Production Of Concrete Blocks Research Articles

Solid waste from aluminum recycling process: characterization and reuse of its economically valuable constituents

Due to economic advantages, many companies in Brazil recover Al from the process of crushing and water-leaching of secondary aluminum dross. Wastes from this process (non-metallic products and salts) are usually landfilled or disposed without treatment, causing many environmental damages. The purpose of this work is to investigate, in a recycling company sited in São Paulo metropolitan area (Brazil), the potential use of the non-metallic product (NMP) in the production of concrete blocks and to evaluate the presence of important chemical compounds that may be useful for other applications. Chemical and mineralogical analyses revealed that NMP is composed of refractory and abrasive oxides (α-Al 2O 3, MgAl 2O 4, SiO 2) and an important source of transition alumina: α-Al(OH) 3. Concrete blocks were made by adding two parts of NMP to one part of cement and four parts of sand. The blocks were tested according to the Brazilian standard (NBR7173/1982) and they passed dimension, humidity and absorption tests but not compressive strength tests. However, particular NMP constituents have accelerated the strength rate development of the blocks, thus decreasing working time. The commercial use of NMP can reduce the amount of discarded wastes contributing to environmental preservation.

Recycled construction debris as an aggregates. Production of concrete blocks

This paper analyzes the use of recycled construction and demolition debris as aggregate for the construction of concrete blocks to be used in sealing masonry. Initial studies addressed the definition of parameters used in the mix of conventional materials (traditionally used in the production of concrete blocks), involving cylindrical test specimens (100x200 mm), molded with the help of a vibratory table. In addition to these definitions, and based on the mixes showing the best results, a new granulometric range was established, against which the granulometry of the recycled aggregates was adjusted. After the initial studies, concrete blocks were molded with the following dimensions: 100x190x390 mm). Studies have determined the behavior of aggregates in relation to mold humidity specific mass, water absorption, and compression resistance in view of the percentage of recycled debris that composes the total aggregate. For the most part, results suggest that construction and demolition debris can potentially be used in the production of concrete blocks, as well as in other pre-molded artefacts.

Sequencing of jobs in some production system

We consider a real-life problem of scheduling clients orders in the production of concrete blocks in a factory of building industry. This problem can be modelled as a hybrid flow shop scheduling problem with mixed no-wait/no-store constraints and mixed bottleneck/non-bottleneck machines. The objective function is to minimize maximum completion time. To solve the problem, we propose an approximation algorithm based on the tabu search approach.

Proceedings of hydrology symposium no. 4; research watersheds

Environmental concerns related to the disposal of various waste materials have escalated to a worrying level. Depending on the local industries, different types of waste are generated in huge quantities every year. Hence, the demand for more sustainable development has further increased the importance of green construction. In recent years, extensive study efforts have been made to recycle wastes for possible use in the production of concrete products. This is because concrete blocks seem to be the most popular option for the incorporation of recycled waste materials due to the lower quality requirements of materials. This paper reviews published research works on the use of various kinds of wastes (i.e. recycled concrete, crushed brick, soda lime glass, cathode ray tube glass, crumb rubber, ceramic and tile waste, etc.) in the production of concrete blocks. The common concrete block properties as well as the value-added properties of concrete blocks with incorporated waste materials are highlighted and discussed in this paper. Several unique characteristics of recycled crumb rubber, plastic waste and crushed brick enhance the fire resistance, toughness, functional and insulation properties of concrete blocks. Also, the quantity of these materials incorporated into concrete blocks can be maximized up to 100% as natural aggregate replacements, while their usage can also be limited to below 30% in certain applications in order to meet the standard requirements of concrete blocks. The compliance of concrete blocks with standard requirements and the value-added properties have demonstrated good potential for incorporating wastes as aggregate in concrete blocks.