IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 2 Issue 9, September 2015. www.ijiset.com ISSN 2348 – 7968 Assessment of Pumice and Scoria Deposits in Dhamar - Rada’ Volcanic Field SW- Yemen, as a Pozzolanic Materials and Lightweight Aggregates Taha Abdullah Al Naaymi Geology Department, Faculty of Science .Sana’a University, Yemen ABSTRACT: The aim of this study is to assess the suitability of Pumice and Scoria pyroclastics from Dhamar - Rada’ volcanic field as a pozzolanic materials and lightweight aggregates. Tests were conducted as Portland cement was replaced by Pumice powder or Scoria powder within the range of 0 - 25% of standard volume, moreover, the effects of these powders as additives on the physical and mechanical properties of mortar was investigated. Fifteen concrete mixtures were produced in three groups in order to study the effects of the combination of coarse aggregates (Pumice and Scoria) with three types of fine aggregates. These mixtures were designed by replacing coarse Pumice aggregate by coarse Scoria aggregate as (0%, 25%, 50%, 75%, 100%) of volume, and replacing of fine Pumice aggregate and fine Scoria aggregate by sand. Pumice powder and Scoria powder were added to replace 25% of the Portland cement as pozzolanic materials to study the effects of additives and the cement volume reduction on the physical, mechanical and thermal properties of the concrete samples. The results indicated that the use of 25% Pumice powder or 25% Scoria powder as pozzolanic materials satisfies the requirement of Portland pozzolan cement as per ASTM C 595, however, the initial and final concrete setting time increased with the additive dosage increment respectively. Moreover, the AS group of concrete samples can be classified as light weight concrete in terms of unit weight and compressive strength requirements according to ASTM 330, ACI, and RILEM. While the concrete samples in groups BP and CSC, which have 25% pozzolanic materials, can be used for insulation purposes according to ASTM 332 and RILEM classification. Further symmetrical studies for Pumice and Scoria deposits from other locations in Yemen are recommended due to the predicted promising value of these deposits in feasibilizing many items of developing construction projects. INTRODUCTION The use of light construction materials which contribute to feasibility improvement and energy saving has increased in the last decade. The use of lightweight concrete permits greater design flexibility, and substantial cost savings, reduction of dead load, improved cyclic loading structural response, longer spans, better fire rating, thinner sections of smaller size, less reinforcing steel and lower foundation costs,(Short and Kimniburgh,1978),(Topcu,1997),(Satish and Lieif, 2002), in addition to reduce the risk of earthquake damages to structures since the earthquake forces are proportional to the mass of these structures (Yasar et al., 2003). Manufactured lightweight concrete is classified by the ACI committee 213 into three categories according to its strength and density (ACI 213, 1970). The first category is termed low strength corresponding to low density and is mostly used for isolation purposes. The second category of moderate strength and is used for filling and block concrete, while the third category of structural lightweight concrete is used for reinforced concrete. One of the most conventional ways to manufacture lightweight concrete is the use of lightweight aggregates such as Perlite, Pumice, Scoria, Diatomite, and Vermiculite, as these materials are used to produce mortar and concrete,(Neville, 1995), (Hossain, 1999). The specific gravity of concrete can be lowered either by creating pores, therefore using lightweight aggregates instead of ordinary ones, or introducing air into the mortar, or removing the fine fractions of aggregate and 386 IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 2 Issue 9, September 2015. www.ijiset.com ISSN 2348 – 7968 compacting concrete only partially. In all cases the main goal is to introduce voids into the aggregate and the mortar (Gunduz and Ugur, 2004). Pumice and Scoria are an extremely light, porous raw material. They can be found in many parts of the world including various developing countries with areas of past or present volcanic activities, (Grasser and Minke, 1990). While Pumice is used in many applications such as in dental, cosmetic, abrasive, cement, concrete, ceramic, glass, construction industries; both of them are normally used as aggregate in lightweight concrete, building blocks and assorted building products, (Crangle, 2010). Pumice and Scoria aggregates combined with Portland cement and water produce a lightweight , thermal and sound