*Corresponding Author: y.hummaida@uofk.edu (Yousif Hummaida Ahmed) Received 22 Aug 2019 Revised 26 Oct 2019 Accepted 26 Oct 2019 Cement Based Composites 1 (2020) 6-10 xxxx-xxxx © 2019 ACA Publishing. Allrightsreserved. https://doi.org/10.36937/cebacom.2020.001.002 6 Cement Based Composites 1 (2020) 6-10 Cement Based Composites www.acapublishing.com Research Article Proportioning Self Compacting Concrete in Hot Weather Utilizing Limestone Powder Khalid Salah Eldin Babikir, Yousif Hummaida Ahmed Department of Civil Engineering, Faculty of Engineering, University of Khartoum. Abstract Self-compacting concrete (SCC) is a special type of concrete able to flow and compact under its self-weight. The SCC requires high powder content (mainly of cement) up to 600kg/m 3 to achieve its properties. This will be problematic if all cement content in the powder exceeded 400 kg/m 3 used in hot weather of Sudan. This paper investigates addition of Sudanese limestone powder (LSP) to reduce cement content. The LSP dosages between 20% and 28 % (by cement weight) are used in six mixes having maximum cement content 380kg/m 3 . Results show that five trial mixes achieved the self-compactibility tested by slump flow, sieve segregation, V-funnel and U-box tests. Compressive strength of these mixes show that the LSP increases strength with dosage. Therefore, further investigations of hardened concrete properties are recommended for the successful mixes to be applied in real projects in the Sudan. Also, it has been found that dry batching and forced-action pan mixers are the most suitable for producing SCC with high homogeneity compared to commercial tilted-drum mixers. Keywords: Self compacting concrete (SCC), Limestone powder (LSP), Slump flow (SF), Sieve segregation (SR), V-Funnel (VF), U–Box, Hot weather SCC mix design. 1. Introduction According to BS EN 206-9:2010 [1] SCC is defined as "Concrete that is able to flow and compact under its own weight, fill the formwork with its reinforcement, ducts, box outs etc., whilst maintaining homogeneity". It was first developed inside Japan in1986 by Professor Okamura [2]. The idea was picked up and developed in Europe around 1997-2000 [3].There are many advantages of using SCC including: reducing the noise pollution and decrease human's hazard due to vibration, decrease of construction time and labors, increase compressive strength and improving durability caused by reducing permeability, and finishing [4]. SCC mix design has been developed based on key properties of a fresh stage defined as: flow-ability, Passing-ability, Segregation resistance and Viscosity as defined in BS EN 206-9:2010 [1]. There are two types of SCC according to mix materials such as: viscosity modifying admixture (VMA) type and/or powder type [5]. The powder type of SCC requires high cement content. This leads to increase in cost and will be problematic if used in the tropical weather Such as Sudan by increasing thermal cracks, hence reduces durability of concrete. Minerals additives, namely pozzolanic (supplementary cementation materials) such as fly ash, bagasse ash, grand granulated blast furnace slag (GGBS), silica fume, ground brick powder, metakolin, and rice husk ash have been used as partial replacement of cement [6,7]. Also filler materials such as limestone powder (LSP) up to 20% of binder by weight have been used [7]. Moreover, the addition of LSP improves consistence of SCC. It also enhances the rate of cement hydration and strength development, besides improving deformability and stability of SCC [8]. However, SCC needs more quality control and advance mix design, with more testing. Using mineral additives and fillers materials helps to improve properties of SCC. This improvement includes decreasing shrinkage, permeability, as well as increasing compressive strength [9]. In this study an empirical design method [4] has been used to obtain six concretes mix designs in two types of mixers. These SCC mixes are tested for their properties and classified. This paper describes mix design method for the SCC limit maximum cement content to 380 kg/m3in order to reduce hydration heat in tropical weather of Sudan. Moreover, it has investigated the influence of LSP on fresh SCC properties and the effect of mixing procedures. This paper is composed of this section, state of art, materials and methods, results and discussions and conclusions and recommendations. 2. State of The Art 2.1 Mix Design: There are many mix design methods of SCC. The best estimation of SCC proportions is based on trial mixes, i.e. empirical methods, and adjustment of initial mixture [4]. European guideline [3] states indicative typical range of constituents in SCC by weight and volume. It has been reported that SCC mix design is not based on strength similar to normal concrete [9].Okamura and Ouchi [2] stated that SCC could be achieved by achieving stability between flow-ability and viscosity of paste and mortar. A filler (powder) material is a ground material which passed 0.15 mm grounded similar to Portland cement fineness; it can be natural materials or processed mineral materials. It has uniform properties and fineness [10]. According to BS EN 197- 1:1992 [11], filler or additive has been limited to 5% of cement content by weight. However, it allows the use of LSP up to 35% of cement content. The viscosity of cement-based materials can be improved by decreasing water/powder ratio (W/P) and/or using viscosity modifying admixture (VMA).