Mortarless Structures with Hollow Interlocking Blocks – A Review

Cost-effectiveness of structures mostly rely on reduction of building materials. Additionally, the construction time also contributes in economic aspect. Both material and time consumption take part in making conventional construction expensive. Potential of mortarless construction in local regions of Pakistan has not been reported in literature. Thus, the aim of this literature research is to have a comprehensive review of literature about the potential of mortarless construction in local regions. This is accomplished by focusing on articles published in highly reputable journals in last one decade. Pakistan is currently facing an issue of housing demand due to 2.4% annual population growth. Mortarless construction being one of the vibrant techniques has its own pros and cons. Mechanism of interlocking commonly depends on the block shape, applicable restraints and interfacial angles. Interlocking blocks with lugs and keys have the ability to use their topology in maintaining the structural integrity. The peripheral boundary of a block is responsible for maintaining the structural stability by dissipating frictional forces at contact surfaces. Boundary constraints like lintels and tensioned ropes provide additional integrity to whole structure. The interfacial angle between interlocked surfaces determines the resistance of block removal against lateral loading. Local regions in Asia and particularly Pakistan face economic limitations in construction. Practical implementation of mortarless interlocking structures can be economically beneficial provided sufficient robustness for stability

Rock Quality Analysis using Empirical Techniques (RMR & Q-SYSTEM) along the Headrace of a Hydropower Project in Kalam, Swat, Pakistan

The principal goals of this research were to examine the rock mass classification (RMC) and characterization as well as the support assessment for the proposed headrace tunnel route of an approximately 11 km long hydropower project (HPP) in Kalam valley, Khyber Pakhtunkhwa (KP), Pakistan. It was important to look at the key discontinuity factors for the classification of rock masses. To accomplish the aim, field discontinuity surveys were carried out to obtain rock mass parameters, and collected samples along the proposed tunnel route. Furthermore, characterization and classification of rock mass have been done using empirical techniques (ET) such as Beiniawski's Rock Mass Rating (RMR) and Barton's Tunnelling Quality Index (Q). The rock types were identified as Kalam Quartz Diorite, Gabbro and Granodiorite from literature. The prominent discontinuity sets were evaluated by exporting discontinuity data to DIPS. Quality Index was determined by calculating, its parameters, Quality Index values range between 3.74-17.00, 3.74 (poor at DS-04), 7.08-7.33 (fair at DS-01, DS-11 and DS-18) and 10.07-17.00 (good at DS-02, DS-09, DS-13, DS-14, DS-17 and DS-19), whereas, rock mass classification values ranges from 47-60 (fair at DS-01, DS-02, DS-04, DS-09, DS-11, DS-13, DS-14, DS-18, DS-19) to 64 (good at DS-17). The rock support according to the RMR scheme suggests fully grouted systematic bolting 3 to 4 m in length and 1.5 to 2.5 m spaced and 50-100 mm shotcrete in the crown and 50 mm in sides, while Q-system suggests spot bolting to Systematic bolting with 40-100 mm unreinforced shotcrete

A Review of Sustainability Indicators for Small-scale Construction Projects by Private Contractors

Implementation of sustainable construction has become a prerequisite of the global construction sector owing to its cost, time, and waste management. Environmental, social, and economical sustainability indicators are key parameters for attaining sustainability in construction projects. It was inferred from the literature that sustainability in construction projects cannot be achieved without developing these indicators. Prior researchers used numerous statistical and mathematical approaches, such as fuzzy decision-making procedures and structural equation modeling, to develop sustainability in construction projects. Before creating a framework, significant research was conducted to collect important sustainability indicators in construction projects. This literature review examines papers published by reputable publishers, covering the most recent and important investigations. As a result, the current study's objective is to compile the necessary sustainability indicators and create a framework that can be used for small-scale construction projects. The previously established sustainability indicators for construction projects are identified in this present study. However, these indicators were only developed and identified for mega-scale construction projects. This study offers researchers suggestions for framing research for private contractors to achieve sustainability in small-scale construction works by using an integrated strategy to identify the research needs in this field. Sustainability must be incorporated in small-scale construction projects from the beginning of planning and administration, which must be monitored throughout the project

