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Marl Soil Improvement Using Recycled Concrete Aggregates from Concrete Pipes Factory

100%

Raini I. , Raini I. , Cherifi H. , El Qandil M.

tom Vol. 24, nr 10

13--27

The global population continues to grow, ensuing the expansion of urban building construction and the depletion of natural aggregates, which damage the ecosystem. Meanwhile, concrete is one of the most used materials in the civil construction sector, as well as an enormous quantities are produced yearly and poorly regulated due to their harmful environmental impact and significant disposal costs. In addition, the abundance of marl soils in Morocco’s Fez-Meknes region, complications with infrastructure and construction projects are eventually anticipated due to the soil’s vulnerability to changes in moisture content swelling, shrinking, and mechanical characteristics, associated with, high water absorption, and low bearing capacity. This paper emphasizes the suitability of reusing concrete waste (CW) originated from one of multiple concrete plants in the Fez-Meknes region as recycled concrete aggregates (RCAs) in marl soil’s improvement. In this investigation, different mixtures incorporating 15%, 30%, 45%, and 60% of RCAs were examined. The laboratory tests were conducted to classify the soil through the different additions and determine its strength and deformation parameters. Results indicate that higher additions of RCA led to sustainable soil improvement, as evidenced by a decrease in plasticity and an improvement in grain size distribution and compaction quality. The compaction quality improved up to 45% of RCA’s addition with an increase in dry density as well as bearing capacity, coupled with a decrease in plasticity values, which indicates the insensitivity to water and the effectiveness of the treatment. This treatment remains an ideal solution to stabilize these types of soil for economic, ecological and technical reasons.

The impact of polypropylene fibre addition on the CBR value

84%

Dobrzycki P.

tom Vol. 16, no. 2

81--88

The classic test for soil or aggregate bearing capacity in road construction is the CBR test. The results of the CBR were determined for gravelly sand and sand with the addition of 1.5% cement, as well as for their mixtures with 18 mm long polypropylene fibres in the amounts of 0.1%, 0.2% and 0.3%. The effect of compaction and time of curing of samples stabilised with hydraulic binder were also determined. The natural soil without cement and fibre additions had relatively high CBR values. The additions of 0.1% and 0.2% polypropylene fibres to the dry mass of the soil resulted in an approximately 2-fold increase in the CBR value for the samples compacted using the standard method. Increasing the amount of fibres to 0.3% caused a reduction in the CBR value to that obtained without fibre addition. For samples compacted using the modified Proctor method, the observations are different. Only the sample with 0.2% fibre addition achieved a slightly higher CBR value. Moreover, the addition of 1.5% cement and the length of treatment increased the CBR values.

Zależność Kalifornijskiego Wskaźnika Nośności CBR od układu warstw konstrukcyjnych nawierzchni drogowych

67%

Chmielewski R. , Waliszewski D.

tom nr 7

66--67

W artykule przedstawiono problem określania i interpretacji Kalifornijskiego Wskaźnika Nośności CBR w przypadku gruntów „wątpliwych” stanowiących podłoże gruntowe dla nawierzchni drogowych i lotniskowych. Zwiększający się ruch kołowy powoduje konieczność stosowania złożonego układu warstw konstrukcyjnych generujących zróżnicowane obciążenia stałe na grunt. Obciążenia na podłoże gruntowe i naprężenia przez nie wywoływane są zmienne w zależności od kategorii ruchu oraz ciężaru warstw konstrukcyjnych. Na podstawie proponowanych zestawów typów nawierzchni z Katalogu Typowych Nawierzchni Podatnych i Półsztywnych (od KR1 do KR7) przeprowadzono wiele oznaczeń CBR w przypadku gruntów „wątpliwych”. Pozwoliło to określić zmienność parametru CBR od zastosowanego w czasie badania obciążenia stałego imitującego naciski od układu warstw konstrukcyjnych. Uzyskane wyniki badań umożliwiły również analizę wpływu nośności podłoża gruntowego w zależności od stosowanego układu nawierzchni i pośrednio kategorii ruchu.

The paper presents the problem of defining and interpreting the Californian Bearing Ratio, which is a subsoil for road and airport pavements. Increasing circular motion makes it necessary to use a complex set of construction layers generating differentiated fixed loads on the ground. The load on the subsoil and the stresses generated by them are variable depending on the traffic category and the weight of the above construction layers. Based on the proposed pavement type sets from the Katalog Typowych Nawierzchni Podatnych i Półsztywnych (from KR1 to KR7) a number of CBRs have been performed for problematic soils. This allowed us to determine the variability of CBR parameters from the applied static load implicitly applying pressure from the structural layers. The obtained results also made it possible to analyze the influence of soil substrate load depending on the surface system and traffic categories.