CH 8 SELF-CONSOLIDATING CONCRETE at site

Scc

1. CHAPTER 8: SELF-COMPACTING CONCRETE

2. Development of SCC

3. WHAT IS SELF-COMPACTING CONCRETE? Self-compacting concrete (SCC) is a special type of concrete which can be placed and consolidated under its own weight without any vibration effort due to its excellent deformability, and which at the same time is cohesive enough to be handled without segregation or bleeding. A highly flowable type of concrete that spreads into the form without the need for mechanical vibration Uses superplasticisers and stabilisers to significantly increase the ease and rate of flow It maintains all concrete’s durability and characteristics

4. SCC PROPERTIES Produces resistance to segregation by using mineral fillers or fines Shall be flowable – required to flow and fill special forms under its own weight Have a slightly higher strength compared to traditional vibrated concrete

5. SCC Self-Consolidating Concrete — fresh concrete that can flow around reinforcement and consolidate within formwork under its own weight without vibration and that exhibits no defect due to segregation or bleeding. ACI ConcreteTerminology

6. APPLICATIONS OF SCC Used in bridges and even on pre-cast sections Drilled shafts Columns Earth retaining systems Areas with a high concentration of rebar and pipes/conduits

7. Akashi Kaikyō Bridge Xihoumen Bridge, Zhoushan, Zhejiang Province, P.R. China Great Belt Bridge

8. ADVANTAGES & BENEFITS OF SCC Improved constructability. Labor reduction. Bond to reinforcing steel. Improved structural Integrity. Accelerates project schedules. Reduces skilled labor. Flows into complex forms. Reduces equipment wear. Minimizes voids on highly reinforced areas. Produces superior surface finishes. Superior strength and durability. Allows for easier pumping procedure. Fast placement without vibration or mechanical consolidation. Lowering noise levels produced by mechanical vibrators. Produces a uniform surface. Allows for innovative architectural features. It is recommended for deep sections or long-span applications. Produces a wider variety of placement techniques

9. FACTORS AFFECTING SCC The factors that may affect the behavior and performance of SCC : Hot weather. Long haul distances can reduce flowability. Delays on job site could affect the concrete mix design performance. Job site water addition to SCC may not always yield the expected increase in flowability and could cause stability problems.

10. SPECIAL CONSIDERATIONS FOR SCC A full capacity mixer of self-compacting concrete might not be feasible due to potential spillage along the road, producing environmental and contamination hazards. Formwork should be designed to withstand the fluid concrete pressure that will be higher than regular concrete. SCC may have to be placed in lifts in taller elements. Production of SCC requires more experience and care than the conventional vibrated concrete. SCC can add more cost to the construction costs

11. DIFFERENCES BETWEEN SCC AND CONVENTIONAL CONCRETE NO. SELF-CONSOLIDATING CONCRETE (SCC) CONVENTIONAL CONCRETE 1. High flowability to undergo compaction by its own weight Compacted by external means of vibration 2. High workability Less workable mix 3. Low water content High water content 4. Low viscosity High viscosity 5.  Give good aesthetic finish Aesthetic finish is not satisfactory 6. Good choice for thick reinforcement works Normal concrete are limited in thick reinforcement areas due to external compaction difficulties.