An Overview of Construction Waste Management

The need of construction projects is increasing day by day in developing countries to improve and build new infrastructures. Due to massive procurement of materials on these projects, significant amount of waste is generated. This waste has substantial impacts not only on project cost but also on the environment.  So waste measurement and its source of generation would be the first initiative to control these wastes. In this regard, around sixty (60) papers were reviewed to determine the most wasteful materials based on past papers literature. Further, to determine the barriers in waste management, frequency analysis was performed. Based on these analysis it was found that design changes, procurement problems, theft and vandalism, etc. are major sources of waste generation. Further, out of twenty five (25) materials, most wasteful were wood, steel, bricks, concrete, tiles, sand, cement and ceiling boards. Moreover, major barriers in waste management are inappropriate regulations, financial issues, lack of standards and lack of awareness programs. So to promote suitable construction, waste management practices must be followed, in this regard more studies are required to focus in developing a comprehensive waste management framework

IoT Based Real Time Early Age Concrete Compressive Strength Monitoring

Concrete Strength determination has been an expensive and hectic job due to its orthodox methodology of measuring concrete strength where cylinders are filled with concrete. Its strength is measured using the crushing of concrete (Compression Test). A significant amount of waste is generated while performing this test multiple times during the execution of the project. The present study proposes a new IoT-based framework comprising a low-cost sensor and a window dashboard to estimate and monitor the real-time early-age concrete strength. This system will significantly help the construction industry to avoid the onsite laboratory testing of concrete for strength. In this study, a temperature sensor, along with an ESP32 microprocessor, is used to acquire and transmit the recorded temperature in real time to a cloud database. The window application developed load data from the cloud database and presented it as figures and graphs related to concrete strength with time. The strength calculated using the developed sensor was compared with the actual strength determined using a compression test for the same mix design, which showed a significant match. The project is a contribution toward the non-destructive testing of concrete. By knowing the concrete strength of any structural member in advance, the practitioners can make decisions well before time to avoid delays in the project

Enhancing the Mechanical Properties of Concrete and Self-Healing Phenomena by adding Bacteria, Silica fume and Fibres

Concrete which is the most useable material in the world after the water has flaws, it is susceptible to cracking over time. These cracks occur in the form of shear cracks, flexural cracks, tension cracks, shrinkage cracks etc. With these cracks, some hair-like cracks also occur in concrete which are not visible during the visual inspection. The propagation of these cracks in concrete allows the water and many other chemicals to seep inside the concrete and leads to a decrease in its properties. Such properties include decreasing durability, erosion of rebars, and progressive failure in the concrete strength. Therefore, the repair of hair-like cracks is also essential for the long-term safety of structures. In the present study the Silica fume, and Polypropylene fibres are added to a rich concrete along with the bacteria named Bacillus Subtilis and Calcium Lactate for enhancement of its mechanical properties and self-healing phenomena. The effect of bacteria in the healing phenomenon and other properties is compared to normal concrete by casting the cylinders and beams. The slump, compressive strength, tensile strength, and self-healing phenomena are tested and found the increase in mechanical properties of concrete. The self-healing phenomena of cracks is observed by the Scanning Electron Microscope (SEM)

A A Review on Properties of Concrete Having Crumb Rubber as Partial Replacement of Fine Aggregates

The problem of waste rubber tires is one of the most serious environmental challenges. Crumb rubber has often been utilized to improve the characteristics of concrete composites. Mechanical treatment, chemical treatment, and thermal treatment are all options for improving the adhesion of crumb rubber aggregates to cement mortar. The purpose of this research is to examine the impact of employing crumb rubber as a partial replacement material in concrete on its fresh and mechanical qualities in order to produce sustainable concrete. The results show that the compressive strength of concrete containing crumb rubber decreases as the proportion of crumb rubber increases

