New Measurements for the Resistivity of Curing Period Concrete

Chloride binding capacity and its effect on the microstructure of mortar made with marine sand (MS), washed MS (WMS) and river sand (RS) were investigated in this study. The chloride contents, hydration products, micromorphology and pore structures of mortars were analyzed. The results showed that there was a diffusion trend for chloride ions from the surface of fine aggregate to cement hydrated products. During the whole curing period, the free chloride content in the mortars made by MS and WMS increased firstly, then decreased and stabilized finally with time. However, the total chloride content of three types of mortar hardly changed. The bound chloride content in the mortars made by MS and WMS slightly increased with time, and the bound chloride content included the MS, the WMS and the RS arranged from high to low. C3A·CaCl2·10H2O (Friedel’s salt) was formed at the early age and existed throughout the curing period. Moreover, the volume of fine capillary pore with a size of 10–100 nm increased in the MS and WMS mortar.

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Influence of Sulphate on the Moisture Movement of Calcium Silicate Brick Masonry Wall

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.133-134.201 ◽

2010 ◽

Vol 133-134 ◽

pp. 201-204

Author(s):

Ibrahim Mohamad H. Wan ◽

B.H. Abu Bakar ◽

M.A. Megat Johari ◽

P.J. Ramadhansyah

Keyword(s):

Relative Humidity ◽

Calcium Silicate ◽

Masonry Wall ◽

Sodium Sulphate ◽

Brick Masonry ◽

Masonry Walls ◽

Moisture Movement ◽

Moisture Expansion ◽

Curing Period ◽

Wet Condition

This paper presents the behaviour of moisture movement of calcium silicate brick masonry walls exposed to sodium sulphate environment. The walls were exposed to three sodium sulphate conditions with sulphate concentrations of5%, 10% and 15%. For comparison, some walls were also exposed to dry and wet condition which acts as a control conditions. All specimens were prepared and cured under polythene sheet for 14 days in a controlled environmental room and maintained at relative humidity and temperature of 80 ± 5% and 25 ± 2°C, respectively. After the curing period, the specimens were exposed to sodium sulphate as well as drying and water exposures, during which moisture movement was measured and monitored for a period of up to 7 months. As a result, the moisture expansion was observed and recorded for all masonry wall specimens after exposed to the sulphate condition.

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Stabilization of Black Cotton Soil using Lime and Phosphogypsum

International Journal of Emerging Trends in Engineering Research ◽

10.30534/ijeter/2021/29942021 ◽

2021 ◽

Vol 9 (4) ◽

pp. 503-507

Keyword(s):

Unconfined Compressive Strength ◽

Expansive Soils ◽

Soil Samples ◽

Black Cotton Soil ◽

Stabilization Method ◽

Curing Period ◽

Problematic Soils ◽

Construction Purpose ◽

Black Cotton Soils ◽

Properties Of Soil

Expansive soils are problematic soils for Civil Engineers. Black cotton (BC) soils possess low strength and high compressibility, due to these properties black cotton soils are considered to be challenging one for analysis. To achieve desired properties of soil for construction purpose these black cotton soil must be enhanced to meet its requirement. To modify the properties of black cotton soils, many treatment methods are there. In this paper an attempt has been made to improve the properties of black cotton soil by using industrial waste through stabilization method. By stabilizing the soil properties are enhanced and make it suitable for subgrade construction. In this work, the combined effect of Lime and Phosphogypsum (PG) on compaction characteristics, Atterberg’s Limit, Unconfined Compressive Strength (UCS) for original soil, California Bearing Ratio (CBR) and direct shear Test of a black cotton soil with percentage varying of Lime and Phosphogypsum was carried out. The soil samples were tested for tri-axial compression test and CBR tests were carried out after 4 days curing period. From the results, it has been inferred that the black cotton soil treated with Lime and Phosphogypsum in the percentages of (4:4) has better strength characteristics. Hence, it may be concluded that Lime and Phosphogypsum can be used for stabilization of black cotton soils for pavement subgrade

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Mechanical Performance of Steam-Cured Self-Compacting Concrete Incorporating Silica Fume and Limestone Powder

International Journal of Engineering Research in Africa ◽

10.4028/www.scientific.net/jera.56.111 ◽

2021 ◽

Vol 56 ◽

pp. 111-122

Author(s):

Youcef Ghernouti ◽

Bahia Rabehi ◽

Sabria Malika Mansour

Keyword(s):

