Freeze-Thaw Performance and Moisture-Induced Damage Resistance of Base Course Stabilized with Slow Setting Bitumen Emulsion-Portland Cement Additives

Freeze-thaw (FT) cycles and moisture susceptibility are important factors influencing the geotechnical characteristics of soil-aggregates. Given the lack of published information on the behavior of cement-bitumen emulsion-treated base (CBETB) under environmental conditions, especially freezing and thawing, this study investigated the effects of these additives on the CBETB performance. The primary goal was to evaluate the resistance of CBETB to moisture damage by performing FT, Marshall conditioning, and AASHTO T-283 tests and to evaluate the long-term stripping susceptibility of CBETB while also predicting the liquid antistripping additives to assess the mixture’s durability and workability. Specimens were stabilized with Portland cement (0%–6%), bitumen emulsion (0%–5%), and Portland cement-bitumen emulsion mixtures and cured for 7 days, and their short- and long-term performances were studied. Evaluation results of both the Marshall stability ratio and the tensile strength ratio show that the additions of additives increase the resistance of the mixtures to moisture damage. Results of durability tests performed for determining the resistance of compacted specimens to repeated FT cycles indicate that the specimen with the 4% cement-3% bitumen emulsion mixture significantly improves water absorption, volume changes, and weight losses. This indicates the effectiveness of this additive as a road base stabilizer with excellent engineering properties for cold regions

Comparison between mixtures of asphalt with Palm Oil Shells and coconut Shells as additives

The finding of other alternative material that has become the concern of various works lies in the fact that the material is to serve as an additive in asphalt mixes to enhance its physical properties. This paper deals with a laboratory study which compares the performance of hot mix asphalt (HMA) with the use of palm oil shells (POS), also with coconut shells (CS) as an additive and control samples. Both the palm oil shells and coconut shells are put in separately, taking up the shape of coarse aggregate with the size of 4.75 mm. The amount of these palm oil shells and coconut shells blended into the mixes is expressed in respective percentage (0,5, 10, 15 and 20%) of the total weight of the size 4.75 mm of aggregate. The Superpave method was employed to design the mixes. Samples were prepared and put to the test for the rutting characteristic as the indicator to the performance examined. It was observed that the addition of the coconut shells has made the HMA better with respect to their resilient modulus under 40˚C of temperature, it is cleared that 20% of CS as additive is the best percentage in term of resilient modulus among the percentages that have been chosen. However, it is contrary for the POS. The POS and CS addition will lead to that the asphalt concrete becoming more responsive to permanent deformation (static and dynamic creep) for more than 5% of shells content. In general, the CS emerges as better additives than POS in the HMA

Performance evaluation of road base stabilized with styrene–butadiene copolymer latex and Portland cement

This study investigated the effects of the addition of a carboxylated styrene–butadiene emulsion (Tylac® 4190) and Portland cement on the long-term performance of road base. To achieve the goals of this study, a literature review, laboratory investigation, and data processing and analyses were accomplished. The specimens stabilized with Portland cement (0–6%) and Tylac® 4190 (5–10%) and subjected to different stress sequences in order to study the unconfined compressive strength, flexural strength, soaked and unsoaked California bearing ratio, dynamic creep, and wheel-tracking characteristics of 7-day-cured specimens. The permanent strain behavior of the samples was assessed by the Zhou three-stage creep model. The results of dynamic creep and wheel-tracking tests showed that the permanent deformation characteristics were considerably improved by the addition of a 4% Portland cement–8% Tylac® 4190 mixture, which resulted in reduction of permanent strain of the mixture. The use of the 4% cement–8% Tylac® 4190 mixture increased the flexural strength by 81.4% and 288.2% as compared to the use of 4% cement and 8% Tylac® 4190, respectively. Keywords: Road base, Long-term performance, Stabilized, Wheel tracking, Permanent strain, Polyme

Fundamentals of soil stabilization

Abstract Clayey soils are usually stiff when they are dry and give up their stiffness as they become saturated. Soft clays are associated with low compressive strength and excessive settlement. This reduction in strength due to moisture leads to severe damages to buildings and foundations. The soil behavior can be a challenge to the designer build infrastructure plans to on clay deposits. The damage due to the expansive soils every year is expected to be $1 billion in the USA, £150 million in the UK, and many billions of pounds worldwide. The damages associated with expansive soils are not because of the lack of inadequate engineering solutions but to the failure to identify the existence and magnitude of expansion of these soils in the early stage of project planning. One of the methods for soil improvement is that the problematic soil is replaced by suitable soil. The high cost involved in this method has led researchers to identify alternative methods, and soil stabilization with different additives is one of those methods. Recently, modern scientific techniques of soil stabilization are on offer for this purpose. Stabilized soil is a composite material that is obtained from the combination and optimization of properties of constituent materials. Adding cementing agents such as lime, cement and industrial byproducts like fly ash and slag, with soil results in improved geotechnical properties. However, during the past few decades, a number of cases have been reported where sulfate-rich soils stabilized by cement or lime underwent a significant amount of heave leading to pavement failure. This research paper addressed the some fundamental and success soil improvement that used in civil engineering field