Ultra-high performance concrete – properties and technology

Abstract

Abstract. The paper deals with information concerning properties and technology of a new generation cementitious composite i.e. Ultra-High Performance Concrete. High performance here means both high strength and high durability under the influence of environmental factors. This group of composites is mainly represented by Reactive Powder Concretes (RPC), which show both outstanding durability and mechanical properties. Characteristic features of RPC are mainly due to the very low water-cement ratio, which involves application of superplasticizer, significant reduction of aggregate grains size as well as hydrothermal treatment. In the first part of the paper selected properties of RPC are compared to ordinary concrete and to other groups of new generation concrete. Moreover, fundamental technological factors influencing properties of RPC are described as well. The second part deals with the RPC developed at Cracow University of Technology. The presented test results are mainly focused on the influence of steel fibres content on mechanical properties of reactive powder concrete and hydrothermal treatment on composites microstructure. The quantitative and qualitative evaluation of this relationship expand the knowledge of the UHPC technology. Finally, the third part presents the most significant and newest structures which have been erected with the use of RPC.

Open porosity of cement pastes and their gas permeability

“…Regardless of its many drawbacks, this method is considered to be very valuable and to provide a lot of information about the structure of the material being tested. Because of the broad range of pore identification, this method is also used to assess the microporosity structure of many other materials with a mineral skeleton, including advanced cement composites like High Performance Concrete (HPC), Ultra High Performance Concrete (UHPC) and Reactive Powder Concrete (RPC) [24][25][26].…”

Effect of Mix Proportion Parameters on Behaviors of Basalt Fiber RPC Based on Box-Behnken Model

“…where k is the number of factors and C p is the number of center points. Through the BBD method, a quantitative mathematical relationship (linear equation of quadratic polynomial) can be obtained to accurately reflect the relationship between process variables and response variables, Equation (2).…”

“…Silicon-containing materials such as silica fume and fly ash are usually added into RPC as active components. SiO 2 in these materials reacts with Ca(OH) 2 and calcium silicate hydrate (C-S-H) produced by cement hydration to generate a cementitious substance [2], which can improve the microstructure of matrix [3]. The compressive strength of RPC can reach 200-800 MPa, which has superior mechanical properties compared with traditional concrete materials.…”

Influence of the Physicochemical Properties of Portland Cement on the Strength of Reactive Powder Concrete

“…its class, mineralogical and chemical composition and, finally, its specific surface area is very important since it is a factor influencing properties of the concrete mixture and, consequently, of the matured composite. The average values of the water-binder ratio in RPCs are in the range of 0.18 -0.25 [3], [4], [9]- [11], which in some cases allows obtaining the value of compressive strength exceeding 200 MPa. A parameter associated with consistency of the mixture (in the case of RPC usually expressed in cm as a flow measured on table for mortars [12]), according to [13], should be within very narrow limits of 25 -30 cm.…”