influence of Si content on the microstructures and properties of the carbon foam was studied. Results show that the pore number decreases and the strut thickness increases with an increasing of Si content. In addition, bulk density also increases with increasing Si content but the porosity decreases. Si addition to the mesophase pitch reduces the number of microcracks on the cell wall of the carbon foam remarkably which results in an increase of compressive strength for the carbon foams. Compressive strengths improve by 46%, 176% and 339% at Si additions of 30%, 40% and 50% (wt %), respectively. Carbon foam with a relatively high compressive strength of 24.6 MPa and a porosity of 61% are obtained when 50 wt% Si is added.

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