Ambient noise analysis for characterizing sub-surface dynamic parameters

Ambient noise analysis of horizontal to vertical spectral ratio (HVSR) method has been used widely to provide reliable estimates of the site fundamental frequency and to constrain the inversion of near-surface shear wave velocity. The present paper focuses on the site measurement using the aforementioned analysis by means of the HVSR method for characterizing sub-surface dynamic parameters in the City of Banda Aceh, Indonesia. A Guralp CMG-6TD broadband seismometer was used in this study to cover a wide frequency range from 0.033 Hz to 50 Hz in standard operation. The instrument was deployed at two different sites (i.e. Location#1 of Blang Padang and Location#2 of Stadion Dirmutala) in the City of Banda Aceh for at least 2 hours for ambient noise recording. This continuous of 2 hours' microtremor time series was separated into 30 minutes record from which the site fundamental frequency and shear wave velocity of the measured site were deduced. The later sub-surface dynamic parameter was validated using another technique of reflection seismic. This investigation suggests the fundamental frequency of 0.45 Hz at Location#1 and of 0.65 Hz at Location#2. The estimated shear wave velocity of the top 30 m, Vs,30 of this investigation is 165 m/s at Location#1 and 156 m/s at Location#2. Both the site fundamental frequency and shear wave velocity are important for infrastructure design in the high seismic region of Banda Aceh, Indonesia

Constitutive Relations for Concrete Properties Under Acid Environment

Abstract The relationships between concrete properties (strength, porosity, and carbonation) and time attacked by acid environment were studied. Current environmental condition with acid rain caused air, soil, and water is acidic. It threats the degradation building with concrete construction. Two groups were organized in this research. One of them which was defined as control specimen was immersed in water curing. The other one was immersed in a solution of 5% sulfuric acid (PH3) for the purpose of simulating the acidic environment in the laboratory. Different from other reports, the cubes were not previously immersed in water for 28 days but directly immersed in acid solution after being demoulded for one day. Furthermore, the constitutional equations from laboratory experiment were validated by embedding the specimens in acid soil (real acid condition) with similar PH. The results showed that due to immersion in sulphuric acid 5%, concrete had a decreased strength, increased porosity and the occurrence of carbonation at the age of 3–90 days. The result from laboratory experiment for compressive strength was similar with that of a field experiment. Furthermore the relationship between the age of concrete and its porosity considered valid for the age of under 14 days. However, the relationship between the age of concrete and carbonation event judged invalid with that from a field experiment. The results established that the constitutive relations of the properties of concrete in the acid environment were considerably divided by the type of the acid environment

A Review of Double Layer Rubberized Concrete Paving Blocks

The objective of this paper is to presents and study a review of waste material i.e. tyre rubber granules as a partial aggregate replacement in different percentage and size of rubber granules; and different thickness of block layer. Waste tyre rubber is found to be very high in toughness. Owing to its technological and economical advantages, both strength and toughness of concrete can be increased. Incorporation of waste tyre rubber granules as aggregates in concrete mixture not only improves the toughness of concrete, but also improves the acoustics element by the increase of sound absorption level. Previous studies on rubberized concrete paving blocks (RCPB) especially on ability of pavement to absorb sound is very limited. Various tests will be carried out to evaluate engineering properties of double layer RCPB with 10, 20, 30, and 40% replacements of waste tyre rubber granules by weight of aggregate. The sound absorption level of double layer RCPB with different thickness of layer will be studied

A Review of Porous Concrete Block Pavement for Heavy Rainfall

In recent years, the popularity of porous concrete block has grown in the industry but there is still lack of knowledge on how and when porous concrete block is appropriate. The objectives of this paper is to presents and study a pre-view of porous concrete block used for pavement by using different size of aggregate and effect of permeability on porous concrete block during heavy raining season. Large volume of surface water runoff needs to handle during this season to prevent water ponding on the roads surface. Porous concrete blocks has proved to be effective and meet most of the requirement to solve the problem. The investigation on the different size of aggregate use in porous concrete block and its performance is very limited. However, further researches are ongoing by the authors to study performance of porous concrete block for pavement in mechanical and chemical properties will evaluate. Various tests were carried out to evaluate durability of porous concrete block made with 10 to 8 mm and 8 to 5 mm size of aggregate in concrete mix. On the other hand, the results of compressive strength, porosity and clogging test from previous investigation were present in this study

Physico-mechanical characteristics of tropical granite boulders in weathered heterogeneous zones for geotechnical design purposes

The presence of isolated or clustered granite boulders in tropical weathered masses commonly formed a very thick heterogeneous zone in weathering Zone 3 to 5. The boulders with various characteristics are always misinterpreted during the geotechnical design process due to being poorly understood and studied. This study aims to determine the physico-mechanical characteristics of boulders in different weathering zones for design purposes. The parameters studied include boulder types, porosity, density, durability, point load and uniaxial compressive strength. Results revealed boulders in weathering Zone 3, 4 and 5 can be classified into Type A, B and C, respectively. These boulders have significant differences in physical and mechanical properties. The boulders in Zone 4 and 5 consists of corestone, ringlets and saprolites and the boulders in Zone 3 have no ringlets. Corestones have the highest durability, point load and compressibility strength with a median of 94.5%, 7.80 MPa and 187.07 MPa, respectively. The ringlets possess the highest porosity range of 23.3%–31.3% compared with saprolite. Saprolite in Zone 5 has the lowest durability, point load and compressive strength with respectively less than 7%, 0.22 MPa and 1 MPa. The various characteristics of the boulders in different weathering zones could influence the geotechnical design model