Papers by Parviz Ghoddousi
Delays and budget overruns in construction projects have been a lifelong problem in many developi... more Delays and budget overruns in construction projects have been a lifelong problem in many developing countries including Iran. Previous studies within Iranian construction context have wholeheartedly acknowledged the contribution of low labour productivity to the foregoing challenges rampant in the Iranian construction industry. In this context, identifying the factors adversely affecting labour productivity seems to be the first step towards resolving the aforementioned issues. Taking into account the crucial role of road construction projects in Iran as a developing country, this paper presents the results of one of the first studies conducted in Iranian road projects aiming at identifying and ranking the major factors influencing the labour productivity of road contractors. The literature review findings established that one of the key aspects of a project affecting labour productivity concerns the project's nature and working environments. Hence, the impacts levels of 8 overarching factors associated with working environments in road construction projects were investigated through conducting a questionnaire survey eliciting the viewpoints of CEOs of 60 contractor companies active in road construction projects in Iran. The outcomes ascertained the main factors pertaining the projects nature and environment acting as the determinants of labour productivity in road contractor companies. The primary factors were ranked as: (1) procurement policies, (2) weather conditions, (3) technologies deployed, (4) quality auditing procedures, (5) congestion and overcrowding on the site, (6) complexity of the projects, (7) site geographical conditions, and (8) reworks. The findings of the study would contribute to the body of construction management knowledge by highlighting the factors affecting labour productivity as the prerequisite for any attempt geared towards improving labour productivity
ABSTRACT The OPM3 self-assessment questionnaire is utilized in this paper first to evaluate matur... more ABSTRACT The OPM3 self-assessment questionnaire is utilized in this paper first to evaluate maturity state of the large sized construction companies in Iran based on a survey of 81 companies out of 326 which hold a grade one certificate. The main acquisitions of the research are as follows: although all companies having a grade one license are authorized to perform projects of the same size and complexity which practically they do, but definitely they are not in the same level in terms of organizational project management maturity. The data reflected that companies are in reasonable condition in the standardize stage, but they have to put in a lot of effort to improve their situation in other stages mentioned in OPM3.In addition, the band scores achieved by this test are related to some of companies' success factors. The results showed some 59% of Iranian largest companies have a maturity degree less than 50%. Also, no remarkable consistency between the company's maturity degree extracted from OPM3 questionnaire and its historical precedence was observed. Above all, it was conceded that only companies which demonstrate noticeable maturity levels have been able to win the tenders of international projects.
In light of the lack of interest in implementing waste management in developing countries such as... more In light of the lack of interest in implementing waste management in developing countries such as Iran; exploring the barriers to waste management implementation becomes relevant as the driving force behind conducting the present study. Major barriers identified in previous studies, were selected through a review of literature. Afterwards, a questionnaire survey was administered among different categories of Iranian construction contractors and 101 duly completed questionnaires were received. Ranking of 15 barriers through statistical analysis revealed the absence of a systematic regulatory regime for Construction and Demolition (C&D) waste management for construction projects. Among other findings, a lack of attention to waste management in regulations; lack of necessary skills and knowledge among construction practitioners; lack of economically viable methods for managing waste; and lack of attention to waste management within the dominant culture of the community were identified ...
Technics Technologies Education Management
The OPM3 self-assessment questionnaire is utilized in this paper first to evaluate maturity state... more The OPM3 self-assessment questionnaire is utilized in this paper first to evaluate maturity state of the large sized construction companies in Iran based on a survey of 81 companies out of 326 which hold a grade one certificate. The main acquisitions of the research are as follows: although all companies having a grade one license are authorized to perform projects of the same size and complexity which practically they do, but definitely they are not in the same level in terms of organizational project management maturity. The data reflected that companies are in reasonable condition in the standardize stage, but they have to put in a lot of effort to improve their situation in other stages mentioned in OPM3.In addition, the band scores achieved by this test are related to some of companies' success factors. The results showed some 59% of Iranian largest companies have a maturity degree less than 50%. Also, no remarkable consistency between the company's maturity degree extr...
