A STUDY OF SELF-COMPACTING CONCRETE MADE WITH MARGINAL AGGREGATES Shamsad Ahmad∗, Abul Kalam Azad, and Mohammed Abdul Hameed Department of Civil Engineering King Fahd University of Petroleum & Minerals Dhahran, Saudi Arabia
1. INTRODUCTION Self-compacting concrete (SCC), developed first in Japan in the late 1980s, represents one of the most significant advances in concrete technology in the last two decades. SCC was developed to ensure adequate compaction through self-consolidation and facilitate placement of concrete in structures with congested reinforcement and in restricted areas. SCC can be described as a high performance material which flows under its own weight without requiring vibrators to achieve consolidation by complete filling of the formworks even when access is hindered by narrow gaps between reinforcement bars . The high flowability of SCC makes it possible to fill the formwork without vibration . The constituent materials used for the production of SCC are the same as those for conventionally vibrated normal concrete except that SCC contains a lesser amount of aggregates and larger amount of powder (cement and filler particles smaller than 0.125 mm) and special plasticizer to enhance flowability. Fly ash, glass filler, limestone powder, silica fume, etc. are used as the filler materials. High flowability and high segregation resistance of SCC are obtained by using: (i) a larger quantity of fine particles, i.e. a limited aggregate content (coarse aggregate: 50% of the concrete volume and sand: 40% of the mortar volume) ; (ii) a low water/powder ratio; and (iii) a higher dosage of superplasticizer and stabilizer [4, 5]. Stabilizer is needed for SCC mixes for maintaining proper cohesiveness so that highly flowable SCC would not segregate. Typical ranges of proportions and quantities of the constituent materials for producing SCC are reported in the literature [2, 6–9]. Relevant information regarding design of SCC mixtures is reported by Su et al. , Patel et al.  and Sonebi [11 and 12]. Various tests for assessment of compactibility and flowability are described by EFNARC . The strength of SCC has been reported by many researchers [10, 13–15]. The bond behavior of SCC was found to be better than that of normally vibrated concrete . A relatively low modulus of elasticity can be expected, because of the high content of ultra fines and additives as dominating factors and, accordingly, minor occurrence of coarse and stiff aggregates at SCC [17, 18]. Shrinkage and creep of the SCC mixtures have not been found to be greater than those of traditional vibrated concrete [9, 19, and 20]. Studies on durability characteristics of SCC, namely, water absorption, initial surface absorption, water permeability, and chloride permeability, have shown that SCC has either performed better or same as the normal concrete [9, 10, 21]
Address for correspondence: PO Box 1403 King Fahd University of Petroleum & Minerals Dhahran-31261, Saudi Arabia Fax: 966-3-8602879 E-mail: email@example.com Paper Received 25 June 2007; Revised 21 January 2008; Accepted 22 March 2008
The Arabian Journal for Science and Engineering, Volume 33, Number 2B
Shamsad Ahmad, Abul Kalam Azad, and Mohammed Abdul Hameed
In view of the fact that SCC has not yet made any inroad into Saudi Arabia’s construction industry, this study was undertaken with the aim to shed some informative data on SCC made from locally available aggregates. Most of the coarse aggregates available in the eastern region of Saudi Arabia are crushed tertiary age weaker dolomitic limestone. As the aggregates are porous, highly absorptive, relatively soft, and excessively dusty, they can be classified as “marginal”. The aeolian dune sands in the coastal areas form the main source of fine aggregate. These sands are essentially fine grained and have narrow grading with...