Structural Concrete Contents for Volume 9 (2008)

Written on 19 August 2011.

No. 1, March 2008 - Contents

1. Editorial
   P.G. Gambarova
2. Recent development in fire design of concrete structures
   N.P. Høj
   Abstract     Article
3. Concrete spalling assessment methodologies and polypropylene fibre toxicity analysis in tunnel fires
   G.A. Khoury
   Abstract     Article
4. Today's concretes exposed to fire-test results and sectional analysis
   P. Bamonte, P.G. Gambarova and A. Meda
   Abstract     Article
5. Non-linear and plastic analysis of RC beams subjected to fire
   P. Riva and J.-M. Franssen
   Abstract     Article
6. Flexural response of reinforced concrete beams exposed to fire
   V. Kodur and M. Dwaikat
   Abstract     Article
7. Mass transport through concrete walls subjected to high temperature and gas pressure
   A. Laghcha, G. Debicki and B. Masson
   Abstract     Article

No. 2, June 2008 - Contents

1. Editorial
   K. Sakai
   Article
2. An experimental investigation on beam supported reinforced concrete skew slabs
   K. U. Muthu, M. U. Aswath, A. Prabhakara
   Abstract     Article
3. A finite element formulation for concrete structures in plane stress
   G. Bertagnoli, V. I. Carbone
   Abstract     Article
4. Strength and durability of high-volume fly ash concrete
   G. Baert, A.-M. Poppe, N. De Belie
   Abstract     Article
5. Mechanical properties of high-volume fly ash self-compacting concrete mixtures
   P. Dinakar, K. G. Babu, M. Santhanam
   Abstract     Article

No. 3, September 2008 - Contents

1. Editorial
   S. Helland
   Article
2. Bond behaviour of NSM FRP strips in service
   K. Borchert, K. Zilch
   Abstract     Article
3. Analysis and cost optimisation of prestressed concrete joists in beam-block floors
   V.C. de Castilho, M.C. Vidigal de Lima
   Abstract     Article
4. Load carrying capacity of cracked concrete railway sleepers
   H. Thun, S. Utsi, L. Elfgren
   Abstract     Article
5. Effect of grout proportions on strength of two-stage concrete
   H.S. Abdelgader, A.A. Elgalhud
   Abstract     Article

No. 4, December 2008 - Contents

1. Concrete coating for marine pipelines
   M. Braestrup
   Abstract     Article
2. Post-heating bond behaviour between lightweight fibrous concrete and steel
   R.H. Haddad, Z.G. Al-Kofahi
   Abstract     Article
3. Engineering the construction of the Stonecutters Bridge concrete backspans
   G. Morgenthal, R. Sham, K. Yamane
   Abstract     Article
4. Fatigue life of short-span reinforced concrete railway bridges
   M. Pimentel, E. Brühwiler, J. Figueiras
   Abstract     Article

Structural Concrete, Vol. 11, no. 4, December 2010

Written on 19 August 2011.

Utilisation of olive waste ash in mortar mixes

N. M. Al-Akhras, University of Dammam, Dammam, Saudi Arabia
M. Y. Abdulwahid, Koya University, Kurdistan Regional, Iraq

Huge amounts of olive waste residues are accumulated every year in olive-oil-producing countries, making an environmental impact. This study investigates the utilisation of olive waste ash in mortar mixes to reduce the environmental pollution arising from olive waste residue. Three olive waste ash levels were considered in the study: 5, 10 and 15%. The other experimental parameters investigated in the study were: replacement type (cement or sand), curing type (moist and autoclaving) and aggregate type (silica and limestone sand). The properties investigated in the study include: fresh properties (workability and setting time), mechanical properties (compressive and flexural strength) and microstructure of mortar. The mortar mixture proportions were 1: 3: 0.7 by weight for cement, sand and water, respectively. The results showed that the setting time and workability of mortar decreased with increasing the olive waste ash content. The mechanical properties of mortar increased with increasing the olive waste ash content as a partial replacement for the sand. On the other hand, the compressive and flexural strength of mortar decreased when more cement was replaced with olive waste ash. The mechanical properties of olive waste ash mortar using silica sand showed higher values compared to those using limestone sand. Scanning electron microscopy images show that the hardened matrix of mortar containing 15% olive waste ash as a partial replacement for silica sand was denser and had a more homogeneous microstructure in comparison with the reference and mortar mixes with olive waste ash as cement replacement. 

Structural Concrete, Vol. 11, no. 4, December 2010

Written on 19 August 2011.