insulating, fire resistant lightweight floor fills, insulating structural floor decks and variety of other permanent insulating applications, (Failla et al., 1997), (Gunduz, 2008). Pumice is a natural material of volcanic origin produced by the release of gases during the solidification of acidic lavas such as of Rhyolite or Dacite composition (60 -70% SiO2). It is light colored, cellular, almost frothy rock made up of glass-walled bubble casts, as it may occur as coherent massive blocks composed of highly vesicular glassy lava in either a flow or vent filling; or it may be more or less fragmented by violent eruption. The main use for Pumice is as an aggregate in lightweight building blocks and assorted building products, (Founie, 2005). In Europe, Pumice was used in ancient Rome over 2000 years ago and many notable Pumice structures are still standing today ,(Grasser and Minke, 1990). While, Scoria is a vesicular glassy lava rock of Basaltic to Andesitic composition (40 - 60 % SiO2) ejected from a volcanic vent during explosive eruption. The vesicular nature of Scoria is due to the escape of volcanic gases during eruption. Scoria is typically dark gray to black in color, mostly due to its high iron content. It consists of highly vesicular basic material having much higher density than Pumice (Lefond, 1983, Harben, 1995, KiliÇ et al., 2009). The glassy matrix of Scoria fragments and over several million years devitrifies to products, thus the most economically valuable Scoria deposits are late Tertiary or Quaternary in age (Mathers et al., 2000). Volcanic ash (like fly ash), volcanic Pumice and Scoria are pozzolanic materials because of their reaction with lime liberated during the hydration of cement (Jackson, 1983). Amorphous silica present in the pozzzolanic materials combines with lime and forms cementitious materials. These materials can also improve the durability of concrete and the rate of gain in strength and can reduce the rate of liberation of heat that is beneficial for mass concrete (Hossain, 2003). Lightweight concrete made with Pumice and pozzolanic cement with volcanic ash/lime have survived more than 2000 years and provides an example of low strength concrete with a very long term performance, (Rivera and Cabrera, 1999). Along the last several decades numerous studies have been carried out on the use of volcanic ash, Pumice, Scoria, fly ash and other natural materials as cement replacement material, such as (Hossain, 2004, 2006, 2007), (Hossain, et al., 2010), (Yasar et al., 2003), (Aydin and Gul, 2006) and (Siddique, 2012). In Yemen, many geological studies have described the nationwide volcanic fields and volcanic deposits, but only few of them have described Pumice as a construction material and assessed it for manufacturing lightweight concrete and thermal insulators. Moreover, no studies for assessing Pumice and Scoria deposits as a pozzolanic materials have been performed. Schulze, 1978, reconnaissanced the Pumice and pumicite deposits in Dhamar - Rada’ area, and GEOMIN, 1985, studied construction and industrial rocks in Y.A.R. Al-Razihi et al., 2000, described volcanic glass in Yemen, furthermore in 2009, Al-Sabri studied the geology and economic potentiality of Scoria deposits in Dhamar-Rada’ volcanic field. He suggested that the Scoria deposits are suitable as a lightweight aggregate, and cement additive. The aim of this study is to assess the Pumice and Scoria deposits in Dhamar - Rada’ volcanic field as pozzolanic materials and lightweight aggregates for producing lightweight concrete and insulation concrete. 387 IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 2 Issue 9, September 2015. www.ijiset.com ISSN 2348 – 7968 Geological investigation Volcanic rocks within the Arabian plate take place throughout the western Arabian peninsula over a south - to - north distance of 3000 km, from Yemen through Saudi Arabia ,Jordan and Syria ( Al-Sabry, 2009 ), together they are one of the world’s largest alkali volcanic provinces , with approximate area of 180,000 Km² (Mattash, 1994). The Cenozoic-Quaternary volcanic rocks of Yemen previously divided into an older “Trap” series and younger “Volcanic “ series (Beydoun et al., 1998) .The Yemen “Trap” series outcrops over a large area of western Yemen on the high plateau to the east of the Red sea with smaller northern area south of Sa`dah center, with total area of 50,000 Km² (Mattash, 1994). The Yemen volcanic series cover a total area of about 9,000 Km² in more restricted and disconnected occurrences on high plateau above the Yemen Trap series, in Marib graben and sporadically, along the Gulf of Aden from Bab Al-Mandab in the west at the entrance of Red sea to Bir Ali area SW of Mukalla, and then again