Effect of Locust Bean Pod Ash and Eggshell Ash on the Mortar Compressive and Flexural Strengths of Cement Blends

Abstract

An increase in the generation of biogenic wastes such as locust bean pods and eggshells coupled with the need to drive sustainability in the cement industry has led the use of these wastes as cement replacement materials. The paper aims to investigate the effect of locust bean pod ash (LBPA) and eggshell ash (ESA) on the mortar compressive and flexural strength of ternary cement blends. The LBPA was obtained by calcining locust bean pod (LBP) at various temperatures of 800-900 °C and time of 60-120 minutes at an interval of 50 °C and 30 minutes respectively to determine the optimal conditions. The chemical composition of Ordinary Portland cement (OPC), LBPA and ESA were obtained via X-ray Fluorescence (XRF) Spectrometer and LBPA chemical composition did not satisfy one of the requirements specified by ASTM C618-01 (2001) with SiO 2 + Al 2 O 3 +Fe 2 O 3 of 30.42 wt. % which is less than 50 wt. %, but satisfies SO 3 content requirement of 0.7 wt. % and Loss on Ignition (LOI) of 7.12 wt. % and contains 19.42 wt. % CaO which is within the range of 10-30 wt. % CaO is class C pozzolan. The compressive strength of blended cement mortars at the early age of 2 and 7 days produced better strengths for cement blends with higher ESA content than LBPA especially at LBPA/LBPA-ESA ratio of 0, 0.4 and 0.6 for 2.5 wt. % cement replacement respectively. The early strength gain could be attributed to the provision of more nucleation sites by ESA inclusion which results in the acceleration of cement hydration rate. On the other hand, the enhanced strengths at 28 days of cement blended with various replacement from 2.5-10 wt. % could be attributed to the pozzolanic reaction between the available lime and reactive silica from LBPA despite clinker diminution which was close to control. Another reason for enhanced strength' could be attributed to the increased potassium content by an increase in LBPA content resulting in a gradual strength gain (retarder) muscovite formation K 2 Al 2 Si 6 Al 4 O 20 (OH) 4. All cement blends experienced an increase in the mortar compressive and flexural strengths as the curing day progressed with some blends producing enhanced strength compared to control especially with 1.5 ESA1LBPA produced the best strength at 50.15 (6.82) N/mm 2 against 48.80 (6.80) N/mm 2. This enhanced strength could be related to the pozzolanic activity and the high potassium content from LBPA despite clinker diminution, especially at 28 days.

Performance of high strength concrete containing locust bean pod ash as cement replacement

“…The flexural strength behavior of LBPA HSC is similar to that of compressive strength (Figure 3). The result indicates that flexural strength increased with curing age consistent with [24], [29]. The flexural strength of L05 and L10 were 6.4 and 5.2% higher than control concrete at 28 days with L05 showing the best performance.…”

“…The observed increase in strength can be attributed to the substantial surface area of LBPA, which facilitates the pozzolanic reaction leading to the formation of C-S-H gel. Additionally, [29] reported an improvement in flexural strength as the curing period progressed. Some blends had greater strength than the control.…”

Potential Heterogeneous Catalysts from Three Biogenic Residues toward Sustainable Biodiesel Production: Synthesis and Characterization

“…At that temperature, it becomes the major phase, and main peak next to SiO 2 (Figure 3) The hexagonal crystalline phase of potassium aluminum silicate, KAlSiO 4 , (Kalsilite, JCPDS 01‐076‐0635) was also observed at $${2\theta }$$ of $${55.04^\circ{}}$$ . Nath et al [23] . reported the presence of K 2 O in Brassica nigra plant ash catalyst calcined at 550 °C with comparable $${2\theta }$$ value at $${27.80^\circ{}}$$ , $${39.52^\circ{}}$$ , $${46.70^\circ{}{\rm \ }}$$ and $${48.12^\circ{}}$$ .…”

“…Akpenpuun et al [41] . and Olubajo et al [23] . reported the presence of SiO 2 , Al 2 O 3 and Na 2 O in the calcined ash sample of locust bean pod (LBP).…”

“…Due to the abundant nature of periwinkle shell residues (38.5 tons) which are naturally rich in calcium carbonate, [21] melon seed husk (about 500,000 tons/y), which is rich in Ca, K, and Na [22] and locust bean pod husk (about 200,00 tons/y) which is rich Ca, K and magnesium compounds [23] making them be further studied as a suitable feedstock for the development of heterogeneous base catalysts. There seems to be limited information on the development of heterogeneous base catalysts from these biogenic residues for biodiesel synthesis despite the fact that they are rich in alkali elements whose oxide is suitable to be used as a heterogeneous base catalyst.…”