Table of Contents
Why is Ggbs used in concrete?
Durability; GGBS reduces the likelihood of concrete thermal cracking, and it improves concrete’s resistance to damage from alkali-silica reaction, sulphates and chlorides. Concrete in aggressive environments is much more durable with the use of GGBS as a partial replacement for the cement.
What is the fineness of Ggbs?
Typical physical properties
| Colour: | off-white |
|---|---|
| Specific gravity: | 2.9 |
| Bulk density: | 1000 – 1100 kg/m3 (loose) 1200 – 1300kg/m3 (vibrated) |
| Fineness: | >350m2/kg |
What is the shrinkage value of concrete?
Physically, concrete that experiences a drying shrinkage of about 0.05 percent (500 millionths or 500 x 10-6) will shrink approximately 0.6 inches per 100 feet (50 mm for every 100 m).
How does Ggbs affect concrete strength?
Compressive strength of concrete containing GGBS is increased by 6% to 17% than the ordinary concrete subjected tosulphate attack with the variation of age. 5. The concrete containing GGBS shows increase compressive strength by8% to 18% than ordinary concrete subjected to acid attack with variation of curing period.
What are disadvantages of Ggbs?
Disadvantages of Ground Granulated Blast Furnace Slag (GGBS) in Concrete
- Additional quality control costs.
- Slow and small hydration heat, not suitable in precast factories or during winter concreting.
- Faster carbonation rate decreased service life span due to reinforcement corrosion.
How much Ggbs can be used in concrete?
between 20 and 80%
GGBS proportions A typical combination is 50% GGBS with 50% CEM I, but percentages of GGBS anywhere between 20 and 80% are commonly used. The greater the percentage of GGBS, the greater will be the effect on concrete properties.
What is the difference between fly ash and Ggbs?
There is a wide variation in the chemical properties of fly ash and GGBS. Fly ash is low in calcium oxide content but rich in silica and alumina while GGBS is relatively high in calcium oxide. The combination of these two materials can be more beneficial when used as a stabilizing agent than using them individually.
Does Ggbs make concrete stronger?
Strength gain in GGBS concrete Typically the 7-day strength of a ggbs concrete will be 55-65% of the 28-day strength compared to 70-80% for a similar CEM I Portland cement concrete. The reduction in early-strength will be more noticeable at high GGBS levels and low temperatures.
Does Ggbs increase strength?
GGBS concrete gains more strength than the PC concrete after the age of 28 day till 56 day. The mechanical properties of blended concrete for various levels of cement replacement have been observed as higher than control concrete mix having no GGBS.
What are the properties of Ggbs?
On the basis of present work we found that GGBS in concrete improves workability, compressive strength, flexural strength, split tensile strength and decreases the density & water absorption characteristics of hardened concrete. As a result the cost of concrete decreases.
How do I activate Ggbs?
The activation of GGBS involves the initial dissolution of the solid particles by alkaline hydrolysis, followed by the polycondensation of C-(A)-S-H gel [[2], [3], [4]]. Previous studies [[5], [6], [7], [8], [9]] have shown AAS mixes to provide high strength, good durability and high resistance to chemical attack.
Which is better fly ash or Ggbs?
The reaction heat per unit mass of GGBS is only 16ยท7% higher than that of fly ash. The main reason for the difference of hydration heats between GGBS binder and fly ash binder is that GGBS shows much higher hydraulic activity than fly ash.
What is the maximum percentage of Ggbs in concrete?
GGBS proportions A typical combination is 50% GGBS with 50% CEM I, but percentages of GGBS anywhere between 20 and 80% are commonly used. The greater the percentage of GGBS, the greater will be the effect on concrete properties.
What is shrinkage and types of shrinkage?
Shrinkage is an inherent property of concrete. The shrinkage in concrete can be defined as the volume changes observed in concrete due to the loss of moisture at different stages due to different reasons. Types of Shrinkage in Concrete. Plastic Shrinkage in Concrete. Drying Shrinkage in Concrete.
How do you reduce concrete shrinkage?
How to Reduce Shrinkage of Concrete at Construction Site?
- Reduce Water Quantity.
- Add Additives.
- Aggregate.
- Protect Concrete Surface from Rapid Drying.
- Time of Concreting.
- Proper Concrete Compaction.
- Proper Curing.
- Adequate Contraction Joints and Steel Detailing.
What is Ggbs list its advantages?
GGBS can be used as a partial replacement of OPC cement in concrete production at batching plants. It is highly cementitious and high in calcium silicate hydrates (CSH) which is a strength enhancing compound which improves the strength, durability and appearance of the concrete.
What is the density of Ggbs?
The Physical properties are specific gravity 2.9, Bulk density 1200 Kg/m3 and fineness 350 m2/Kg.
What is the effect of GGBS on concrete properties?
The greater the percentage of GGBS, the greater will be the effect on concrete properties. With GGBS, the setting time will be extended slightly, perhaps by about 30 minutes. The effect will be more pronounced at high levels of GGBS and/or low temperatures.
What is the difference between GGBS and sulphate resistant Portland cement?
It is seen that higher the replacement amount of GGBS lesser is the expansion. It is found that, even special cement like sulphate resisting Portland cement (SPRC), that itself have a low C3A content performs less compared with GGBS concrete. The resistance against sulphate is done by the GGBS particles in three different ways as mentioned below:
What percentage of Cem I and GGBS should I use?
A typical combination is 50% GGBS with 50% CEM I, but percentages of GGBS anywhere between 20 and 80% are commonly used. The greater the percentage of GGBS, the greater will be the effect on concrete properties. With GGBS, the setting time will be extended slightly, perhaps by about 30 minutes.
What is the resistance of GGBS particles against sulphate?
The resistance against sulphate is done by the GGBS particles in three different ways as mentioned below: The GGBS itself have no C3A. More the amount of GGBS replaced with cement, lesser the overall constitution of C3A. The GGBS as a part of pozzolanic reaction utilizes a majority of calcium hydroxide.