Solid Concrete Block Research Articles

Analysis on the characteristics of spatiotemporal distribution and their causes of temperature and strength in three-graded mass concrete

The use of prefabricated mass concrete blocks have gained increasing attention in construction industry. However, excessive temperature due to hydration can easily cause cracks, and the development of strength influences the lift and transportation time, thus affecting the efficiency of the precast yard. In this paper, the temperature field of three-graded mass concrete was simulated using Midas Civil, and compared to the measured results. In addition, the strength of concrete at different ages and locations was tested with different methods, and the influence of temperature inside the mass concrete on strength was explored. The results show that the finite element simulation basically agrees with the experimental temperature and can provide scientific guidance for the construction of three-graded mass concrete. The compressive strength of the specimens under the same conditions is consistent with that of the surface core samples of solid concrete blocks, and the rebound strength at different ages is lower than the compressive strength of the surface core samples. The temperature inside mass concrete has both positive and negative effects on the formation of concrete microstructure, high temperature can promote cement hydration and pozzolanic effect of fly ash to form more compact C-S-H gel. But under prolonged high temperature conditions, it can also cause morphology of CH to be coarse and loose, forming scattered needle shaped AFt. At different ages, the compressive strength of the core samples inside the concrete block is greater than that of the surface core samples. As the age increases, the concrete strength at the core location with the highest temperature may not necessarily be the highest. As the age increases, for example, at 7 days, the concrete strength at the core location with the highest temperature is 6.46% higher than that at the surface, while the concrete strength is 15.6% lower than that at locations with relatively lower temperatures.

Mechanisms and advancements in microwave-enhanced CO2 mineralization of lightweight porous concrete

Lightweight porous concrete (LPC) typically exhibits low early strength, which can be addressed by enhancing early strength through carbon dioxide (CO2) mineralization curing while achieving permanent CO2 sequestration. The efficacy of this process relies on maintaining optimal moisture levels. This study investigates the influence of moisture content on the performance of solid waste-based lightweight porous concrete blocks (RSFAC) subjected to microwave heating pretreatment. Moisture levels were adjusted to 10%, 20%, 30%, and 40% (initial water-to-cement ratio of 45.4%) before undergoing mineralization curing within an environment set at a temperature of 20 °C, relative humidity 75%, and a CO2 concentration of 40% for a duration of 0.5 h. The impact of moisture content on RSFAC's compressive strength, carbon sequestration rate, mineralization products, and microstructure was evaluated. Results indicate that compared to conventional oven pretreatment methods requiring nearly 10 h, microwave pretreatment technology achieves equivalent water content within just 50 min, significantly reducing the time needed for mineralization pretreatment. RSFAC, when pretreated with microwave heating, outperforms untreated samples (Ref-0 and Ref-1) in terms of compressive strength and carbon sequestration efficiency. Optimal performance was observed at a moisture content level of 30%, with the highest recorded compressive strength achieved at 1, 3, and 7 d respectively. At the curing age of 7 d, the compressive strength reached up to 2.32 MPa while the carbon sequestration rate reached approximately 11.61%. Furthermore, aragonite and calcite (tetrahedral and hexahedral), without poorly crystalline spherulites, were identified as the main crystalline CaCO3 generated by RSFAC under this specific moisture content condition; pores larger than 50 nm served as primary reaction sites for RSFAC mineralization curing, whereas there was a significant increase in pore proportion with sizes less than 20 nm after filling with mineralization products.

Pushout tests on demountable bolted angle shear connectors for steel-concrete composite structures

Welded connectors are commonly utilized in steel-concrete composite construction. However, these connectors lack demountability, hindering the recycling or reuse of steel sections. In response to this limitation, high-strength bolts have been proposed as alternatives to traditional welded shear connectors to facilitate demountability. Nevertheless, the use of numerous high-strength bolts may negatively impact construction costs due to their limited capacity. This paper introduces a novel solution: the bolted angle shear connector. Comprising a standard angle section, a smaller size angle section functioning as a hat, and a high-strength bolt, this connector aims to balance the demountability advantage while avoiding the drawbacks associated with high-strength bolts. To assess its performance, the proposed connector was embedded into a solid concrete block, and horizontal pushout tests were conducted on 31 specimens. Variables considered included the angle section size, bolt diameter, bolt grade, concrete compressive strength, loading direction, and bolt thread condition. The findings reveal that the proposed connectors demonstrate a ductile response, meeting the mandated slip capacity of at least 6 mm according to EN 1994–1-1. Two distinct failure modes were observed: bolt fracture and a combination of concrete crushing and angle bending. The shear resistances at 6 mm slip ranged from 146 kN to 280 kN, influenced by the angle size and concrete compressive strength. Capacities were formulated as functions of these variables, leading to the development of design recommendations, which are presented in this paper.

