Calcium Silicate Blocks Research Articles

Measured effect of resilient edge joints on airborne sound insulation of heavyweight wall

It is common assumption that resilient joints around a heavyweight construction improve sound insulation between adjacent rooms. Effect of resilient joints on sound insulation has not been studied sufficiently. This study investigated how the joint resiliency around a heavyweight wall affected sound reduction index (SRI) measured directly through the construction. A calcium silicate block wall was built three times in a laboratory using three different joint types A−C between the wall and the building frame: A) all four edge joints rigid, B) three resilient and one rigid joint, C) all four joints resilient. SRI was determined for A−C. Total loss factor (TLF) was determined for A−C by measuring structural reverberation time using hammer impact stimulus. SRI reduced, remarkably, with increasing level of joint resiliency. For joint type A Rw was 50 dB while it was 45 dB for B and 43 dB for C. Correspondingly, TLF reduced with increasing level of resiliency. The effect of joint type was evident above the critical coincidence frequency 185 Hz of the wall. Resilient joints prevented the sound transmission to the building frame, which increased sound radiation to the receiving room. Therefore, heavyweight wall should be mounted to surrounding heavy constructions using rigid joints.

Effect of resilient joints on the airborne sound insulation of single-leaf heavyweight constructions

The joint between a heavyweight construction and the surrounding building frame can be rigid or resilient. It is often believed that a resilient joint improves sound insulation. The purpose of this study was to investigate how the joint resiliency of a single-leaf heavyweight construction affects the sound reduction index and the total loss factor. A masonry wall of 10 m2 (220 kg/m2 calcium silicate block wall) was built three times (A−C) in laboratory using three different joint types between the wall perimeter and the test opening frame: A - All four joints rigid; B - Three joints resilient and one rigid; C - All four joints resilient. The sound reduction index was determined using both pressure and intensity method. The total loss factor was determined by measuring the structural reverberation time using hammer impacts. The sound reduction index reduced significantly with increasing level of resiliency. For joint type A, the weighted sound reduction index, Rw, was 50 dB while it was 45 dB for B and 43 dB for C. Correspondingly, the total loss factor reduced from A to C, i.e., with increasing joint resiliency. The effect of joint type was evident above the coincidence frequency (250 Hz) of the block wall. Resilient joint prevented the energy transmission from the wall to the building frame, which increased the sound radiation to the air, which was reflected as reduced sound reduction index. The results imply that the joints of a heavyweight construction shall be rigid if high sound reduction index is desired above the coincidence frequency. On the other hand, the increased joint resiliency improved the sound reduction index at most frequency bands below the coincidence frequency. Resilient joints around heavyweight construction can be beneficial in situations where the reduction of low-frequency noise is of primary concern.

Experimental investigation of negative temperature’s influence during block laying on mechanical properties of calcium silicate block masonry

This research analyzed the use of hollow masonry blocks made from calcium silicate, which were bonded using thin-layer and general purpose mortars. In particular, this article examines how low and negative environmental temperatures affect the mechanical properties of masonry during the process of block laying. Experimental research focuses on two stages of hardening, the first being the mechanical properties of masonry immediately after the mortar thaws in the joints. The second stage in our research examined the mechanical properties of masonry when warming mortar continues to harden. Performed research have shown that block laying at low temperatures affects both the compressive strength and the modulus of elasticity of masonry. Depending on the type of mortar used, the aforementioned modulus decreases to 15%, which has a direct impact on the load-bearing capacity of vertically loaded masonry constructions. This study shows that thin-layer mortar used in the laying of calcium silicate hollow blocks exhibits greater vertical deformations at the initial loading stage.

Experimental investigation of the bed joint influence on mechanical properties of hollow calcium silicate block masonry

The article discusses the influence of the bed joint thickness and mortar strength on properties of calcium silicate (CS) block behavior under short-term static load. The investigation of masonry samples made of hollow CS blocks is presented in this paper. The specimens were made of two types of hollow CS blocks, combined with general purpose mortar of three different strengths and thin layer mortar of two different strengths. During the analysis of masonry with thin layer mortar the moisture influence on mechanical properties of masonry was also investigated. The experimental investigation has shown that the height of mortar bed joints has a larger influence on the mechanical properties of masonry when mortar of lower strength is used. Moistening CS blocks with thin layer mortar did not have a significant influence on the mechanical properties of masonry.

Experimental investigations on the initial shear strength of masonry with earth mortars

In this paper, a comparative study on the initial shear strength of masonry with earth mortars is presented. Triplet tests were carried out to characterise the shear bond strength of five different types of earth mortar, three purely mineral and two with vegetable additives (wood and straw chaff), using calcium silicate blocks. In spite of their lower bulk densities, mortars with chaffs reached a value of compressive strength comparable to the values shown by the purely mineral mortars. The characteristic initial shear strengths of all the tested earth mortars were between two and five times higher than the minimum values for initial shear strengths required by standards. To assess the influence of blocks pre-wetting, a comparison between calcium silicate blocks and earth blocks was performed to evaluate the results obtained from the standard test procedure compared to the more common practice of using earth mortars in combination with earthen blocks.