Heat Treatment ◽

Silica Fume ◽

Mechanical Performance ◽

Limestone Powder ◽

Maximum Temperature ◽

Self Compacting Concrete ◽

Curing Period ◽

Heat Treated ◽

Binder Ratio ◽

Mechanical Strengths

In this paper, influence of heat treatment on evolution of mechanical strengths at early age, less than 24hours of self-compacting concretes containing limestone powder and silica fume as fine materials was investigated experimentally. Two compositions of self-compacting concrete have been studied; the first is elaborated with silica fume addition and the second with limestone powder, each mixture were prepared with a constant water/binder ratio of 0.39. Concrete samples were either cured in water at (23±1°C), or steam cured at 65°C maximum temperature over six hours (6h) curing period. Tests of mechanical strengths were performed on specimens cooled down slowly to room temperature after heating.The obtained results show that all self-compacting mixtures exhibited satisfying fresh properties and check EFNARC specifications of self-compacting concrete (slump flow diameter higher than 650mm, L-box ratio higher than 80% and sieve stability less than 17%).Mechanical strengths of concrete containing limestone addition are slightly lower than those of concrete based on silica fume at all ages. Moreover, heat treatment generates an improvement of compressive and flexural strength. Interesting compressive strengths are obtained. At 24 hours, after heat treatment, the strengths are already greater than 35 MPa. The values are 37 MPa and 40 MPa for self-compacting concrete containing limestone powder and silica fume respectively compared to 40 MPa and 46 MPa obtained at 7 days for the corresponding non-heat treated concretes. Compressive strength gain of SCCs mixtures with limestone powder and with silica fume, undergoing heat treatment at the age of 24hours is 85% and 75% respectively compared to SCCs mixtures cured in water.

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Effect of the degree of corrosion on bond performance of Cement Polymer Composite (CPC) Coated steel rebars

MATEC Web of Conferences ◽

10.1051/matecconf/201819904010 ◽

2018 ◽

Vol 199 ◽

pp. 04010

Author(s):

Deepak K. Kamde ◽

Radhakrishna G. Pillai

Keyword(s):

Bond Strength ◽

Polymer Composite ◽

Continuous Monitoring ◽

Coated Steel ◽

Bond Performance ◽

Pull Out ◽

Curing Period ◽

Uncoated Steel ◽

Concrete Coating ◽

Steel Rebars

Currently, large infrastructures (bridges, highways, etc.) are designed for more than 100 years. To achieve long service life, coated rebars (mostly, cement polymer composite (CPC) coated rebars) are being used to enhance the corrosion resistance. However, inadequately coated rebars can lead to premature corrosion. This can also affect the bond between the rebar and the concrete. To assess the effect of CPC coating on bond strength, pull-out specimens of (150×150×100) mm with 12 mm diameter rebar with 100 mm embedded length were cast and tested. For this, three replica specimens with two types of reinforcement namely, i) Uncoated steel ii) CPC coated steel were cast. To induce corrosion, additional five specimens with CPC coated steel rebars were cast with premixed chloride and cured for 28 days. During the curing period, continuous monitoring of corrosion potential and rate was done and degree of corrosion was assessed. The effect of degree of corrosion on bond of steel-concrete-coating interface was quantified. The CPC coated rebars without corrosion exhibited 10% bond reduction. CPC coated rebars with corrosion exhibited 30-70% reduction in bond strength. Also, the corrosion is found to adversely influence the stiffness of the bond.

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Effect of Fly Ash and Slag on the Resistance to H2S Attack of Oil Well Cement

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.79-82.71 ◽

2009 ◽

Vol 79-82 ◽

pp. 71-74

Author(s):

Qi Wang ◽

Lin Qiao ◽

Peng Song

Keyword(s):

Fly Ash ◽

Compression Strength ◽

Blended Cement ◽

Oil Well ◽

X Ray Diffraction ◽

X Ray ◽

Curing Period ◽

Oil Well Cement ◽

Xrd Patterns ◽

Well Cement

In this paper, the resistance to H2S attack of pastes made from slag-fly ash blended cement used in oil well (SFAOW) was studied, in which fly ash (FA) was used at replacement dosages of 30% to 60% by weight of slag. Samples of SCOW and SFAOW pastes were demoulded and cured by immersion in fresh water with 2 Mp H2S insulfflation under 130oC for 15 days. After this curing period, compression strength and permeability of the samples were investigated. The reaction mechanisms of H2S with the paste were carried out through a microstructure study, which included the use of x-ray diffraction (XRD) patterns and scanning electron microscope (SEM). Based on the obtained data in this study, incorporation of FA into SCOW results in the comparable effects in the resistance to H2S attack. When the replacement dosage of slag is about 40%, the paste exhibits the best performance on resistance to H2S attack with compression strength 36.58Mp.

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Effect of TiO2Nanoliquid on the Properties of Cement Mortar

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i3.12.16029 ◽

2018 ◽

Vol 7 (3.12) ◽

pp. 223

Author(s):

C Prabalini ◽

Z Aysha Farsana ◽

A Sumathi

Keyword(s):

Outer Surface ◽

Cement Mortar ◽

Heat Of Hydration ◽

New Methods ◽

Curing Period ◽

Lime Water ◽

To Come ◽

Strength And Durability

Mortar/Concrete is effectively used in the construction of buildings. In the view of developing the infrastructure, it is essential to come up with new methods. Generally, the mortar which is being used has numerous pores in it and thus the strength gets reduced and the absorption increases. To reduce the durability problems nano liquid is being added. Nano liquid has the advantages of anti microbial and anti UV action. This paper deals with the nano liquid on the properties of cement mortar with two curing medium (water and saturated lime water) for 3, 7 and 28 days and the results were compared with control mortar in terms of strength and durability. Nano liquid was added in terms of 2.5ml, 5ml, and 7.5ml per kg of cement. After the completion of curing period the nano liquid is uniformly sprayed on the outer surface of the mortar cube. Since the nano liquid emits heat, the curing is made with lime to reduce the heat of hydration.

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