Effects of Uncrushed Aggregate on the Mechanical Properties of No-Fines Concrete

et al. 2019

Self Cite

Self-weight of a structure comprises a major portion of the overall structural load which causes conservative structure design. Reduction of structures’ self-weight is an active area of research today. One of the options is to use lightweight concrete and no-fines concrete is one of its types. This type of concrete is made with coarse aggregates, cement, and water. From the density point of view, it is the lighter concrete compared to normal weight concrete but it exhibits less strength. Normally no-fines concrete is manufactured with uniform size aggregates. The performance of no-fines concrete depends on the cement-aggregate ratio and water-cement (w/c) ratio. This study focuses on investigating experimentally the effect of gradation of coarse aggregates and the w/c ratio on unit weight and compressive strength of no-fines concrete. NFC with two cement-aggregate ratios (1:6 and 1:8) having seven combinations of coarse aggregate gradations (10-5 mm, 16-13mm, 20-16mm, 20-13mm, 20-10mm, 16-10mm and 20-5mm) were studied. Two w/c ratios are considered 0.38 and 0.42. The effect of coarse aggregate gradation, cement-aggregate ratio and w/c ratio are studied in terms of unit weight and compressive strength of NFC. The results reveal the pronounced effect of aggregate gradation on the compressive strength and unit weight of the concrete. Also, a substantial effect on the unit weight and compressive strength is observed with the variation in cement-aggregate ration and the w/c ratio.

Section: Introductionmentioning

confidence: 99%

Effect of Coarse Aggregate Gradation and Water-Cement Ratio on Unit Weight and Compressive Strength of No-fines Concrete

Tunio

et al. 2019

Self Cite

“…Improvement in the performance of no-fines concrete has also been attempted using very small quantities of fines in concrete, showing improvement in strength but a reduction in its permeability characteristics, which, in some cases, is the main requirement [19]. Other studies attempted to improve no-fines concrete using uncrushed aggregates [20], fly ash with admixtures [21], different mixtures and water-binder ratios [22], GGBS [23], etc.…”

Section: Literature Reviewmentioning

confidence: 99%

Assessment of the Flexural Strength of No-Fines Recycled Aggregate Concrete Prisms

Rahu

Oad

et al. 2023

This study investigated experimentally the flexural strength of no-fines recycled aggregate concrete, produced using 20-70% replacement of conventional coarse aggregates with coarse aggregates from demolished waste. Six prisms in each dosage with a 1:4 mix and 0.5 water-binder ratios were prepared. A batch of prisms with conventional aggregates was also cast to compare them with the proposed concrete. An equal number of samples were cured for 7 and 28 days and tested under a gradually increasing central point load to examine failure load, central deflection, and flexural strength. The comparison of results showed an increasing trend in deflection with an increase in the dosage of recycled aggregates. The 7-day cured samples had approximately 2.6 times the deflection of conventional concrete. However, the deflection at all replacement levels remained less than that allowed by ACI-318. The results showed a decreasing trend in flexural strength with an increase in the dosage of recycled aggregates. The 40% replacement sample had a less than 20% strength reduction and is recommended as the optimum level of replacement of conventional aggregates for the production of no-fines recycled aggregate concrete.

“…Therefore, its use is limited to pathways and parking [16], road pavement with limited traffic [17,18], and blocks instead of bricks [19,20]. Several attempts have been conducted to improve the strength of no-fines concrete by using partial replacement (up to 20%) of coarse aggregates with fine aggregates [18,21,22], reduced w/c and a/c ratios [23][24][25][26], fibers [27][28][29], admixtures including superplasticizers [26,30], and un-crushed aggregates [31], recycled coarse aggregates [32], or mixes of un-crushed and recycled aggregates [33]. Despite these efforts, still the strength of no-fines concrete is questionable.…”

Section: Introductionmentioning

confidence: 99%

Quality of Recycled Aggregates and Compressive Strength of No-Fines Recycled-Aggregate Concrete

Dahri

Oad

et al. 2021

This research paper presents the laboratory investigations of the compressive strength of no-fines concrete made with demolished waste as coarse aggregates used in percentages from 20% to 100%. The basic properties of aggregates were determined. Sieve analysis of both conventional and recycled aggregates was conducted to ensure the existence of well-graded aggregates in concrete. Nine concrete mixes were designed with an aggregate-cement ratio of 4. Additionally, three batches were prepared (conventional, recycled, conventional no-fines concrete) and the results were compared. For all mixes, the water-cement ratio was equal to 0.5. In each batch, 5 cylinders of standard size (total 60 samples) were prepared and cured for 28 days. The weight of the specimens was determined and compressive strength was checked in a Universal Testing Machine under gradually increasing load. A decrease in weight and compressive strength was recorded for the batches of the proposed concrete. Results show that at 40% replacement level the loss of compressive strength is 19% and the weight reduction of the samples was equal to 9%.