Strength properties of HPC using binary, ternary and quaternary cementitious blends

K. Chinnaraju, Anna University, Chennai, Tamilnadu, India
K. Subramanian, Coimbatore Institute of Technology, Coimbatore, Tamilnadu, India
S. R. R. Senthil Kumar, P.P.G. Institute of Technology, Saravanampatti, Coimbatore, Tamilnadu, India

Use of high-performance concrete for structural applications has grown substantially in recent years. This paper focuses on studying the effect of different supplementary cementitious materials (silica fume, fly ash, ground granulated blast furnace slag, and their combinations) on strength characteristics of high-performance concrete. An experimental test programme was conducted to study the effect of such admixtures on compressive strength at 7 days and 28 days, splitting tensile and flexural tensile strengths at 28 days for high-performance concrete. A set of 60 different concrete mixtures were cast and tested with different cement replacement levels (0, 10, 20 and 30% by weight of cement) by various combinations of fly ash and ground granulated blast furnace slag with silica fume as addition (0, 2.5, 5, 7.5, 10 and 12.5% by weight of cement) for each combination. Super plasticiser was added at different dosages to achieve a constant range of slump for desired workability with a constant water-binder (w/b) ratio. Based on the test results the influence of such admixtures on strength aspects were critically analysed and discussed. A regression analysis has been carried out to relate compressive strength to flexural and splitting tensile strengths. 

Structural Concrete, Vol. 11, no. 4, December 2010

Written on 19 August 2011.

Flowable high-strength system as repair material

E. T. Dawood, School of Housing, Building and Planning, Universiti Sains Malaysia, Penang, Malaysia
M. Ramli, School of Housing, Building and Planning, Universiti Sains Malaysia, Penang, Malaysia 

The use of steel fibres in concrete or mortar is known for its potential to enhance the flexural toughness, the energy dissipation and the impact resistance for many structural applications, especially in building repairs and other civil engineering works. The use of steel fibres in flowable mortar provides a great advantage in arresting cracks and enhancing the flexural rigidity of the composite material. Hence, this experimental investigation was performed to provide a clear indication and understanding of the behaviour and structural performance in engineering construction. The experimental tests conducted were: density, compressive strength, splitting tensile strength, flexural strength and toughness indices tests. These tests are required to show that the best performance of high-strength flowable mortar or high-strength flowing concrete could be fulfilled by using steel fibres and the optimal percentages of silica fume as partial replacement of cement. The conductivity of the repair material was evaluated by adoption of some combined systems of repair materials with concrete to determine the bond action of this repair material (flowable high-strength system). The results indicate that the high-strength flowing concrete has an excellent performance in terms of compressive strength for the repaired system. On the other hand, the high-strength flowable mortar improves significantly the tensile strength of the repaired system. 

Structural Concrete, Vol. 11, no. 4, December 2010

Written on 19 August 2011.

Punching of RC slabs under eccentric loads

M. Farzam, University of Tabriz, Iran
N. A. Fouad, Institut für Bauphysik, Leibniz University,Germany
J. Grünberg, Institut für Bauphysik, Leibniz University,Germany
M. Y. Fard, University of Tabriz, Iran

The main objective of this paper is to study the effect of eccentricity of loads on the ultimate punching resistance and rotational capacity of slabs. A mechanical model recently proposed by Muttoni, which has been developed to predict the punching capacity of slab-column connections under concentric loads, is developed in the same manner as that of Broms to be applicable for the investigation of rotational capacity of slabs under eccentric loads. Furthermore, the effect of eccentricity of load on the ultimate punching resistance and the rotational capacity of slabs with respect to column is numerically studied performing a non-linear finite-element analysis using Atena. The numerical analyses consist of calculations of selected punching tests. The factors affecting the behaviour of the connections, such as the ratio of tension reinforcement, the type of reinforcement steel and the concrete compression strength are studied parametrically. The results of the analyses are compared with Eurocode 2 and ACI code predictions and with the mechanical model previously proposed by Broms and the model developed by Muttoni. 

Structural Concrete, Vol. 11, no. 3, September 2010

Written on 19 August 2011.

Study of underwater concrete using two-stage (preplaced aggregate) concrete in Libya

Hakim Abdelgader, Al-Fateh University, Libya
Manal Najjar, Al-Fateh University, Libya
Tareq Azabi, Bonyan Consulting Engineers, Tripoli, Libya 

Placement of concrete underwater is necessary in the implementation of most in-shore, and off-shore structures. The pouring of underwater concrete is considered to be a challenge for engineers, even during the design stage or during implementation and supervision. This is because many precautions must be taken to ensure the success of the casting process. The most important of these is to protect the fresh concrete from the water during the casting process to avoid the risk of wash-out of the cement past and segregation of aggregates. Concrete can be placed underwater successfully through good design of the concrete mix and choosing the most suitable method for placing of the concrete. There are new techniques for underwater concreting such as grouted aggregate; this is known as the two-stage concrete method. The main objective of this paper is to present the capability of pouring concrete underwater using this method. A laboratory model was prepared, visually investigated and tested by extracting core samples, then performing compressive, tensile and ultrasonic pulse velocity tests. From the results obtained it has been observed that concrete can be poured successfully underwater using the two-stage method, and it is recommended that this research may be developed by using different water-cement ratios and cement-sand ratios to obtain the optimum mix design; also, different types of aggregates, which are available in local quarries, may be used.