Influence of elevated temperatures on physical and compressive strength properties of concrete containing palm oil fuel ash

The residual compressive strength of concrete containing palm oil fuel ash (POFA) after exposure to elevated temperatures and subsequent cooling was investigated. Specimens from ordinary Portland cement (OPC) and POFA concrete mixes were prepared and subjected to various temperature levels. The POFA concrete contains 20% partial replacement of cement by weight and the temperature levels are; 100, 300, 500 and 800 °C. Two cooling systems which include cooling at room temperature by the natural breeze and water-spray were involved. Compressive strength test was conducted on control specimens as well as concrete specimens revived through the two cooling systems. Physical properties accompanying thermal degradations were also assessed. Residual performance as a ratio of residual strength to original strength was evaluated. The residual performance was found to be higher in POFA concrete than in the normal concrete. In addition, water-cooling was realized to aggravate strength reduction in both normal and POFA concretes when compared with air-cooling. High temperature and cooling system were also found to have great influence on physical properties, such as; mass loss, discolouration and crack patterns

Compressive strength loss and reinforcement degradations of reinforced concrete structure due to long-term exposure

Degradations due to long-term weathering actions on a reinforced concrete structure were investigated. Compressive strength and reinforcement corrosion developments of a prototype RC structure were monitored for 6 years using destructive and non-destructive tests which include periodic coring, compressive strength, rebound hammer, ultrasonic pulse velocity, carbonation, half-cell and tensile strength tests. Eventually, results have shown that more than a quarter of peak compressive strength can be lost within 5 years of continuous exposure. Corrosion of the exposed bars within the range of the testing period was also observed to be quite alarming. Thus, defects caused by prolonged actions of environmental factors may pose serious threats on the integrity of partially completed structures especially abandoned projects

Influence of non-hydrocarbon substances on the compressive strength of natural rubber latex-modified concrete

Inclusion of polymeric substances into hydraulic cement concrete has made a tremendous impact towards improving its performance properties. However, polymers to be included into concrete should neither cause damage to its mechanical capacities nor to its durability characteristics. This article reports experimental findings regarding influence of non-hydrocarbon substances present in natural rubber latex (NRL) on the compressive strength of NRL-modified concrete. Six selected clonal latexes were chemically analyzed for thirteen compositional parameters each. The latexes are used in making modified concretes and specimens obtained from these concretes were given both moisture and dry curing treatments for effective cement-hydration and latex-film formations respectively. Eventually, concretes modified with latexes containing higher non-hydrocarbon substances especially volatile fatty acids (VFA) and zinc were observed to suffer significant compressive strength losses. Indeed, 12.4% loss in compressive strength was recorded against concrete modified with the latex having the highest contents of VFA and zinc. However, 2% and 4% increase in the strength over normal concrete were observed in relation to two of the latexes investigated

Concrete compressive strength with prepackaged polymer-modified cementitious mortar as modifier

The objective of this study is to evaluate concrete compressive strength with inclusion of Local Prepackaged Polymer-Modified Cementitious Mortar (PPMM) as a new modifier. 18 ordinary Portland concrete (OPC) cubes size 100 mm were prepared and cured according to ASTM C192 and a total of 180 polymer-modified concrete (PMC) cubes 100 mm size were prepared and cured according to JIS A 1171:2000 and JIS A 1171:2000 modified. The inclusion of PPM varies from 5% to 25%. From this research, the compressive strength of PMC produce has significantly increase compare to OPC. The PMC specimens which being cured according to JIS A 1171:2000 modified has recorded the maximum strength

Effect of post-curing regime on density, compressive strength and crosslinking of polymer concrete

Polymer concrete is produced from polymer binder, aggregates, and filler. Its curing follows the polymerization process once polymer additive is added, and can be accelerated through post-curing. In this study, the Orthophthalic- and Isophthalic-based polymer concrete (Ortho-PC and Iso-PC) were cured and investigated at different curing temperature (30°C, 50°C and 70°C) and period (1, 3, 6, 16, 24 hours) to complete the compressive strength development. Effect of curing temperature and period on apparent density, compressive strength, and morphology properties were investigated. The outcomes exhibited that all specimens had achieved full compressive strength within 6 hours of curing time at both 50°C and 70°C. When cured at 30°C, this went up to more than 16 hours of curing period to achieve the same compressive strength. The form of crosslinking at different curing conditions was captured in Scanning Electron Microscope, SEM images. Results also showed that curing temperature and period insignificant affected the apparent density. This study can be used as references to manufacturer, fabricator, and engineers when dealing with polymer concrete which goes for post-curing method as curing process