Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : compacting concrete

Performance of Self-Compacting Concrete Containing Pozzolanic Materials in Aggressive Environment

L.A. Zghair; Q.J. Frayyeh; M.M. Salman

Engineering and Technology Journal, 2017, Volume 35, Issue 5, Pages 439-444

The aims of this study is to investigate the resistance of different SCC mixtures to aggressive solutions. The investigation included the type of the cementitious materials (silica fume and high reactivity Attapulguite-HRA) and limestone powder (chalk powder and Al-gubra). The powder content of the mixes was kept constant, 500 kg/m3. The slump flow, L-box, and V-funnel were performed for mixes in there fresh state. In the present work, the specimens were immersed in sulfuric acid solution with a concentration of 0. 5% up to 289 days after normal curing for 28 days. After concrete has hardened, two types of test are performed. Firstly, destructive tests are conducted including (compressive strength, splitting tensile strength, and modulus of rupture). Secondly, a mass loss as non-destructive test is performed. The results obtained from this work, show that concrete mixes with chalk powder only, had the best resistance to sulfuric acid solution comparable with concrete made with Pozzolanic materials the reduction in compressive strength was 25. 9 %. In addition, concrete mixes with HRA had the worst resistance.

Behavior of Tapered Self-Compacting Reinforced Concrete Beams Strengthened by CFRP

T.S. al-Attar; S.S. Abdulqader; S.K. Ibrahim

Engineering and Technology Journal, 2017, Volume 35, Issue 3, Pages 197-203

This study presents an experimental investigation on the behavior of fourteen reinforced self-compacting concrete tapered beams with or without strengthening. The strengthening was applied by using carbon fiber reinforced polymer (CFRP) to beams with simply supported span and subjected to two points loading. Those beams have an overall length of 2000 mm, a width of 150 mm and a height of 250 mm at supports (hs) and a mid-span depth (hm) varies between 150 mm and 200 mm and with different strengthening scheme, they are investigated to evaluate the behavior at experimental test and to study the effect of the parameters which include haunch angle α, shear-span to effective depth ratio a/d and strengthening strips number and locations on beams behavior. The experimental results show that decreasing the value of haunch angle α increased the load capacity by about 56% and decreased the corresponding deflection while when tapered beams are strengthened by CFRP the ultimate load is increased up to 39% with decrease of deflection. On the other hand, increasing a/d ratio leads to a decrement in load capacity and increment in deflection.

Structural Behavior of Self Compacting Reinforced Concrete Deep Beams Containing Openings

Nabeel A. AL-Bayati; Bassman R. Muhammad; Ahmed Salam Hasan

Engineering and Technology Journal, 2016, Volume 34, Issue 12, Pages 2310-2317

Eleven simple span reinforced self-compacting concrete deep beams were tested under symmetrically two points top load to examine the influence of the transverse circular openings on their behavior. The variables investigated involve shear span to effective ratio a/d, opening sizes and locations and the amount of inclined reinforcement around the openings. All the beams had the same overall dimension, flexural reinforcement and concrete compressive strength. The test results showed that when the opening positioned at the center of the shear span significantly affects the behavior of the beams tested regardless of a/d ratio and size investigated. Also, it was found that when the opening of a large diameter positioned away from the load path either in thetopor bottom region of the beam reduces the cracking and ultimate load considerably. The inclined reinforcement around the opening was observed to be very efficient in improving the ultimate load capacities and deflection response.

Fresh and Hardened Properties ofLightweight Self CompactingConcrete Containing Attapulgite

Waleed A. Abbas; Qais J.Frayyeh; Shubbar J. Al Obaidey

Engineering and Technology Journal, 2016, Volume 34, Issue 9, Pages 1767-1781

The main objectives of this study were investigating the possibility of producing lightweight self -Compacting concrete (LWSCC) by using artificial coarse lightweight aggregate manufactured by burning locally available Attapulgite clay, estimating the optimum dosage of high reactivity Attapulgite (HRA) and studying its effects on fresh and hardened properties of LWSCC when using it as a partial replacement by weight of cement.Tests results showed that, It is possible to produce (LWSCC) by using Attapulgite as artificial coarse (LWA) and (HRA).The optimum content for (HRA) used in this study was 10 %, the percentages of increment in compressive strength and splitting tensile strength with 10% (HRA) relative to reference mix were (10.0%, 12.1%, 11.1% and 12.4%) and ( 12.0%, 18.2%, 16.6% and 16.2%) for 7, 28, 56 and 90 days respectively.The values of the calculated equilibrium density ranged between (1788 and 1829) kg/m3

Behavior and Strength of Concentrically Loaded Flat Slabs Using Self-Compacting High Strength Concrete With and Without Openings with Steam Curing

Esraa Khudhair Mohsin Abuzaid

Engineering and Technology Journal, 2016, Volume 34, Issue 3, Pages 648-663

Openings in slabs are usually required for plumbing, fire protection pipes, and ventilation ducts and air conditioning.
This study presents an experimental investigation on the influence of openings on the punching shear strength of high reinforced concrete flat plates. Five models of slab-column connection of (1000 x 1000 x 70mm) simply supported along the four edges are tested. The slabs are loaded concentrically by a central stub column. The main variables studied are the size(100x100mm and 200x100mm)and location(at 35 mm , at 135mm from center of slab and at the corner of slab) of the openings and used steam curing method.
Experimental results are recorded and studied at various stages of loading, deflection at the center of the slab, at distance (150mm) from the center of the slab in two directions and at the edge of the tested slab out of support. First cracking load and ultimate load capacity are also recorded.

