Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Metakaolin


Characteristics of Eco-Friendly Metakaolin Based Geopolymer Concrete Pavement Bricks

Wasan Ismail Khalil; Qias J. Frayyeh; Mahmood F. Ahmed

Engineering and Technology Journal, 2020, Volume 38, Issue 11, Pages 1706-1716
DOI: 10.30684/etj.v38i11A.1699

The purpose of this work is to investigate the possibility to recycled and reused of waste clay brick and waste plastic as constituents in the production of green Geopolymer concrete paving bricks. Powder of clay brick waste (WBP) was used as a partial replacement of Metakaolin (MK) in Geopolymer binder. Moreover, recycled clay brick waste aggregate (BA) and plastic waste aggregate (PL) were incorporated as coarse aggregate in mixtures of Metakaolin based Geopolymer concrete (MK-GPC) pavement bricks. Six types of mixtures were prepared and cast as pavement bricks with dimensions of 150×150×100 mm. All samples have been tested for compressive strength, water absorption and abrasion resistance at age of 28 days; and compared the results with the requirements of Iraqi specification No.1606-2006. The MK-GPC pavement bricks present a compressive strength of 31-47MPa, water absorption of 3.66% to5.32% and abrasion resistance with groove length between 21.78mm to 18.91 mm. These types of pavement bricks are classified as a medium to light capacity for weight loading, and it is possible to be used in wide range of paving applications, especially in aggressive wearing environment.

Performance of Geopolymer Concrete Exposed to Freezing and Thawing Cycles

Mohammed H. Shamsa; Basil S. Al-Shathr; Tareq S. al-Attar

Engineering and Technology Journal, 2019, Volume 37, Issue 3A, Pages 78-84
DOI: 10.30684/etj.37.3A.1

In this study, the effect of rapid freezing and thawing (ASTM C666 – procedure A) on three different types of Geopolymer concrete studied using three types of pozzolanic material: fly ash, metakaolin and ground granulated blast furnace slag (GGBFS). The Geopolymer concrete was prepared using 400 kg of the pozzolanic material with alkaline liquid prepared at 8 molar concentration with normal fine and coarse aggregates. The ratio of alkaline to fly ash and GGBFS was 1.5: 1 and for metakaolin was 2: 1 for workability and compressive strength requirements. Specimens (100 × 100 × 400) mm were exposed to 100, 200 and 300 cycles of freezing and thawing. The decrease in measured compressive strength was (23, 43, and 26%) for Fly ash, metakaolin and GGBFS respectively. The investigated types of concrete showed good resistance to freezing and thawing. The durability factor of these types was (77%, 68%, and 81%) for fly ash, metakaolin, and GGBFS respectively.

Some Properties of Concrete Containing High Fraction Volume of Metakaolin

Kais J. Frieh; Waleed A.Abbas; Marawan Mohammed Hamid

Engineering and Technology Journal, 2014, Volume 32, Issue 1, Pages 230-248

In this research, a study has been made on the effect of high fractional volume of replacement Metakaolin that results from grinding and burning the local kaolin from (Doeakhla zone / west of Baghdad / Iraq) with fineness of 18000 cm2/gm., and with temperature 700°C for one hour, on some properties of concrete (compressive strength, splitting tensile strength, flexural strength, modulus of elasticity, density,
absorption and drying shrinkage). Also, non-destructive tests have been made (Schmidt rebound hummer and Ultrasonic pulse velocity). In this study, ten concrete mixes have been used in two Groups to get a compressive strength 40 N/mm2 at 28 days. In Group A, the percentage replace of Metakaolin have been changed from (0-70) % by weight of cement with percent increment equal to 10% for each mix, and
change the maximum size of aggregates to determine the effect of changing the surface area of aggregate as variable on the properties of concrete-containing Metakaolin, The tests for all mixes were made at ages ranged from 1 day to 90 days after mixing and replacement a dosage of superplasticizer by water content of the mix to make a constant workability with slump 50±5mm. The aim of this research is to
find a type of concrete that can be used in dams as one of the types of mass concrete, concluded from this research that replacing 70% Metakaolin instead of cement mixing the compressive strength aged 90 days less than the 63%, splitting strength at 28 days less than 27%, flexural strength at 28 days less than about 27%, the modulus
of elasticity at 28 days less than 54%, density of less than about 8% at 28 days, the absorption rate increases about 27% and drying shrinkage 1.65 * 10-4 at 60 days when compared all these tests with the reference concrete.

Studying the Compatibility between Metakaolin Repair Materials And Concrete Substrate

Maan S. Hassan; Zainab T. Hadad; Shaymaa T.Kadhim

Engineering and Technology Journal, 2010, Volume 28, Issue 19, Pages 5857-5868

In this study, the compatibility of Metakaolin repair mortar and substrate concrete was investigated in three stages. First: individual properties of Metakaolin as a pozzolanic material and conventional repair materials(cement mortar), and two types of concrete, such as compressive strength, split tensile strength, and flexural strength, were determined using standard ASTM test procedure. Second: the bond
strength of composite cylinder for different combinations of repair materials and substrate concrete were evaluated. Third: the compatibility was investigated using a composite beam of repair material and substrate concrete under third point loading.
The experimental results indicated that repairing weak substrate concrete by Metakaolin modified repair material is not preferable du to disparity in mechanical properties and create high level of mismatch between them. Furthermore, bond strength is considered as great influence factor on the success range of repair system.

Fusion Face and Palmprint for Human Recognition via Spectral Eigenvector

Hana; a M. Salman

Engineering and Technology Journal, 2009, Volume 27, Issue 4, Pages 787-798

The Biometrics recognition systems act as an efficient method with broad
applications in the area of: security access control, personal identification to humancomputer
communication. From other hand, some biometrics have only little variation
over the population, have large intra-variability over time, or/and are not present in all
the population. To fill these gaps, a use of multimodal biometrics is a first choice
solution [1].
This paper describes a multibiometrics method for human recognition based on
new teacher vector identified as spectrum eigenface, and spectrum eigenpalm. The
proposed combination scheme exploits parallel mode capabilities of the fusion feature
vectors in matching level and invokes certain normalization techniques that increase its
robustness to variations in geometry and illumination for face and palmprint. The
correlation distance is used as a similarity measure. A threshold value is used to
prevent the imposter for being recognized. Experimental results demonstrate the
effectiveness of the new method compared to the unimodal biometrics for spectrum
eigenface/eigenpalm.

Modeling Time to Corrosion Initiation in High-Performance Ferrocement Exposed to Chlorides Environments

J. Forth; Maan S. Hassan; S. A. Salih

Engineering and Technology Journal, 2009, Volume 27, Issue 1, Pages 18-31

The applications of a mineral admixture, or a zinc coating to steel surface, or a
combination of both are methods used for the corrosion prevention of ferrocement
element in this study. Results of a study to evaluate many corrosion protection systems
with metakaolin and/or galvanized steel mesh are presented in six U-shaped specimens.
Specimens were built to simulate exposure conditions typical for marine environment.
Laboratory data collected along duration of 40 weeks of exposure were used in
modeling the cover depth as a function of time to corrosion initiation of the investigated
corrosion prevention methods. Methods used to assess the condition of specimens
included chloride concentration measurements, and corrosion rates. Model predictions
show that the ferrocement specimen of high-performance mortar with metakaolin
provides much better level of protection against moisture and chlorides than the
conventional specimen, by delay rate of chloride ingress. Application of a galvanized
steel mesh causes an elevation of the chloride threshold resulting in an additional
increase in the predicted time to corrosion initiation.