2. Experimental program
2.1. Materials
2.1.1. Cement and bagasse ash
ASTM Type I ordinary Portland cement was used in all concrete mixtures. Bagasse
ash from a sugar factory in central Thailand was ground using a ball mill until
the particles retained on a No. 325 sieve (with openings of 45 lm) were less than
5wt% and was assigned as BA. The physical properties and chemical composition
of the cement and ground bagasse ash are listed in Tables 1 and 2, respectively.
2.1.2. Aggregates
Crushed limestone with a maximum size of 20 mm and a specific gravity of 2.67
was used as a coarse aggregate. River sand with a fineness modulus of 2.44 and a
specific gravity of 2.65 was used as a fine aggregate.
2.2. Concrete mixtures
Ground bagasse ash (BA) was used to replace Type I Portland cement at 10, 20,
and 30wt% of binder. The binder content and water to binder (W/B) ratio of all types
of concrete were adjusted to be constant at 350 kg/m3 and 0.50, respectively. The
mix proportions are presented in Table 3. The slump of fresh concrete was controlled
to remain in the range of 150–200 mm using superplasticizer.
2.3. Compressive strength
Concrete cylinders 100 mm in diameter and 200 mm in height were used to
determine the compressive strength. The concrete samples were removed from
their molds after casting for 24 h and cured in water until their testing age. The
compressive strength of all concrete samples was determined at ages of 28 and
90 days.