José Manuel Gómez-Soberón

Porosity of recycled concrete with substitution of recycled concrete aggregate: An experimental study

In this paper, we present the experimental analysis of samples of recycled concrete (RC) with replacement of natural aggregate (NA) by recycled aggregate originating from concrete (RCA). The results of the tests of mechanical properties of RC were used for comparison with tests of mercury intrusion porosimetry (MIP), in which the distribution of the theoretical pore radius, critical pore ratio, the surface area of the concrete, threshold ratio and average pore radius were studied at ages of 7, 28 and 90 days. The results showed some variation in the properties of the RC with respect to ordinary concrete. Porosity increases considerably when NA is replaced by RCA. Additionally, a reduction in the mechanical properties of the RC is seen compared with ordinary concrete when porosity increases.In this paper, we present the experimental analysis of samples of recycled concrete (RC) with replacement of natural aggregate (NA) by recycled aggregate originating from concrete (RCA). The results of the tests of mechanical properties of RC were used for comparison with tests of mercury intrusion porosimetry (MIP), in which the distribution of the theoretical pore radius, critical pore ratio, the surface area of the concrete, threshold ratio and average pore radius were studied at ages of 7, 28 and 90 days. The results showed some variation in the properties of the RC with respect to ordinary concrete. Porosity increases considerably when NA is replaced by RCA. Additionally, a reduction in the mechanical properties of the RC is seen compared with ordinary concrete when porosity increases.

SHRINKAGE OF CONCRETE WITH REPLACEMENT OF AGGREGATE WITH RECYCLED CONCRETE AGGREGATE

This paper gives results of an experimental analysis of samples of concrete where a portion of the natural aggregate was replaced with recycled aggregate originating from recycled concrete aggregate (RCA). Experimental analysis was performed to obtain shrinkage properties (basic and dried) of the concrete containing RCA (CRCA). The percentages of replacement of natural aggregate with RCA were 0, 15, 30, 60, and 100%, with test conditions of 50% RH and 20 deg C. Results of these trials are compared with reference concrete tests at an age of 270 days. These results demonstrate an increase in the shrinkage of the CRCA that is proportional to the amount of RCA used as a replacement for the natural aggregate. When compared to the reference concrete, the drying shrinkage evidences significant changes; however, the evolution over time is similar to that of standard concrete.

Porosity of recycled concrete with substitution of recycled concrete aggregate

In this paper, we present the experimental analysis of samples of recycled concrete (RC) with replacement of natural aggregate (NA) by recycled aggregate originating from concrete (RCA). The results of the tests of mechanical properties of RC were used for comparison with tests of mercury intrusion porosimetry (MIP), in which the distribution of the theoretical pore radius, critical pore ratio, the surface area of the concrete, threshold ratio and average pore radius were studied at ages of 7, 28 and 90 days. The results showed some variation in the properties of the RC with respect to ordinary concrete. Porosity increases considerably when NA is replaced by RCA. Additionally, a reduction in the mechanical properties of the RC is seen compared with ordinary concrete when porosity increases.In this paper, we present the experimental analysis of samples of recycled concrete (RC) with replacement of natural aggregate (NA) by recycled aggregate originating from concrete (RCA). The results of the tests of mechanical properties of RC were used for comparison with tests of mercury intrusion porosimetry (MIP), in which the distribution of the theoretical pore radius, critical pore ratio, the surface area of the concrete, threshold ratio and average pore radius were studied at ages of 7, 28 and 90 days. The results showed some variation in the properties of the RC with respect to ordinary concrete. Porosity increases considerably when NA is replaced by RCA. Additionally, a reduction in the mechanical properties of the RC is seen compared with ordinary concrete when porosity increases.

Creep of Concrete with Substitution of Normal Aggregate by Recycled Concrete Aggregate

This paper gives experimental results on properties of concrete with replacement of natural aggregate by recycled concrete aggregate (RCA). Experimental data on the creep behavior of concrete mixtures (basic and drying creep) was obtained. The replacement factors of natural aggregate by RCA were 0, 15, 30, 60, and 100%, and the test conditions were 50% RH and 20 deg C. The results of these trials were used to provide a comparison with results of tests on the reference concrete, for ages up to 270 days. Results reveal considerable increase in creep with increase in replacement of natural aggregate with RCA. Drying creep in particular evidences more of a significant increase when compared to the reference concrete.

Relationship Between Gas Adsorption and the Shrinkage and Creep of Recycled Aggregate Concrete

In this work, an experimental analysis is described of specimens of recycled concrete (RC) made with replacement of natural aggregate with recycled aggregate originating from concrete (RCA). An experimental analysis to obtain the shrinkage and creep properties (basic and by drying) of RC was performed. The replacement fraction of natural aggregate with RCA were 0 %, 15 %, 30 %, 60 % and 100 % and the test conditions were 50 % RH and 20 °C. The results of these trials were compared with mercury intrusion porosimetry (MIP) and gas adsorption (nitrogen) tests, at 90 days. In the results, an increase in the shrinkage and creep properties of the RC with respect to conventional concrete was observed, while porosity values increased. However, the deformation evolution over time is similar to conventional concrete.

