Construction and demolition waste in concrete: property of pre-molded parts for paving

Abstract

Construction and demolition waste (CDW) production is a growing factor on a global scale and its incorrect disposal becomes an increasingly common problem in cities. It is estimated to represent, on average, 50% of the urban solid waste mass in the world. In this sense, an alternative to the destination is their reuse. In this work, the properties of interlocking concrete pieces for paving with the CDW in substitution to large aggregates were analyzed. The substitution occurred in fractions from 20 to 100 wt% of CDW in cylindrical test specimens to find the ideal substitution content, so that to prepare pre-molded concrete blocks. The piece properties obtained were analyzed according to Brazilian standards for compressive strength and water absorption. Therefore, the influence of the residue incorporation in the pieces, from the technical viewpoint, was verified. The sample that presented the best performance had a substitution of 20% of the natural aggregate by crushed CDW.

Influence of particle size distribution of conventional fine aggregate and construction demolition waste aggregate in Portland cement mortar

“…One of the parameters that affects significantly cement composites regards the textural parameters of isolated grains in the aggregates such as grain size (expressed in terms of granulometric composition), shape, surface texture, and mineralogical composition [1]. In addition to the factors related to the characteristics of the particle system, the number of grains in each fraction and how these particles are placed in their equilibrium position have to be considered, since the particle size distribution of the system determines whether there is an increase in the packing density or not [2,3]. Bulk density is the aggregate property that takes particle packing into consideration.…”

“…Bulk density is the aggregate property that takes particle packing into consideration. This property, added to the factors previously mentioned, also considers grain distribution (whether continuous or not), fine content (fine fraction ratio), and grain porosity (open porosity disturbs packing due to its irregular shape) [2][3][4]. Taking into consideration this information, for the production of more durable mortars and concretes, an aggregate with better particle packing is necessary.…”

“…An optimal dosage of the mixture (mortar and concrete) depends on the maximum packing density of the constituent materials since this generates a system with lower porosity, which generally promotes a lower hydration degree [2,4]. The hydration degree is related to the water demand, which is consequently related to the surface area and internal porosity of the grain.…”

Mechanical Properties of Concrete Using Recycled Aggregates Obtained from Old Paving Stones

“…The construction industry is still one of the largest waste generators today [4][5][6]. However, historically it has been a necessary pillar for the development of our communities.…”

Influência do teor de material pulverulento (<75 μm) do agregado miúdo de resíduos de construção e demolição em argamassas de cimento Portland

“…Uma das alternativas na construção civil é a reciclagem e reutilização de resíduos de construção e demolição (RCD). Estudos acerca da utilização deste material como agregado em argamassas e concretos vêm sendo desenvolvidos a fim de [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]: reduzir a quantidade de material descartado nos aterros, amenizando a emissão de CO 2 ; reduzir o consumo de energia gasto no transporte e mineração; e diminuir a necessidade de exploração de Influência do teor de material pulverulento (<75 μ μm) do agregado miúdo de resíduos de construção e demolição em argamassas de cimento Portland…”