Assessment of Metakaolin Blended Palm Kernel Shell Solid Concrete Blocks as a Sustainable Building Material

The effectiveness of Palm kernel shell (PKS) as a coarse aggregate substitute in metakaolin added solid concrete masonry blocks is examined in this paper. Control solid concrete blocks and Palm Kernel Shell (PKS) added concrete blocks with metakaolin were cast with sizes of 250mm × 200mm × 150mm and a mix ratio of 1:3:6 by varying the water-binder (w/b) ratio in 0.55, 0.60, and 0.65. The blocks were water cured for 28 days before batching, which was done per volume. There were 0%, 5%, 10%, 15%, 20%, 25% and 30% replacements of coarse aggregate with PKS, respectively. Slump tests were conducted on fresh concrete and the blocks were made using solid block making machine. At the end of 28 days curing period, compressive strength tests were conducted on hardened concrete blocks using a compression testing apparatus. The findings indicated that the slump height increased with the water-binder ratio but reduced with the proportion of PKS. For higher substitutions of coarse aggregate with PKS, favourable results are obtained with a w/b ratio of 0.60. According to IS: 2185 (Part 1) - 2005, solid concrete masonry blocks must possess a minimum compressive strength of 5N/mm2. Although several samples meet this requirement, the optimized sample in terms of strength was a block with 25% PKS replacement at a w/b ratio of 0.60. The density, water absorption, and initial rate of absorption of the optimized sample were found to be lower than those of the control samples, however, both samples exhibit a similar pattern in alternate wetting and drying tests.

Evaluation of the thermal conductivity and transmittance coefficient of earthen constructive elements

The aim of this work is to determine the thermal conductivity of different earthen constructive elements produced with materials typical of the central-eastern part of the Province of Santa Fe (Argentina), and to evaluate their suitability to be used in the construction of envelopes that comply with the thermal insulation requirements of the corresponding National Regulations. For this purpose, test specimens were made following the different earth construction techniques used in the region (compressed earth block, adobe, rammed earth (tapia), wattle and daub (quincha), and plaster), and their thermal conductivity coefficient was measured, with which the thermal transmittance of different earth construction packages was calculated. The results obtained indicate that the earth construction techniques evaluated show, in all cases, a better thermal performance than traditional solid ceramic brick or concrete block walls, with wattle and daub being the technique with the highest thermal insulation capacity.

Computational modelling in a high rise building with different building envelope materials for sustainable living

This research focuses on identifying a sustainable material for building envelope for energy efficacy in naturally ventilated high rise residential buildings through CFD. Convective heat transfer is observed in three levels of the 14 storied highrise naturally ventilated building using three different building envelope materials ? burnt clay bricks, solid concrete block, and hollow concrete block. To artificially create the environment with CFD the different temperatures and velocities are used. The boundary conditions - initial outdoor temperatures 30 ?C and 23 ?C, respectively, were kept constant and the initial outdoor velocities 1 m/s to 10 m/s, were varied and simulated at 12 noon condition. Simulation results reveal, higher indoor temperatures in the roof exposed floor. At 30?C it is observed that there is a 0.2-0.3?C temperature difference between the burnt clay brick wall and the hollow concrete block wall through the varied velocities. In all cases of air velocities, the air temperature in the indoor spaces of the solid concrete block wall was found to be highest. This proves that solid concrete block wall has the highest conductivity and least resistivity over the other two materials. In the hollow concrete block, the process of conduction is slow and apparently the temperature in the indoor spaces is reduced. Thus, the results clearly indicate that the temperature in the indoor spaces of the hollow block building envelope was comparatively low when compared to the other two building materials.