An Experimental Study of Mortars with Recycled Ceramic Aggregates. Deduction and Prediction of the Stress-Strain

The difficult current environmental situation, caused by construction industry residues containing ceramic materials, could be improved by using these materials as recycled aggregates in mortars, with their processing causing a reduction in their use in landfill, contributing to recycling and also minimizing the consumption of virgin materials. Although some research is currently being carried out into recycled mortars, little is known about their stress-strain (σ-ε); therefore, this work will provide the experimental results obtained from recycled mortars with recycled ceramic aggregates (with contents of 0%, 10%, 20%, 30%, 50% and 100%), such as the density and compression strength, as well as the σ-ε curves representative of their behavior. The values obtained from the analytical process of the results in order to finally obtain, through numerical analysis, the equations to predict their behavior (related to their recycled content) are those of: σ (elastic ranges and failure maximum), ε (elastic ranges and failure maximum), and Resilience and Toughness. At the end of the investigation, it is established that mortars with recycled ceramic aggregate contents of up to 20% could be assimilated just like mortars with the usual aggregates, and the obtained prediction equations could be used in cases of similar applications.

Metamorphosis in the Porosity of Recycled Concretes Through the Use of a Recycled Polyethylene Terephthalate (PET) Additive. Correlations between the Porous Network and Concrete Properties

In the field of construction, sustainable building materials are currently undergoing a process of technological development. This study aims to contribute to understanding the behavior of the fundamental properties of concretes prepared with recycled coarse aggregates that incorporate a polyethylene terephthalate (PET)-based additive in their matrix (produced by synthesis and glycolysis of recycled PET bottles) in an attempt to reduce their high porosity. Techniques to measure the gas adsorption, water porosity, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to evaluate the effect of the additive on the physical, mechanical and microstructural properties of these concretes. Porosity reductions of up to 30.60% are achieved with the addition of 1%, 3%, 4%, 5%, 7% and 9% of the additive, defining a new state in the behavioral model of the additive (the overdosage point) in the concrete matrix; in addition, the porous network of these concretes and their correlation with other physical and mechanical properties are also explained.

Mechanical properties of mortars containing recycled ceramic as a fine aggregate replacement

We study the behavior of mortars where 0%, 10%, 20%, 30%, 50% and 100% of their original natural sand was replaced by ceramic sand in a search of potential new building materials that will help to conserve natural resources and that are environmentally friendly. In this paper, the physical properties of the sands and their derived mortars, including their compressive strength, flexural strength, and shrinkage due to base and total drying, are characterized. Our results show that the compressive and flexural strengths of the recycled mortars decrease proportionally to the amount of natural sand replacement used. A similar behavior is observed for the shrinkage due to drying in mortars with low ceramic substitutions (10%, 20% and 30%). Based on these findings, we believe that the use of mortars made with recycled sand (with substitution contents lower than 30%) could be feasible in applications where the mechanical requirements are low.

Fresh-State Properties of Mortars with Recycled Glass Aggregates: Global Unification of Behavior

Due to the current problems related to the generation of diverse wastes and the extraction of nonrenewable materials to be used in the construction sector, the alternative use of waste glass could be a sustainable option with environmental and economic benefits, in case of being feasible its use as a replacement of the usual aggregates to manufacture recycled mortars. In this research, one presents a study of the fresh-state properties of the mortars containing 15, 30, 60, and 100% recycled glass aggregates as a replacement for the usual aggregate, providing the experimental results of consistency, density, and air content. Using the experimental results, and by means of a numerical and statistical analysis of these, a diagram of triple interaction that allows us to unify the behavior of the studied properties is constituted; making feasible with this, the prediction of the behavior of these properties with respect to variables as their ratio water/cement, aggregate/cement, and different percentages of replacement of aggregates.

Influence of the shape of the natural aggregates, recycled and silica fume on the mechanical properties of pervious concrete

Currently the problems of water quality are increasing; much of the material is rinsed and is dragged into streams, rivers, and groundwater from the contaminated superficial draining, which contains materials that are applied to the soil surface. Therefore is that the provide the greatest amount of uncontaminated water to the subsurface is of great importance, since it can still potentially solve some important collateral problems, such as the settlement in the soil, which is related largely to levels low capacity of the aquifer. Therefore, use Pervious Concrete (PCo) can help prevent physical barrier between rainwater and underground (especially in urban areas). For the investigation of the feasibility of PCo three types of aggregate were used: Round Natural Aggregate (RNA), Natural Crushed Aggregate (NCA) and Recycled Aggregate from Concrete crushed (RAC),since the shape of the aggregates generally determines the mechanical properties; and yet very little is known about their correlation with permeability. Moreover, concrete recycling is an effective way for the elimination of debris from demolition as well as replace part of the cement by waste material as the Silica Fume (SF); in both cases, these actions production decreases and CO2 emissions associated with their production.