Study on Mechanical and Durability Properties of Concrete Incorporating GGBS

Abstract

With increase in industrialization, quality of air, water and soil is also getting severely affected. These factors lead to degradation in life of concrete. To resist aggressive envi- ronment, demand for durable concrete is increasing continuously. The state of Gujarat has witnessed establishment of cement plants producing Portland slag cement using 40% of replacement of OPC with slag during last one year. The areas within and surrounding to Gujarat are having more than 1000 km long coastline. salinity & other issues in soil and water possess significant potential of using GGBS in concrete for achieving good pro- tection for Engineering structures to sulphates and chlorides. This strategy is considered to be useful to reduce costs, conserve energy, and reduce waste volumes. Mechanical and durability properties of M25 and M40 grade concrete is evaluated in the present study. Three concrete mixes are prepared replacing GGBS by 0%, 40% and 60% of OPC, respectively. Compressive strength, exure strength, split tensile, modulus of elasticity and bond strength properties of three concrete mixes is evaluated after com- pletion of curing period of 28, 60 and 90 days. Compressive strength results of both slag concrete is lower at age of 28 days as compared to that of control concrete. With increase in curing period compressive strength of concrete is also increased at all age. compressive strength of 40% cement replacement with GGBS showed better results as compared to that of other concrete mixes at 60 and 90 days. Flexure strength of slag concrete is lower at 28 days as compared to that of control concrete for both grade. With increase in curing time exure strength increases at all ages. Flexure strength of 60% replacement resulted in better performance as compared to that of other concrete mixes at 90 days. Split tensile strength reduced for slag concrete at age of 28 days. For split tensile, addition of 60% GGBS resulted in poor performance of slag concrete as compared to that of control concrete for both grade at all ages. Modulus of elasticity results for slag concrete mixes are at par compared to control concrete mix for both grade at all age. Bond strength results for M25 slag concrete is higher as compared to that of control concrete at 90 days, but for M40 grade control concrete preformed better as compared to slag concrete mixes at 90 days. Acid resistance, sulphate resistance and chloride resistance is measured by submerging concrete specimens in 5% H2SO4, 5% Na2SO4 and 5% NaCl solution, respectively upto duration of 30, 60 and 90 days. Acid exposure test results show that weight loss is higher for control concrete as compared to that of both slag concrete at all age. Compressive strength of both grade control concrete reduced at higher rate as compared to that of slag concrete at all age for acid exposure. The sulphate exposure test results show minor weight gain in both grade of concrete for all three mixes at all age. Reduction in com- pressive strength is higher for control concrete as compared to that of slag concrete due to sulphate attack at all age. The chloride exposure test results showed similar results as that of the sulphate exposure for all concrete mixes. In accelerated corrosion test it has been observed that with increase in slag content, rate of corrosion decreases for con- crete mixes. For the RCPT, both slag concrete performed excellent compared to that of control concrete at all age. Overall it can be stated that increase in GGBS dosage has resulted into better performance of concrete with respect to various durability properties attempted in present investigation.It can be stated that addition of 40% GGBS in M25 and M40 grade concrete mixes performed well as compared to control mix in terms of mechanical and durability prop- erties. Further addition of GGBS upto 60% enhanced durability properties only while mechanical properties are at par compared to that of control concrete.