Probabilistic Analysis of Strength of Structural Concrete for Post-Code Buildings in Developing Countries

Code compliance and quality construction remain a point of interest for developing countries. For structural vulnerability studies on reinforced concrete buildings, researchers usually adopt random strength parameters to represent the compressive strength of concrete for various structural members. This matter becomes a challenge if researchers are dealing to quantify the structural response of code-compliant buildings. Since the research on the response of code-compliant buildings is limited hence this paper aims at data collection and presenting the probabilistic trends in compressive strength variation of structural concrete being used or has been used in multiple projects of the federal capital city of Pakistan for code-compliant buildings. The data has been collected from well-reputed academic and commercial testing labs in the area for past 10 years (the timeline after implementation of BCP 2007). Compressive strength testing records of concrete cylinders for 28 days strength have been sorted for different structural members i.e., beams, columns, shear walls, slabs and footings separately. From the selected data, histograms have been plotted for each member category and mean values with standard deviations have been highlighted. Obtained results are further compared with anticipated design compressive strengths which were obtained from different tagged reports, design offices and resident engineers of the sites. The produced results would lead to true representation of structural strength of concrete for code-compliant buildings, to be further studied for structural vulnerability and risk assessments of the desired areas in developing countries

Effect of Casting Technique on the Compressive Behaviour of Fully Recycled Aggregate Concrete

The research work presented in this contribution investigated the impact of Compression Casting Technique (CCT) on the compressive behavior of fully Recycled Aggregates Concrete (RAC). RAC mix containing 30% fine aggregates, 70% coarse aggregates and 15% cement by weight of total aggregates was prepared under two different casting pressures (i.e., 25 & 35 MPa). For the purpose of comparison, Natural Aggregate Concrete (NAC) mix was also prepared under same casting pressures. Samples of RAC mix were also made by compaction through vibration. Recycled concrete aggregates required for this study were prepared by crushing of damaged concrete samples having compressive strength in the range of 21 to 28 MPa. Compressive response was evaluated in terms of compressive strength and modulus of elasticity (MOE). Ultrasonic pulse velocity test was employed to check the quality of internal matrix of concrete samples prepared by CCT and vibration. The results demonstrated positive effect of CCT on the properties of concrete resulting in higher compressive strength and MOE compared to properties of concrete prepared by compaction through vibration. With the increase in casting pressure from 25 to 35 MPa, compressive strength and MOE of RAC was increased by 21% and 29%, respectively. It was found that RAC mix exhibited inferior properties (i.e., compressive strength and MOE) compared with NAC mix

Regression Model for Predicting Soaked CBR from UCC

ABSTRACT. Flexible pavement is a multi-layered structure with a subgrade layer acting as the pavement structure’s foundation. The performance and strength of soil for its use as a subgrade are ascertained by its California Bearing Ratio (CBR) value. CBR test is a technically extensive and labor-intensive mechanism that could cause delays in carrying out construction projects, which would raise the construction cost. Therefore, highway engineers need to design a predictive model for quick assessment of the CBR of subgrade soil. In this research, eight specimens of disturbed soil were obtained from Rawalpindi Division, Pakistan. All soil samples were subjected to laboratory testing and categorized according to the AASHTO soil Classification System. The specimens were subjected to soaked CBR, and unconfined compression tests based on Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) values, acquired from the Modified Proctor Compaction test. An empirical correlation between soaked CBR and unconfined compressive strength test is developed by the Suitable Trend-Line Method in Microsoft excel. From the single linear regression model, the value of the coefficient of correlation is found (0.98) indicating a very good correlation between soaked CBR and UCC strength test. Keywords: Regression Model, Correlation Coefficient, California Bearing Ratio (CBR), UCC strength