Lightweight concrete blocks produced using expanded polystyrene and foaming agent

In the present scenario disposal of waste is one of the challenging tasks for most of the engineers. Hence an alternative has been found, by using waste material such as EPS (expanded polystyrene) in solid concrete blocks. That has reduced the impact of quarrying operations, processing on environment and also economical. As compared to other materials such as steel and timber, the use of lightweight foamed concrete has numerous advantages, including cost savings, fast compaction, and ease of application. We investigated Cellular Light Weight Concrete (CLC) using Expanded Polystyrene Beads in this study (EPS). CLC is not a recent invention; it has existed since the dawn of time. We have used cement, Manufactured Sand (M−Sand), fly ash (class F), Ground Granulated Blast Furnace Slag (GGBS), polypropylene fibers, EPS, foaming agent that is Benzoyl Alcohol and Water. CLC is used widely because it is less in density. In this research work, Water quality, compressive strength, and thermal conductivity tests were performed on hardened blocks with EPS beads. The addition of fly ash and GGBS to the mix reduced water demand by reducing hydration and carbon footprint, resulting in a reduction in shrinkage, but it also reduced the compressive strength of the blocks by around 25–50 percent. Concrete with a density of less than 1800 kg/m3 is commonly referred to as lightweight concrete. This research focuses on research into lightweight concrete with Expanded Polystyrene (EPS) beads.

Solid Concrete block Arch behaviour in Substructures

Now a days the cost of construction is increasing due to increase in cost of materials. It is required to reduce by implementing the arch foundations using solid concrete blocks. The bending moment and shear acting over the cross-sectional area are significantly smaller contrasted with that of beams of same span and carrying the similar load. Using different materials arches can be constructed. This type of construction will save the materials cost and also improve the structural behavior of solid concrete block arches. Uniformly distributed load has been tried using loading frame. An impact of rise of arch on load carrying capacity has been studied. A cement mortar 1:6 proportions is used in the joints. First crack has been observed at the load of 17.658kN/m which is around 80% of ultimate load. Hence this type of foundations can be recommended upto two storied buildings

EXPERIMENTAL INVESTIGATION OF MECHANICAL PROPERTIES OF SOLID CONCRETE BLOCK MASONRY EMPLOYING DIFFERENT MORTAR RATIOS

This research work aims to investigate experimentally the mechanical properties of solid concrete blocks as an individual unit and assembly (block masonry) employing different mortar mix ratios. The material properties of the concrete block unit, such as compressive strength and unit weight were explored by taking three samples from the four local factories. The block masonry assemblages were subjected to various load patterns for the evaluation of compressive strength, diagonal tensile strength and shear strength. For the bond, four types of mortars i.e., cement – sand (1:4), cement – sand (1:8), cement – sand – khaka (1:2:2) and cement – sand – khaka (1:4:4) were used in the joints of concrete block masonry assemblages. (Khaka is a by-product formed in the stone crushing process). For each type of mortar, three samples of block masonry were fabricated for compressive strength, shear strength and diagonal tensile strength, and tested in the laboratory. It is observed that the replacement of sand by khaka enhanced the mechanical properties of masonry.

Implementation and evaluation of the underwater crack repair in the hollow concrete block of the gravity wharf

Concrete block quay wall is the most popular type of structures in the gravity wharf. The concrete block can be generally categorized into two types: solid and hollow concrete blocks. Compared to the solid concrete block, the hollow concrete block can reduce the usage of concrete significantly and increase the resistance to sliding and overturning. This paper studied the application of hollow concrete blocks in the gravity wharf of Qingdao Port. It was discovered that in the application, the main problem was the crack development in the hollow concrete blocks. The paper first analysed the reason of crack development in the structure by conducting laboratory model tests. It was found that the contact conditions between two hollow concrete blocks was the key of the crack development. In order to improve the performance of the structure of hollow concrete blocks, an effective scheme, which can repair the cracks in the underwater environment and increase the bearing capacity of the gravity wharf, is proposed. The scheme contains two main procedures. The first step is to use the invented mending material to fill up the cracks. The next is to use the grouting technique to bond the rockfill inside the block holes and the hollow concrete blocks together. The model tests, field tests in 1980s and 2010 have proved the effectiveness of the scheme. This paper provides reference for the construction of similar structures.

