PSI - Issue 64

Nathália Andrade da Silva et al. / Procedia Structural Integrity 64 (2024) 1460–1467 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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hydration. Such absorption not only reduces the water-to-cement ratio but also impacts on the bio-concretes characteristics, such as the workability of the mixture at fresh state and mechanical properties. In terms of binder, Andreola (2017) developed bamboo bio-concrete utilizing only cement as binder while Silva (2019) and Andreola (2021) studied the replacement of part of the cement used in the mixtures with metakaolin (Mk) and fly ash (FA) (Table 3). The bio-concretes incorporating 30% Mk were defined based on positive results from previous studies with other plant aggregates (Da Gloria, 2020), as well as its lower environmental impacts (Caldas et al., 2020). Fly ash was selected for its beneficial effect on workability and the possibility of incorporation of high amount. To ensure effective workability in mixtures containing a higher volume of bio-aggregates and/or a reduced water to-binder ratio, it might be essential to introduce superplasticizer admixture. This guarantees an improvement of workability without the necessity of augmenting the volume of water in the bio-concrete. Since adding plant aggregates to the cement mixture can slow down the hydration process and the hardening of the matrix, it may be necessary to introduce calcium chloride as a setting accelerator, in order to demold samples after 24h of casting. For bamboo bio-concrete, typical proportions range from 2% to 3% in relation to the mass of cement, as detailed in Table 3. The majority of research conducted so far has concentrated on utilizing bamboo aggregates as a complete replacement for conventional fine aggregates within a mix consisting of binders, admixtures and water. However, more recent studies have introduced new materials to expand the potential properties and applications of these bio concretes. Siqueira et al. (2023), in contrast, proposed exploring the use of bamboo particles as a replacement for mineral coarse aggregates with particles size comparable to gravel. This necessitated incorporating sand into the bamboo bio-concretes, which had not been done previously. The objective of including sand and coarse bamboo aggregate is to develop bio-concrete that meets the necessary mechanical requirements for structural applications.

Table 3. Bamboo bio-concrete dosage.

Cementitious Materials

Calcium chloride (%)

Other material s

% Bio aggregates

w/cm

VMA (%) SPA (%)

Author

C (%)

Mk (%)

FA (%)

RHA (%)

Andreola (2017)

45; 47; 50

100

0

0

-

0.40; 0.45 ;0.50

0.125

-

-

-

Silva (2019) Lima (2020)

25; 35; 45

60

30

10

-

0.40

-

-

3.0

-

45

40

30

30

-

0.40

0.05

1.0

2.0

-

Andreola (2021) Sá (2022) Siqueira et al. (2023)

60; 50; 40; 30

10; 20; 30; 40

0.30; 0.32; 0.35; 0.37; 0.40

40

30

-

0.10

1.0

2.0

-

35; 40; 45

30

30

40

-

0.30

-

-

3.0

Soil

40; 50; 60

10; 20; 30

0.0; 0.50

25

30

-

0.30; 0.32; 0.35

-

3.0

Sand

C = Cement; Mk = Metakaolin; FA = Fly Ash; RHA = Rice Husk Ash; w/cm = water/cementitious material; VMA = Viscosity Modifier Agent; SPA = Superplasticizer

2.3. Fresh state behavior The flow table test is conducted to assess the workability of bio-concrete containing fine bamboo aggregate at fresh state. Its purpose is to determine whether any adjustments in dosage are needed to ensure that the bio-concrete can be effectively molded and shaped through vibration, ultimately leading to a uniform final product. The data presented in Figure 2 demonstrates a consistent pattern across all studies featuring bamboo aggregates, showing that higher levels of bio-aggregates content are associated with decreased spread of the bio-concrete. In simpler terms, an increase in plant aggregate within the mixture leads to reduced workability. This is primarily attributed to the decrease in cementitious paste as the proportion of bamboo particles rises.