Volcanic Scoria as Cement Replacement

Numerous volcanic scoria (VS) cones are found in many places of the world. Many of them have not yet been investigated, although few have been used as binders for a very long time. The use of natural pozzolans as cement replacement could be considered as a common practice in the construction industry due to the related economic, ecologic and performance benefits. This chapter highlights the advantages and disadvantages of the use of volcanic scoria as cement replacement in concrete mixes in terms of fresh and hardened concrete properties. The chemical and mineralogical composition of volcanic scoria samples collected from 36 countries is presented in this chapter, with some further analysis. The effects of using volcanic scoria as cement replacement on some paste, mortar and concrete properties, such as the setting times, the heat of hydration, the compressive strength, the water permeability and the chloride penetrability, have been studied. The improvement in resistance against the chemical attack of volcanic scoria-based cement mortar has also been highlighted. Some estimation equations depending on the data available in literature have also been derived from the analyzed data. The modification of the microstructure of VS-based cement paste has been confirmed, as well

Effect of Adding Lime and Volcanic Scoria on the Performance of Recycled Concrete Aggregates

In the study, lime and volcanic scoria have been added as cement replacement in an attempt to improve the performance of recycled aggregate concrete. The use of such eco-friendly materials could also promote a further greening practice in the concrete industry. The concrete performance was evaluated in terms of mechanical properties and concrete permeability. Mechanical properties investigated include compressive strength and modulus of elasticity of concrete. Water permeability, chloride penetrability have particularly been studied to evaluate the permeability properties. The results revealed that the use of such materials could produce greater compressive and modulus of elasticity than those of the recycled aggregate concrete alone. Further, the results showed that permeability properties of recycled aggregate concrete have significantly been improved with addition of these additions. Basaltic aggregates were used for comparison and SEM analysis was employed as well

Thermally Treated Clay as a Stabilizing Agent for Expansive Clayey Soil: Some Engineering Properties

The objective of this research was to investigate the effect of adding thermally treated clay on some engineering properties of the untreated expansive clayey soil. Three expansive clayey soil samples obtained from three different sites in the south of Syria have been investigated. They were thermally treated up to three different levels (450°C, 650°C and 850°C) for 3 hours. Three replacement levels of thermally treated clay were used, i.e. 0%, 10% and 20%. The X-ray diffractometer (XRD) technique has been used to detect the crystalline and glassy phase in the clayey samples before and after the thermal treatment. Pozzolanic activity of the thermally treated clayey soil has been studied using the modified Chapelle test and the mechanical strength test at each of the temperature levels. Atterberg limits, compaction, free swell, swelling pressure and linear shrinkage have particularly been investigated. Test results revealed the positive effect of thermally treated clay when added to the natural soil. Plasticity index (PI) was reduced by about 60% when 20% thermally treated clay was added to the natural soil. In addition, 6% lime was added to further investigate the combined effect of lime and calcined clay on the properties of the clayey expansive soil. All investigated properties were significantly improved when 20% thermally treated soil and 6% lime were added together. For instance, swelling pressure and linear shrinkage values were reduced to less than 15% or even much less when compared with those of the natural soil. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis were employed as well

Mechanical strength development of mortars containing volcanic scoria-based binders with different fineness

The benefits of using natural pozzolan as cement replacement are often associated with shortcomings such as the need to moist-curing for longer time and a reduction of strength at early ages. The objective of the study is to investigate the influence of binder fineness on the mechanical strength development of scoria-based binder mortars. In the study, mortar specimens have been produced with four types of binder: one plain Portland cement (control) and three scoria-based binders with three replacement levels: 25%, 30% and 35%, respectively. All scoria-based binders have been inter-ground into four different Blaine fineness: 2400, 3200, 4200 and 5100 cm2/g. The development of the compressive and flexural tensile strength of all mortar specimens with curing time has been investigated. The effects of the Blaine fineness of the scoria-based blended cement on the compressive and flexural strengths of mortar have been evaluated at curing ages of 2, 7, 28 and 90 days, respectively. Particle size distribution measured by a laser diffractometer has been considered in the study. Test results revealed that there is a decrease in strength with increasing amounts of scoria. In addition, there was found an increase in strength with increasing the Blaine fineness values. No direct relationship between Blaine and particle size distribution was observed. Effects of Blaine fineness on some physical properties of blended cements such as water demand, setting times and soundness have also been investigated. Further, an estimation equation for strength development incorporating the effects of fineness measured either by Blaine or by particle size distribution has been derived by the authors

Assesment of Alkali Resistance of Basalt Used as Concrete Aggregates

The objective of this paper is to report a part of an ongoing research on the influence of using crushed basalt as aggregates on one of durability-related properties of concrete (i.e. alkali-silica reaction which is the most common form of Alkali-Aggregate Reaction). Alkali resistance has been assessed through several methods specified in the American Standards. Results of petrographic examination, chemical test (ASTM C289) and accelerated mortar bar test (ASTM C1260) have particularly been reported. In addition, the weight change and compressive strength of 28 days cured concrete containing basaltic aggregates were also reported after 90 days of exposure to 10% NaOH solution. Dolomite aggregate were used in the latter test for comparison. The experimental results revealed that basaltic rocks quarried from As-Swaida’a region were suitable for production of aggregates for concrete. According to the test results, the studied basalt aggregates can be classified as innocuous with regard to alkali-silica reaction. Further, the 10% sodium hydroxide attack did not affect the compressive strength of concrete

Acid Resistance, Water Permeability and Chloride Penetrability of Concrete Containing Crushed Basalt as Aggregates

Abstract: Basaltic rocks are used extensively as engineering materials including aggregates for Portland cement concrete and asphalt concrete. Syria is very rich in Basaltic rocks. There are reserves estimated to be several billion tonnes according to recent geological investigations. The annual production of concrete in Syria is about 20 million m 3 , containing about 35 million tonnes of aggregates. Due to some concerns, use of basalt as concrete aggregate is very limited in Syria. Because of additional costs of transportation of dolomite aggregate produced in quarries located about 200 km far from the southern region, studying suitability of basaltic rocks occurring in As-Swaida'a region as local aggregate source would be very important. As-Swaida is basically an agricultural city. However, it has recently witnessed urban and industrial developments. This paper is part of larger research on evaluating the basaltic rocks extracted from As-Swaida'a region, as a potential source of concrete aggregate. Effects of aggressive acidic environments on concrete have been investigated through 3 months of exposure to 5% H 2 SO 4 , 10% HCl, 5% HNO 3 and 10% CH 3 COOH solutions. In addition, concrete permeability measured in terms of water penetration depth was evaluated for concrete after two curing time of 28 and 90 days. A RCPT (Rapid chloride penetration test) has also been carried out according to ASTM C 1202. Dolomite aggregate were used for comparison. Petrographical, chemical and physical characteristics of basaltic rocks have been reported as well. The experimental results revealed that As-Swaida'a basaltic rocks were suitable for production of crushed rock aggregates for concrete production. The resistance to all acidic solutions, except H 2 SO 4 solution, was improved substantially with the use of basalt aggregate. In addition, the resistance to water permeation and to chloride penetration of concrete increased with the use of basalt aggregates compared with dolomite aggregate. Moreover, definite correlations were noted between some acidic attacks