Performance of Aerated Concrete Blocks Under Varying Temperatures

Aerated concrete blocks (AC) are widely used as masonry in building construction because of their light weight and low density. Try to determine the strength, bonding, cracking and thermal behavior of aerated concrete blocks at different temperatures, mortar ratios and thickness. The results show that at temperatures above 100°C, the strength will decrease and cracks will appear, and the bonding behavior will vary with the thickness and proportion of the mortar. Compared with the solid concrete block model, Thermal Comfort Research shows better thermal comfort.

Innovative sandwich-like composite biopanels – towards a new building biomaterials concept for structural applications in nonconventional building systems

ABSTRACT Redirecting the actual construction industry, which is one of the major sources of global pollution, is relevant to achieve green innovation efficiency. Researching on the potentials of wood species can lead to propose alternatives that allow reducing/reinventing conventional building materials and systems. This investigation aims to determine, evaluate and analyze the biomechanical/structural properties and performances of lightweight sandwich-like composite biopanels made of bamboo, melina and balsa. A total of 92 samples were experimentally tested under compression, bending, shear, tension, density, moisture content, glue and ply-delamination. The experimental data were validated and compensated through 82 finite element analyses. The acquired results were compared with equivalent sections of conventional materials in terms of strength, rigidity, structural behavior and mechanical efficiency. E.g. the results show the biopanels are up to two and three times more mechanically resistant than solid wall bricks and concrete block walls, respectively; and, up to nine times higher in terms of mechanical efficiency than steel. The results from the biomechanical analyses confirm the practical utilization of the wall biopanels into nonconventional building projects even as structural elements; most important, the implementation of the proposed wall biopanels into actual building systems would significantly reduce fatalities and destroyed dwellings during seismic and windy events due to its remarkable flexibility, strength and ductility.

Influence of Facing on the Performance of GRS Bridge Abutments

The paper reports the construction and surcharge load testing of two large-scale GRS bridge abutment models in an outdoor test station to investigate the influences that the facing type used could have on their load-bearing performance. The facing types examined included commonly used concrete masonry units (CMU) and much larger solid concrete blocks. Reinforcement spacing was kept at 200 mm in both models within the FHWA recommendations. Results show that using large facing blocks in the model abutment led to significant improvements in its load–deformation performance relative to that of the model with the CMU facing alternative. It is concluded that even though the structural contribution of facing is not relied upon in the FHWA guidelines, large-block facing construction could help improve the structural performance of GRS abutments in GRS-IBS projects.

A Comparative Study on Various Strength Parameters of Solid Concrete Blocks, Solid Concrete Blocks with Fly Ash and Hollow Concrete Blocks

The article discusses the various strength parameters of conventional bricks, solid concrete blocks, solid concrete blocks with fly ash and hollow concrete blocks. Due to growing population, the demand for conventional bricks too increased so we invent various alternatives for the construction of wall. Because of different strength parameters, we find alternatives such as solid concrete blocks, solid concrete blocks with fly ash and hollow concrete locks that should be used for present construction work. The use of concrete masonry units for high rise load-bearing construction has created a need for concrete blocks with high compressive strength.

EXPERIMENTAL ANALYSIS OF HEAT CONDUCTION THROUGH HOLLOW BUILDING BLOCKS

Experimental investigation of heat transfer for solid and hollow concrete blocks with 2, and 3 evenly spaced cavities in them is explored to determine the most appropriate number of cavity in building blocks for effective energy consumption in building without compromising the strength of the blocks and building. The samples were tested based on their crushing strength and heat flow resistance. The results show that for the same block size, increasing the number of holes leads to a corresponding increase in the heat resistant value of the block without compromising it’s physical strength greatly.

Analysis of Intensity and Insulation Temperature Field of Composite Self-insulated Divider

In order to save building resources and protect the environment and improve the insulation performance of the cut blocks, this paper analyzes the strength and thermal insulation temperature field of composite self-insulated blocks based on the finite element method. This paper simulates the structure and dimensions of the core in the composite self-insulation block. The results show that: The composite self-insulating block and the solid concrete block have the same strength and withstand the same pressure. Under the premise of satisfying the light weight, a self-insulation block with good energy-saving and thermal insulation performance is developed.