Punching Shear Behavior of Fibrous Self -Compacting Concrete Flat Slabs

Mutaz Kadhim Medhlom

Engineering and Technology Journal, 2014, Volume 32, Issue 12, Pages 2874-2890

This research is devoted to study the mechanical properties of fibrous self-compacting concrete (FSCC) as materials as well as studying the punching shear behavior of FSCC slabs. The experimental program includes investigating the effect of steel fiber volumetric ratio (Vf) and absence of limestone powder on some important mechanical properties of FSCC such as compressive strength, modulus of elasticity, splitting tensile strength and modulus of rupture. Additional experimental tests are also conducted to study the effect of Vf, steel reinforcement ratio (ρ) and slab thickness on the punching shear behavior (in terms of load-deflection response and ultimate failure load),and the failure characteristics of the punching shear (in terms of observation of failure, shape of the failure zone, size of the failure zone, failure angles, critical section perimeters and ultimate punching shear stress ) of simply supported reinforced FSCC slabs having dimensions of 1000×1000× 50 or 70 mm under concentrated load at the center of the slab.

Direct Shear Behavior of Carbon Fiber Reinforced Self- Compacting Concrete

Kaiss F. Sarsam; Tareq S. Al-Attar; Ghzwan Ghanim Jumah

Engineering and Technology Journal, 2014, Volume 32, Issue 10, Pages 2491-2513

This paperrepresents an experimental and statistical investigation for the behavior of connectionpoints produced by using self-compacting concrete and subjected to direct shear. The investigation also includes the effect of carbon fiber inclusion as reinforcement on self-compacting concrete (SCC) behavior in direct shear.
This study gives results of sixteen push-off or direct shear specimens in four groups. Variations include volume fraction for carbon fiber (V_f= 0.00, 0.50, 0.75 and 1.00) % for every percentage change in the steel reinforcement. The steel reinforcement parameter ρ_vf f_y values are (0.00, 2.66, 5.33 and 7.99) MPa(where ρ_vf varies from 0.00 to 0.0173 and f_y=585.7MPa) . The main material properties studied include compressive strength, splitting tensile strength and modulus of rupture. Measurements of deformations were made throughout testing of shear specimens.
The dimension of the shear plane in the push-off specimenswas 170x185 mm. The shear reinforcement was normal to the shear plane. Specimens were cast by using SCC which is a type of high performance concreteand reinforced with carbon fiber.
This work aims to investigate the direct shear behavior of SCC with or without carbon fiber at constant water to cementitious materials ratio of 0.3 by weight. It is found that using carbon fiber increased the direct shear strength. However, carbon fiber alone (without reinforcement) leads to brittle failure. In contrast, adding rebars leads to higher strain and more ductile behavior-increased shear capacity is obtained when higher steel quantity is used. The aim of adding carbon fibers was the increase of the horizontal strain (displacement). It was found that the optimum percentage of volume fraction was 0.75 % for fresh and hardened concrete.
In addition, the effects of carbon fiber on compressive strength of SCC lead to a drop in compressive strength (f_c^') compared with reference specimens. This drop in f_c^' was 2.39, 8.38 and 13.58% for V_f=0.50, 0.75 and 1.00%, respectively. In contrast, the splitting tensile strength increased by 3.34, 31.2 and 18.2 as compared with the cylinder strength without carbon fibers atV_f equal to0.50, 0.75 and 1.00% respectively. The modulus of rupture increased by [11.9, 21.99 and 13.83%] as compared with SCC without carbon fibers at〖 V〗_f equal to 0.50, 0.75 and 1.00% respectively.
Based on push-off tests results for this work and those available in the literature, two statisticalmodels have been established using regression analysis. Four variables f_c^',f_ct,ρ_vf f_y and V_f, were included in these models. Both models showed good representation according to their coefficients of variation (COV)values. Verification of the models were done by using 273 observations from literature and the present work.

A Data Base for Self-Compacting Concrete in Iraq

Shakir A. Al-Mishhadani; Mays F. Al-Rubaie

Engineering and Technology Journal, 2009, Volume 27, Issue 6, Pages 1206-1218

Self-Compacting Concrete is considered one of most remarkable developments in
concrete technology. It is a new type of high performance concrete with the ability of
flowing under its own weight and without the need of vibrations. Recently, a great native
interest had been derived towards self-compacting concrete.
This work aims to present a summary study about properties of fresh selfcompacting
concrete depending on the results obtained by some native researches, thus
focusing on the main common features between their results. It had been focused on the
effect of type and proportions of constituent materials incorporated in producing selfcompacting
concrete. This considered the most influential factors in controlling its