Contractors World

The online digital publication for construction, demolition, mining and quarrying industries.

November-December 2009
 

Buyers Guide
Adjust type size
decrease font size increase font size
previous page   PAGE 18   next page
HOME PAGE 

October 2009 ISSUE  - Contractors World, the digital publication for construction, mining, quarrying and demolition industries
October 2009

SEPTEMBER 2009 ISSUE  - Contractors World, the digital publication for construction, mining, quarrying and demolition industries
Sept 2009


CP&E
Contractors Plant & Equipment

NOVEMBER 2009 ISSUE  - CP&E - Contractors Plant & Equipment -  the digital publication for construction, mining, quarrying and demolition industries
Nov 2009

 

 CHINA - Breath-Taking Tunnelling Project - cont


Special Concrete wet spraying machinesSpecial Concrete wet spraying machines

Initially, a Putzmeister SPM 500 PC concrete wet spray manipulator is being used to secure the excavation and will be joined by a second machine of the same type.

The all-wheel-drive and all-wheel-steered concrete wet spray systems have a concrete pump, which delivers an extremely even supply of shotcrete via hydraulic control.

The shotcrete is applied with a highly mobile spray nozzle in combination with special spray arm kinematics.

The hydraulic parallel guide of the front telescopic spray arm makes it possible to automatically keep the complete telescopic spraying arm with nozzle in a horizontal position, regardless of the angle of the first boom arm.

 


Technical data for the SPM 500 PC concrete wet spray system

Working height of the SA 14 telescopic spray arm:                       4.5 to 16 m

Delivery rate of the double piston shotcrete pump:                      4 to 30 m³/h

Volume of the additive tank:                                                         1,000 l

Delivery rate of the additive metering unit:                                   30 – 700 l/min

Compressor output:                                                                      9 m³/min.

Volume of the water tank:                                                            195 l

Power cable:                                                                                 50 m (100 m optional)

Pump and boom operation:                                                          cable remote control

Drive output of the carrier vehicle                                                  75 kW


Low temperatures and “thin air” take their toll

At temperatures as low as -36°C and atmospheric pressure reduced by one-third, the tunnelling operations, at an altitude of 3,380 m, put a strain on workers and machine operators.

Typical symptoms experienced by site staff include shortness of breath, exhaustion, headaches and nausea. In case of emergency, there is oxygen equipment available at the construction site.
However, the equipment copes well with the conditions.

The compressor output of the shotcrete unit at this altitude is still at 100% (air volume times pressure remains constant), but the low static pressure has an effect on the suction in the shotcrete pump, at least in theory. The compressor output of the shotcrete unit at this altitude is still at 100% (air volume times pressure remains constant), but the low static pressure has an effect on the suction in the shotcrete pump, at least in theory.

However, at a maximum delivery rate of 30 m³/h, this loss in output cannot be detected in practice.

The low temperatures are a problem (the annual average is below 0° C), especially during the winter months.

This results in the formation of ice in the tunnels, which means that the shotcrete aggregates have to be stored in such a way that they do not freeze, and that the additive and water for the concrete batches, as well as for cleaning remains “free-flowing".

[cont]

 
 

previous page   PAGE 18   next page
 
red divide
CW Contractors World - the digital publication for construction industry   cmldir.com
Online Buyers Guide of Construction, Quarrying & Mining Suppliers.

 

Published by VVV Limited
Content compiled and edited by:
Roger Lindley MCIM

©VVV Ltd 2009 All Rights Reserved

 

Contractors World - Eco Friendly publishingBy reading this page on line you are helping to save trees.

Trees saved up to December 1, 2009: 2+

 

CONTRACTORS WORLD
CML House
7 Bell Mead
Sawbridgeworth
Herts CM21 9ES
UK
Tel: +44 1279 600598
Email: info@contractorsworld.info
URL: http://www.contractorsworld.info

To advertise in Contractors World see details at   http://www.contractorsworld.info/support/advertising-uk.php

Contractors World, CP&E - Contractors Plant & Equipment and the CW Supplements are independent publications published through CWMags. The mention of companies and/or products within the editorial pages or in advertisements does not infer any endorsement by the publisher or editors. All editorial is freely given, without conditions and at the sole discretion of the editor. Opinions expressed by contributors are not necessarily those of the publishers.

Copying, reproduction, decoding or disassembly of content or computer code by any means of any part of the publication is prohibited unless prior approval is provided by VVV Ltd in writing and confirmation received of agreement with any terms and conditions applicable. PDF version may be downloaded for personal use but no content may be used for promotional purposes or copied to web sites.