Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Compressive strength

Studying the Effect of Adding Marble and Porcelain Waste on Mechanical Properties of Concrete Containing Recycled Aggregate

A.S. AL-Luhybi

Engineering and Technology Journal, 2017, Volume 35, Issue 7, Pages 668-674

In this research an experimental study was carried out to investigate the effect of adding marble and porcelain waste as replacement of sand by certain percentages on mechanical properties of concrete containing (100%) recycled coarse aggregate and compare its properties with concrete mixture containing natural coarse and fine aggregate. Four mixes were prepared the first one is the control mix having natural coarse and fine aggregate, second mix containing (100%) recycled aggregate and natural fine aggregate, third mix containing (100%) recycled aggregate and (5%) marble waste as replacement of sand and last mix containing recycled aggregate(100%) and (10%) porcelain waste as replacement of sand.The ratios of Added Materials (marble, porcelain waste) depended on the results obtained from tested cement mortar cubes having different proportions of the two materials, the selected ratios were the ones giving the highest compression strength. The results of tests showed that using of recycled coarse aggregate as alternative to natural coarse aggregate gives good quality concrete and a compressive strength higher than the compressive strength of original concrete by (5.1%) and it helps increasing modulus of rupture by (19.5%) compared to the original concrete. The results show that using recycle aggregate lead to reducing tensile strength by (35%) compared to the original concrete. Using of marble waste as replacement of sand lead to significant increase in compressive strength by (5.1%), while using porcelain waste gives same compressive strength of reference mix. Using marble and porcelain waste lead to significant increase in tensile strength reach to (35%) and (17.6%) respectively. The results show there is an increase in modulus of rupture when using marble and porcelain waste reach to(24%) and (19.5%) respectively, but it reduced workability of concrete mixtures.

Study the Effects of Nano-Materials Addition on Some Mechanical Properties of Cement Mortar

F.A. Rasin; L.K. Abbas; M.J. Kadhim

Engineering and Technology Journal, 2017, Volume 35, Issue 4, Pages 348-355

This research involves nano-materials addition and interaction with cement mortar behavior for many mortar samples under variable curing time with constant water to cement ratio (W/C = 0.5). Some mechanical properties such as (compressive and flexural strength tests), durability (by water absorption test) were studied. The effect on the (Al-Mass cement) Ordinary Portland Cement (OPC) type (I) by additives with small amounts of nano-particles (SiO2) and (Al2O3) were investigated in this research. The nano materials additives were added on the mixture of mortar with the percentages (1, 2, 3, 4 and 5%) for both nano materials with constant (W/C) ratio and also the amount of the fine aggregate used three times the amount of cement. The results shows that, the strength of the mortar consist both nano materials give better properties than mortar without nano materials in all tests. But nano silica additive gives good properties up to (3%) than mortar with nano alumina additive which give proprietress up to (2%).

Investigate and Comparison Effect add Amorphous and Crystalline - Nano SiO2 on Properties of Concrete

Rami Joseph Aghajan Sldozian

Engineering and Technology Journal, 2015, Volume 33, Issue 3, Pages 547-555

In this paper, the study included the comparison between amorphous silica and crystalline silica (quartz), and with nano scale size, two types of silicawere added to concrete by ratios (5%, 10%, 15%, and 20%) as a replacement by the weight of cement. Destructive and non-destructive tests wereconducted on the specimens, the results show in destructive test the compressive and tensile strength increase in 15%wt addition ratio in both types of silica, but in amorphous silica was high than in quartz.The results of non-destructive tests show in (Schmidt Hammer) the 15% ratio in both kinds of silica show high hardness than other ratios. Ultra sonic (pules velocity) test, noted the better quality was in 15% ratio in amorphous silica and also show fastest pules velocity.

Effect of Using Windows Waste Glass as Coarse Aggregate on Some Properties of Concrete

Abdelmaseeh Bakos Keryou; Gailan Jibrael Ibrahim

Engineering and Technology Journal, 2014, Volume 32, Issue 6, Pages 1519-1529

In this experimental study, local waste glass (WG) gathered from Turkey-made windows glass has been used as a partial replacement of coarse aggregates with 0, 20, 25, and 30% percentages of replacement by weight. Some mechanical and other properties of the concrete, produced this way have been studied at both fresh and hardened stages.
The experimental results obtained from testing the specimens prepared from concrete mixes with water/cement ratio equal to 0.5, showed that using WG resulted in decreasing the slump and fresh density due to angular grain shape, whereas the compressive, splitting, and flexural strengths noticeably enhanced. Tests revealed that with increasing the WG percentage the strengths gradually increase up to a given limit beyond which they decrease. The maximum effect was reached at 25% percentage of replacement. At this percentage the increases in the compressive, splitting tensile and flexural strengths at 28-day age were 30, 38 and 31 %, respectively. The results of this study indicate a considerable economical effect from using the optimum percentage of WG (25%) as partial replacement of coarse aggregate.