Nanomaterials, 2019
There is a constant drive to improve the properties of recycled concrete owing to its inferior st... more There is a constant drive to improve the properties of recycled concrete owing to its inferior strength and fracture toughness compared to normal concrete and recent progress in graphene oxide (GO) nanomaterials impelling nanosized reinforcements to recycled concrete. Here, GO-modified natural sand (NS)- or recycled sand (RS)-based mortars (GONMs or GORMs) with six GO fractions (wGOs) were fabricated to explore their 28 d mechanical strengths (f28t, f28c), fracture toughness (KIC, δc), and microhardness (Hv), as well as their crystal phases (using X-ray powder diffraction) and microstructures (using scanning electronic microscopy). Results reveal, greater enhancements in mechanical strengths (4.50% and 10.61% in f28t, 4.76% and 13.87% in f28c), fracture toughness (16.49% and 38.17% in KIC, 160.14% and 286.59% in δc), and microhardness (21.02% and 52.70% in Hv) of GORM with just 0.025 wt‰ and 0.05 wt‰ GO, respectively, with respect to the control are achieved when comparing with thos...
Construction and Building Materials, 2020
h i g h l i g h t s It is tried to compare wet and dry conditions effect on skid resistance of mi... more h i g h l i g h t s It is tried to compare wet and dry conditions effect on skid resistance of mixtures. Different nano-particles including nano-SiO 2 , halloysite nanotube and nano-montmorillonite evaluated in this study. The relationship between the volume loss and porosity of concrete containing nano-materials is presented. It is tried to relate the skid resistance to the porosity and surface roughness.
Construction and Building Materials, 2018
h i g h l i g h t s Effects of siliceous particles at nano, micro, and macro scales in self-conso... more h i g h l i g h t s Effects of siliceous particles at nano, micro, and macro scales in self-consolidating mortars were assessed. Mechanical and durability properties, surface characteristics and early age shrinkage were investigated. Interfacial transition zone and the microstructures were studied by using SEM, TGA and AFM. Based on TGA results, pozzolanic reaction of samples containing silica fume and nanosilica are almost the same. Higher silica percentage in sand reduces improvement of abrasion resistance due to using SCMs. According to AFM image, surface skid resistance was improved by using SCMs and sands with lower SiO 2 percent.
Technics Technologies Education Management
Delays and cost overruns are the pervasive problems of Iranian construction industry. One of the ... more Delays and cost overruns are the pervasive problems of Iranian construction industry. One of the major reasons for the current state is the well-known problem of low productivity of Iranian construction sector. Enhancing the work output or productivity of human resources in construction projects is one of the most effective available remedies to address the foregoing issue. This paper aims at presenting the findings of a questionnaire survey conducted in Iranian construction industry to investigate one of the most dominating factors affecting productivity, namely leadership strategies of the project managers. The survey questionnaire consisted of 10 questions directed to 60 project managers of road construction companies. Statistical analysis performed and the ranking of the influencing factors with a great impact on the productivity of construction workers identified. The analysis indicated that the five most important matters related to leadership strategies, significantly affecti...
Design, Production and Placement of Self-Consolidating Concrete, 2010
Abstract. One of the most challenging problems that can confront a repair engineer is that the co... more Abstract. One of the most challenging problems that can confront a repair engineer is that the completed structure is a monolithic mass that is free from cracks, especially with regard to the plastic shrinkage cracking in concrete flatwork. The more roughness in the surface of ...
Minimizing of cement paste volume not only decreases the cost of construction but also improves m... more Minimizing of cement paste volume not only decreases the cost of construction but also improves many of attributions regarding durability in self-consolidating concrete. In this paper, a mixture design method of Self-Consolidating Concrete based on minimum cement paste volume is proposed that descends cost of construction, more over because of creating a systematic modification process, achieving desired mixture is accelerated. It's understood from the results that amount of minimum required cement paste in selfconsolidating concrete is dependable on aggregate size distribution and composition of cement paste, more over in self-consolidating concrete, it is probable that minimum amount of required cement paste is needed in aggregate composition that haven’t maximum packing density.
