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WELCOME TO THE WORLD OF CONCRETE PUMPING. Concrete Required. Concrete needed (m 3). Time / Months. What is Ready Mixed Concrete?. It is concrete that is delivered to site in a fresh, liquid state from a remote batching plant upon order. Types of Ready-Mixed Concrete. Dry Mix Wet Mix
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Concrete Required Concrete needed (m3) Time / Months
What is Ready Mixed Concrete? It is concrete that is delivered to site in a fresh, liquid state from a remote batching plant upon order.
Types of Ready-Mixed Concrete • Dry Mix • Wet Mix • Temperature controlled Concrete • Produced in accordance with SS289
How is it done? • Overview of a Batching Plant(BP) • Materials- Aggregates, Sand, Cement and Water are weighted.
Raw materials Water • Aggregates, sand on conveyor belt into the mixer
Advantages • Hassle-free, Fast • Reliability • Quality control is ensured • Less labour required • Space saving on site • Able to meet fluctuating demand • Design Mix is possible
Disadvantage • Cost • 24 hours is needed for an order
Quality Control?? • Slump test • Cube strength test • Aggregate test • Temperature Test • SS 78
Environment Friendly?? • ISO 14001 certified • Recycled water • Cement dust filter
CRITERIA • Well-bond constituent materials • Facilitates the radial movement of sufficient grout along pipeline • Ablility to deform
IF NOT…. • Segregation • Bleeding/Dewatering • Lumpiness
ADMIXTURES - IMPROVING PERFORMANCE -
WHY ADMIXTURES? • Increase workability of concrete 2. To produce specific requirements for the mix, e.g. durability & strength 3. Special Conditions
REFRESHING ON SOME TERMS.... W/C ratio Slump test Workability
TYPES OF ADMIXTURES a) water-reducing admixtures b) retarders and accelerators c) water-thickening admixtures d) air-entraining admixtures e) others
WATER-REDUCING ADMIXTURES What is it? • Plasticiser, SuperPlasticizers, • (SuperFluidizers, SuperFluidifiers, Super Water-Reducers or High Range Water-Reducers) • - Lower water mix requirement • - Amount of water reduction achievable depends on dosage and initial slump Comments • - Difficulties can arise if there is any significant vertical length of pipeline. • Plasticizers should not be used in concrete mixes with high voids content which are prone to segregation
Retarders & Accelerators What is it? Retarders -delay the setting of concrete-offset the effects of high temperatures, long distance pumping & cold joint prevention.- effective use in slip formwork • Accelerators • increase the rate of hydration-shorten the setting time -increase the rate of hardening or strength development. Comment -concrete with accelerator will set more quickly and impacts on schedule -Combining retarder in the bottom half of a thick slab and normal concrete in the top half
The rest… ..not suitable for Singapore (due to climate)
Water-thickening agents What is it? • More cohesive and higher viscosity • Used on leaner mixes • “water-wrapping-aggregate” effect Comments - Used in any mix to provide lubrication and reduce friction.
Air-entraining agents What is it? • Bubbles created • Alters the properties of concrete both in its plastic and hardened state. • Plastic = reduce both water and fine aggregates contents • Hardened = Gives hydraulic relief to any water freezing effect Comments • -Limited the amount of air. • Escape of air • Adding a plasticizer, if there is a concern of over dosage
Other types of admixtures • Pulverized Fly Ash (PFA) • Microsilica • Steel, glass fibre and polypropylene fibres
Thank You for Your Attention Presented by Hing Kai Sin ADD Marketing
Concrete Delivered (m3/hr) Height / m3
