Journal of Materials and Engineering Structures

161-166

Authors: Rizwan A Khan, Atul Sharma

This study investigated the fresh and hardened properties of Self-Compacting Concrete (SCC) with different types and amounts of admixtures. Six mixes were prepared by replacing 30% of cement with different percentages of fly ash (FA), lime powder (LP) and metakaolin (MK). Water- Cement ratio was kept constant at 0.41 and superplasticizer dosage of 1% by weight of cement. The filling and passing ability were investigated through Slump Flow, J-Ring, V-funnel and L-box test before filling the moulds. The compressive strength of hardened SCC cubes was also measured after specified days of curing (7, 14, 28 & 60 days). The workability test results showed that as FA was replaced by increasing percentages of LP and MK, the mixes became dense and hence less workable. It was observed that the compressive strength showed an increase with increasing percentage replacement of FA with LP and MK. This increase was higher for mixes with MK than that of mixes with LP.

181-195

Authors: Y. Riyad, B. Kissi, I. Mrani, M.A. Parron, R.C.M. Dolores

Seismic retrofitting of constructions vulnerable to earthquakes is a current problem of great political and social relevance. During the last sixty years, moderate to severe earthquakes have occurred in Morocco (specifically in Agadir 1960 and Hoceima 2004). Such events have clearly shown the vulnerability of the building stock in particular and of the built environment in general. Hence, it is very much essential to retrofit the vulnerable building to cope up for the next damaging earthquake. In this paper, the focus will be on a comparative study between two techniques of seismic retrofitting, the first one is a reinforcement using carbon fiber reinforced polymer (CFRP) applied to RC elements by bonding , and the second one is a reinforcement with a shear wall. For this study, we will use a non-linear static analysis -also known as Pushover analysis - on a reinforced concrete structure consisting of beams and columns, and composed from eight storey with a gross area of 240 m², designed conforming to the Moroccan Seismic code

107-116

Authors: K. Kapoor, S. P. Singh, Bhupinder Singh

This paper reports the durability properties of Self Compacting Concrete (SCC) made with Recycled Concrete Aggregates (RCA) as partial/full replacement of Natural Coarse Aggregates (NCA). The effect of RCA on fresh properties of SCCs was measured using slump flow test, V-funnel test, L-box test and J-ring test. Whereas the durability properties like such as initial surface absorption, water permeability, capillary suction and rapid chloride penetrability were investigated to study the effect of varying content of RCA on SCC. The compressive strength of different SCC mixes was also determined for reference. The results indicate that increasing the content of RCA in SCC leads to deterioration in durability related properties of SCC. The compressive strength has also been found to decrease with increasing RCA content. It has been seen that the reduction in the performance has been marginal up to 50% replacement level of RCA, but 100% replacement of RCA has been found to significantly affect the durability related properties and compressive strength.

129-147

Authors: Rahul Sharma, Rizwan A. Khan

Concrete is the most widely used composite in the world. Ordinary Portland cement (OPC) is the most commonly used binding material but the energy required for its production is large and its production leads to release of green house gases in the atmosphere therefore, the need for supplementary cementitious material is real. The utilization of Fly Ash (FA), Silica Fume (SF),Metakaolin (MK) and Ground Granulated Blast Furnace Slag (GGBS), as a pozzolanic material for concrete has received considerable attention in the recent years. This interest is a part of the widely spread attention directed towards the utilization of wastes and industrial byproducts in order to minimize the Portland cement consumption, the manufacture of which is being environment damaging. The paper reviews were carried out on the use of FA, SF, MK and GGBS as partial pozzolanic replacement for cement in concrete. The literature demonstrates that GGBS was found to increase the mechanical and durability properties at later age depending upon replacement level. Silica fume concrete performed better than OPC concrete even at early period for production of high strength concrete and high performance concrete. Fly ash increases the later age strength due to slow rate of pozzlanic reaction. Metakaolin was found to improve early age strength as well as long term strength but had poor workability.

59-73

Authors: N Singh, S P Singh

The paper presents the results of an investigation conducted to examine carbonation resistance of Self Compacting Concrete (SCC) made with coarse Recycled Concrete Aggregates (RCA). In total, five SCC mixes were prepared by systematically replacing coarse Natural Aggregates (NA) by RCA at 0, 25, 50, 75 and 100%. In order to measure the carbonation resistance of SCC made with RCA, accelerated carbonation tests were performed for 4 and 12 weeks of exposure to carbon dioxide. The carbonation resistance has been evaluated after curing periods of 28 and 90 days. In addition to this, the compressive strength of all the mixes was also obtained after 7, 28 and 90 days of curing and ultra-sonic pulse velocity tests (UPV) were also conducted. The results indicate that with the increase in the content of RCA as replacement of NA, decrease in the carbonation resistance, compressive strength and UPV was observed for all SCC mixes. It has been observed that the SCC mixes containing low percentages of RCA (i.e. 25%) as replacement of NA do not impart detrimental behaviour in the overall performance but higher replacement levels (>50%) have been found to deteriorate the performance in terms of carbonation resistance, compressive strength and UPV.

83-93

Authors: Berrabah Hamza Madjid, Adda Bedia El Abbas, Naceri Mokhtar

The transverse shear behavior of the composite beams can be critical and must therefore be properly represented by the various models of structures normally used to predict their behavior or to identify their properties. We propose in this work, a warpage analysis in short laminated beams using a simple analytical approach based on the theories of higher order.

14-22

Authors: Hocine Hammoum, Akli Yahiaoui, Bachir Achour

We develop, in this paper, a method of calculating the water hammer inspired by the graphic construction of Bergeron, which we qualify as analytical method. In helping us of these graphs, we get the relationships that allow calculating the flow rates and pressures along a penstock. The flow of water is carried out by gravity adduction connecting at upstream a storage tank and at downstream a valve. In this first part, we neglect the pressure losses. The study will focus on water hammer-induced by a slow closing of the valve. A practical example will be presented at the end of this work in order to illustrate the exposed method.