U ovom radu prikazan je eksperimentalni program ocjenjivanja robusnosti za četiri različita samoz... more U ovom radu prikazan je eksperimentalni program ocjenjivanja robusnosti za četiri različita samozbijajuća betona (eng. Self Compacting Concrete - SCC). Projektirana je kontrolna mješavina te tri serije mješavina s razlikama u osnovnim svojstvima u svježem stanju. Za ocjenu robusnosti u odabranim mješavinama se mijenjala količina vode. Ispitane mješavine su zatim rangirane primjenom metode višeatributnog odlučivanja. Rezultati pokazuju da smanjenje otpornosti na segregaciju i smanjenje sposobnosti zaobilaženja prepreka uzrokuje značajno smanjenje robusnosti samozbijajućih betona.An experimental program aimed at evaluating robustness of four distinct types of self-compacted concrete (SCC) is presented in this paper. A control mix was designed and three series of mixes were made, with variation of principal fresh mix properties. In order to evaluate robustness, the selected mixes were subjected to variations in water content. The tested mixes were then ranked using the multi-attribute ...
Proceedings of the International Symposium on Automation and Robotics in Construction (IAARC)
Cement based material such as mortar and concrete are brittle in nature and crack under low tensi... more Cement based material such as mortar and concrete are brittle in nature and crack under low tensile stress and strain levels. Adding discontinuous fibers as reinforced concrete remedy some concern related to cement based material brittleness and poor resistance to crack growth. After cracking the fibers arrest between two crack faces and provide mechanisms that abate their unstable propagation []. Fibers bridging force is achieved by transmission of the bond interfacial stress between the fiber and surrounding matrix. The resistance of the section to further crack opening depends largely on the fiber pullout mechanisms and related possibilities including complete fiber pullout or fiber fracture []. The high levels of interfacial shear strength may prevent fibers from complete debonding and result in fiber fracture. Although the strength of composite may increase, its toughness reduces significantly and failure is brittle. On contrary the low interfacial shear strength causes complet...
The aim of this study was to evaluate the effect of self-consolidating concrete mixture component... more The aim of this study was to evaluate the effect of self-consolidating concrete mixture components on yield stress (static and dynamic yield stress) and plastic viscosity. Accordingly, mixtures with different water-cement ratio and the amount of limestone powder (100, 150 and 200 kg/m3) were made. In addition, cement has been replaced with different percentages of silica fume, slag and metakaolin. Results show that increase in water to cement ratio cause decrease in yield stress and plastic viscosity. On the other hand, increasing in limestone content leads to yield stress reduction. Over time, this yield stress increased while the plastic viscosity of mixtures showed no significant change. By replacing the silica fume, yield stress increased but plastic viscosity unchanged while metakaolin cause increasing in both parameters.
Scientia Iranica, 2021
This study investigated the e ects of supplementary cementitious materials with changes to the st... more This study investigated the e ects of supplementary cementitious materials with changes to the structure of the concrete pores based on Coe cient of Thermal Expansion (CTE) at di erent ages. The results indicated a descending trend for the CTE of the reference concrete up to 60 days (decreasing by about 12%), after which it remained constant. On the contrary, a di erent trend was observed for the slag-containing concrete; in other words, the descending trend started after 60 days and its CTE declined by 10% up to 120 days. In the following, two equations for the concrete were presented to estimate its CTE during its lifetime based on its CTE at the age of seven days. In all concretes, the CTE reduction was associated with the reduced porosity. Moreover, the results of evaluating the pore size distribution showed that with a decrease in the pore diameter, the CTE decreased as well, indicating a strong relationship between the median diameter of the pores and the CTE. Given that the CTE depends on the aggregates and cement paste, a model was proposed based on the CTE of the cement paste and its packing density to estimate the CTE of the concrete.
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Papers by Parviz Ghoddousi