Civil Engineering Materials Research Papers (original) (raw)
The effectiveness of concrete surface treatment materials such as silanes, siloxanes, etc., in preventing concrete deterioration due to sulfate attack, carbonation, and chloride-induced reinforcement corrosion was investigated. The... more
The effectiveness of concrete surface treatment materials such as silanes, siloxanes, etc., in preventing concrete deterioration due to sulfate attack, carbonation, and chloride-induced reinforcement corrosion was investigated. The effectiveness of these materials in decreasing the sulfate ...
Crumb rubber modifier (CRM) is considered one of the most commonly used modifiers that enhances the rheological properties of asphalt binders. Optimizing the interaction process between CRM and asphalt binder to enhance the asphalt... more
Crumb rubber modifier (CRM) is considered one of the most commonly used modifiers that enhances the rheological properties of asphalt binders. Optimizing the interaction process between CRM and asphalt binder to enhance the asphalt binder’s elasticity without additional additives is the main purpose of the article. Rheological properties were measured in this article for neat asphalt and crumb rubber modified asphalt (CRMA) binders. Two sets of interactions were selected. In the first interaction set, one interaction temperature (190°C), one interaction speed (3,000 rpm), and different interaction times (0.5, 1, 2, 4, and 8 h) were used. The used CRM percentage was 10 % by weight of the neat asphalt binder. Two sources of asphalt binder, one source and different percentages of CRM, one interaction temperature (190°C), one interaction speed (3,000 rpm), and different interaction times were selected for the second interaction set. This set was designated to confirm the rheological properties obtained for the first set. Thermogravimetric analysis (TGA) was performed on CRM particles before and after their interaction with asphalt binder after different interaction times. The CRMA binders that interacted for the entire 8-h interaction times had significantly enhanced properties, especially the elasticity, as compared to the neat asphalt binder. The 8-h interaction time showed the highest CRM dissolution percentage by dissolution and TGA testing. At this interaction time, more CRM components were released into the asphalt binder liquid phase, which was detected by observing Fourier-transform infrared peaks at 966 cm−1 for polypropylene and 699 cm−1 for polystyrene.
The paper is focused on the comparison between uniaxial and biaxial laboratory test results for the polyester coated fabric. A short literature review concerning coated woven fabrics with emphasis on biaxial tensile tests is presented. A... more
The paper is focused on the comparison between uniaxial and biaxial laboratory test results for the polyester coated fabric. A short literature review concerning coated woven fabrics with emphasis on biaxial tensile tests is presented. A description of the polyester coated fabric under biaxial test by means of constitutive models and material parameter values is proposed. To establish the right values of the ultimate tensile strength flat and curved grips are tested.
- by João Coroado and +1
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- Materials Engineering, Civil Engineering, Recycling, Ceramics
Use of a reliable and accurate measuring system to determine lateral pressure exerted on formwork by self-consolidating concrete can lead to economic and safe formwork systems. In this paper, a portable and field-compatible pressure... more
Use of a reliable and accurate measuring system to determine lateral pressure exerted on formwork by self-consolidating concrete can lead to economic and safe formwork systems. In this paper, a portable and field-compatible pressure device is developed to enable factors affecting lateral pressure of fresh concrete on formwork system to be explored prior to conducting onsite full-scale tests. The pressure device requires a sample of 16 liters of fresh concrete to determine lateral pressure envelope that can be exerted by a concrete column of up to 13 m in height. The pressure device enables the simulation of such concrete head using an overhead pressure exerted onto the fresh concrete. A number of parameters are used to validate the pressure device, including placement rate as well as mix designs of various paste volume, slump flow, w/cm, maximum size of aggregate, and dosages of chemical admixtures. The test results indicated that the repeatability of the lateral pressure values obt...
