Abstract
Reactive Powder Concrete (RPC) is an ultra-high performance concrete which has superior mechanical and physical properties, and composed of cement and very fine powders such as quartz sand and silica fume with very low water/ binder ratio and Superplasticizer. Heat treatment is a well-known method that can further improve the performance of (RPC). The current research including an experimental study of the effect of different curing conditions on mechanical properties of reactive powder concrete (compressive strength, modulus of rupture and splitting tensile strength), the curing conditions includes three type of curing; immersion in water at temperature of 35 OC (which is considered as the reference-curing situation), immersion in water at temperature of 90 OC for 5 hours daily and curing with hot steam for 5 hours daily) until 28 days according to ASTM C684-99 [8]. This research includes also the study of effect of adding silica fume as percentage of cement weight on mechanical properties of reactive powder concrete for different percentage ratios (5%,10% and 15%). Super plasticizer is also used with ratio of (1.8%) by weight of cementitious material; constant water cement ratio (0.24) was used for all mixes. For each reactive concrete mix, it has been cast into a cubes of (150*150*150) (to conduct the compression test), a cylinders of 150mm diameter with 300mm height (to conduct split test) and prisms of (500*100*100)mm to conduct the modulus of rupture test. The results showed that the best method of curing (according to its enhancing the RPC mechanical properties) is the method of immersion in hot water at temperature 90 OC for the all silica fume percentages, and the best used silica fume percentage was (10%) for the all used curing methods.
Highlights
The conventional concrete has a compressive strength of usually less than 40 MPa
The additive is commercially known as PC260, which is different from the standard super-plasticizers, which consists of long chain polycarboxylic ether polymers, which makes the concrete smooth and gives high compressive strength and the plasticizer is suitable for use with ordinary Portland Cement
The key to the production of Reactive Powder Concrete (RPC) is the high cement content, glass sand (150-600) micrometer, and the ratio of water to cement is very low with high content of super plasticizer, where the mortar consisting of quartz sand, cement and silica fume have a great effect on providing high resistance
Summary
The conventional concrete has a compressive strength of usually less than 40 MPa. It is relatively brittle and its resistant to plastic deformation is relatively low and have low tensile strength and the cracks appears fast. The Reactive Powder Concrete RPC, which was manufactured in France in the 1990s is a new type of high performance concrete which has good mechanical properties and durability [2] [3]. Researchers reported that application of different heat cure processes improve mechanical properties of RPC [4] The aim of the heat treatment of concrete is to increase the hydration speed and decrease the setting and hardening period. Besides conventional water curing (standard) of setting concrete, resistance can be gained in a shorter time with different curing methods. These kinds of cures that facilitate the resistance gaining are generally categorized as heat treatment [5]. Heat treatment is a well-known method that can further improve the performance of (RPC)
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