Characterization and Use of Construction and Demolition Waste from South of Brazil in the Production of Foamed Concrete Blocks

Abstract

Featured Application: The use of construction and demolition waste (CDW) in the development of building materials has been done constantly. The CDW from Passo Fundo region of Rio Grande do Sul/Brazil can be used in development of foamed concrete fully replacing the natural sand. Abstract:The main objective of this study was to evaluate the use of construction and demolition waste (CDW) from the Passo Fundo region of Rio Grande do Sul (RS), Brazil, in the development of aerated foamed concrete. This waste had not yet been characterized or even reused. CDW was processed (sieved only), characterized, and used as an aggregate, completely substituting natural sand. The influence of CDW granulometry and the amount of foam upon compressive strength, wet and dry bulk density, water absorption, and the air voids of concrete blocks were determined. Results showed that CDW has regular characteristics for the development of aerated foamed concrete. Compressive strength and density decreased as the amount of foam increased, while water absorption and air voids also increased. Also, CDW that was classified as coarse showed higher compressive strength. On average, CDW medium-sized particles had a higher air void content, while water absorption showed little variation with respect to granulometry. CDW residue from the region of study can be used as aggregate for the development of aerated foamed concrete. However, it must characterized before being used to guarantee the quality of the final product.

Effect of Additives, Cement Type, and Foam Amount on the Properties of Foamed Concrete Developed with Civil Construction Waste

“…CCW was used as an aggregate that totally replaces natural sand. This residue was collected in the region of Passo Fundo-RS-Brazil and characterized by Favaretto et al [22]. Figure 1a shows the grain size curve for the CCW used and Figure 1b shows the CCW.…”

“…The analysis technique described in British standard BS EM 480-11 [35] and by other authors [22,36,37] was used to determine the pore size. Two specimens of each sample were prepared, one specimen for the longitudinal section and another for the transverse section.…”

“…When increasing the amount of foam the compressive strength decreases. This occurs due to air being incorporated into the foam, as a result of which pores forms in the structure, decreasing the density and, consequently, the compressive strength [22,23]. Also, the compressive strength increases significantly when the curing time is increased, i.e., an average increase of approximately 40% in compressive strength can be obtained.…”

“…Another important factor that is directly related to the compressive strength of FC is the amount of foam added. Favaretto et al [22] observed that by increasing the amount of foam in the mortar the compressive strength decreases. Falliano et al [23] evaluated the effect of curing conditions, cement type, foaming agent, dry density, and presence of a superplasticizer on the development of the 28-day compressive strength, and concluded that all factors had a significant influence on the compressive strength; for example, the presence of the superplasticizer associated with the cellophane curing condition has led to an increase in the compressive strength as compared to the case without a superplasticizer.…”

Evaluation of the Physical and Mechanical Properties of Autoclaved and Foamed Concrete Blocks Marketed in Passo Fundo/RS Brazil

“…The characteristics found can be related to the formation properties of the pores, While the AACB has the formation of a larger number of voids with smaller diameters, the FCCB has a smaller number of pores, but these are of a larger diameter, which can be seen by comparing the densities of the samples. Another characteristic to be emphasized is the capillarity of the pores since the AACB has more spherical and separated pores and the FCCB presents amorphous aspects connected by capillaries, directly affecting its strength, since its structure is directly connected with the distribution of forces within the matrix (CORTELASSI; TORALLES-CARBONARI, 2008;FAVARETTO et al, 2017;PEDRO et al, 2017). This difference between the capillaries of the autoclaved concrete block and the foamed concrete block is shown in Figure 4.…”