This paper presents results from an experimental study including testing five reinforced concrete beams in order to investigate the efficiency of external strengthening of such beams when provided with large openings within their shear... more
This paper presents results from an experimental study including testing five reinforced concrete beams in order to investigate the efficiency of external strengthening of such beams when provided with large openings within their shear zones. Firstly tow beams were considered. One of these beams was solid without any openings and was considered as a control beam. The second beam was provided with one opening within the shear zone but without any strengthening and was also considered as a control beam. Secondly, three beams provided with openings at the same location and having the same dimensions like the second. Such three beams were externally strengthened with steel plates along the opening edges. It was found that the steel plates used for strengthening and its configuration scheme significantly affects the efficiency of strengthening in terms of beam deflection, steel strain, cracking, ultimate capacity and failure mode because using steel plates restored the beam shear strength .Finally, theoretical analysis was performed for all tested beams with openings in order to calculate the ultimate shear force carried by such beams. Equations presented by empirical formulas found in the literature were used to perform the theoretical analysis. Good agreement was observed between the theoretical results and the experimental ones.
Over the years, there has been mounting interest in the use of recycled tire rubbers in highway construction. Tire rubber-filled concrete, a rubberized Portland cement concrete with a portion of aggregates replaced by tire rubber... more
Over the years, there has been mounting interest in the use of recycled tire rubbers in highway construction. Tire rubber-filled concrete, a rubberized Portland cement concrete with a portion of aggregates replaced by tire rubber particles, represents an alternative of using ...
Construction of buildings, both residential and commercial settings, carried in the city of Arusha located in northern Tanzania has been an absolute challenge in ensuring the desired qualities are maintained to acceptable aesthetic... more
Construction of buildings, both residential and commercial settings, carried in the city of Arusha located in northern Tanzania has been an absolute challenge in ensuring the desired qualities are maintained to acceptable aesthetic levels. This is due to attacks by efflorescence to finished surfaces that severely damage structural components including structural concrete, steels and paintings. This study analyzes associated construction materials including sand, pumice and ground water sourced from Njiro soils and ground waters, Oldonyosambu pumice quarries and Mirongoine river sand. The findings revealed presence of various chemical elements that when dissolved in water they react to form bicarbonate compounds, that entail severe destruction to finished surfaces and other parts of a structure. However, the study suggests some precautionary and remedial measures in effort to suppress the problem.
The combustion ash of a common nonwood biomass (wheat straw) was evaluated for value-added use in production of geo-polymer concrete where alkali aluminosilicate hydrates are the primary binder constituents. The wheat straw ash was... more
The combustion ash of a common nonwood biomass (wheat straw) was evaluated for value-added use in production of geo-polymer concrete where alkali aluminosilicate hydrates are the primary binder constituents. The wheat straw ash was supplemented with other raw materials in order to achieve a desired chemical balance. The binder composition that performed well in experimental work comprised wheat straw ash:coal fly ash:metakaolin:gypsum at 0.50:0.25:0.25:0.05 weight ratios. The wheat straw ash–based concrete as well as a control portland cement concrete were subjected to a comprehensive experimental investigation. The workability, set time, compressive strength, residual compressive strength after immersion in boiling water, flexural strength, density, moisture absorption, voids content, capillary sorptivity, and acid and fire resistance of concrete materials were evaluated. The experimental results indicated that the nonwood biomass ash–based geopolymer concrete materials with proper binder formulation can provide desired mechanical attributes, moisture barrier qualities, durability, and fire resistance when compared with normal portland cement concrete.
Correlation and regression in this paper were employed as analytical tools to study the degree of relationship as well as the nature and strength of the relationship between green concrete properties and percentage replacement of cement... more
Correlation and regression in this paper were employed as analytical tools to study the degree of relationship as well as the nature and strength of the relationship between green concrete properties and percentage replacement of cement with civil engineering materials. Pearson product-moment method and Spearman's correlation coefficient were extensively used to show how correlation analysis can be practically applied in green concrete research. Least square regression line method for both linear relationship and non-linear relationship was also used to analyse the nature of the relationship between percentage replacement of cement with a pozzolana and green concrete properties like compressive strength and water absorption. The results of correlation analysis showed that Pearson product-moment is a better method for analysing green concrete properties when compared with Spearman's correlation coefficient, since Pearson's method takes cognizance of the actual data values unlike Spearman's use of data positions. The results of regression analysis also revealed that, for data whose trendline is polynomial in shape with the highest power of its assumed equation higher than that of quadratic equation, it is better to analyse such data using least square regression line method for linear relationship than least square regression line method for non-linear relationship. This is supported by the substantial difference in the predicted values of 40.79MPa and 36.20MPa for linear and non-linear relationship respectively for 35% replacement of cement with rice husk ash along with fly ash.