Impact Resistance of Lightweight Chopped Worn-Out Tires Concrete

Zaid M. K. Al-Azzawi; Dhafir T. F. Al-Khameesi

Engineering and Technology Journal, 2010, Volume 28, Issue 16, Pages 5200-5212

This study summarizes results of an experimental investigation of the
impact resistance of 12 lightweight concrete slabs made from incorporating chopped worn-out tires (Ch.W.T.) into the mixes as a partial replacement of the sand in mortar mixes, and as partial replacement for both sand and gravel for concrete mixes; volumetrically.
The main variables were; the partial replacement ratio (PRR) and the shape of the falling mass (striker). Data were obtained pertaining to compressive strength, static and dynamic modulus of elasticity, and modulus of rupture. In addition, the crack pattern under impact loading was studied to provide insight into the internal behavior and failure mechanism of lightweight Ch.W.T. concrete slabs. Results of this work indicate that incorporating Ch.W.T. into mortar and concrete mixes succeeded in reducing its unit weight from 17.9% to 26.2% according to type of mix and partial replacement ratio. In contrast, the ultimate
impact resistance, expressed in the number of blows required for complete separation of the specimen, increased from 91% to 186% for mortar mixes depending on the partial replacement ratio and the type of falling mass; and did not decreased significantly for concrete mixes.

Using Citric Acid As An Admixture and It's Influence on Some Properties of Concrete

Wasan I. Khalil

Engineering and Technology Journal, 2009, Volume 27, Issue 1, Pages 32-41

The objective of this investigation is to find the effectiveness of the citric acid as
retarding admixture. The experimental results indicate that the optimum dosage of citric
acid is 0.02% by weight of cement. This dosage causes a delay in initial and final setting
time of 1:42 and 3:18 hour: minute, respectively; and a reduction in water-cement ratio
of 13% relative to reference concrete mix. So, citric acid can be classified according to
ASTM-C494 as water-reducing and retarding chemical admixture type D.
The investigation also extends to evaluate the effect of using citric acid on
properties of concrete such as, compressive strength, splitting tensile strength, modulus
of rupture and dynamic modulus of elasticity at normal conditions and after exposure to
salt solutions. Generally the results indicate that using citric acid in concrete enhance it's
properties at normal conditions, the percentage increase in compressive strength,
splitting tensile strength, modulus of rupture and dynamic modulus of elasticity at age
180 days was about 56%, 13%, 24% and 8% respectively relative to reference concrete.
Also it was observed that concrete containing citric acid has good performance after 180
days exposure to salt solution in comparison with reference concrete.

Effect of Coarse Aggregate Characteristics on Drying Shrinkage of Concrete

Tareq Salih Al-Attar

Engineering and Technology Journal, 2008, Volume 26, Issue 2, Pages 146-153

Concrete is a composite material, consisting, mainly, of three phases: coarse
aggregate, cement mortar, and the interface zone between them. The characteristics
of the interface zone largely govern the bond between cement paste or mortar and
aggregate. The restraining effect of aggregate to drying shrinkage strain depends
much on the bond between aggregate and cement paste.
In this paper, it is aimed to investigate the effect of coarse aggregate
characteristics, that affect bond strength, such as; type, shape, surface texture, and
moisture content, on drying shrinkage. Four types of coarse aggregate were used.
Three of them were normal-weight, while the fourth was a light-weight one. Each
type of coarse aggregate was used in two moisture conditions, dry and saturated.
The testing program extended to 150-days age and comprised; length change,
modulus of elasticity, compressive and splitting tensile strength of concrete.
It is concluded that using saturated coarse aggregate always yields higher
shrinkage strain than dry aggregate. The percentage increase seems to be affected
by the aggregate water absorption. At early ages, After 28 days, there is large
differences in relative shrinkage for different mixes. Later than 28 days, the
variation in ratios settled to approximately fixed values