Self-Compacting Concrete Prepared Using Rice Husk Ash Waste from Electric Power Plants

We investigated self-compacting concrete (SCC) mixtures containing rice husk ash (RHA) from electric power plants. Type 1 Portland cement (OPC) was partially replaced by RHA at levels of 0%, 10%, 20%, or 40% of the total weight of the binder materials (OPC or RHA, 275, 325, or 375 kg/m3). The mixtures were adjusted to maintain slump flow diameters of 50 ± 2.5 or 60 ± 2.5 cm. The RHA was in the form of partially amorphous silicon dioxide (SiO2) particles with an equivalent volume mean particle size of 24.32 µm. Increasing the RHA fraction resulted in a decrease in unit weight and an increase in the corresponding water/binder ratio and T50 V-funnel times. Use of 20% RHA produced a material with a long-term compressive strength similar to the control SCC.</jats:p

The Use of Residual Rice Husk Ash from Thermal Power Plant as Cement Replacement Material in Producing Self-Compacting Concrete

This paper presents the properties of self-compacting concrete (SCC) incorporating residual rice husk ash (RHA) from thermal power plant. It was ground by a mechanical grinding method using ceramic ball mill until having the volume moment mean of 24.32 micrometer. The cementitious materials (Portland cement Type 1, OPC, and RHA) for all SCC mixtures content was kept constantly at 550 kg/m3. RHA was partially replaced in Portland cement (0, 10, 20 and 40%wt.) in producing SCC with the controlled water/cementitious (W/C) ratios of 0.28 and 0.33 by weight. Tests of fresh state properties were investigated including slump flow, V-funnel flowing time, unit weight. Further, compressive strength and ultrasonic pulse velocity were tested. It is concluded that an optimum RHA replacement level of 20%wt. has the best performance of the SCC with different levels of RHA.</jats:p

The main issue working with migrant construction labor: a case study in Thailand

PurposeThe purpose of this paper is to study and prioritize the problems impacted on construction work together migrant laborers, by using the Delphi technique. The case study is construction work in Bangkok and metropolitan zones, Thailand.Design/methodology/approachThe framework of the perceived issues caused by working with migrant construction labors especially migrant construction laborers from neighboring countries were identified from literature reviews. The issue list was sent to 162 experts seeking for their opinions. Subsequently, a questionnaire was created from 58 items of suitable issue lists according to expert's opinions. The questionnaires were then submitted to 147 respondents from construction contractor companies. Their responses were calculated and prioritized by means of the Delphi techniqueFindingsThe polling data showed its constancy on the second round of survey. There were 34 out of 58 items passed consensus criteria. The issue “Foreman obtained incompetent or inadequate trained migrant labors when relocate them from/to other site or job” ranked 1st in priority ranking with the average score of 4.56. Subproblems were appropriately prioritized according to their mean scores.Practical implicationsThe results of this research were expected to facilitate construction operators in making appropriate decisions and primary solution concerning main issue factors in working with migrant labors, in order to help even more increasing competition efficiency in Thai construction industries.Originality/valueThe research provides a list of main issue occurred in the case study. These outcomes are also expected to provide important information for other case studies on the issue working with migrant construction labor.</jats:sec