Porous concrete pavement containing nanosilica from black rice husk ash

Rice husk is a waste from the agricultural industry. It has been found that the main inorganic element in rice husk is silica. Rice husk ash (RHA) as a replacement material in the conventional concrete mixture has been widely studied around the world. However, there is a lack of documented research on nano production from RHA used as a replacement cement in porous concrete pavement mixtures. This study employed the top-down approach via dry grinding in a mechanical ball mill to generate a nano-black RHA (nano-BRHA). As a result, nano-BRHA was successfully generated with an optimum duration of 63 hours and median size of 66 nm. The results also indicated that the particle size of BRHA was significantly decreased with increasing grinding time. In addition, the morphology of the nano-BRHA changed with grinding duration. Finally, the use of nano-BRHA produced porous concrete pavement with good strength and permeability, and sound absorption

Data for: Mesoscopic Modeling of the Impact Behavior and Fragmentation of Porous Concrete

In this work, real porous concrete mixtures, which have been experimentally produced and tested, were analyzed numerically. The numerical output was also compared with experimental results

Design and Analyses of Porous Concrete for Safety Applications

Engineering Structure

Data for: Mesoscopic Modeling of the Impact Behavior and Fragmentation of Porous Concrete

In this work, real porous concrete mixtures, which have been experimentally produced and tested, were analyzed numerically. The numerical output was also compared with experimental results.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

The potentials of porous concrete for ballistic protection

A special porous concrete has been developed by the Delft University in collaboration with TNO. The concrete has a static compressive strength of 45 MPa. It fragments at impact into small size debris relative to reference concrete. The porous concrete was developed at laboratory scale and tested at small scale. In collaboration with the Military Science faculty of NLDA a procedure was developed to upscale the production. Panels of 0.5m x 0.5m x 0.10m were produced at slightly lower strength than realized at lab scale. These panels were used to investigate the ballistic performance of the porous concrete. The ballistic resistance proved to be comparable to that of reference concrete. The instant crushing feature of the concrete causes additional damage at the front side but the damage zone was still limited in size. Spalling at the rear side proved to be limited in comparison to the reference normal concrete. To further improve the ballistic resistance of the porous concrete, it was infiltrated with a polymer. Tests showed a considerable improvement of the penetration resistance, relative to the noninfiltrated porous concrete. The paper first summarizes the characteristics of the porous concrete developed at lab scale. The ballistic test data are presented and analyzed. The ballistic response mechanism of the porous concrete is compared with the mechanism in normal concrete. From this analysis the alternative of filling the pores emerges. Finally the paper presents the initial ballistic results for the infiltrated porous concrete

Investigation of porous concrete through macro and meso-scale testing

In designing a porous concrete, containing a high volume of air pores, the effects of its mesoscale phases on its macro level properties have to be known. For this purpose, porous concretes having different aggregate gradings and cement paste compositions were investigated through macro-scale strength tests. The tests showed that aggregate grading had a predominant effect on the properties of porous concrete in comparison with cement paste composition. Replacing cement by silica fume even slightly lowered the strength values of the porous concretes which was explained by the presence of agglomerates. Meso-scale tension tests were also conducted to determine the tensile strength of the ITZ. The tests at the two different scales revealed that, even though the ITZ phase did not become weaker with the presence of silica fume with the inclusion of agglomerates, the strengths of macro-size samples were lowered due to the bulk cement paste phase being degraded.Structural EngineeringCivil Engineering and Geoscience

Introduction to concrete: A resilient material system

The strength of concrete is its heterogeneous composition. It is a system that is formed by the chemical process of hydration, producing crystalline and amorphous reaction products interlocking and binding the aggregates together. The material grows in time, resulting in a resilient system that is sufficiently strong to carry loads but can also respond to environmental conditions. Crack initiation and crack growth at the various scale levels govern the mechanical tensile response of the heterogeneous concrete material. Therefore, the fracture mechanics principles of strength and energy criteria help in understanding and modelling the response mechanisms. The internal stress conditions and defect distributions are at (i) meso-level, governed by the aggregate grading, mortar and bonding (ITZ) properties, and at (ii) micro-level, defining the mortar properties (aggregates-cement matrix, ITZ and capillary pore system). The structure at micro/nano-level (cement matrix and micro-pore system) gives the sub-scale condition for the mortar. In this chapter we will describe the concrete system and the material structure from the material science point of view at the microscopic and mesoscopic levels, respectively. It provides general background information for the chapters that follow. © 2013 Woodhead Publishing Limited All rights reserved

Investigating porous concrete with improved strength: Testing at different scales

Porous concrete incorporates a high percentage of meso-size air voids that makes its mechanical characteristics remarkably different from normal concrete. A research project was undertaken to design a special type of porous concrete, that fractures into small fragments when exposed to impact loading while having sufficient static strength, to be used in protective structures such as safety walls or storages for explosives. In the concretes designed, while a sufficient static strength was required, high porosity was essential to facilitate the formation of multiple cracks and the subsequent fracturing. Production of porous concretes having improved static compressive strengths was accomplished by modifying the mixture design and the compaction technique; while the design procedure was supported by macro and mesoscale mechanical testing, computed tomography, microscopy and X-ray diffraction analysis

Mesoscopic modeling of the impact behavior and fragmentation of porous concrete

This study presents the numerical analyses conducted to investigate the impact behavior of different porous concretes, which have also been cast and tested experimentally. For a realistic representation of the real porous concretes containing arbitrary shaped air pores, a mesh generation code was developed in which the aggregates in the mixtures were directly extracted through computed tomography. In the code, mineralogically different aggregates in porous concretes with gravel could also be individually defined. In the explicit finite element analyses conducted, porous concrete was considered as a four-phase material, consisting of aggregates, interfacial transition zones (ITZ), bulk cement paste and air. The pore size distribution and the fragmentation behavior of the concretes were also numerically analyzed. Among the parameters that have been investigated both numerically and experimentally, aggregate grading, which determines the porosity and pore size distribution of the material, was found to have a dominant effect on the strength as well as the fragmentation properties of porous concretes. Although the amount of ITZ is higher in mixtures containing finer aggregates, those mixtures had higher impact strengths compared to coarser aggregate ones again owing to their much finer pore structures.</p

Impact behavior of model porous concretes

In this work, findings of a numerical study performed to investigate the impact behavior of porous concrete, modeled as a four phase cementitious composite consisting of aggregates, cement paste, interfacial transition zones (ITZ) and air, are presented. The numerical analyses contributed to the process of designing a special type of concrete for safety purposes i.e. as a protective building material to be used in safety walls outside important buildings or munition magazines for storing explosives. In case of an explosion, large concrete fragments that are formed, cause a very important threat. Therefore, in the scope of a research project, designing a special type of concrete having sufficient strength, but fracturing into small fragments under impact loading was aimed. In the numerical analyses, model porous concretes, in which the amounts and properties of pores and aggregates could be varied individually, were used to see the sole effect of each parameter. According to the results, it was found that at constant total porosity, the impact strength increased with decreasing pore size while multiple fragmentation was observed. On the other hand, the impact strengths of porous concretes with different size aggregates (with constant total aggregate content and porosity) were approximately the same when no ITZ was defined. However, when ITZ was present, the impact strength was found to decrease as the aggregates were finer. This trend was also valid for the respective full concretes. Representative experimental results of porous concretes were also presented in order to support the numerical results.Accepted Author ManuscriptApplied MechanicsMaterials and Environmen