Effect of carbon-negative aggregates on the strength properties of concrete for permeable pavements

ABSTRACT Permeable pavements are engineered to temporarily store water to reduce flooding during rainfall events. Permeable pavements are distinguished primarily based on their surface materials which can vary from concrete, asphalt, clay brick, concrete pavers or plastic grids. This paper examined the effect of lightweight carbon-negative aggregates (CNA) on the behaviour of concrete intended for use as solid concrete block pavers in permeable pavements. Performance indicators targeted compressive strength, splitting tensile strength, density and water absorption. CNA were produced and sourced from manufacturing firm Carbon8 Systems in Kent U.K which applies patented accelerated carbonation technology to solidify incinerated ash into useful eco-friendly aggregates. The methodology involved substituting natural aggregates (NA) by mass, with CNA at percentages varying from 0 to 100. A scanning electron microscope was used to examine the aggregate–mortar interface. Both the compressive and tensile strengths decreased exponentially with the addition of CNA. Average 28-day compressive and splitting tensile strengths ranged from 69 MPa (10,000 PSI) to 18 MPa (2600 PSI) and 3.84 MPa (560 PSI) to 1.23 MPa (178 PSI) respectively. Density values decreased linearly with the addtion of CNA with average values ranging from 2200–2600 kg/m3. ⁠Conversely, water absorption increased with increases in CNA with average values ranging from 1.66% to 9.17%. Depending on the loading requirements, CNA can replace NA in solid permeable pavement blocks by up to 100%.

Measurement of Attenuation by Building Structures in Cellular Network Bands

The power transmitted through obstacles is lower than the incident one due to reflection and absorption by them and this attenuation of electromagnetic waves reduces the radio coverage of any wireless communication system. This letter presents a study for the loss introduced by multiple building structures: brick, cavity and solid concrete block, and plasterboard walls; tile and slate roofs; and ten types of modern windows. The investigation is conducted in an anechoic chamber over the frequency range from 400 MHz to 2.7 GHz. Normal incidence is considered and both linear copolarizations (vertical–vertical and horizontal–horizontal) are tested. Strong frequency- and polarization-dependent attenuation is observed for the cavity concrete block wall and windows. The results demonstrate that the windows have the highest losses among the tested structures, which can reach up to 50 dB.

Manufacturing optimization using Tsukamoto fuzzy inference system method: A case study in block paving and solid concrete block industry

Fuzzy method has advantages in solving real-world problems that are mostly non-binary and non-linear, such as calculating the optimization of production quantities. A case study for the application of this method was applied in UD. Setia Kawan Company that run the production of solid concrete and block paving. The problems faced by this company is the high demand for products resulting in short stock and sometimes over stock due to unstable customer ordering and inaccurate management in production planning. From the calculations, the number of solid concrete block produced by the company on the period of October 2016, December 2016 and February 2017 was not optimal. According to Tsukamoto’s FIS, the optimal number of solid concrete block in the third period is 9973, 9562 and 12.087 unit of solid concrete block. While the number of block paving produced by the company on the period of November 2016, December 2016 and January 2017 was also not optimal. According to Tsukamoto’s FIS analysis, the optimal number of block paving in the third period should be 9.116, 10.113 and 7.120 unit of block paving

Propuesta de valores de referencia para la resistencia de diseño a compresión diagonal y compresión de la mampostería en el estado de Guerrero, México

El objetivo del presente artículo es proponer valores de resistencia de diseño a compresión diagonal y compresión de la mampostería en Guerrero. Para esto se normalizó la información histórica experimental de 16 años. Considerando las características de los datos se evaluaron los resultados mediante comparación de valores y análisis de coeficientes de variación. Del primer parámetro se propuso 0.45 MPa y 0.20 MPa en mampostería de tabique recocido y bloques huecos pegada con morteros tipos I y II; en mampostería de tabicón y mortero tipo I se propuso 0.45 MPa. Respecto al segundo parámetro, el valor sugerido es 1.9 MPa para todas la piezas y morteros. Los resultados servirán como una guía de diseño y revisión en construcciones de mampostería.