This paper investigates the formation of Calcium Silicate Hydrate (C-S-H) as a product ofpozzolanic reactions in a cement paste with cement partially replaced with crushed recycled glass at therate of 10% and 20%. Three different particle sizes for crushed glass used in this study were in therange of 150-75μm, 75-38μm and lower than 38μm; and a water to cement ratio of 0.45 was used for allspecimens. This study showed that the formation of Calcium Hydroxide Ca(OH)2 is decreased while theformation of C-S-H is increased simultaneously at 90 days for 75-38μm and <38μm glass powder. Theuse of waste glass as a partial cement replacement improves the cement strength through the formationof C-S-H due to the pozzolanic reaction with Ca(OH)2 improving the strength of the mortar.
PurposeThis paper aims to identify the critical project management success factors and analyze those factors to achieve a sustainable construction industry in Bangladesh.Design/methodology/approachThis study identified 41 major problematic factors from the related literature. In this research, a detailed questionnaire survey was conducted among the experts and stakeholders of the construction industry of Bangladesh. The survey was carried out on a Likert scale and ranked the critical factors using the relative importance index (RII). The 41 problematic factors were divided into five group factors and ranked by the RII index to prioritize the factors. Finally, stakeholders' opinions were analyzed with the critical assessed factors, which was a very effective technique to eliminate the risks and uncertain occurrences in the construction industry of Bangladesh.FindingsThe factors analysis revealed that cost overrun, traffic jam, low wedges, slow payment for completed works and financial issues of the owner were leading critical factors in construction projects. Moreover, the critical factors are divided into five-factor groups, namely, financial management, monitoring and feedback, competency management, communication and coordination management, and risk management, which exhibit 0.767, 0.720, 0.711, 0.710 and 0.658 RII values. After all, the stakeholders' opinion suggested that implementing modern tools and techniques can help to avoid the critical situation in the construction industry of Bangladesh.Practical implicationsThe construction industry of Bangladesh is moving away from stable construction work day by day. Previously, the potential CSFs were discussed unstructured way. Hence, detecting early warning signals in a structured way has become necessary for the building firm's survival.Originality/valueThough some scattered critical issues are discussed in different literature, the critical issues of the Bangladeshi construction industry were not investigated extensively. Therefore, this study finds out the potential critical issues of the construction industry of Bangladesh to accumulate such harmful construction issues in a single platform so that the construction industry can have an overview of them with the help of innovative technologies.
This study intends to investigate the early pozzolanic reaction of Nanosilica (nS) modified cement paste (NMCP) by the characterization technique of Calcium Hydroxide (CH) and Calcium Silicate Hydrate (C-S-H ) using Fourier Transform Infrared Spectroscopy (FT-IR). NMCP samples were prepared with water-binder ratio of 0.50. nS of 5-15nm particle size were used as 1%, 3% ,5% ,7% and 10% replacement of cement by weight. All samples were cured in the concrete laboratory at daily room temperature (T) and relative humidity (RH) in the range of 18-28oC and 65-90%, respectively. Powdered samples were prepared and tested at day 1,7,21 and 28. It was found that characterization technique used were able to give satisfactory qualitative indication of pozzolanic reactivity of NMCP by the presence and absence of C-S-H and C-H that can indicate which replacement has higher pozzolanicity. NMCP exhibited a higher pozzolanic reactivity compare to conventional cement paste by which cement performance was enhanced.
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