Experimental investigations on the initial shear strength of masonry with earth mortars

In this paper, a comparative study on the initial shear strength of masonry with earth mortars is presented. Triplet tests were carried out to characterise the shear bond strength of five different types of earth mortar, three purely mineral and two with vegetable additives (wood and straw chaff), using calcium silicate blocks. In spite of their lower bulk densities, mortars with chaffs reached a value of compressive strength comparable to the values shown by the purely mineral mortars. The characteristic initial shear strengths of all the tested earth mortars were between two and five times higher than the minimum values for initial shear strengths required by standards. To assess the influence of blocks pre-wetting, a comparison between calcium silicate blocks and earth blocks was performed to evaluate the results obtained from the standard test procedure compared to the more common practice of using earth mortars in combination with earthen blocks.

Evaluation of dampness-induced strength reduction of calcium silicate blocks

Due to its numerous technical advantages as well as health benefits, sand-lime brick is increasingly used in the construction of brick walls, especially in residential buildings. Unfortunately, the occurrence of damp leads to a sharp deterioration of the technical properties of the material and the environmental conditions inside the building. Given the importance of this issue, an attempt was made to diagnose the extent of dampness variability of the main hygrothermal and strength characteristics of calcium silicate products. The study involved the basic material properties (density in dry and water-saturated conditions), moisture-related properties (capillary adsorption coefficient and sorptivity), thermal coefficients (thermal conductivity and volumetric heat capacity) as well as mechanical properties (compressive strength). This article describes diagnostic studies that were conducted to assess the extent of the effect of dampness on the strength of sand-lime products. In order to render the diagnosis more comprehensive and to include a wider range of silicate blocks available on the market, it was decided to examine three groups of silicate blocks (strength class 15, 20 and 25) obtained from three different factories. It was demonstrated that for all the examined groups dampness caused a significant decrease in compressive strength ranging from about 30% to about 40%.

With calcium silicate blocks, always a comfortable room climate

With calcium silicate blocks, always a comfortable room climate

Resource efficiency of calcium silicate units

AbstractDue to the current importance of sustainability, the federal association of the calcium silicate masonry unit industry has taken intensive interest in the question of the resource efficiency of calcium silicate masonry units and construction and has carried out an extensive investigation to this end. The study subjected all stages of calcium silicate, from raw materials reserves and their extraction, production and use in building to recycling, including all transport routes and energy demands, to detailed analysis and critically examined the sustainability of calcium silicate blocks. The present article explains and evaluates the entire life cycle of calcium silicate masonry units.

Displacement capacity of contemporary unreinforced masonry walls: An experimental study

A research project on the displacement capacity of contemporary unreinforced masonry (URM) walls is underway at the Institute of Structural Engineering of ETH Zurich. The development of the basis for the displacement-based design of URM structures is the prime objective of the present project. In the experimental phase of the project, a total of 10 static-cyclic shear tests on full-scale URM walls made of clay and calcium-silicate blocks were performed to investigate the effects of various factors, i.e. unit type, vertical pre-compression level, aspect ratio, size, and boundary conditions, on the displacement capacity of URM walls. This paper presents and discusses the obtained test results. All the walls (regardless of their failure mode) exhibited limited displacement capacity. The test results show that as the vertical pre-compression level increases, the displacement capacity decreases. Furthermore, they indicate a possible reduction in the displacement capacity of URM walls in the case of an increase in the height or a decrease in the aspect ratio, i.e. the height divided by the length. It is also shown that the values recommended by the current codes of practice for the displacement capacity of URM walls cannot be considered as reliable. Finally, a simple empirical model for the displacement capacity of contemporary URM walls is proposed, based on the results obtained from the tests.

Strength of masonry subjected to in-plane loading: A contribution

The present paper discusses the strength of unreinforced masonry subjected to in-plane loading. Applying the methods of the theory of plasticity, the state of stresses under investigation and compatible failure mechanisms are discussed and an extension (new regime) to an existing failure criterion for in-plane loaded masonry without tensile strength is given. This new regime takes into account slip failure along the head joints line which could be observed in compression tests and which could compromise the safety of the design based on the existing criterion. In addition, a novel proposal for the simplified variation of uniaxial masonry strength as a function of the angle of inclination of the principal compressive stress relative to the head joints direction is derived and proposed for practical applications. Further, the present paper gives an overview of an experimental program comprising the author’s own compression tests on wall elements made of concrete and calcium-silicate blocks as well as of clay brick masonry that was carried out at ETH Zurich. The results of these tests, together with those from further tests carried out by other researchers, have been used for the verification of the abovementioned proposal for the simplified variation of uniaxial masonry strength. A satisfactory agreement between the proposed simplification and test data has been found.