Concrete Technology for Concrete Pumps
35Pages

Concrete Technology

Concrete Technology

Imprint Imprint Editor Putzmeister Concrete Pumps GmbH Max-Eyth-Straße 10, 72631 Aichtal, Germany Contents Contents Layout and Print Offizin Scheufele GmbH & Co. KG 70597 Stuttgart, Germany © 2011 by Putzmeister Concrete Pumps GmbH All rights reserved 6th Edition 12/2011 BP 2158-6 GB 2 Concrete Components – Base materials and their influences 9 1.1 1.2 1.3 1.4 1.5 1.6 Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Addition of water . . . . . . . . . . . . . . . . . . . . . ....

Contents Preliminary comments Contents Preliminary comments 5 Short guide to avoiding and eliminating faults 5.1 5.2 For the delivery of concrete and charging of the concrete pump . . . . . . . . . . . . . . . . 59 When pumping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 "Concrete is an artificial stone which is made from a mixture of cement, aggregates and water – and if necessary also with concrete admixtures and concrete additions (concrete additives) – by the hardening of the cement paste...

- according to the type of conveying and placing, -► cast concrete, pumped concrete, underwater concrete and sprayed concrete. - according to the type of compacting, the following types of concrete are -► tamped, rod, vibrated, jolted and spun concrete, easily workable concrete, self-compacting concrete • Green concrete concrete after initial setting and during hardening; can no longer be placed (it has begun to develop hardness) • Hardened concrete after hardening - according to the type of surface conditions, hardened concrete is subdivided exposed concrete, washed concrete, smooth...

Preliminary comments Nowadays, the pumping of freshly-mixed concrete is a link in the process chain that one can scarcely imagine living without. With the current state of concrete technology, pumpable concrete is no longer classed as a special concrete, instead it is a construction material regulated by the concrete standard DIN EN 206-1 / DIN 1045-2 with a specified composition as required with reinforced concrete for reinforced components (from C16/20, consistency F3). However, every good pump operator should have a basic knowledge of concrete technology. Pump operators should know which...

Concrete components The numerical data of the property classes usually refer to the minimum strength attained by test specimens after 28 days at a certain w/c ratio, measured in the respective countryspecific unit (e.g. in Germany: N/mm2, in Austria: kp/cm2). The strength development is by no means complete after 28 days; however, this value usually forms the basis for the strength calculation and the granting of permission to use the building. The setting of the cement (hydration) is a very complicated process where water is bound chemically and physically. When mixing cement and water a...

Suitable water is mixing water in accordance with DIN EN 1008. This standard includes gui- delines for limiting the content of harmful substances that have a corrosive action or may impair hardening. In general: drinking water is always suitable as mixing water. mum and maximum particle sizes for each class are specified, e.g. 0/2; 0/4; 2/8; 8/16; 16/32. The aggregate of a type of concrete usually consists of a mix of fine, medium and coarse grain. This composition may be naturally present in a quarrying site. Usually, how- ever, the natural grain mix or the mix that results when rocks are...

Concrete components Concrete components The distribution of coarse and fine aggregates in the grain mix influences the specific surface to be wetted, and hence directly affects the requirement for cement paste. The quantities of water and cement paste required for an aggregate mixture also depend on the shape of the granules. Fig. 4 illustrates this with the example of a cube representing a "compact" grain and a plate with the same volume representing a "flat" grain which has a surface 2/3 times greater than that of the "compact" grain. For "broken" grain, this difference is even greater,...

Concrete components Concrete components 1.4 Concrete admixtures 1.5 Concrete additives Admixtures influence the properties of fresh or hardened concrete. In Germany, concrete admixtures must either correspond to a standard, possess a test mark from the Deutsches Institut für Bautechnik (German Institute of Construction Technology), or have a CE conformity declaration. Admixtures are usually powdered substances that are added to the concrete. They mainly work physically and usually serve as an aid for better workability, less water repellence (bleeding), higher structural imperviousness or...

Concrete components Concrete components I Air-entraining agents (LP) Concrete with high resistance to frost and thawing salt must have a minimum content necessary the for larger volume prevented invoids (smaller than 0.3 than water. If the obtained of the voids entraining agents.space concrete then the concrete may can beThe additional airfrozen water is of micro air Ice has athis extension. mm) which burst. expansion by adding air offer the I Water resisting admixtures (DM) These are used to improve the water imperviousness of the concrete. Water resisting stances that may be harmful...

Concrete components 1.6 Concrete composition - mix calculation The composition of fresh concrete is specified by defined limits in the standards DIN EN 206-1/ DIN 1045-2. Depending on the environment, concrete is divided into exposition classes*, which refer to the corrosion of concrete and reinforcements. Limits for the composition and properties of concrete - reinforcement corrosion 'refer to section 3.1 on page 32 Concrete components Limits for the composition and properties of concrete - concrete corrosion