Abstract:
The goal of research is to study the possibility of using bagasse fly ash that adsorbed lead and chromium to partially replace cement for production of interlocking concrete paving blocks and hollow concrete blocks. The study focuses on physical and chemical properties of bagasse fly ash that adsorbed lead and chromium. It also studied the compressive strength development of concrete blocks which contained the bagasse fly ashes. In addition, there was also test of leaching characteristics of the heavy metals from the concrete blocks according to the procedure described in the Sixth notification of Ministry of Industry BE 2540 (1997). The experimental results indicated that bagasse fly ash could not be classified as a pozzolanic material according to the requirements in ASTM C618. When the different types of bagasse fly ashes were used to replace the cement in the mixes at the ratio of 1:1.1:1.9 (cement:sand:gravel), the resulting compressive strengths showed little difference among them. The experimental compressive strengths and the varied cement replacement and water-to-cement ratios were found to be represented by Gaussian equations. The water-to-cement ratio was subsequently determined to be 0.536 from the equation using the condition of 7-day curing time, 15 percent replacement, and resulting strength of 200 kg/cm² . The above condition was then used to make interlocking concrete paving blocks and hollow concrete blocks and the resulting strengths were 210 kg/cm² and 203 kg/cm² , respectively. Environmental impact evaluation of the concrete samples containing chromium and lead-sorbed bagasse fly ashes was carried out following the leaching procedure described in the Sixth notification of Ministry of Industry BE 2540 (1997). Heavy metal concentrations in the leachates were lower than the standards