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Showing 1-5 of 9 Abstracts search results

Document: 

SP326-45

Date: 

August 10, 2018

Author(s):

Maurizio Nicolella

Publication:

Symposium Papers

Volume:

326

Abstract:

The goal of this research was to evaluate the behavior over time of mortars obtained from three different types of recycled material, and specifically aimed to obtain thermal insulation plasters.

The typology of samples was identified based on experimentations conducted at the University of Madrid, with 11 different types of specimens made with cement, river sand, expanded clay (with different particle size), recycled XPS (with different particle size), and recycled ceramic remains.

The good results suggested submitting the samples in the laboratory of Building Engineering of the University of Naples Federico II to the following tests: rainfall resistance, thermal shock resistance, accelerated aging resistance in climatic chamber.

In the present paper, the final results, with a preliminary assessment of the suitability for use of these mortars with external coating function in determined climatic contexts, are proposed.


Document: 

SP324_09

Date: 

April 1, 2018

Author(s):

Stefano De Santis, Gianmarco de Felice

Publication:

Symposium Papers

Volume:

324

Abstract:

A shake table investigation was carried out on a full-scale U-shaped masonry assemblage to study the effectiveness of Steel Reinforced Grout (SRG) for the improvement of the out-of-plane seismic capacity of masonry walls. Natural accelerograms were applied with increasing scale factor up to failure. A first session of tests was performed on the unreinforced specimen, that collapsed by out-of-plane overturning. Steel tie bars were then installed to prevent overturning. In this case, severe damage developed due to bending. Finally, the wall was retrofitted with horizontal strips of Ultra High Tensile Strength Steel cords, externally bonded to the masonry with lime based mortar, and steel connectors. SRG led to a significant improvement of the seismic capacity, strongly limited damage development, and entailed small modifications of the dynamic properties of the specimen. Since the reinforcement had a thickness of less than 10mm, it is suitable for applications within the plaster layer during the maintenance work of the façades without modifying their appearance.


Document: 

SP173-34

Date: 

September 1, 1997

Author(s):

M. Collepardi

Publication:

Symposium Papers

Volume:

173

Abstract:

When the historical buildings of the Republic of Venice were erected all the construction materials and the corresponding techniques were always carefully selected. Even at that time architects were aware of the importance of the durability of buildings in a very hostile environment such as that existing in Venice characterized by permanent humid air and capillary rise of salty water from the foundations. In particular cementitious materials were adopted in agreement with the empirical rules of the Romans’ experience and adapted for the particular Venetian environment. The present paper examines two specific cementitious materials which became very popular throughout the world: the stucco plaster and the terrazzo concrete. At the time of the Republic of Venice, chemical admixtures were not available. Therefore, masonry artisans and architects developed a special know-how to manufacture durable materials. This was based on the use of mineral admixtures and natural substances, the invention of innovative binders and the development of special application techniques. After the advent of portland cement and especially of chemical admixtures, modem stucco plaster and terrazzo concrete can be produced with different (not necessarily better) properties and at higher rates of productivity. The present paper examines the microstructural aspect, the composition, the performance, and the manufacturing process of the original and modem materials.

DOI:

10.14359/6208


Document: 

SP91-62

Date: 

February 1, 1986

Author(s):

L. D. Wakeley and A. D. Buck

Publication:

Symposium Papers

Volume:

91

Abstract:

An expansive grout, based on Class H cement, an expan- sive admixture consisting essentially of plaster of paris (calcium sulfate hemihydrate), and a Class C fly ash, was proportioned for use underground. Specimens of this grout, and of five modified versions of it, were tested to determine the effects of using two ther fly ashes, with or without silica fume, on compressive strength, volume change, phase composition, and microstructure. Properties were monitored to 960-days age. Up to 365-days age, specimens of the mixture modified with Class F fly ash had lower compressive strengths and generally more expansion than did those of the original composition. At ages of 90 days and greater, the same was true of samples prepared with a second Class C fly ash. Substitution of silica fume for 5 or 10 percent of the cement gave higher early strength, but the combination of the second Class C fly ash and 10 percent silica fume gave the lowest strengths at ages of 90 days and greater. Despite the substitutions, properties were markedly similar, compressive strength from all modifications exceeded 90 MPa at 365 days, and phase composition and microstructures became more similar with time.

DOI:

10.14359/10121


Document: 

SP73-05

Date: 

March 1, 1982

Author(s):

Ray W. Clough and Akira Niwa

Publication:

Symposium Papers

Volume:

73

Abstract:

The basic purpose of this research was to investigate the feasibility of studying the nonlinear earthquake response behavior of concrete arch dams on a 20 ft. square shaking table. Assuming a length scale of l/150, the essential similitude requirements for the model material are derived. The development of suitable plaster, celite, sand and lead powder mixtures is described, and the proportions and properties of adopted materials are listed. Shaking table tests are described of a segmented arch rib model designed of this material to simulate the monolith joint opening behavior of an arch dam, and preliminary results are presented. Also, the test of a model of Koyna Dam is mentioned, where the model behavior simulated the observed cracking of the prototype. The principal conclusion of the investigation is that shaking table research is a practical means of studying the nonlinear earthquake response of concrete arch dams, including their actual failure mechanisms.

DOI:

10.14359/6775


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